From 417ef03e41febfef3fca9691a4edaa29808adb9a Mon Sep 17 00:00:00 2001
From: John Breaux <j@soft.fish>
Date: Tue, 5 Sep 2023 01:54:50 -0500
Subject: [PATCH] 0.2.0: Feature update and Refactor - Each major module
 (lexer, parser, assembler) has its own error type   - These error types are
 somewhat interconnected, but their     dependency relationships are one-way
 and well defined - The AST is no longer responsible for assembling itself   -
 The Assembler (assembler::Assembler) will now visit every AST node     and
 accumulate words   - Words are assumed to be little-endian. - There are now a
 set of assembler directives that affect the   generated output:   - .word
 <Number>: inserts a single word in the output   - .words [<Number>,*]:
 inserts multiple words in the output   - .byte <Number>: Alias for .word   -
 .bytes [<Number>,*]: Alias for .words   - .string "String": inserts a
 null-terminated UTF-8 encoded string   - .strings ["String",*]: "" multiple
 strings   - Data is always word-aligned at the moment. - There are now
 assembler directives that affect the AST during   parsing:   - .include
 "path/to/file": Parses the contents of a file directly     into the AST     -
 Included files have their own defines, but *share* labels.       This is
 because .defines are a tokenizer construct, and       including a file
 creates a new buffer and tokenizer.     - Circular includes are NOT checked
 for at the moment.       It is very easy to exhaust the stack. - General
 cleanup of several functions, comments, TODOs, etc. - main.rs was moved to
 make room for upcoming improvements to the UI

TODO:
- REPL mode is only partially compatible with .define directive
- Branching to a label will branch to the data AT the label,
  not the label itself. I doubt this is correct behavior.
  - In case br <label> is meant to use the absolute address,
    I've created a .org directive (currently unimplemented)
    for specifying the load address of the program.
---
 Cargo.toml                                    |   2 +-
 src/assembler.rs                              | 197 +++++++++++
 src/assembler/error.rs                        |  56 ++++
 src/bin/msp430-asm/main.rs                    |  61 ++++
 src/error.rs                                  | 130 ++------
 src/hash.rs                                   |  19 +-
 src/lexer.rs                                  |  23 +-
 src/lexer/error.rs                            |  68 ++++
 src/lexer/ignore.rs                           |   4 +-
 src/lexer/preprocessed.rs                     |  36 ++-
 src/lexer/token.rs                            |  30 +-
 src/lexer/token_stream.rs                     |  26 +-
 src/lib.rs                                    |  11 +-
 src/linker.rs                                 |  20 --
 src/main.rs                                   |  42 ---
 src/parser.rs                                 | 186 ++---------
 src/parser/comment.rs                         |   5 +-
 src/parser/directive.rs                       |  90 +++++-
 src/parser/error.rs                           |  74 +++++
 src/parser/identifier.rs                      |  23 +-
 src/parser/instruction.rs                     |  20 +-
 src/parser/instruction/encoding.rs            |  18 +-
 src/parser/instruction/encoding/builder.rs    |   8 +-
 .../instruction/encoding/encoding_parser.rs   |  30 +-
 .../instruction/encoding/jump_target.rs       |  51 ++-
 src/parser/instruction/encoding/number.rs     |  55 ++--
 .../instruction/encoding/primary_operand.rs   |  60 ++--
 src/parser/instruction/encoding/register.rs   |  19 +-
 .../instruction/encoding/secondary_operand.rs |  26 +-
 src/parser/instruction/encoding/width.rs      |   2 +-
 src/parser/instruction/opcode.rs              | 306 +++++++++---------
 src/parser/label.rs                           |  11 +-
 src/parser/line.rs                            |  72 +++++
 src/parser/parsable.rs                        |  54 +++-
 src/parser/root.rs                            |  51 +++
 valid.asm                                     |  12 +-
 36 files changed, 1160 insertions(+), 738 deletions(-)
 create mode 100644 src/assembler.rs
 create mode 100644 src/assembler/error.rs
 create mode 100644 src/bin/msp430-asm/main.rs
 create mode 100644 src/lexer/error.rs
 delete mode 100644 src/linker.rs
 delete mode 100644 src/main.rs
 create mode 100644 src/parser/error.rs
 create mode 100644 src/parser/line.rs
 create mode 100644 src/parser/root.rs

diff --git a/Cargo.toml b/Cargo.toml
index 81a52c6..c8246e4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "msp430-asm"
-version = "0.1.0"
+version = "0.2.0"
 edition = "2021"
 authors = ["John Breaux"]
 publish = false
diff --git a/src/assembler.rs b/src/assembler.rs
new file mode 100644
index 0000000..e9273b9
--- /dev/null
+++ b/src/assembler.rs
@@ -0,0 +1,197 @@
+// © 2023 John Breaux
+//! Traverses an AST, assembling instructions.
+//!
+//! [Assembler] carries *some* state
+
+use crate::parser::preamble::*;
+use error::AssemblyError;
+use std::collections::HashMap;
+use std::path::Path;
+
+pub mod error;
+
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum IdentType {
+    Word,
+    Jump,
+}
+
+/// Takes in an AST's [Root], and outputs a sequence of bytes
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
+pub struct Assembler {
+    out: Vec<u16>,
+    /// A map from Labels' [Identifier]s to their location in the binary
+    labels: HashMap<Identifier, usize>,
+    /// A list of all referenced [Identifier]s in the binary, and their locations
+    identifiers: Vec<(usize, Identifier, IdentType)>,
+}
+
+impl Assembler {
+    pub fn assemble(r: &Root) -> Result<Vec<u16>, AssemblyError> {
+        let mut out = Self::default();
+        out.visit_root(r)?;
+        Ok(out.out)
+    }
+    pub fn load(&mut self, r: &Root) -> Result<(), AssemblyError> { self.visit_root(r) }
+    pub fn out(self) -> Vec<u16> { self.out }
+    
+    fn last_mut(&mut self) -> Result<&mut u16, AssemblyError> { self.out.last_mut().ok_or(AssemblyError::EmptyBuffer) }
+    fn push_default(&mut self) -> usize {
+        self.out.push(Default::default());
+        self.out.len() - 1
+    }
+}
+
+impl Assembler {
+    /// Visits the [Root] node of a parse tree
+    fn visit_root(&mut self, r: &Root) -> Result<(), AssemblyError> {
+        // Visit the entire tree
+        for (num, line) in r.lines() {
+            self.visit_line(line).map_err(|e| e.ctx(r.file().unwrap_or(Path::new("stdin")), *num))?;
+        }
+        // Link identifiers
+        for (idx, id, id_type) in self.identifiers.iter() {
+            let Some(&num) = self.labels.get(id) else { return Err(AssemblyError::UnresolvedIdentifier(id.clone())) };
+            let offset = (num as isize - *idx as isize) * 2;
+            *self.out.get_mut(*idx).expect("idx should be a valid index into out") |= match id_type {
+                IdentType::Word => offset as u16,
+                IdentType::Jump => JumpTarget::squish(offset)?,
+            };
+        }
+        Ok(())
+    }
+
+    /// visit a [Line]
+    fn visit_line(&mut self, line: &Line) -> Result<(), AssemblyError> {
+        match line {
+            Line::Insn(insn) => self.visit_instruction(insn),
+            Line::Label(label) => self.visit_label(label),
+            Line::Directive(d) => self.visit_directive(d),
+            _ => Ok(()),
+        }
+    }
+
+    /// Visits a [Directive]
+    fn visit_directive(&mut self, node: &Directive) -> Result<(), AssemblyError> {
+        match node {
+            Directive::Org(_) => todo!("{node}"),
+            Directive::Define(..) => (),
+            Directive::Include(r) => self.visit_root(r)?,
+            Directive::Byte(word) | Directive::Word(word) => self.out.push((*word).into()),
+            Directive::Bytes(words) | Directive::Words(words) => {
+                for word in words {
+                    self.out.push((*word).into());
+                }
+            }
+            Directive::String(s) => self.visit_string(s)?,
+            Directive::Strings(strs) => {
+                for s in strs {
+                    self.visit_string(s)?;
+                }
+            }
+        };
+        Ok(())
+    }
+
+    /// Visits a [Label]
+    fn visit_label(&mut self, node: &Label) -> Result<(), AssemblyError> {
+        // Register the label
+        match self.labels.insert(node.0.to_owned(), self.out.len()) {
+            Some(_) => Err(AssemblyError::RedefinedLabel(node.0.to_owned())),
+            _ => Ok(()),
+        }
+    }
+
+    /// Visits an [Instruction]
+    fn visit_instruction(&mut self, insn: &Instruction) -> Result<(), AssemblyError> {
+        self.push_default();
+        self.visit_opcode(insn.opcode())?;
+        self.visit_encoding(insn.encoding())?;
+        Ok(())
+    }
+
+    /// Visits an [Opcode]
+    fn visit_opcode(&mut self, node: &Opcode) -> Result<(), AssemblyError> {
+        *self.last_mut()? |= *node as u16;
+        Ok(())
+    }
+
+    /// Visits an [Encoding]
+    fn visit_encoding(&mut self, node: &Encoding) -> Result<(), AssemblyError> {
+        *self.last_mut()? |= node.word();
+        match node {
+            Encoding::Single { dst, .. } => {
+                self.visit_primary_operand(dst)?;
+            }
+            Encoding::Jump { target } => {
+                self.visit_jump_target(target)?;
+            }
+            Encoding::Double { src, dst, .. } => {
+                self.visit_primary_operand(src)?;
+                self.visit_secondary_operand(dst)?;
+            }
+        }
+        Ok(())
+    }
+
+    /// Visits a [JumpTarget]
+    fn visit_jump_target(&mut self, node: &JumpTarget) -> Result<(), AssemblyError> {
+        match node {
+            JumpTarget::Number(num) => self.visit_number(num),
+            JumpTarget::Identifier(id) => {
+                self.visit_identifier(id, self.out.len() - 1, IdentType::Jump)?;
+                Ok(())
+            }
+        }
+    }
+
+    /// Visits a [SecondaryOperand]
+    fn visit_secondary_operand(&mut self, node: &SecondaryOperand) -> Result<(), AssemblyError> {
+        use SecondaryOperand as O;
+        if let O::Indexed(_, num) | O::Absolute(num) = node {
+            self.push_default();
+            self.visit_number(num)?;
+        }
+        Ok(())
+    }
+
+    /// Visits a [PrimaryOperand]
+    fn visit_primary_operand(&mut self, node: &PrimaryOperand) -> Result<(), AssemblyError> {
+        use PrimaryOperand as O;
+        match node {
+            O::Indexed(_, num) | O::Absolute(num) | O::Immediate(num) => {
+                self.push_default();
+                self.visit_number(num)?;
+            }
+            O::Relative(id) => {
+                let addr = self.push_default();
+                self.visit_identifier(id, addr, IdentType::Word)?;
+            }
+            _ => (),
+        }
+        Ok(())
+    }
+
+    /// Visits a number and writes it into the last index
+    fn visit_number(&mut self, node: &Number) -> Result<(), AssemblyError> {
+        *self.last_mut()? |= u16::from(*node);
+        Ok(())
+    }
+
+    /// Visits a number and appends it to the output buffer
+    fn visit_string(&mut self, node: &str) -> Result<(), AssemblyError> {
+        for (idx, byte) in node.bytes().chain([0u8].into_iter()).enumerate() {
+            if idx % 2 == 0 {
+                self.push_default();
+            }
+            *self.last_mut()? |= (byte as u16) << (8 * (idx % 2));
+        }
+        Ok(())
+    }
+
+    /// Visits an [Identifier], and registers it to the identifier list
+    fn visit_identifier(&mut self, node: &Identifier, addr: usize, ty: IdentType) -> Result<(), AssemblyError> {
+        self.identifiers.push((addr, node.clone(), ty));
+        Ok(())
+    }
+}
diff --git a/src/assembler/error.rs b/src/assembler/error.rs
new file mode 100644
index 0000000..08c4a34
--- /dev/null
+++ b/src/assembler/error.rs
@@ -0,0 +1,56 @@
+// © 2023 John Breauxs
+use crate::parser::{error::ParseError, preamble::*};
+use std::{
+    fmt::Display,
+    path::{Path, PathBuf},
+};
+
+#[derive(Debug)]
+pub enum AssemblyError {
+    UnresolvedIdentifier(Identifier),
+    RedefinedLabel(Identifier),
+    JumpedTooFar(Identifier, isize),
+    ParseError(ParseError),
+    // TODO: This, better'
+    Context(Box<AssemblyError>, PathBuf, usize),
+    EmptyBuffer,
+}
+
+impl AssemblyError {
+    pub(super) fn ctx<P: AsRef<Path> + ?Sized>(self, file: &P, line: usize) -> Self {
+        Self::Context(self.into(), file.as_ref().into(), line)
+    }
+}
+
+impl From<ParseError> for AssemblyError {
+    fn from(value: ParseError) -> Self { Self::ParseError(value) }
+}
+
+impl Display for AssemblyError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::UnresolvedIdentifier(id) => {
+                write!(f, "Identifier {id} is undefined, but referenced anyway.")
+            }
+            Self::RedefinedLabel(id) => {
+                write!(f, "Redefined label '{id}'.")
+            }
+            Self::JumpedTooFar(id, num) => {
+                write!(f, "Label '{id}' is too far away. ({num} is outside range -0x400..=0x3fe)")
+            }
+            Self::ParseError(e) => Display::fmt(e, f),
+            Self::Context(e, file, line) => write!(f, "{}:{line}:\n\t{e}", file.display()),
+            Self::EmptyBuffer => Display::fmt("Tried to get last element of output buffer, but buffer was empty", f),
+        }
+    }
+}
+
+impl std::error::Error for AssemblyError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::ParseError(e) => Some(e),
+            Self::Context(e, ..) => Some(e),
+            _ => None,
+        }
+    }
+}
diff --git a/src/bin/msp430-asm/main.rs b/src/bin/msp430-asm/main.rs
new file mode 100644
index 0000000..cf1f111
--- /dev/null
+++ b/src/bin/msp430-asm/main.rs
@@ -0,0 +1,61 @@
+//! Simple frontend for the assembler
+
+use msp430_asm::preamble::*;
+use std::error::Error;
+use std::io::Read;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut repl = true;
+    for arg in std::env::args() {
+        match arg.as_str() {
+            "-" | "-f" | "--file" => repl = false,
+            _ => (),
+        }
+    }
+
+    let mut buf = String::new();
+    if repl {
+        let mut line = String::new();
+        while let Ok(len) = std::io::stdin().read_line(&mut line) {
+            match len {
+                0 => break,    // No newline (reached EOF)
+                1 => continue, // Line is empty
+                _ => {
+                    // Try to parse this line in isolation (this restricts preprocessing)
+                    match Parser::default().parse(&line) {
+                        Ok(_) => {
+                            buf += &line;
+                        }
+                        Err(error) => println!("{error}"),
+                    }
+                    line.clear();
+                }
+            }
+        }
+        match Assembler::assemble(&Parser::default().parse(&buf)?) {
+            Err(error) => println!("{error}"),
+            Ok(out) => {
+                for word in out {
+                    print!("{:04x} ", word.swap_bytes())
+                }
+            }
+        }
+
+        println!();
+    } else {
+        std::io::stdin().lock().read_to_string(&mut buf)?;
+        let tree = Parser::default().parse(&buf);
+        match &tree {
+            Ok(tree) => {
+                //msp430_asm::linker::Printer::default().visit_root(tree);
+                for insn in msp430_asm::assembler::Assembler::assemble(tree)? {
+                    print!("{:04x} ", insn.swap_bytes())
+                }
+                println!();
+            }
+            Err(error) => eprintln!("{error}"),
+        }
+    }
+
+    Ok(())
+}
diff --git a/src/error.rs b/src/error.rs
index a024e8d..c6b46ee 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,126 +1,39 @@
 // © 2023 John Breauxs
 //! Common error type for [msp430-asm](crate) errors
 
