AnyRange: Add AnyRange for taking any range in error

src/cpu.rs

@@ -476,22 +476,27 @@ impl CPU {
             return Ok(self);
         }
         self.cycle += 1;
+        let opchunk = self
+            .screen
+            .get(self.pc as usize..)
+            .ok_or(Error::InvalidAddressRange {
+                range: (self.pc as usize..).into(),
+            })?;
         // fetch opcode
-        let opcode: &[u8; 2] = if let Some(slice) = bus.get(self.pc as usize..self.pc as usize + 2)
-        {
-            slice
-                .try_into()
-                .expect("`slice` should be exactly 2 bytes.")
-        } else {
-            return Err(Error::InvalidAddressRange {
-                range: self.pc as usize..self.pc as usize + 2,
-            });
-        };
+        let opcode: &[u8; 2] =
+            if let Some(slice) = self.screen.get(self.pc as usize..self.pc as usize + 2) {
+                slice
+                    .try_into()
+                    .expect("`slice` should be exactly 4 bytes.")
+            } else {
+                return Err(Error::InvalidAddressRange {
+                    range: (self.pc as usize..self.pc as usize + 4).into(),
+                });
+            };
 
         // Print opcode disassembly:
         if self.flags.debug {
-            self.timers.insn = Instant::now();
-            std::print!(
+            std::println!(
                 "{:3} {:03x}: {:<36}",
                 self.cycle.bright_black(),
                 self.pc,

src/error.rs

@@ -3,7 +3,8 @@
 
 //! Error type for Chirp
 
-use std::ops::Range;
+pub mod any_range;
+use any_range::AnyRange;
 
 use crate::cpu::bus::Region;
 use thiserror::Error;
@@ -15,7 +16,7 @@ pub type Result<T> = std::result::Result<T, Error>;
 #[derive(Debug, Error)]
 pub enum Error {
     /// Represents a breakpoint being hit
-    #[error("Breakpoint hit: {addr:03x} ({next:04x})")]
+    #[error("breakpoint hit: {addr:03x} ({next:04x})")]
     BreakpointHit {
         /// The address of the breakpoint
         addr: u16,
@@ -23,37 +24,37 @@ pub enum Error {
         next: u16,
     },
     /// Represents an unimplemented operation
-    #[error("Unrecognized opcode: {word:04x}")]
+    #[error("opcode {word:04x} not recognized")]
     UnimplementedInstruction {
         /// The offending word
         word: u16,
     },
     /// The region you asked for was not defined
-    #[error("No {region} found on bus")]
+    #[error("region {region} is not present on bus")]
     MissingRegion {
         /// The offending [Region]
         region: Region,
     },
-    /// Tried to fetch [Range] from bus, received nothing
-    #[error("Invalid range {range:04x?} for bus")]
+    /// Tried to fetch data at [AnyRange] from bus, received nothing
+    #[error("range {range:04x?} is not present on bus")]
     InvalidAddressRange {
-        /// The offending [Range]
-        range: Range<usize>,
+        /// The offending [AnyRange]
+        range: AnyRange<usize>,
     },
     /// Tried to press a key that doesn't exist
-    #[error("Invalid key: {key:X}")]
+    #[error("tried to press key {key:X} which does not exist")]
     InvalidKey {
         /// The offending key
         key: usize,
     },
     /// Tried to get/set an out-of-bounds register
-    #[error("Invalid register: v{reg:X}")]
+    #[error("tried to access register v{reg:X} which does not exist")]
     InvalidRegister {
         /// The offending register
         reg: usize,
     },
     /// Tried to convert string into mode, but it did not match.
-    #[error("Invalid mode: {mode}")]
+    #[error("no suitable conversion of \"{mode}\" into Mode")]
     InvalidMode {
         /// The string which failed to become a mode
         mode: String,