+use super::*;
 use std::fmt::Display;
 
-use super::{
-    lexer::token::{OwnedToken, Types},
-    *,
-};
-
-// TODO: Store more error context in error. for example:
-// Error {ExpectationFailed{...}, WhileParsing(Register)}
-
 #[derive(Debug)]
 pub enum Error {
-    /// Produced by [Parser](crate::parser::Parser::parse<T>())
-    ParseError(parser::root::Root, Box<dyn std::error::Error + 'static>),
-    /// Any other error, tagged with [Context]. Created by [`Error::context()`]
-    Contextual(Context, Box<Self>),
-    /// Produced by [Token] when the input is entirely unexpected.
-    UnexpectedSymbol(String),
-    /// Produced by [`TokenStream::expect`] when the next [Token] isn't the expected [Type]
-    UnexpectedToken {
-        expected: Type,
-        got: OwnedToken,
-    },
-    /// Produced by [`TokenStream::expect_any_of`] when the next [Token] isn't any of the expected
-    /// [Types](Type)
-    AllExpectationsFailed {
-        expected: Types,
-        got: OwnedToken,
-    },
-    /// Produced by
-    /// [Number](parser::preamble::Number)[::parse()](parser::parsable::Parsable::parse())
-    /// when the parsed number contains digits too high for the specified radix
-    UnexpectedDigits(String, u32),
-    /// Produced by
-    /// [Opcode](parser::preamble::Opcode)[::parse()](parser::parsable::Parsable::parse())
-    /// when the opcode passed lexing but did not match recognized opcodes.
-    ///
-    /// This should be interpreted as a failure in lexing.
-    UnrecognizedOpcode(String),
-    /// Produced by [Register](parser::preamble::Register)
-    /// when attempting to convert from a [str] that isn't a register (pc, sp, sr, cg, or r{number})
-    NotARegister(String),
-    /// Produced by [Register](parser::preamble::Register)
-    /// when attempting to convert from a [u16] that isn't in the range 0-15
-    RegisterTooHigh(u16),
-    /// Produced by
-    /// [SecondaryOperand](parser::preamble::SecondaryOperand)
-    /// when the joke "secondary immediate" form is out of range 0..=1
-    FatSecondaryImmediate(isize),
-    /// Produced by [Number](parser::preamble::Number) when the number is too
-    /// wide to fit in 16 bits (outside the range `(-2^15) .. (2^16-1)` )
-    NumberTooWide(isize),
-    /// Produced by [JumpTarget](parser::preamble::JumpTarget)
-    /// when the jump offset is outside the range (-0x3ff..0x3fc)
-    JumpedTooFar(isize),
-    /// Produced by [JumpTarget](parser::preamble::JumpTarget)
-    JumpedOdd(isize),
-    EndOfFile,
+    /// Produced by [lexer]
+    LexError(lexer::error::LexError),
+    /// Produced by [parser]
+    ParseError(parser::error::ParseError),
+    /// Produced by [assembler]
+    AssemblyError(assembler::error::AssemblyError),
 }
 
-impl Error {
-    pub fn context(self, c: Context) -> Self {
-        match self {
-            Self::Contextual(..) => self,
-            _ => Self::Contextual(c, Box::new(self)),
-        }
-    }
+impl Error {}
 
-    // Extracts the root of the error tree
-    pub fn bare(self) -> Self {
-        match self {
-            Self::Contextual(_, bare) => bare.bare(),
-            _ => self,
-        }
-    }
+impl From<lexer::error::LexError> for Error {
+    fn from(value: lexer::error::LexError) -> Self { Self::LexError(value) }
+}
 
-    pub fn swap(mut self, other: Self) -> Self {
-        if let Self::Contextual(_, err) = &mut self {
-            _ = std::mem::replace(err.as_mut(), other)
-        }
-        self
-    }
+impl From<parser::error::ParseError> for Error {
+    fn from(value: parser::error::ParseError) -> Self { Self::ParseError(value) }
+}
 
-    pub fn expected<E: AsRef<[Type]>, T: Into<OwnedToken>>(expected: E, got: T) -> Self {
-        match expected.as_ref().len() {
-            1 => Self::UnexpectedToken { expected: expected.as_ref()[0], got: got.into() },
-            _ => Self::AllExpectationsFailed { expected: expected.as_ref().into(), got: got.into() },
-        }
-    }
-
-    pub fn mask_expectation(mut self, expected: Type) -> Self {
-        match self {
-            Error::UnexpectedToken { got, .. } => self = Error::UnexpectedToken { expected, got },
-            Error::AllExpectationsFailed { got, .. } => self = Error::UnexpectedToken { expected, got },
-            Error::Contextual(context, err) => {
-                self = Error::Contextual(context, Box::new(err.mask_expectation(expected)))
-            }
-            _ => (),
-        }
-        self
-    }
+impl From<assembler::error::AssemblyError> for Error {
+    fn from(value: assembler::error::AssemblyError) -> Self { Self::AssemblyError(value) }
 }
 
 impl Display for Error {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Error::Contextual(ctx, error) => write!(f, "{ctx}: {error}"),
-            Error::ParseError(_, error) => write!(f, "{error}"),
-            Error::UnexpectedSymbol(sym) => write!(f, "Unexpected item in bagging area: \"{sym}\""),
-            Error::UnexpectedToken { expected, got } => write!(f, "Expected {expected}, got {got}."),
-            Error::AllExpectationsFailed { expected, got } => write!(f, "Expected {expected}, got {got}."),
-            Error::UnexpectedDigits(number, radix) => write!(f, "Number `{number}` is not base {radix}."),
-            Error::UnrecognizedOpcode(op) => write!(f, "{op} is not an opcode"),
-            Error::NotARegister(reg) => write!(f, "{reg} is not a register"),
-            Error::RegisterTooHigh(reg) => write!(f, "r{reg} is not a register"),
-            Error::FatSecondaryImmediate(num) => write!(f, "Secondary immediate must be #0 or #1, not #{num}"),
-            Error::NumberTooWide(num) => write!(f, "{num} does not fit in 16 bits"),
-            Error::JumpedTooFar(num) => write!(f, "{num} is too far away: must be in range (`-1022..=1024`.)"),
-            Error::JumpedOdd(num) => write!(f, "Jump targets only encode even numbers: {num} must not be odd."),
-            Error::EndOfFile => write!(f, "Unexpected end of file"),
+            Error::LexError(e) => Display::fmt(e, f),
+            Error::ParseError(e) => Display::fmt(e, f),
+            Error::AssemblyError(e) => Display::fmt(e, f),
         }
     }
 }
@@ -128,8 +41,9 @@ impl Display for Error {
 impl std::error::Error for Error {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match self {
-            Error::ParseError(_, e) => Some(e.as_ref()),
-            _ => None,
+            Error::LexError(e) => Some(e),
+            Error::ParseError(e) => Some(e),
+            Error::AssemblyError(e) => Some(e),
         }
     }
 }
diff --git a/src/hash.rs b/src/hash.rs
index 2ca7dce..2c0dcdd 100644
--- a/src/hash.rs
+++ b/src/hash.rs
@@ -1,14 +1,19 @@
 // © 2023 John Breaux
 //! Convenience functions and traits for dealing with hashable data
 pub type Hash = u64;
+
+/// Calculates a hash using Rust hashmap's default hasher.
+pub fn hash<T: std::hash::Hash>(hashable: T) -> Hash {
+    use std::hash::Hasher;
+    let mut hasher = std::collections::hash_map::DefaultHasher::new();
+    hashable.hash(&mut hasher);
+    hasher.finish()
+}
+
 pub trait FromHash: From<Hash> {
-    /// Hashes anything that implements [type@Hash] using the [DefaultHasher](std::collections::hash_map::DefaultHasher)
-    fn hash<T: std::hash::Hash>(hashable: T) -> Hash {
-        use std::hash::Hasher;
-        let mut hasher = std::collections::hash_map::DefaultHasher::new();
-        hashable.hash(&mut hasher);
-        hasher.finish()
-    }
+    /// Hashes anything that implements [type@Hash] using the
+    /// [DefaultHasher](std::collections::hash_map::DefaultHasher)
+    fn hash<T: std::hash::Hash>(hashable: T) -> Hash { hash(hashable) }
     fn from_hash<T: std::hash::Hash>(hashable: T) -> Self
     where Self: Sized {
         Self::from(Self::hash(hashable))
diff --git a/src/lexer.rs b/src/lexer.rs
index 568f272..318b833 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -1,28 +1,15 @@
 // © 2023 John Breaux
 //! Iterates over [`&str`](str), producing [`Token`s](Token)
 
-// Things we need:
-// ✔ 1. Lexer/Tokenizer
-// ✔     1. Instructions
-// ✔         1. Instruction mnemonics /ad.../
-// ✔         2. Byte/Word Mode Marker /(.\[bw\])?/
-// ✔     2. Operands
-// ✔         1. Registers /(r1[0-5]|r[0-9])/
-// ✔         2. Immediate Values /#/
-// ✔         3. Absolute addresses /&/
-// ✔         4. Numbers /[0-9A-Fa-f]+
-// ✔         5. Jump Offsets: basically numbers /$?([+-]?[0-9A-Fa-f]{1,4})/
-// ✔     3. Label definitions /(^.*):/
-// ✔     4. Comments (may be useful for debugging)
-
 pub mod context;
+pub mod error;
 pub mod ignore;
 pub mod preprocessed;
 pub mod token;
 pub mod token_stream;
 
-use crate::Error;
 use context::Context;
+use error::LexError;
 use token::{Token, Type};
 use token_stream::TokenStream;
 
@@ -70,13 +57,13 @@ impl<'text> TokenStream<'text> for Tokenizer<'text> {
     // Tokenizer has access to the source buffer, and can implement expect and peek without cloning
     // itself. This can go wrong, of course, if an [Identifier] is expected, since all instructions and
     // registers are valid identifiers.
-    fn expect(&mut self, expected: Type) -> Result<Self::Item, Error> {
+    fn expect(&mut self, expected: Type) -> Result<Self::Item, LexError> {
         let token = Token::expect(&self.text[self.idx..], expected).map_err(|e| e.context(self.context()))?;
         self.count(&token);
         Ok(token)
     }
     fn peek(&mut self) -> Self::Item { Token::from(&self.text[self.idx..]) }
-    fn peek_expect(&mut self, expected: Type) -> Result<Self::Item, Error> {
-        Token::expect(&self.text[self.idx..], expected)
+    fn peek_expect(&mut self, expected: Type) -> Result<Self::Item, LexError> {
+        Token::expect(&self.text[self.idx..], expected).map_err(|e| e.context(self.context()))
     }
 }
diff --git a/src/lexer/error.rs b/src/lexer/error.rs
new file mode 100644
index 0000000..652dcf2
--- /dev/null
+++ b/src/lexer/error.rs
@@ -0,0 +1,68 @@
+// © 2023 John Breauxs
+use super::{
+    context::Context,
+    token::{OwnedToken, *},
+};
+use std::fmt::Display;
+
+#[derive(Debug)]
+pub enum LexError {
+    /// Any other error, tagged with [Context]. Created by [`Error::context()`]
+    Contextual(Context, Box<Self>),
+    /// Produced by [Token] when the input is entirely unexpected.
+    UnexpectedSymbol(String),
+    /// Produced by [`TokenStream::expect`] when the next [Token] isn't the expected [Type]
+    UnexpectedToken { expected: Type, got: OwnedToken },
+    /// Produced by [`TokenStream::expect_any_of`] when the next [Token] isn't any of the
+    /// expected [Types](Type)
+    AllExpectationsFailed { expected: Types, got: OwnedToken },
+}
+
+impl LexError {
+    pub fn context(self, c: Context) -> Self {
+        match self {
+            Self::Contextual(..) => self,
+            _ => Self::Contextual(c, Box::new(self)),
+        }
+    }
+
+    // Extracts the root of the error tree
+    pub fn bare(self) -> Self {
+        match self {
+            Self::Contextual(_, bare) => bare.bare(),
+            _ => self,
+        }
+    }
+
+    pub fn expected<E: AsRef<[Type]>, T: Into<OwnedToken>>(expected: E, got: T) -> Self {
+        match expected.as_ref().len() {
+            1 => Self::UnexpectedToken { expected: expected.as_ref()[0], got: got.into() },
+            _ => Self::AllExpectationsFailed { expected: expected.as_ref().into(), got: got.into() },
+        }
+    }
+
+    pub fn mask_expectation(mut self, expected: Type) -> Self {
+        match self {
+            LexError::UnexpectedToken { got, .. } => self = LexError::UnexpectedToken { expected, got },
+            LexError::AllExpectationsFailed { got, .. } => self = LexError::UnexpectedToken { expected, got },
+            LexError::Contextual(context, err) => {
+                self = LexError::Contextual(context, Box::new(err.mask_expectation(expected)))
+            }
+            _ => (),
+        }
+        self
+    }
+}
+
+impl Display for LexError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            LexError::Contextual(ctx, error) => write!(f, "{ctx}: {error}"),
+            LexError::UnexpectedSymbol(sym) => write!(f, "Unexpected item in bagging area: \"{sym}\""),
+            LexError::UnexpectedToken { expected, got } => write!(f, "Expected {expected}, got {got}."),
+            LexError::AllExpectationsFailed { expected, got } => write!(f, "Expected {expected}, got {got}."),
+        }
+    }
+}
+
+impl std::error::Error for LexError {}
diff --git a/src/lexer/ignore.rs b/src/lexer/ignore.rs
index f9b4eb7..a9f89b5 100644
--- a/src/lexer/ignore.rs
+++ b/src/lexer/ignore.rs
@@ -38,7 +38,7 @@ impl<'t, T> TokenStream<'t> for Ignore<'t, T>
 where T: TokenStream<'t>
 {
     fn context(&self) -> Context { self.inner.context() }
-    fn expect(&mut self, expected: Type) -> Result<Self::Item, Error> {
+    fn expect(&mut self, expected: Type) -> Result<Self::Item, LexError> {
         self.inner.allow(self.ignore);
         self.inner.expect(expected)
     }
@@ -48,7 +48,7 @@ where T: TokenStream<'t>
         self.inner.peek()
     }
 
-    fn peek_expect(&mut self, expected: Type) -> Result<Self::Item, Error> {
+    fn peek_expect(&mut self, expected: Type) -> Result<Self::Item, LexError> {
         self.inner.allow(self.ignore);
         self.inner.peek_expect(expected)
     }
diff --git a/src/lexer/preprocessed.rs b/src/lexer/preprocessed.rs
index d97ec96..4d4ab2e 100644
--- a/src/lexer/preprocessed.rs
+++ b/src/lexer/preprocessed.rs
@@ -1,6 +1,6 @@
 // © 2023 John Breaux
-//! Preprocesses a [`TokenStream`], substituting tokens for earlier tokens based on in-band ".define"
-//! rules
+//! Preprocesses a [`TokenStream`], substituting tokens for earlier tokens based on in-band
+//! ".define" rules
 use super::*;
 use std::collections::{HashMap, VecDeque};
 
@@ -47,21 +47,27 @@ impl<'t, T: TokenStream<'t>> Preprocessed<'t, T> {
     /// Gets a mutable reference to the inner [TokenStream]
     pub fn inner_mut(&mut self) -> &mut T { self.inner }
 
-    fn define(&mut self, token: Token<'t>) -> Result<(), Error> {
+    /// Preserve the next token in the queue
+    fn enqueue(&mut self, token: Token<'t>) -> Token<'t> {
+        self.queue.push_back(token);
+        token
+    }
+
+    /// Process .define directives in the preprocessor
+    fn define(&mut self, token: Token<'t>) -> Result<(), LexError> {
         if !(token.is_variant(Type::Directive) && token.lexeme().starts_with(".define")) {
             return Ok(());
         }
         // Tokenize the subdocument
         self.allow(Type::Directive);
-
-        self.require(Type::Space).map_err(|e| e.context(self.context()))?;
+        self.allow(Type::Space);
 
         let Some(k) = self.inner.next() else { return Ok(()) };
         if !self.sub_types.contains(&k.variant()) {
             self.sub_types.push(k.variant());
         };
 
-        self.require(Type::Space).map_err(|e| e.context(self.context()))?;
+        self.allow(Type::Space);
 
         let mut replacement = vec![];
         loop {
@@ -71,7 +77,10 @@ impl<'t, T: TokenStream<'t>> Preprocessed<'t, T> {
                     // ignore comments
                     self.inner.next();
                 }
-                _ => replacement.push(self.inner.next().unwrap()),
+                _ => {
+                    let next = self.inner.next().unwrap();
+                    replacement.push(self.enqueue(next));
+                }
             }
         }
         self.sub_table.insert(k, replacement);
@@ -92,10 +101,10 @@ where T: TokenStream<'t>
 {
     fn context(&self) -> Context { self.inner.context() }
 
-    fn expect(&mut self, expected: Type) -> Result<Self::Item, Error> {
+    fn expect(&mut self, expected: Type) -> Result<Self::Item, LexError> {
         match self.queue.front() {
             Some(&token) if token.is_variant(expected) => Ok(self.queue.pop_front().unwrap_or_default()),
-            Some(&token) => Err(Error::expected([expected], token).context(self.context())),
+            Some(&token) => Err(LexError::expected([expected], token).context(self.context())),
             None => {
                 // Only resolve defines when expecting, otherwise you'll run into issues.
                 if let Ok(next) = self.inner.expect(expected) {
@@ -109,10 +118,9 @@ where T: TokenStream<'t>
                     }
                     return if self.queue.is_empty() { self.inner.expect(expected) } else { self.expect(expected) };
                 }
-                Err(Error::expected([expected], self.inner.peek()))
+                Err(LexError::expected([expected], self.inner.peek()).context(self.context()))
             }
         }
-        // TODO: preprocessor step
     }
 
     fn peek(&mut self) -> Self::Item {
@@ -130,10 +138,10 @@ where T: TokenStream<'t>
         }
     }
 
-    fn peek_expect(&mut self, expected: Type) -> Result<Self::Item, Error> {
+    fn peek_expect(&mut self, expected: Type) -> Result<Self::Item, LexError> {
         match self.queue.front() {
             Some(&token) if token.is_variant(expected) => Ok(token),
-            Some(&token) => Err(Error::expected([expected], token).context(self.context())),
+            Some(&token) => Err(LexError::expected([expected], token).context(self.context())),
             None => {
                 if let Ok(next) = self.inner.peek_expect(expected) {
                     return Ok(next);
@@ -146,7 +154,7 @@ where T: TokenStream<'t>
                         self.peek_expect(expected)
                     };
                 }
-                Err(Error::expected([expected], self.inner.peek()))
+                Err(LexError::expected([expected], self.inner.peek()))
             }
         }
     }
diff --git a/src/lexer/token.rs b/src/lexer/token.rs
index 60934b4..f3e2dbe 100644
--- a/src/lexer/token.rs
+++ b/src/lexer/token.rs
@@ -1,7 +1,9 @@
 // © 2023 John Breaux
-//! A [Token] is a [semantically tagged](Type) sequence of characters
+//! A [Token] is a [semantically tagged](Type) sequence of characters.
+//!
+//! Token, and the tokenizer, intend to copy as little as possible.
 
-use crate::Error;
+use super::error::LexError;
 use regex::Regex;
 use std::{
     fmt::{Debug, Display},
@@ -21,10 +23,10 @@ impl<$t> $type {
     /// Lexes a token only for the expected `variant`
     ///
     /// Warning: This bypasses precedence rules. Only use for specific patterns.
-    pub fn expect(text: &$t str, expected: Type) -> Result<Self, Error> {
+    pub fn expect(text: &$t str, expected: Type) -> Result<Self, LexError> {
         match expected {$(
             $out => Self::$func(text),
-        )*}.ok_or(Error::UnexpectedToken {
+        )*}.ok_or(LexError::UnexpectedToken {
             expected,
             got: Self::from(text).into(),
         })
@@ -137,6 +139,10 @@ pub enum Type {
     LParen,
     /// Close-Indexed-Mode marker
     RParen,
+    /// Open Square Bracket
+    LBracket,
+    /// Closed Square Bracket
+    RBracket,
     /// Indirect mode marker
     Indirect,
     /// absolute address marker
@@ -145,6 +151,8 @@ pub enum Type {
     Immediate,
     /// Valid identifier. Identifiers must start with a Latin alphabetic character or underline
     Identifier,
+    /// A string, encased in "quotes"
+    String,
     /// Assembler directive
     Directive,
     /// Separator (comma)
@@ -209,6 +217,12 @@ regex_impl! {<'text> Token<'text> {
     pub fn expect_r_paren(text: &str) -> Option<Self> {
         regex!(Type::RParen = r"^\)")
     }
+    pub fn expect_l_bracket(text: &str) -> Option<Self> {
+        regex!(Type::LBracket = r"^\[")
+    }
+    pub fn expect_r_bracket(text: &str) -> Option<Self> {
+        regex!(Type::RBracket = r"^]")
+    }
     pub fn expect_indrect(text: &str) -> Option<Self> {
         regex!(Type::Indirect = r"^@")
     }
@@ -218,8 +232,11 @@ regex_impl! {<'text> Token<'text> {
     pub fn expect_immediate(text: &str) -> Option<Self> {
         regex!(Type::Immediate = r"^#")
     }
+    pub fn expect_string(text: &str) -> Option<Self> {
+        regex!(Type::String = r#"^"[^"]*""#)
+    }
     pub fn expect_directive(text: &str) -> Option<Self> {
-        regex!(Type::Directive = r"^\.\S+")
+        regex!(Type::Directive = r"^\.\w+")
     }
     pub fn expect_identifier(text: &str) -> Option<Self> {
         regex!(Type::Identifier = r"^[A-Za-z_]\w*")
@@ -255,10 +272,13 @@ impl Display for Type {
             Self::Plus => Display::fmt("plus sign", f),
             Self::LParen => Display::fmt("left parenthesis", f),
             Self::RParen => Display::fmt("right parenthesis", f),
+            Self::LBracket => Display::fmt("left bracket", f),
+            Self::RBracket => Display::fmt("right bracket", f),
             Self::Indirect => Display::fmt("indirect", f),
             Self::Absolute => Display::fmt("absolute", f),
             Self::Immediate => Display::fmt("immediate", f),
             Self::Identifier => Display::fmt("identifier", f),
+            Self::String => Display::fmt("string", f),
             Self::Directive => Display::fmt("directive", f),
             Self::Separator => Display::fmt("comma", f),
             Self::EndOfFile => Display::fmt("EOF", f),
diff --git a/src/lexer/token_stream.rs b/src/lexer/token_stream.rs
index 1039eee..7fe2df0 100644
--- a/src/lexer/token_stream.rs
+++ b/src/lexer/token_stream.rs
@@ -11,12 +11,14 @@ pub trait TokenStream<'text>: Iterator<Item = Token<'text>> + std::fmt::Debug {
     fn context(&self) -> Context;
 
     /// Creates an iterator that skips [Type::Space] in the input
+    #[inline]
     fn ignore(&'text mut self, variant: Type) -> Ignore<'text, Self>
     where Self: Sized {
         Ignore::new(variant, self)
     }
 
     /// Creates a [TokenStream] that performs live substitution of the input
+    #[inline]
     fn preprocessed(&'text mut self) -> Preprocessed<'text, Self>
     where Self: Sized {
         Preprocessed::new(self)
@@ -26,51 +28,57 @@ pub trait TokenStream<'text>: Iterator<Item = Token<'text>> + std::fmt::Debug {
     fn peek(&mut self) -> Self::Item;
 
     /// Returns the next [Token] if it is of the expected [Type], without advancing
-    fn peek_expect(&mut self, expected: Type) -> Result<Self::Item, Error>;
+    fn peek_expect(&mut self, expected: Type) -> Result<Self::Item, LexError>;
 
     /// Consumes and returns a [Token] if it is the expected [Type]
     ///
     /// Otherwise, does not consume a [Token]
-    fn expect(&mut self, expected: Type) -> Result<Self::Item, Error>;
+    fn expect(&mut self, expected: Type) -> Result<Self::Item, LexError>;
 
     /// Ignores a [Token] of the expected [Type], propegating errors.
-    fn require(&mut self, expected: Type) -> Result<(), Error> { self.expect(expected).map(|_| ()) }
+    #[inline]
+    fn require(&mut self, expected: Type) -> Result<(), LexError> { self.expect(expected).map(|_| ()) }
 
     /// Ignores a [Token] of the expected [Type], discarding errors.
+    #[inline]
     fn allow(&mut self, expected: Type) { let _ = self.expect(expected); }
 
     /// Runs a function on each
-    fn any_of<T, U>(&mut self, f: fn(&mut Self, Type) -> Result<U, Error>, expected: T) -> Result<U, Error>
+    fn any_of<T, U>(&mut self, f: fn(&mut Self, Type) -> Result<U, LexError>, expected: T) -> Result<U, LexError>
     where T: AsRef<[Type]> {
         for &expected in expected.as_ref() {
             match f(self, expected).map_err(|e| e.bare()) {
                 Ok(t) => return Ok(t),
-                Err(Error::UnexpectedToken { .. }) => continue,
+                Err(LexError::UnexpectedToken { .. }) => continue,
                 Err(e) => return Err(e.context(self.context())),
             }
         }
-        Err(Error::expected(expected, self.peek()).context(self.context()))
+        Err(LexError::expected(expected, self.peek()).context(self.context()))
     }
 