src/error/any_range.rs

@@ -0,0 +1,69 @@
+// (c) 2023 John A. Breaux
+// This code is licensed under MIT license (see LICENSE for details)
+
+//! Holder for any [Range]
+
+// This is super over-engineered, considering it was originally meant to help with only one LOC
+use std::ops::{Range, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive};
+use thiserror::Error;
+
+#[macro_use]
+mod macros;
+
+#[derive(Clone, Debug, Error, PartialEq, Eq, Hash)]
+#[error("Failed to convert variant {0} back into range.")]
+/// Emitted when conversion back into a [std::ops]::Range\* fails.
+pub struct AnyRangeError<Idx>(AnyRange<Idx>);
+
+/// Holder for any [Range]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum AnyRange<Idx> {
+    /// Bounded exclusive [Range] i.e. `0..10`
+    Range(Range<Idx>),
+    /// Unbounded [RangeFrom], i.e. `0..`
+    RangeFrom(RangeFrom<Idx>),
+    /// Unbounded [RangeFull], i.e. `..`
+    RangeFull(RangeFull),
+    /// Bounded inclusive [RangeInclusive], i.e. `0..=10`
+    RangeInclusive(RangeInclusive<Idx>),
+    /// Unbounded [RangeTo], i.e. `..10`
+    RangeTo(RangeTo<Idx>),
+    /// Unbounded inclusive [RangeToInclusive], i.e. `..=10`
+    RangeToInclusive(RangeToInclusive<Idx>),
+}
+
+variant_from! {
+    match impl<Idx> (From, TryInto) for AnyRange<Idx> {
+        type Error = AnyRangeError<Idx>;
+        Range<Idx> => AnyRange::Range,
+        RangeFrom<Idx> => AnyRange::RangeFrom,
+        RangeFull => AnyRange::RangeFull,
+        RangeInclusive<Idx> => AnyRange::RangeInclusive,
+        RangeTo<Idx> => AnyRange::RangeTo,
+        RangeToInclusive<Idx> => AnyRange::RangeToInclusive,
+    }
+}
+
+/// Convenient conversion functions from [AnyRange] to the inner type
+impl<Idx> AnyRange<Idx> {
+    try_into_fn! {
+        /// Converts from [AnyRange::Range] into a [Range], else [None]
+        pub fn range(self) -> Option<Range<Idx>>;
+        /// Converts from [AnyRange::RangeFrom] into a [RangeFrom], else [None]
+        pub fn range_from(self) -> Option<RangeFrom<Idx>>;
+        /// Converts from [AnyRange::RangeFull] into a [RangeFull], else [None]
+        pub fn range_full(self) -> Option<RangeFull>;
+        /// Converts from [AnyRange::RangeInclusive] into a [RangeInclusive], else [None]
+        pub fn range_inclusive(self) -> Option<RangeInclusive<Idx>>;
+        /// Converts from [AnyRange::RangeTo] into a [RangeTo], else [None]
+        pub fn range_to(self) -> Option<RangeTo<Idx>>;
+        /// Converts from [AnyRange::RangeToInclusive] into a [RangeToInclusive], else [None]
+        pub fn range_to_inclusive(self) -> Option<RangeToInclusive<Idx>>;
+    }
+}
+
+impl<Idx> From<AnyRange<Idx>> for AnyRangeError<Idx> {
+    fn from(value: AnyRange<Idx>) -> Self {
+        AnyRangeError(value)
+    }
+}

src/error/any_range/macros.rs

@@ -0,0 +1,33 @@
+//! Macros for AnyRange
+
+/// Generate From and TryFrom impls for each variant
+macro_rules! variant_from {(
+    match impl<$T:ident> $_:tt for $enum:path {
+        type Error = $error:path;
+        $($src:path => $variant:path),+$(,)?
+    }
+) => {
+    // The forward direction is infallible
+    $(impl<$T> From<$src> for $enum {
+        fn from(value: $src) -> Self { $variant(value) }
+    })+
+    // The reverse direction could fail if the $variant doesn't hold $src
+    $(impl<$T> TryFrom<$enum> for $src {
+        type Error = $error;
+        fn try_from(value: $enum) -> Result<Self, Self::Error> {
+            if let $variant(r) = value { Ok(r) } else { Err(value.into()) }
+        }
+    })+
+}}
+
+/// Turns a list of function prototypes into functions which use [TryInto], returning [Option]
+///
+/// # Examples
+/// ```rust,ignore
+/// try_into_fn! { fn range(self) -> Option<Other>; }
+/// ```
+macro_rules! try_into_fn {
+    ($($(#[$doc:meta])? $pub:vis fn $name:ident $args:tt -> $ret:ty);+ $(;)?) => {
+        $($(#[$doc])? $pub fn $name $args -> $ret { $args.try_into().ok() })+
+    }
+}