     /// Returns the next [Token] if it is of the expected [Types](Type), without advancing
-    fn peek_expect_any_of<T>(&mut self, expected: T) -> Result<Self::Item, Error>
+    #[inline]
+    fn peek_expect_any_of<T>(&mut self, expected: T) -> Result<Self::Item, LexError>
     where T: AsRef<[Type]> {
         self.any_of(Self::peek_expect, expected)
     }
     /// Consumes and returns a [Token] if it matches any of the expected [Types](Type)
     ///
     /// Otherwise, does not consume a [Token]
-    fn expect_any_of<T>(&mut self, expected: T) -> Result<Self::Item, Error>
+    #[inline]
+    fn expect_any_of<T>(&mut self, expected: T) -> Result<Self::Item, LexError>
     where T: AsRef<[Type]> {
         self.any_of(Self::expect, expected)
     }
     /// Ignores a [Token] of any expected [Type], discarding errors.
+    #[inline]
     fn allow_any_of<T>(&mut self, expected: T)
     where T: AsRef<[Type]> {
         let _ = self.expect_any_of(expected);
     }
     /// Ignores a [Token] of any expected [Type], propegating errors.
-    fn require_any_of<T>(&mut self, expected: T) -> Result<(), Error>
+    #[inline]
+    fn require_any_of<T>(&mut self, expected: T) -> Result<(), LexError>
     where T: AsRef<[Type]> {
         self.any_of(Self::require, expected)
     }
diff --git a/src/lib.rs b/src/lib.rs
index 3784dce..e879dd1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -27,6 +27,7 @@
 //! │     └─ Encoding::Single
 //! │        ├─ Width
 //! │        └─ PrimaryOperand
+//! │           ├─ Identifier       // Label, for relative-addressed data/code
 //! │           ├─ Register         // Direct, indexed, indirect or indirect-post-increment register.
 //! │           └─ Number           // Index, absolute address or immediate value.
 //! ├─ Line
@@ -35,9 +36,11 @@
 //! │     └─ Encoding::Double
 //! │        ├─ Width
 //! │        ├─ PrimaryOperand
+//! │           ├─ Identifier       // Label, for relative-addressed data/code
 //! │        │  ├─ Register         // Direct, indexed, indirect or indirect-post-increment register.
 //! │        │  └─ Number           // Index, absolute address or immediate value.
 //! │        └─ SecondaryOperand
+//! │           ├─ Identifier       // Label, for relative-addressed data/code
 //! │           ├─ Register         // Direct or indexed register
 //! │           └─ Number           // Index or absolute address
 //! ├─ Line
@@ -45,6 +48,7 @@
 //! │     ├─ Opcode
 //! │     └─ Encoding::Jump
 //! │        └─ JumpTarget
+//! │           ├─ Identifier       // Label
 //! │           └─ Number           // Even, PC-relative offset in range (-1024..=1022)
 //! └─ Line
 //!    └─ EndOfFile
@@ -53,21 +57,20 @@
 pub mod preamble {
     //! Common imports for msp430-asm
     use super::*;
+    pub use assembler::Assembler;
     pub use error::Error;
-    pub use hash::{FromHash, Hash};
     pub use lexer::{
         context::Context,
         token::{Token, Type},
         token_stream::TokenStream,
         Tokenizer,
     };
-    pub use linker::{Linker, Visitor};
     pub use parser::Parser;
 }
 
 use preamble::*;
 pub mod error;
-pub mod hash;
+
+pub mod assembler;
 pub mod lexer;
-pub mod linker;
 pub mod parser;
diff --git a/src/linker.rs b/src/linker.rs
deleted file mode 100644
index 8dab54c..0000000
--- a/src/linker.rs
+++ /dev/null
@@ -1,20 +0,0 @@
-// © 2023 John Breaux
-/// TODO: tree traversal and label resolution
-use crate::parser::preamble::*;
-pub trait Visitor<T> {
-    // visit_node for all nodes
-    fn visit_register(&mut self, r: &Register) -> T;
-    fn visit_number(&mut self, n: &Number) -> T;
-    fn visit_width(&mut self, w: &Width) -> T;
-    fn visit_primary_operand(&mut self, p: &PrimaryOperand) -> T;
-    fn visit_secondary_operand(&mut self, d: &SecondaryOperand) -> T;
-    fn visit_jump_target(&mut self, t: &JumpTarget) -> T;
-    fn visit_encoding(&mut self, e: &Encoding) -> T;
-    fn visit_opcode(&mut self, o: &Opcode) -> T;
-    fn visit_instruction(&mut self, i: &Instruction) -> T;
-    fn visit_directive(&mut self, d: &Directive) -> T;
-    // the most important one: resolve identifiers
-    fn visit_identifier(&mut self, i: &Identifier) -> T;
-}
-/// TODO: [Linker]
-pub struct Linker;
diff --git a/src/main.rs b/src/main.rs
deleted file mode 100644
index 2a16f8a..0000000
--- a/src/main.rs
+++ /dev/null
@@ -1,42 +0,0 @@
-//! Simple frontend for the assembler
-
-use msp430_asm::preamble::*;
-use std::io::Read;
-
-fn main() -> Result<(), Error> {
-    let mut repl = true;
-    for arg in std::env::args() {
-        match arg.as_str() {
-            "-" | "-f" | "--file" => repl = false,
-            _ => (),
-        }
-    }
-
-    let mut buf = String::new();
-    if repl {
-        while let Ok(len) = std::io::stdin().read_line(&mut buf) {
-            match len {
-                0 => break, // No newline (reached EOF)
-                1 => {
-                    // create a token steam
-                    match Parser::default().parse(&buf) {
-                        Ok(tree) => println!("{tree:x}"),
-                        Err(error) => println!("{error}"),
-                    }
-                    buf.clear(); // Reuse buf's allocation
-                    continue;
-                } // Line is empty
-                _ => (),
-            }
-        }
-    } else {
-        std::io::stdin().lock().read_to_string(&mut buf).map_err(|_| Error::EndOfFile)?;
-        let tree = Parser::default().parse(&buf);
-        match &tree {
-            Ok(tree) => println!("{tree:x}"),
-            Err(error) => eprintln!("{error}"),
-        }
-    }
-
-    Ok(())
-}
diff --git a/src/parser.rs b/src/parser.rs
index 4fc8e14..6fe8293 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,15 +1,20 @@
 // © 2023 John Breaux
 //! Parses [`Tokens`](crate::Token) into an [abstract syntax tree](Root)
 
-use crate::{Error, Hash, TokenStream, Type};
-use std::fmt::{Debug, Display, LowerHex};
+use crate::{TokenStream, Type};
+use error::ParseError;
+use preamble::*;
+use std::{
+    fmt::{Debug, Display},
+    path::Path,
+};
 
 pub mod preamble {
     //! All the different AST node types
     use super::*;
     // Traits
     pub use parsable::Parsable;
-
+    // Nodes
     pub use comment::Comment;
     pub use directive::Directive;
     pub use identifier::Identifier;
@@ -24,173 +29,38 @@ pub mod preamble {
     pub use label::Label;
     pub use line::Line;
     pub use root::Root;
+    // Error
+    pub use error::ParseError;
 }
-use preamble::*;
 
 pub mod parsable;
 
 pub mod comment;
 pub mod directive;
+pub mod error;
 pub mod identifier;
 pub mod instruction;
 pub mod label;
-
-pub mod line {
-    // © 2023 John Breaux
-    //! [`Line`] contains a single subcomponent of the document. Multiple instructions on the same document line will be treated as if they took up multiple [`Line`s](Line).
-    //! 
-    //! A line contains one of:
-    //! - [`Label`]
-    //! - [`Instruction`]
-    //! - [`Directive`]
-    //! - [`Comment`]
-    //! - [Nothing](Line::Empty)
-    use super::*;
-
-    /// A line contains any one of:
-    /// - [`Label`] (definition)
-    /// - [`Instruction`]
-    /// - [`Directive`]
-    /// - [`Comment`]
-    /// - Nothing at all
-    #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-    pub enum Line {
-        Empty,
-        Insn(Instruction),
-        Comment(Comment),
-        Directive(Directive),
-        Label(Label), // TODO: Label resolution
-        EndOfFile,    // Expected end of file
-    }
-
-    impl Parsable for Line {
-        fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
-        where T: TokenStream<'text> {
-            Ok(
-                match stream
-                    .peek_expect_any_of([
-                        Type::Endl,
-                        Type::Insn,
-                        Type::Comment,
-                        Type::Directive,
-                        Type::Identifier,
-                        Type::EndOfFile,
-                    ])?
-                    .variant()
-                {
-                    Type::Endl => {
-                        stream.next();
-                        Self::Empty
-                    }
-                    Type::Insn => Self::Insn(Instruction::parse(p, stream)?),
-                    Type::Comment => Self::Comment(Comment::parse(p, stream)?),
-                    Type::Directive => Self::Directive(Directive::parse(p, stream)?),
-                    Type::Identifier => Self::Label(Label::parse(p, stream)?),
-                    Type::EndOfFile => {
-                        stream.next();
-                        Self::EndOfFile
-                    }
-                    _ => unreachable!("stream.peek_expect_any_of should return Err for unmatched inputs"),
-                },
-            )
-        }
-    }
-    impl Display for Line {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                Self::Empty => writeln!(f, "\n"),
-                Self::Label(arg0) => Display::fmt(arg0, f),
-                Self::Insn(arg0) => Display::fmt(arg0, f),
-                Self::Directive(arg0) => Display::fmt(arg0, f),
-                Self::Comment(arg0) => Display::fmt(arg0, f),
-                Self::EndOfFile => write!(f, "; End of file."),
-            }
-        }
-    }
-    impl LowerHex for Line {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            match self {
-                Line::Insn(arg0) => LowerHex::fmt(arg0, f),
-                _ => Ok(()),
-            }
-        }
-    }
-}
-
-pub mod root {
-    // © 2023 John Breaux
-    use super::*;
-
-    /// Contains the entire AST
-    #[derive(Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
-    pub struct Root(pub Vec<Line>);
-
-    // TODO: Get data out of ParseTree
-    // TODO: Maybe implement some sort of follower
-    impl Parsable for Root {
-        fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
-        where T: TokenStream<'text> {
-            let mut lines = vec![];
-            loop {
-                match Line::parse(p, stream) {
-                    Ok(Line::EndOfFile) => break,
-                    Ok(line) => lines.push(line),
-                    Err(e) => {
-                        return Err(Error::ParseError(Self(lines), Box::new(e)));
-                    }
-                }
-            }
-            Ok(Root(lines))
-        }
-    }
-
-    impl Display for Root {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            for line in self.0.iter() {
-                f.pad(&format!("{line} "))?;
-            }
-            Ok(())
-        }
-    }
-    impl LowerHex for Root {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            for line in self.0.iter() {
-                LowerHex::fmt(line, f)?;
-            }
-            Ok(())
-        }
-    }
-    impl Debug for Root {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            for line in self.0.iter() {
-                Display::fmt(line, f)?;
-                Debug::fmt(line, f)?;
-            }
-            Ok(())
-        }
-    }
-}
-
-/// The type for [Parser] callbacks
-pub type EmitComment = Box<dyn FnMut(&str)>;
-pub type DefineLabel = Box<dyn FnMut(&Identifier) -> Result<(), Error>>;
+pub mod line;
+pub mod root;
 
 pub struct Parser {
     radix: u32,
-    // TODO: callbacks for emitted token sequences?!
-    on_label: Option<DefineLabel>,
-    on_comment: Option<EmitComment>,
 }
 
 impl Parser {
-    pub fn parse_with<'t>(self, stream: &'t mut impl TokenStream<'t>) -> Result<Root, Error> {
+    pub fn parse_with<'t>(self, stream: &'t mut impl TokenStream<'t>) -> Result<Root, ParseError> {
         Root::parse(&self, &mut stream.ignore(Type::Space))
     }
-    pub fn parse<T>(self, input: &T) -> Result<Root, Error>
+    pub fn parse<T>(self, input: &T) -> Result<Root, ParseError>
     where T: AsRef<str> + ?Sized {
         Root::parse(&self, &mut super::Tokenizer::new(input).preprocessed().ignore(Type::Space))
     }
-    pub fn parse_one<T>(self, input: &T) -> Result<Line, Error>
+    pub fn parse_file<P>(self, path: &P) -> Result<Root, ParseError>
+    where P: AsRef<Path> + ?Sized {
+        self.parse(&std::fs::read_to_string(path.as_ref())?).map(|r| r.set_file(path.as_ref().into()))
+    }
+    pub fn parse_one<T>(self, input: &T) -> Result<Line, ParseError>
     where T: AsRef<str> + ?Sized {
         Line::parse(&self, &mut super::Tokenizer::new(input).preprocessed().ignore(Type::Space))
     }
@@ -198,24 +68,10 @@ impl Parser {
     /// Sets the default radix for [Token](crate::lexer::token::Token) -> [Number]
     /// conversion
     pub fn radix(mut self, radix: u32) { self.radix = radix; }
-
-    /// Inform the caller of a new identifier definition
-    pub fn define_label(&mut self, l: &Identifier) -> Result<(), Error> {
-        match self.on_label.as_mut() {
-            Some(f) => f(l),
-            _ => Ok(()),
-        }
-    }
-    /// Inform the caller of an identifier being used
-    pub fn emit_comment(&mut self, d: &str) {
-        if let Some(f) = self.on_comment.as_mut() {
-            f(d)
-        }
-    }
 }
 
 impl Default for Parser {
-    fn default() -> Self { Self { radix: 16, on_label: None, on_comment: None } }
+    fn default() -> Self { Self { radix: 16 } }
 }
 
 impl Debug for Parser {
diff --git a/src/parser/comment.rs b/src/parser/comment.rs
index edefaa8..c3fc86c 100644
--- a/src/parser/comment.rs
+++ b/src/parser/comment.rs
@@ -5,10 +5,9 @@ use super::*;
 pub struct Comment(pub String);
 
 impl Parsable for Comment {
-    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: TokenStream<'text> {
-        let token = stream.expect(Type::Comment)?;
-        Ok(Self(token.lexeme().to_string()))
+        Ok(Self(stream.expect(Type::Comment)?.lexeme().to_string()))
     }
 }
 impl Display for Comment {
diff --git a/src/parser/directive.rs b/src/parser/directive.rs
index 9f4d169..24fb9e5 100644
--- a/src/parser/directive.rs
+++ b/src/parser/directive.rs
@@ -1,32 +1,90 @@
 // © 2023 John Breaux
 //! A [`Directive`] issues commands directly to the [`Tokenizer`](crate::Tokenizer) and
 //! [Linker](crate::Linker)
+
+use std::path::PathBuf;
+
 use super::*;
-use crate::hash::FromHash;
+use crate::lexer::token::OwnedToken;
+
+// TODO: Parse each kind of *postprocessor* directive into an AST node
+//  - .org 8000:                Directive::Org { base: Number }
+//  - .define ident tt...       Directive::Define { } ; should this be in the AST? How do I put this
+//    in the AST?
+//  - .include "<filename>"     Directive::Include { Root } ; should this include an entire AST in
+//    the AST?
+//  - .word 8000                Directive::Word(Number)
+//  - .words dead beef          Directive::Words(Vec<u16>|Vec<Number>)
+//  - .byte ff                  Directive::Byte(Number)
+//  - .bytes de, ad, be, ef     Directive::Bytes(Vec<u8>)
+//  - .string "string"          Directive::String(String)
+//  - .ascii "string"           Directive::Ascii(Vec<u8>)
 
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct Directive(pub Hash, pub String);
-
-impl Directive {
-    fn str<S: ToString>(mut self, s: S) -> Self {
-        self.1 = s.to_string();
-        self
-    }
+pub enum Directive {
+    Org(Number),
+    Define(Vec<OwnedToken>),
+    Include(Root), // TODO: create and parse an entire AST, and stick it in Include
+    Byte(Number),
+    Bytes(Vec<Number>),
+    Word(Number),
+    Words(Vec<Number>),
+    String(String),
+    Strings(Vec<String>),
 }
 
-impl From<Hash> for Directive {
-    fn from(value: Hash) -> Self { Self(value, String::new()) }
-}
+impl Directive {}
 
 impl Parsable for Directive {
-    fn parse<'text, T>(_p: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: TokenStream<'text> {
-        // expect a directive
         let d = stream.expect(Type::Directive)?;
-        // send the directive to the listener
-        Ok(Self::from_hash(d.lexeme()).str(d.lexeme()))
+        // match on the directive
+        Ok(match d.lexeme() {
+            ".org" => Self::Org(Number::parse(p, stream)?),
+            ".define" => {
+                let mut tokens = vec![];
+                loop {
+                    match stream.peek().variant() {
+                        Type::Endl | Type::EndOfFile => break,
+                        _ => tokens.push(stream.next().unwrap_or_default().into()),
+                    }
+                }
+                Self::Define(tokens)
+            }
+            ".include" => {
+                // Try to get path
+                Self::Include(Parser::default().parse_file(&PathBuf::parse(p, stream)?)?)
+            }
+            ".byte" => Self::Byte(Number::parse(p, stream)?),
+            ".bytes" => Self::Bytes(Vec::<Number>::parse(p, stream)?),
+            ".word" => Self::Word(Number::parse(p, stream)?),
+            ".words" => Self::Words(Vec::<Number>::parse(p, stream)?),
+            ".string" => Self::String(String::parse(p, stream)?),
+            ".strings" => Self::Strings(Vec::<String>::parse(p, stream)?),
+            e => Err(ParseError::UnrecognizedDirective(e.into()))?,
+        })
     }
 }
+
 impl Display for Directive {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{}", self.1) }
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Directive::Org(num) => write!(f, ".org {num}"),
+            Directive::Define(rep) => {
+                write!(f, ".define")?;
+                for t in rep {
+                    write!(f, " {t}")?;
+                }
+                Ok(())
+            }
+            Directive::Include(r) => Display::fmt(r, f),
+            Directive::Byte(num) => write!(f, ".org {num}"),
+            Directive::Bytes(v) => write!(f, ".bytes {v:?}"),
+            Directive::Word(num) => write!(f, ".org {num}"),
+            Directive::Words(v) => write!(f, ".bytes {v:?}"),
+            Directive::String(s) => write!(f, ".string \"{s}\""),
+            Directive::Strings(s) => write!(f, ".string \"{s:?}\""),
+        }
+    }
 }
diff --git a/src/parser/error.rs b/src/parser/error.rs
new file mode 100644
index 0000000..0b3bf88
--- /dev/null
+++ b/src/parser/error.rs
@@ -0,0 +1,74 @@
+// © 2023 John Breauxs
+use super::*;
+use crate::lexer::error::LexError;
+
+#[derive(Debug)]
+pub enum ParseError {
+    /// Produced by [lexer](crate::lexer)
+    LexError(LexError),
+    /// Produced by [std::io]
+    IoError(std::io::Error),
+    /// Produced by [Number](Number)[::parse()](Parsable::parse())
+    /// when the parsed number contains digits too high for the specified radix
+    UnexpectedDigits(String, u32),
+    /// Produced by [Opcode](Opcode)[::parse()](Parsable::parse())
+    /// when the opcode passed lexing but did not match recognized opcodes.
+    ///
+    /// This is always a lexer bug.
+    UnrecognizedOpcode(String),
+    /// Produced by [Directive](Directive)[::parse()](Parsable::parse())
+    /// when an unknown or unimplemented directive is used
+    UnrecognizedDirective(String),
+    /// Produced by [Register] when attempting to convert from a [str]
+    /// that isn't a register (pc, sp, sr, cg, or r{number})
+    NotARegister(String),
+    /// Produced by [Register] when the r{number} is outside the range 0-15
+    RegisterTooHigh(u16),
+    /// Produced by [SecondaryOperand] when the joke "secondary immediate" form
+    /// is out of range 0..=1
+    FatSecondaryImmediate(isize),
+    /// Produced by a [Number] too wide to fit in 16 bits
+    /// (outside the range `(-2^15) .. (2^16-1)` )
+    NumberTooWide(isize),
+    /// Produced by [JumpTarget](parser::preamble::JumpTarget)
+    /// when the jump offset is outside the range (-0x3ff..0x3fc)
+    JumpedTooFar(isize),
+    /// Produced by [JumpTarget](parser::preamble::JumpTarget)
+    JumpedOdd(isize),
+}
+
+impl From<LexError> for ParseError {
+    fn from(value: LexError) -> Self { Self::LexError(value) }
+}
+impl From<std::io::Error> for ParseError {
+    fn from(value: std::io::Error) -> Self { Self::IoError(value) }
+}
+
+impl Display for ParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::LexError(error) => Display::fmt(error, f),
+            Self::IoError(error) => Display::fmt(error, f),
+            Self::UnexpectedDigits(number, radix) => write!(f, "Number `{number}` is not base {radix}."),
+            Self::UnrecognizedOpcode(op) => write!(f, "{op} is not an opcode"),
+            Self::UnrecognizedDirective(d) => write!(f, "{d} is not a directive."),
+            Self::NotARegister(reg) => write!(f, "{reg} is not a register"),
+            Self::RegisterTooHigh(reg) => write!(f, "r{reg} is not a register"),
+            Self::FatSecondaryImmediate(num) => write!(f, "Secondary immediate must be #0 or #1, not #{num}"),
+            Self::NumberTooWide(num) => write!(f, "{num} does not fit in 16 bits"),
+            Self::JumpedTooFar(num) => write!(f, "{num} is too far away: must be in range (`-1022..=1024`.)"),
+            Self::JumpedOdd(num) => {
+                write!(f, "Jump targets only encode even numbers: {num} must not be odd.")
+            }
+        }
+    }
+}
+impl std::error::Error for ParseError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::LexError(e) => Some(e),
+            Self::IoError(e) => Some(e),
+            _ => None,
+        }
+    }
+}
diff --git a/src/parser/identifier.rs b/src/parser/identifier.rs
index dd88815..3caefbb 100644
--- a/src/parser/identifier.rs
+++ b/src/parser/identifier.rs
@@ -1,22 +1,18 @@
 // © 2023 John Breaux
-//! An [Identifier] stores the name of an identifier
+//! An [Identifier] stores the hash of an identifier
 use super::*;
+use std::rc::Rc;
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub enum Identifier {
-    Hash(Hash),
-    Str(String),
+pub struct Identifier {
+    str: Rc<str>,
 }
 
 impl Identifier {
-    fn str<T: AsRef<str>>(s: T) -> Self { Self::Str(s.as_ref().into()) }
-}
-
-impl From<Hash> for Identifier {
-    fn from(value: Hash) -> Self { Self::Hash(value) }
+    fn str<T: AsRef<str>>(s: T) -> Self { Self { str: s.as_ref().to_owned().into() } }
 }
 
 impl Parsable for Identifier {
-    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: TokenStream<'text> {
         let token = stream.expect(Type::Identifier)?;
         match token.variant() {
@@ -26,10 +22,5 @@ impl Parsable for Identifier {
     }
 }
 impl Display for Identifier {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Identifier::Hash(_) => Display::fmt("Unresolved", f),
-            Identifier::Str(s) => Display::fmt(s, f),
-        }
-    }
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { Display::fmt(&self.str, f) }
 }
diff --git a/src/parser/instruction.rs b/src/parser/instruction.rs
index a61828b..38bfaa5 100644
--- a/src/parser/instruction.rs
+++ b/src/parser/instruction.rs
@@ -15,7 +15,7 @@ pub mod encoding;
 pub mod opcode;
 
 /// Contains the [Opcode] and [Encoding] information for a single msp430 instruction
-#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Instruction(Opcode, Encoding);
 
 impl Instruction {
@@ -24,11 +24,11 @@ impl Instruction {
     /// Gets the Instruction as a [u16]
     pub fn word(&self) -> u16 { self.0 as u16 | self.1.word() }
     /// Gets the [extension words]
-    pub fn ext_words(&self) -> (Option<u16>, Option<u16>) { self.1.extwords() }
+    pub fn ext_words(&self) -> [Option<u16>; 2] { self.1.extwords() }
 }
 
 impl Parsable for Instruction {
-    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where
         Self: Sized,
         T: crate::TokenStream<'text>,
@@ -50,17 +50,3 @@ impl From<Instruction> for u16 {
 impl Display for Instruction {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{}{}", self.0, self.1) }
 }
-
-impl LowerHex for Instruction {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let (word, (ext_src, ext_dst)) = (self.word(), self.ext_words());
-        write!(f, "{:04x} ", word.swap_bytes())?;
-        if let Some(e) = ext_src {
-            write!(f, "{:04x} ", e.swap_bytes())?
-        }
-        if let Some(e) = ext_dst {
-            write!(f, "{:04x} ", e.swap_bytes())?
-        }
-        Ok(())
-    }
-}
diff --git a/src/parser/instruction/encoding.rs b/src/parser/instruction/encoding.rs
index 1b65f95..1a44938 100644
--- a/src/parser/instruction/encoding.rs
+++ b/src/parser/instruction/encoding.rs
@@ -32,7 +32,7 @@ use encoding_parser::EncodingParser;
 /// // Print the Encoding
 /// println!("{encoding}");
 /// ```
-#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum Encoding {
     Single { width: Width, dst: PrimaryOperand },
     Jump { target: JumpTarget },
@@ -52,20 +52,20 @@ impl Encoding {
     pub fn reflexive() -> ReflexiveBuilder { Default::default() }
     ///
     pub fn word(&self) -> u16 {
-        match *self {
-            Encoding::Single { width, dst } => u16::from(width) | dst.mode() | dst.register() as u16,
-            Encoding::Jump { target } => target.word(),
+        match self {
+            Encoding::Single { width, dst } => u16::from(*width) | dst.mode() | dst.register() as u16,
+            Encoding::Jump { target } => target.word().unwrap_or_default(),
             Encoding::Double { width, src, dst } => {
-                u16::from(width) | src.mode() | dst.mode() | dst.register() as u16 | ((src.register() as u16) << 8)
+                u16::from(*width) | src.mode() | dst.mode() | dst.register() as u16 | ((src.register() as u16) << 8)
             }
         }
     }
     /// Returns extwords for instruction
-    pub fn extwords(&self) -> (Option<u16>, Option<u16>) {
+    pub fn extwords(&self) -> [Option<u16>; 2] {
         match self {
-            Encoding::Double { src, dst, .. } => (src.ext_word(), dst.ext_word()),
-            Encoding::Single { dst, .. } => (dst.ext_word(), None),
-            Encoding::Jump { .. } => (None, None),
+            Encoding::Double { src, dst, .. } => [src.ext_word(), dst.ext_word()],
+            Encoding::Single { dst, .. } => [dst.ext_word(), None],
+            Encoding::Jump { .. } => [None, None],
         }
     }
 }
diff --git a/src/parser/instruction/encoding/builder.rs b/src/parser/instruction/encoding/builder.rs
index 4c62910..63080d5 100644
--- a/src/parser/instruction/encoding/builder.rs
+++ b/src/parser/instruction/encoding/builder.rs
@@ -17,7 +17,7 @@ impl SingleBuilder {
         self
     }
     /// Build
-    pub fn end(&self) -> EncodingParser { EncodingParser::Single { width: self.width, dst: self.dst } }
+    pub fn end(self) -> EncodingParser { EncodingParser::Single { width: self.width, dst: self.dst } }
 }
 
 #[derive(Debug, Default)]
@@ -29,7 +29,7 @@ impl JumpBuilder {
         self.target = Some(target);
         self
     }
-    pub fn end(&self) -> EncodingParser { EncodingParser::Jump { target: self.target } }
+    pub fn end(self) -> EncodingParser { EncodingParser::Jump { target: self.target } }
 }
 
 #[derive(Debug, Default)]
@@ -54,7 +54,7 @@ impl DoubleBuilder {
         self.dst = Some(dst);
         self
     }
-    pub fn end(&self) -> EncodingParser { EncodingParser::Double { width: self.width, src: self.src, dst: self.dst } }
+    pub fn end(self) -> EncodingParser { EncodingParser::Double { width: self.width, src: self.src, dst: self.dst } }
 }
 
 #[derive(Debug, Default)]
@@ -72,5 +72,5 @@ impl ReflexiveBuilder {
         self.reg = Some(reg);
         self
     }
-    pub fn end(&self) -> EncodingParser { EncodingParser::Reflexive { width: self.width, reg: self.reg } }
+    pub fn end(self) -> EncodingParser { EncodingParser::Reflexive { width: self.width, reg: self.reg } }
 }
diff --git a/src/parser/instruction/encoding/encoding_parser.rs b/src/parser/instruction/encoding/encoding_parser.rs
index 71b57e1..c59515d 100644
--- a/src/parser/instruction/encoding/encoding_parser.rs
+++ b/src/parser/instruction/encoding/encoding_parser.rs
@@ -2,7 +2,7 @@
 //! An [`EncodingParser`] builds an [`Encoding`] from a [`TokenStream`]
 use super::*;
 
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 /// Builds an [Encoding] using [Tokens](crate::Token) from an input [TokenStream]
 pub enum EncodingParser {
     Single { width: Option<Width>, dst: Option<PrimaryOperand> },
@@ -10,29 +10,27 @@ pub enum EncodingParser {
     Double { width: Option<Width>, src: Option<PrimaryOperand>, dst: Option<SecondaryOperand> },
     Reflexive { width: Option<Width>, reg: Option<SecondaryOperand> },
 }
+
 impl EncodingParser {
     /// Constructs an [Encoding] from this [EncodingParser], filling holes
     /// with the tokenstream
-    pub fn parse<'text, T>(&self, p: &Parser, stream: &mut T) -> Result<Encoding, Error>
+    pub fn parse<'text, T>(self, p: &Parser, stream: &mut T) -> Result<Encoding, ParseError>
     where T: crate::TokenStream<'text> {
         Ok(match self {
-            Self::Single { width, dst } => {
-                let width = width.unwrap_or_else(|| Width::parse_or_default(p, stream));
-                let dst = if let Some(dst) = dst { *dst } else { PrimaryOperand::parse(p, stream)? };
-                Encoding::Single { width, dst }
-            }
+            Self::Single { width, dst } => Encoding::Single {
+                width: width.unwrap_or_else(|| Width::parse_or_default(p, stream)),
+                dst: if let Some(dst) = dst { dst } else { PrimaryOperand::parse(p, stream)? },
+            },
             Self::Jump { target } => Encoding::Jump { target: target.unwrap_or(JumpTarget::parse(p, stream)?) },
-            Self::Double { width, src, dst } => {
-                let width = width.unwrap_or_else(|| Width::parse_or_default(p, stream));
-                let src = if let Some(src) = src { *src } else { PrimaryOperand::parse(p, stream)? };
-                let dst = if let Some(dst) = dst { *dst } else { SecondaryOperand::parse(p, stream)? };
-
-                Encoding::Double { width, src, dst }
-            }
+            Self::Double { width, src, dst } => Encoding::Double {
+                width: width.unwrap_or_else(|| Width::parse_or_default(p, stream)),
+                src: if let Some(src) = src { src } else { PrimaryOperand::parse(p, stream)? },
+                dst: if let Some(dst) = dst { dst } else { SecondaryOperand::parse(p, stream)? },
+            },
             Self::Reflexive { width, reg } => {
                 let width = width.unwrap_or_else(|| Width::parse(p, stream).unwrap_or_default());
-                let reg = if let Some(reg) = reg { *reg } else { SecondaryOperand::parse(p, stream)? };
-                Encoding::Double { width, src: reg.into(), dst: reg }
+                let reg = if let Some(reg) = reg { reg } else { SecondaryOperand::parse(p, stream)? };
+                Encoding::Double { width, src: reg.clone().into(), dst: reg }
             }
         })
     }
diff --git a/src/parser/instruction/encoding/jump_target.rs b/src/parser/instruction/encoding/jump_target.rs
index dcb729d..2d9b731 100644
--- a/src/parser/instruction/encoding/jump_target.rs
+++ b/src/parser/instruction/encoding/jump_target.rs
@@ -5,37 +5,54 @@ use super::*;
 
 /// Contains the [pc-relative offset](Number) or [label](Identifier)
 /// for a [Jump](Encoding::Jump) [Instruction]
-// TODO: Allow identifiers in JumpTarget
-#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct JumpTarget(Number);
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum JumpTarget {
+    Number(Number),
+    Identifier(Identifier),
+}
 
 impl JumpTarget {
-    pub fn word(&self) -> u16 { u16::from(self.0) & 0x3ff }
+    pub fn word(&self) -> Option<u16> {
+        match self {
+            JumpTarget::Number(n) => Some(u16::from(*n) & 0x3ff),
+            JumpTarget::Identifier(_) => None,
+        }
+    }
+    pub fn squish(value: isize) -> Result<u16, ParseError> {
+        match value {
+            i if i % 2 != 0 => Err(ParseError::JumpedOdd(i))?,
+            i if (-1024..=1022).contains(&(i - 2)) => Ok(((value >> 1) - 1) as u16 & 0x3ff),
+            i => Err(ParseError::JumpedTooFar(i))?,
+        }
+    }
+    pub fn unsquish(value: u16) -> isize { (value as isize + 1) << 1 }
 }
 
 impl Parsable for JumpTarget {
-    /// - Identifier
-    /// - Number
-    /// - Negative
-    ///   - Number
-    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
+    // - Identifier
+    // - Number
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: crate::TokenStream<'text> {
         // Try to parse a number
-        let target = Number::parse(p, stream)?;
-        match target.into() {
-            i if i % 2 != 0 => Err(Error::JumpedOdd(i).context(stream.context()))?,
-            i if (-1024..=1022).contains(&(i - 2)) => Ok(Self((target - 2) >> 1)),
-            i => Err(Error::JumpedTooFar(i).context(stream.context()))?,
+        if let Some(num) = Number::try_parse(p, stream)? {
+            Self::try_from(num)
+        } else {
+            // if that fails, try to parse an identifier instead
+            Ok(Self::Identifier(Identifier::parse(p, stream)?))
         }
     }
 }
 
-impl From<JumpTarget> for u16 {
-    fn from(value: JumpTarget) -> Self { value.0.into() }
+impl TryFrom<Number> for JumpTarget {
+    type Error = ParseError;
+    fn try_from(value: Number) -> Result<Self, Self::Error> { Ok(Self::Number(Self::squish(value.into())?.into())) }
 }
 
 impl Display for JumpTarget {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", (1 + isize::from(self.0)) << 1)
+        match self {
+            Self::Number(num) => write!(f, "{:x}", Self::unsquish(u16::from(*num))),
+            Self::Identifier(id) => write!(f, "{id}"),
+        }
     }
 }
diff --git a/src/parser/instruction/encoding/number.rs b/src/parser/instruction/encoding/number.rs
index ed4c3f3..849e0f9 100644
--- a/src/parser/instruction/encoding/number.rs
+++ b/src/parser/instruction/encoding/number.rs
@@ -2,56 +2,54 @@
 //! A [`Number`] represents a 16-bit signed or unsigned word
 use super::*;
 
-// TODO: Allow identifiers/expressions  in place of numbers
-//       - Dependency inversion in TokenStream to allow swapping the parser mid-parse?
-//       - Oh my god, not relying on std::iter::Iterator allows for so many more parsing options
-
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Number(isize, u32); // (value, radix)
 
 impl Parsable for Number {
     // A number is:
-    // RadixMarker[Hex|Oct|Bin]?
-    // - Number
-    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
+    // [Minus|Plus]? RadixMarker[Hex|Dec|Oct|Bin]? Number
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: TokenStream<'text> {
-        use Type::*;
+        use Type as Ty;
         // The number is negative when it begins with a Minus, but Plus is also acceptable.
-        let negative = stream.expect_any_of([Minus, Plus]).map_or(false, |t| t.is_variant(Minus));
+        let negative = stream.expect_any_of([Ty::Minus, Ty::Plus]).map_or(false, |t| t.is_variant(Ty::Minus));
         let radix = match stream
-            .expect_any_of([RadixMarkerHex, RadixMarkerDec, RadixMarkerOct, RadixMarkerBin])
+            .expect_any_of([Ty::RadixMarkerHex, Ty::RadixMarkerDec, Ty::RadixMarkerOct, Ty::RadixMarkerBin])
             .ok()
             .map(|t| t.variant())
         {
-            Some(RadixMarkerHex) => 16,
-            Some(RadixMarkerDec) => 10,
-            Some(RadixMarkerOct) => 8,
-            Some(RadixMarkerBin) => 2,
+            Some(Ty::RadixMarkerHex) => 16,
+            Some(Ty::RadixMarkerDec) => 10,
+            Some(Ty::RadixMarkerOct) => 8,
+            Some(Ty::RadixMarkerBin) => 2,
             _ => p.radix,
         };
-        let number = stream.expect(Number)?;
+        let number = stream.expect(Ty::Number)?;
+        // TODO: Reintroduce error context
         let number = isize::from_str_radix(number.lexeme(), radix)
-            .map_err(|_| Error::UnexpectedDigits(number.lexeme().into(), radix).context(stream.context()))?
+            .map_err(|_| ParseError::UnexpectedDigits(number.lexeme().into(), radix))?
             * if negative { -1 } else { 1 };
         // Ensure number fits within a *signed or unsigned* 16-bit int (it will be truncated to fit)
         Ok(Self(
-            if (-0x8000..0x10000).contains(&number) {
-                number
-            } else {
-                Err(Error::NumberTooWide(number).context(stream.context()))?
-            },
+            if (-0x8000..0x10000).contains(&number) { number } else { Err(ParseError::NumberTooWide(number))? },
             radix,
         ))
     }
 }
+
+impl From<isize> for Number {
+    fn from(value: isize) -> Self { Self(value, 16) }
+}
+
 impl From<Number> for isize {
     fn from(value: Number) -> Self { value.0 as Self }
 }
-impl From<Number> for i32 {
-    fn from(value: Number) -> Self { value.0 as Self }
+
+impl From<u16> for Number {
+    fn from(value: u16) -> Self { Self(value as isize, 16) }
 }
+
 impl From<Number> for u16 {
-    /// Converts this type from the input type.
     fn from(value: Number) -> Self { value.0 as Self }
 }
 
@@ -72,5 +70,12 @@ impl std::ops::Shr<usize> for Number {
 }
 
 impl std::fmt::Display for Number {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{:x}", self.0) }
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self.1 {
+            2 => std::fmt::Binary::fmt(&self.0, f),
+            8 => std::fmt::Octal::fmt(&self.0, f),
+            16 => std::fmt::LowerHex::fmt(&self.0, f),
+            _ => std::fmt::Display::fmt(&self.0, f),
+        }
+    }
 }
diff --git a/src/parser/instruction/encoding/primary_operand.rs b/src/parser/instruction/encoding/primary_operand.rs
index 02009a0..8742e92 100644
--- a/src/parser/instruction/encoding/primary_operand.rs
+++ b/src/parser/instruction/encoding/primary_operand.rs
@@ -5,12 +5,13 @@ use super::*;
 
 /// Contains the first [Register], addressing mode, and Extension Word for a
 /// [one-operand](Encoding::Single) or [two-operand](Encoding::Double) [Instruction]
-#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum PrimaryOperand {
     Direct(Register),
     Indirect(Register),
     PostInc(Register),
     Indexed(Register, Number),
+    Relative(Identifier),
     Absolute(Number),
     Immediate(Number),
     Four,
@@ -27,7 +28,7 @@ impl PrimaryOperand {
         use PrimaryOperand::*;
         match self {
             Direct(_) | Zero => 0,
-            Indexed(_, _) | Absolute(_) | One => 1 << 4,
+            Indexed(_, _) | Relative(_) | Absolute(_) | One => 1 << 4,
             Indirect(_) | Two | Four => 2 << 4,
             PostInc(_) | Immediate(_) | MinusOne | Eight => 3 << 4,
         }
@@ -37,7 +38,7 @@ impl PrimaryOperand {
         use PrimaryOperand::*;
         match self {
             Direct(r) | Indexed(r, _) | Indirect(r) | PostInc(r) => *r,
-            Immediate(_) => Register::pc,
+            Immediate(_) | Relative(_) => Register::pc,
             Absolute(_) | Four | Eight => Register::sr,
             Zero | One | Two | MinusOne => Register::cg,
         }
@@ -53,21 +54,8 @@ impl PrimaryOperand {
 }
 
 impl Parsable for PrimaryOperand {
-    // - Register
-    // - Indirect
-    //     - Register
-    //         - PostInc?
-    // - Number
-    //     - OpenIdx
-    //         - Register
-    //             - CloseIdx
-    // - Absolute
-    //     - Number
-    // - Immediate
-    //     - Number
-    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: crate::TokenStream<'text> {
-        use PrimaryOperand::*;
         // Try parsing as Register (Direct)
         if let Some(r) = Register::try_parse(p, stream)? {
             return Ok(Self::Direct(r));
@@ -79,33 +67,43 @@ impl Parsable for PrimaryOperand {
             stream.expect(Type::RParen)?;
             return Ok(Self::Indexed(reg, idx));
         }
+        // Try parsing as Identifier (Relative, label mode)
+        if let Some(id) = Identifier::try_parse(p, stream)? {
+            return Ok(Self::Relative(id));
+        }
         // Or directly match any of the valid prefix markers
-        // Type::Register and Type::Number are included here to make error messages clearer.
+        // Register, Number, and Identifier are included here to make error messages clearer.
         // their inclusion will cause a negligible slowdown when the next token is not a prefix marker
         // (a failure condition)
-        let token =
-            stream.expect_any_of([Type::Indirect, Type::Absolute, Type::Immediate, Type::Register, Type::Number])?;
+        let token = stream.expect_any_of([
+            Type::Indirect,
+            Type::Absolute,
+            Type::Immediate,
+            Type::Register,
+            Type::Number,
+            Type::Identifier,
+        ])?;
         Ok(match token.variant() {
             Type::Indirect => {
                 let reg = Register::parse(p, stream)?;
                 match stream.expect(Type::Plus) {
-                    Ok(_) => PostInc(reg),
-                    Err(_) => Indirect(reg),
+                    Ok(_) => Self::PostInc(reg),
+                    Err(_) => Self::Indirect(reg),
                 }
             }
-            Type::Absolute => Absolute(Number::parse(p, stream)?),
+            Type::Absolute => Self::Absolute(Number::parse(p, stream)?),
             Type::Immediate => {
                 let number = Number::parse(p, stream)?;
                 match number.into() {
                     // There are two representations for the all-ones constant, since Number preserves
                     // signedness.
-                    -1 | 0xffff => MinusOne,
-                    0 => Zero,
-                    1 => One,
-                    2 => Two,
-                    4 => Four,
-                    8 => Eight,
-                    _ => Immediate(number),
+                    -1_isize | 0xffff => Self::MinusOne,
+                    0 => Self::Zero,
+                    1 => Self::One,
+                    2 => Self::Two,
+                    4 => Self::Four,
+                    8 => Self::Eight,
+                    _ => Self::Immediate(number),
                 }
             }
             _ => unreachable!("Token {token:?} passed expectation but failed match!"),
@@ -119,6 +117,7 @@ impl From<SecondaryOperand> for PrimaryOperand {
             SecondaryOperand::Direct(r) => Self::Direct(r),
             SecondaryOperand::Indexed(r, n) => Self::Indexed(r, n),
             SecondaryOperand::Absolute(n) => Self::Absolute(n),
+            SecondaryOperand::Relative(id) => Self::Relative(id),
             SecondaryOperand::Zero => Self::Zero,
             SecondaryOperand::One => Self::One,
         }
@@ -133,6 +132,7 @@ impl Display for PrimaryOperand {
             Self::Indirect(r) => write!(f, "@{r}"),
             Self::PostInc(r) => write!(f, "@{r}+"),
             Self::Indexed(r, idx) => write!(f, "{idx}({r})"),
+            Self::Relative(id) => Display::fmt(id, f),
             Self::Absolute(n) => write!(f, "&{n}"),
             Self::Immediate(n) => write!(f, "#{n}"),
             Self::Four => Display::fmt("#4", f),
diff --git a/src/parser/instruction/encoding/register.rs b/src/parser/instruction/encoding/register.rs
index e2e1715..7c4c1aa 100644
--- a/src/parser/instruction/encoding/register.rs
+++ b/src/parser/instruction/encoding/register.rs
@@ -30,14 +30,9 @@ pub enum Register {
 }
 
 impl Parsable for Register {
-    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: crate::TokenStream<'text> {
-        stream
-            .expect(Type::Register)
-            .map_err(|e: Error| e.context(stream.context()))?
-            .lexeme()
-            .parse()
-            .map_err(|e: Error| e.context(stream.context()))
+        stream.expect(Type::Register)?.lexeme().parse()
     }
 }
 
@@ -46,7 +41,7 @@ impl From<Register> for u16 {
 }
 
 impl TryFrom<u16> for Register {
-    type Error = Error;
+    type Error = ParseError;
     fn try_from(value: u16) -> Result<Self, Self::Error> {
         use Register::*;
         Ok(match value {
@@ -66,13 +61,13 @@ impl TryFrom<u16> for Register {
             13 => r13,
             14 => r14,
             15 => r15,
-            _ => return Err(Error::RegisterTooHigh(value)),
+            _ => return Err(ParseError::RegisterTooHigh(value)),
         })
     }
 }
 
 impl FromStr for Register {
-    type Err = Error;
+    type Err = ParseError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         use Register::*;
@@ -81,7 +76,9 @@ impl FromStr for Register {
             "sp" => Ok(sp),
             "sr" => Ok(sr),
             "cg" => Ok(cg),
-            _ => str::parse::<u16>(&s[1..]).map_err(|_| -> Self::Err { Error::NotARegister(s.into()) })?.try_into(),
+            _ => {
+                str::parse::<u16>(&s[1..]).map_err(|_| -> Self::Err { ParseError::NotARegister(s.into()) })?.try_into()
+            }
         }
     }
 }
diff --git a/src/parser/instruction/encoding/secondary_operand.rs b/src/parser/instruction/encoding/secondary_operand.rs
index f0aab77..59ca3b1 100644
--- a/src/parser/instruction/encoding/secondary_operand.rs
+++ b/src/parser/instruction/encoding/secondary_operand.rs
@@ -4,28 +4,31 @@
 use super::*;
 
 /// The destination of a [Double](Encoding::Double)
-#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum SecondaryOperand {
     Direct(Register),
     Indexed(Register, Number),
+    Relative(Identifier),
     Absolute(Number),
     // Joke encodings?
     Zero,
     One,
 }
 
+use SecondaryOperand as So;
+
 impl SecondaryOperand {
     pub fn mode(&self) -> u16 {
-        use SecondaryOperand::*;
         match self {
-            Direct(_) | Zero => 0,
-            Indexed(_, _) | Absolute(_) | One => 1 << 7,
+            So::Direct(_) | So::Zero => 0,
+            So::Indexed(_, _) | So::Relative(_) | So::Absolute(_) | So::One => 1 << 7,
         }
     }
     pub fn register(&self) -> Register {
         use SecondaryOperand::*;
         match self {
             Direct(r) | Indexed(r, _) => *r,
+            Relative(_) => Register::pc,
             Absolute(_) => Register::sr,
             Zero | One => Register::cg,
         }
@@ -51,7 +54,7 @@ impl Parsable for SecondaryOperand {
     //   - Number
     // - Immediate
     //   - Number == 0, 1
-    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, crate::Error>
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: crate::TokenStream<'text> {
         use SecondaryOperand::*;
         stream.allow(Type::Separator);
@@ -66,16 +69,22 @@ impl Parsable for SecondaryOperand {
             stream.expect(Type::RParen)?;
             return Ok(Self::Indexed(reg, idx));
         }
-        // Type::Register and Type::Number are included here to make error messages clearer.
+        // Try parsing as Identifier (Relative, label mode)
+        if let Some(id) = Identifier::try_parse(p, stream)? {
+            return Ok(Self::Relative(id));
+        }
+        // Register, Number, and Identifier are included here to make error messages clearer.
         // their inclusion will cause a negligible slowdown when the next token is not a prefix marker
         // (a failure condition) but should not match a token
-        let token = stream.expect_any_of([Type::Absolute, Type::Immediate, Type::Register, Type::Number])?;
+        let token =
+            stream.expect_any_of([Type::Absolute, Type::Immediate, Type::Register, Type::Number, Type::Identifier])?;
         Ok(match token.variant() {
             Type::Absolute => Absolute(Number::parse(p, stream)?),
+            // TODO: Reintroduce error context
             Type::Immediate => match Number::parse(p, stream)?.into() {
                 0 => Zero,
                 1 => One,
-                n => Err(Error::FatSecondaryImmediate(n as isize).context(stream.context()))?,
+                n => Err(ParseError::FatSecondaryImmediate(n))?,
             },
             _ => unreachable!("Token {token:?} passed expectation but failed match!"),
         })
@@ -87,6 +96,7 @@ impl Display for SecondaryOperand {
         match self {
             Self::Direct(r) => Display::fmt(r, f),
             Self::Indexed(r, idx) => write!(f, "{idx}({r})"),
+            Self::Relative(id) => Display::fmt(id, f),
             Self::Absolute(n) => write!(f, "&{n}"),
             Self::Zero => Display::fmt("#0", f),
             Self::One => Display::fmt("#1", f),
diff --git a/src/parser/instruction/encoding/width.rs b/src/parser/instruction/encoding/width.rs
index 0fd5974..3a4924e 100644
--- a/src/parser/instruction/encoding/width.rs
+++ b/src/parser/instruction/encoding/width.rs
@@ -10,7 +10,7 @@ use super::*;
 pub struct Width(bool);
 
 impl Parsable for Width {
-    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: TokenStream<'text> {
         let Ok(token) = stream.expect_any_of([Type::ByteWidth, Type::WordWidth]) else {
             return Ok(Self(false));
diff --git a/src/parser/instruction/opcode.rs b/src/parser/instruction/opcode.rs
index 4790db7..8100e60 100644
--- a/src/parser/instruction/opcode.rs
+++ b/src/parser/instruction/opcode.rs
@@ -71,195 +71,189 @@ pub enum Opcode {
 }
 
 impl Opcode {
-    pub fn takes_width(&self) -> bool {
-        use Opcode::*;
-        match self {
-            Rrc => true,
-            Swpb => false,
-            Rra => true,
-            Sxt => false,
-            Push => true,
-            Call | Reti => false,
-            Jnz | Jz | Jnc | Jc | Jn | Jge | Jl | Jmp => false,
-            Mov | Add | Addc | Subc | Sub | Cmp | Dadd | Bit | Bic | Bis | Xor | And => true,
-            Nop | Pop | Br | Ret | Clrc | Setc | Clrz | Setz | Clrn | Setn | Dint | Eint | Rla | Rlc | Inv | Clr
-            | Tst | Dec | Decd | Inc | Incd | Adc | Dadc | Sbc => true,
-        }
-    }
     /// Resolve an Opcode into an [Opcode] and an [EncodingParser]
     pub fn resolve(self) -> (Opcode, EncodingParser) {
         use super::Encoding as Enc;
-        use Opcode::*;
-        use Register::*;
+        use Register as Reg;
         use {PrimaryOperand as Src, SecondaryOperand as Dst};
         match self {
-            Rrc | Swpb | Rra | Sxt | Push | Call | Reti => (self, Enc::single().end()),
-            Jnz | Jz | Jnc | Jc | Jn | Jge | Jl | Jmp => (self, Enc::jump().end()),
-            Mov | Add | Addc | Subc | Sub | Cmp | Dadd | Bit | Bic | Bis | Xor | And => (self, Enc::double().end()),
-            Nop => (Mov, Enc::double().src(Src::Zero).dst(Dst::Zero).end()),
-            Pop => (Mov, Enc::double().src(Src::PostInc(sp)).end()),
-            Br => (Mov, Enc::double().dst(Dst::Direct(pc)).end()),
-            Ret => (Mov, Enc::double().src(Src::PostInc(sp)).dst(Dst::Direct(pc)).end()),
-            Clrc => (Bic, Enc::double().src(Src::One).dst(Dst::Direct(sr)).end()),
-            Setc => (Bis, Enc::double().src(Src::One).dst(Dst::Direct(sr)).end()),
-            Clrz => (Bic, Enc::double().src(Src::Two).dst(Dst::Direct(sr)).end()),
-            Setz => (Bis, Enc::double().src(Src::Two).dst(Dst::Direct(sr)).end()),
-            Clrn => (Bic, Enc::double().src(Src::Four).dst(Dst::Direct(sr)).end()),
-            Setn => (Bis, Enc::double().src(Src::Four).dst(Dst::Direct(sr)).end()),
-            Dint => (Bic, Enc::double().src(Src::Eight).dst(Dst::Direct(sr)).end()),
-            Eint => (Bis, Enc::double().src(Src::Eight).dst(Dst::Direct(sr)).end()),
-            Rla => (Add, Enc::reflexive().end()),
-            Rlc => (Addc, Enc::reflexive().end()),
-            Inv => (Xor, Enc::double().src(Src::MinusOne).end()),
-            Clr => (Mov, Enc::double().src(Src::Zero).end()),
-            Tst => (Cmp, Enc::double().src(Src::Zero).end()),
-            Dec => (Sub, Enc::double().src(Src::One).end()),
-            Decd => (Sub, Enc::double().src(Src::Two).end()),
-            Inc => (Add, Enc::double().src(Src::One).end()),
-            Incd => (Add, Enc::double().src(Src::Two).end()),
-            Adc => (Addc, Enc::double().src(Src::Zero).end()),
-            Dadc => (Dadd, Enc::double().src(Src::Zero).end()),
-            Sbc => (Subc, Enc::double().src(Src::Zero).end()),
+            Self::Rrc | Self::Swpb | Self::Rra | Self::Sxt | Self::Push | Self::Call | Self::Reti => {
+                (self, Enc::single().end())
+            }
+            Self::Jnz | Self::Jz | Self::Jnc | Self::Jc | Self::Jn | Self::Jge | Self::Jl | Self::Jmp => {
+                (self, Enc::jump().end())
+            }
+            Self::Mov
+            | Self::Add
+            | Self::Addc
+            | Self::Subc
+            | Self::Sub
+            | Self::Cmp
+            | Self::Dadd
+            | Self::Bit
+            | Self::Bic
+            | Self::Bis
+            | Self::Xor
+            | Self::And => (self, Enc::double().end()),
+            Self::Nop => (Self::Mov, Enc::double().src(Src::Zero).dst(Dst::Zero).end()),
+            Self::Pop => (Self::Mov, Enc::double().src(Src::PostInc(Reg::sp)).end()),
+            Self::Br => (Self::Mov, Enc::double().dst(Dst::Direct(Reg::pc)).end()),
+            Self::Ret => (Self::Mov, Enc::double().src(Src::PostInc(Reg::sp)).dst(Dst::Direct(Reg::pc)).end()),
+            Self::Clrc => (Self::Bic, Enc::double().src(Src::One).dst(Dst::Direct(Reg::sr)).end()),
+            Self::Setc => (Self::Bis, Enc::double().src(Src::One).dst(Dst::Direct(Reg::sr)).end()),
+            Self::Clrz => (Self::Bic, Enc::double().src(Src::Two).dst(Dst::Direct(Reg::sr)).end()),
+            Self::Setz => (Self::Bis, Enc::double().src(Src::Two).dst(Dst::Direct(Reg::sr)).end()),
+            Self::Clrn => (Self::Bic, Enc::double().src(Src::Four).dst(Dst::Direct(Reg::sr)).end()),
+            Self::Setn => (Self::Bis, Enc::double().src(Src::Four).dst(Dst::Direct(Reg::sr)).end()),
+            Self::Dint => (Self::Bic, Enc::double().src(Src::Eight).dst(Dst::Direct(Reg::sr)).end()),
+            Self::Eint => (Self::Bis, Enc::double().src(Src::Eight).dst(Dst::Direct(Reg::sr)).end()),
+            Self::Rla => (Self::Add, Enc::reflexive().end()),
+            Self::Rlc => (Self::Addc, Enc::reflexive().end()),
+            Self::Inv => (Self::Xor, Enc::double().src(Src::MinusOne).end()),
+            Self::Clr => (Self::Mov, Enc::double().src(Src::Zero).end()),
+            Self::Tst => (Self::Cmp, Enc::double().src(Src::Zero).end()),
+            Self::Dec => (Self::Sub, Enc::double().src(Src::One).end()),
+            Self::Decd => (Self::Sub, Enc::double().src(Src::Two).end()),
+            Self::Inc => (Self::Add, Enc::double().src(Src::One).end()),
+            Self::Incd => (Self::Add, Enc::double().src(Src::Two).end()),
+            Self::Adc => (Self::Addc, Enc::double().src(Src::Zero).end()),
+            Self::Dadc => (Self::Dadd, Enc::double().src(Src::Zero).end()),
+            Self::Sbc => (Self::Subc, Enc::double().src(Src::Zero).end()),
         }
     }
 }
 
 impl Parsable for Opcode {
-    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(_: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: TokenStream<'text> {
-        stream.expect(Type::Insn)?.parse().map_err(|e: Error| e.context(stream.context()))
+        // TODO: Reintroduce error context
+        stream.expect(Type::Insn)?.parse()
     }
 }
 
 impl FromStr for Opcode {
-    type Err = Error;
+    type Err = ParseError;
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        use Opcode::*;
         //TODO: Reduce allocations here?
         let s = s.to_ascii_lowercase();
         Ok(match s.as_str() {
-            "rrc" => Rrc,
-            "swpb" => Swpb,
-            "rra" => Rra,
-            "sxt" => Sxt,
-            "push" => Push,
-            "call" => Call,
-            "reti" => Reti,
+            "rrc" => Self::Rrc,
+            "swpb" => Self::Swpb,
+            "rra" => Self::Rra,
+            "sxt" => Self::Sxt,
+            "push" => Self::Push,
+            "call" => Self::Call,
+            "reti" => Self::Reti,
 
-            "jne" | "jnz" => Jnz,
-            "jeq" | "jz" => Jz,
-            "jnc" | "jlo" => Jnc,
-            "jc" | "jhs" => Jc,
-            "jn" => Jn,
-            "jge" => Jge,
-            "jl" => Jl,
-            "jmp" => Jmp,
+            "jne" | "jnz" => Self::Jnz,
+            "jeq" | "jz" => Self::Jz,
+            "jnc" | "jlo" => Self::Jnc,
+            "jc" | "jhs" => Self::Jc,
+            "jn" => Self::Jn,
+            "jge" => Self::Jge,
+            "jl" => Self::Jl,
+            "jmp" => Self::Jmp,
 
-            "mov" => Mov,
-            "add" => Add,
-            "addc" => Addc,
-            "subc" => Subc,
-            "sub" => Sub,
-            "cmp" => Cmp,
-            "dadd" => Dadd,
-            "bit" => Bit,
-            "bic" => Bic,
-            "bis" => Bis,
-            "xor" => Xor,
-            "and" => And,
+            "mov" => Self::Mov,
+            "add" => Self::Add,
+            "addc" => Self::Addc,
+            "subc" => Self::Subc,
+            "sub" => Self::Sub,
+            "cmp" => Self::Cmp,
+            "dadd" => Self::Dadd,
+            "bit" => Self::Bit,
+            "bic" => Self::Bic,
+            "bis" => Self::Bis,
+            "xor" => Self::Xor,
+            "and" => Self::And,
 
-            "nop" => Nop,
-            "pop" => Pop,
-            "br" => Br,
-            "ret" => Ret,
-            "clrc" => Clrc,
-            "setc" => Setc,
-            "clrz" => Clrz,
-            "setz" => Setz,
-            "clrn" => Clrn,
-            "setn" => Setn,
-            "dint" => Dint,
-            "eint" => Eint,
-            "rla" => Rla,
-            "rlc" => Rlc,
-            "inv" => Inv,
-            "clr" => Clr,
-            "tst" => Tst,
-            "dec" => Dec,
-            "decd" => Decd,
-            "inc" => Inc,
-            "incd" => Incd,
-            "adc" => Adc,
-            "dadc" => Dadc,
-            "sbc" => Sbc,
-            _ => Err(Error::UnrecognizedOpcode(s))?,
+            "nop" => Self::Nop,
+            "pop" => Self::Pop,
+            "br" => Self::Br,
+            "ret" => Self::Ret,
+            "clrc" => Self::Clrc,
+            "setc" => Self::Setc,
+            "clrz" => Self::Clrz,
+            "setz" => Self::Setz,
+            "clrn" => Self::Clrn,
+            "setn" => Self::Setn,
+            "dint" => Self::Dint,
+            "eint" => Self::Eint,
+            "rla" => Self::Rla,
+            "rlc" => Self::Rlc,
+            "inv" => Self::Inv,
+            "clr" => Self::Clr,
+            "tst" => Self::Tst,
+            "dec" => Self::Dec,
+            "decd" => Self::Decd,
+            "inc" => Self::Inc,
+            "incd" => Self::Incd,
+            "adc" => Self::Adc,
+            "dadc" => Self::Dadc,
+            "sbc" => Self::Sbc,
+            _ => Err(ParseError::UnrecognizedOpcode(s))?,
         })
     }
 }
 
 impl Display for Opcode {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        use Opcode::*;
         write!(
             f,
             "{}",
             match self {
-                Nop => "nop",
-                Pop => "pop",
-                Br => "br",
-                Ret => "ret",
-                Clrc => "clrc",
-                Setc => "setc",
-                Clrz => "clrz",
-                Setz => "setz",
-                Clrn => "clrn",
-                Setn => "setn",
-                Dint => "dint",
-                Eint => "eint",
-                Rla => "rla",
-                Rlc => "rlc",
-                Inv => "inv",
-                Clr => "clr",
-                Tst => "tst",
-                Dec => "dec",
-                Decd => "decd",
-                Inc => "inc",
-                Incd => "incd",
-                Adc => "adc",
-                Dadc => "dadc",
-                Sbc => "sbc",
-                Rrc => "rrc",
-                Swpb => "swpb",
-                Rra => "rra",
-                Sxt => "sxt",
-                Push => "push",
-                Call => "call",
-                Reti => "reti",
-                Jnz => "jnz",
-                Jz => "jz",
-                Jnc => "jnc",
-                Jc => "jc",
-                Jn => "jn",
-                Jge => "jge",
-                Jl => "jl",
-                Jmp => "jmp",
-                Mov => "mov",
-                Add => "add",
-                Addc => "addc",
-                Subc => "subc",
-                Sub => "sub",
-                Cmp => "cmp",
-                Dadd => "dadd",
-                Bit => "bit",
-                Bic => "bic",
-                Bis => "bis",
-                Xor => "xor",
-                And => "and",
+                Self::Nop => "nop",
+                Self::Pop => "pop",
+                Self::Br => "br",
+                Self::Ret => "ret",
+                Self::Clrc => "clrc",
+                Self::Setc => "setc",
+                Self::Clrz => "clrz",
+                Self::Setz => "setz",
+                Self::Clrn => "clrn",
+                Self::Setn => "setn",
+                Self::Dint => "dint",
+                Self::Eint => "eint",
+                Self::Rla => "rla",
+                Self::Rlc => "rlc",
+                Self::Inv => "inv",
+                Self::Clr => "clr",
+                Self::Tst => "tst",
+                Self::Dec => "dec",
+                Self::Decd => "decd",
+                Self::Inc => "inc",
+                Self::Incd => "incd",
+                Self::Adc => "adc",
+                Self::Dadc => "dadc",
+                Self::Sbc => "sbc",
+                Self::Rrc => "rrc",
+                Self::Swpb => "swpb",
+                Self::Rra => "rra",
+                Self::Sxt => "sxt",
+                Self::Push => "push",
+                Self::Call => "call",
+                Self::Reti => "reti",
+                Self::Jnz => "jnz",
+                Self::Jz => "jz",
+                Self::Jnc => "jnc",
+                Self::Jc => "jc",
+                Self::Jn => "jn",
+                Self::Jge => "jge",
+                Self::Jl => "jl",
+                Self::Jmp => "jmp",
+                Self::Mov => "mov",
+                Self::Add => "add",
+                Self::Addc => "addc",
+                Self::Subc => "subc",
+                Self::Sub => "sub",
+                Self::Cmp => "cmp",
+                Self::Dadd => "dadd",
+                Self::Bit => "bit",
+                Self::Bic => "bic",
+                Self::Bis => "bis",
+                Self::Xor => "xor",
+                Self::And => "and",
             }
         )
     }
 }
-
-impl LowerHex for Opcode {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{:04x}", *self as u16) }
-}
diff --git a/src/parser/label.rs b/src/parser/label.rs
index f7e50e4..0b4c484 100644
--- a/src/parser/label.rs
+++ b/src/parser/label.rs
@@ -7,13 +7,12 @@ use super::*;
 pub struct Label(pub Identifier);
 
 impl Parsable for Label {
-    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where T: TokenStream<'text> {
-        Ok(Self(
-            Identifier::parse(p, stream)
-                .and_then(|t| stream.require(Type::Label).and(Ok(t)))
-                .map_err(|e| e.context(stream.context()))?,
-        ))
+        Ok(Self(Identifier::parse(p, stream).and_then(|t| {
+            stream.require(Type::Label)?;
+            Ok(t)
+        })?))
     }
 }
 
diff --git a/src/parser/line.rs b/src/parser/line.rs
new file mode 100644
index 0000000..3e1f7e2
--- /dev/null
+++ b/src/parser/line.rs
@@ -0,0 +1,72 @@
+// © 2023 John Breaux
+//! [`Line`] contains a single subcomponent of the document. Multiple instructions on the same
+//! document line will be treated as if they took up multiple [`Line`s](Line).
+//!
+//! A line contains one of:
+//! - [`Label`]
+//! - [`Instruction`]
+//! - [`Directive`]
+//! - [`Comment`]
+//! - [Nothing](Line::Empty)
+use super::*;
+
+/// A line contains any one of:
+/// - [`Label`] (definition)
+/// - [`Instruction`]
+/// - [`Directive`]
+/// - [`Comment`]
+/// - Nothing at all
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Line {
+    Empty,
+    Insn(Instruction),
+    Comment(Comment),
+    Directive(Directive),
+    Label(Label),
+    EndOfFile, // Expected end of file
+}
+
+impl Parsable for Line {
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
+    where T: TokenStream<'text> {
+        Ok(
+            match stream
+                .peek_expect_any_of([
+                    Type::Endl,
+                    Type::Insn,
+                    Type::Comment,
+                    Type::Directive,
+                    Type::Identifier,
+                    Type::EndOfFile,
+                ])?
+                .variant()
+            {
+                Type::Endl => {
+                    stream.next();
+                    Self::Empty
+                }
+                Type::Insn => Self::Insn(Instruction::parse(p, stream)?),
+                Type::Comment => Self::Comment(Comment::parse(p, stream)?),
+                Type::Directive => Self::Directive(Directive::parse(p, stream)?),
+                Type::Identifier => Self::Label(Label::parse(p, stream)?),
+                Type::EndOfFile => {
+                    stream.next();
+                    Self::EndOfFile
+                }
+                _ => unreachable!("stream.peek_expect_any_of should return Err for unmatched inputs"),
+            },
+        )
+    }
+}
+impl Display for Line {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Empty => writeln!(f, "\n"),
+            Self::Label(arg0) => Display::fmt(arg0, f),
+            Self::Insn(arg0) => Display::fmt(arg0, f),
+            Self::Directive(arg0) => Display::fmt(arg0, f),
+            Self::Comment(arg0) => Display::fmt(arg0, f),
+            Self::EndOfFile => write!(f, "; End of file."),
+        }
+    }
+}
diff --git a/src/parser/parsable.rs b/src/parser/parsable.rs
index 9aaa434..3216ad2 100644
--- a/src/parser/parsable.rs
+++ b/src/parser/parsable.rs
@@ -4,7 +4,7 @@ use super::*;
 /// Parses tokens from [stream](TokenStream) into Self node
 pub trait Parsable {
     /// Parses tokens from [TokenStream](TokenStream) into Self nodes
-    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
     where
         Self: Sized,
         T: TokenStream<'text>;
@@ -12,19 +12,23 @@ pub trait Parsable {
     /// Attempts to parse tokens from [stream](TokenStream) into Self nodes.
     ///
     /// Masks failed expectations.
-    fn try_parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Option<Self>, Error>
+    fn try_parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Option<Self>, ParseError>
     where
         Self: Sized,
         T: TokenStream<'text>,
     {
-        match Self::parse(p, stream).map_err(|e| e.bare()) {
-            Ok(tt) => Ok(Some(tt)),
-            Err(Error::UnexpectedToken { .. }) | Err(Error::AllExpectationsFailed { .. }) => Ok(None),
-            Err(e) => Err(e.context(stream.context())),
+        match Self::parse(p, stream) {
+            Ok(some) => Ok(Some(some)),
+            Err(ParseError::LexError(_)) => Ok(None),
+            Err(e) => Err(e),
         }
     }
 
-    fn parse_and<'text, T, R>(p: &Parser, stream: &mut T, f: fn(p: &Parser, &mut T) -> R) -> Result<(Self, R), Error>
+    fn parse_and<'text, T, R>(
+        p: &Parser,
+        stream: &mut T,
+        f: fn(p: &Parser, &mut T) -> R,
+    ) -> Result<(Self, R), ParseError>
     where
         Self: Sized,
         T: TokenStream<'text>,
@@ -43,3 +47,39 @@ pub trait Parsable {
         Self::parse(p, stream).unwrap_or_default()
     }
 }
+
+macro_rules! parsable_str_types {
+    ($($t:ty),*$(,)?) => {$(
+        impl Parsable for $t {
+            fn parse<'text, T>(_p: &Parser, stream: &mut T) -> Result<Self, ParseError>
+            where T: TokenStream<'text> {
+                Ok(stream.expect(Type::String)?.lexeme().trim_matches('"').into())
+            }
+        }
+    )*};
+}
+use std::{path::PathBuf, rc::Rc};
+parsable_str_types![String, Rc<str>, Box<str>, PathBuf];
+
+/// Vectors of arbitrary parsables are cool
+impl<P: Parsable> Parsable for Vec<P> {
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
+    where T: TokenStream<'text> {
+        // [dead beef]
+        // [A, B,]
+        // [c d e f]
+        // [ something
+        //   else      ]
+
+        stream.require(Type::LBracket)?;
+        stream.allow(Type::Endl);
+        let mut out = vec![];
+        while let Some(t) = P::try_parse(p, stream)? {
+            out.push(t);
+            stream.allow(Type::Separator);
+            stream.allow(Type::Endl);
+        }
+        stream.require(Type::RBracket)?;
+        Ok(out)
+    }
+}
diff --git a/src/parser/root.rs b/src/parser/root.rs
new file mode 100644
index 0000000..62341f3
--- /dev/null
+++ b/src/parser/root.rs
@@ -0,0 +1,51 @@
+use std::path::{Path, PathBuf};
+
+// © 2023 John Breaux
+use super::*;
+
+/// Contains the entire AST
+#[derive(Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Root(Option<PathBuf>, Vec<(usize, Line)>);
+// pub struct Root { pub path: PathBuf, pub lines: Vec<Line> }
+
+impl Root {
+    pub fn file(&self) -> Option<&Path> { self.0.as_deref() }
+    pub(crate) fn set_file(mut self, path: PathBuf) -> Self {
+        self.0 = Some(path);
+        self
+    }
+    pub fn lines(&self) -> &[(usize, Line)] { &self.1 }
+}
+
+impl Parsable for Root {
+    fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, ParseError>
+    where T: TokenStream<'text> {
+        let mut lines = vec![];
+        loop {
+            let number = stream.context().line();
+            match Line::parse(p, stream)? {
+                Line::EndOfFile => break,
+                line => lines.push((number, line)),
+            }
+        }
+        Ok(Root(None, lines))
+    }
+}
+
+impl Display for Root {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        for (num, line) in &self.1 {
+            f.pad(&format!("{num:3}: {line} "))?;
+        }
+        Ok(())
+    }
+}
+
+impl Debug for Root {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        for line in self.0.iter() {
+            Debug::fmt(line, f)?;
+        }
+        Ok(())
+    }
+}
diff --git a/valid.asm b/valid.asm
index 5dc88b6..c32ac7b 100755
--- a/valid.asm
+++ b/valid.asm
@@ -2,6 +2,16 @@
 ; examples of valid assembly
 ;
 
+; testing labels
+jmp main
+
+; testing directives
+.string "ABA"
+.string "ABAB"
+.word 0b0101101001011010
+.words [dead beef]
+
+main:
 ; testing defines
 .define asdfgh #1000
 .define qwerty @sp+
@@ -132,7 +142,7 @@ mov #beef, sp
 mov #beef, sr
 mov #beef, cg
 
-; jmp _register_mode ; TODO: msp430_asm currently has no support for jump labels.
+jmp _register_mode
 jmp 3fe
 jmp -3fc
 ret