From d4432cda7ad3117d5dce66797f7178c0c76900f9 Mon Sep 17 00:00:00 2001
From: John <j@soft.fish>
Date: Wed, 24 Apr 2024 19:52:56 -0500
Subject: [PATCH] cl-structures: Give the StringArena a new home.

---
 compiler/cl-structures/src/arena.rs           | 51 +------------------
 compiler/cl-structures/src/arena/intern.rs    |  2 +-
 .../cl-structures/src/arena/string_arena.rs   | 48 +++++++++++++++++
 3 files changed, 51 insertions(+), 50 deletions(-)
 create mode 100644 compiler/cl-structures/src/arena/string_arena.rs

diff --git a/compiler/cl-structures/src/arena.rs b/compiler/cl-structures/src/arena.rs
index 2baa4f4..ca1e1cb 100644
--- a/compiler/cl-structures/src/arena.rs
+++ b/compiler/cl-structures/src/arena.rs
@@ -1,54 +1,7 @@
-//! Simple, long-lived string buffer
-
-use std::marker::PhantomData;
-use symbol::Symbol;
+//! Simple arena-like allocation
 
 pub mod global_intern;
 pub mod intern;
+pub mod string_arena;
 pub mod symbol;
 
-/// Compactly stores a set of immutable strings, producing a [Symbol] for each one
-#[derive(Debug)]
-pub struct StringArena<T: Symbol> {
-    ends: Vec<usize>,
-    buf: String,
-    _t: PhantomData<fn(T)>,
-}
-
-impl<T: Symbol> StringArena<T> {
-    pub fn new() -> Self {
-        Default::default()
-    }
-    /// # May panic
-    /// Panics if Symbol::from_usize would panic
-    fn next_key(&self) -> T {
-        Symbol::from_usize(self.ends.len())
-    }
-
-    fn get_span(&self, key: T) -> Option<(usize, usize)> {
-        let key = key.into_usize();
-        Some((*self.ends.get(key - 1)?, *self.ends.get(key)?))
-    }
-
-    pub fn get(&self, key: T) -> Option<&str> {
-        let (start, end) = self.get_span(key)?;
-        // Safety: start and end offsets were created by push_string
-        Some(unsafe { self.buf.get_unchecked(start..end) })
-    }
-
-    pub fn push_string(&mut self, s: &str) -> T {
-        if self.ends.is_empty() {
-            self.ends.push(self.buf.len())
-        }
-        let key = self.next_key();
-        self.buf.push_str(s);
-        self.ends.push(self.buf.len());
-        key
-    }
-}
-
-impl<T: Symbol> Default for StringArena<T> {
-    fn default() -> Self {
-        Self { ends: Default::default(), buf: Default::default(), _t: PhantomData }
-    }
-}
diff --git a/compiler/cl-structures/src/arena/intern.rs b/compiler/cl-structures/src/arena/intern.rs
index 71b0ee0..139d22d 100644
--- a/compiler/cl-structures/src/arena/intern.rs
+++ b/compiler/cl-structures/src/arena/intern.rs
@@ -1,6 +1,6 @@
 //! A string interner with deduplication
 
-use super::{symbol::Symbol, StringArena};
+use super::{string_arena::StringArena, symbol::Symbol};
 use hashbrown::hash_table::HashTable;
 use std::hash::{BuildHasher, RandomState};
 
diff --git a/compiler/cl-structures/src/arena/string_arena.rs b/compiler/cl-structures/src/arena/string_arena.rs
new file mode 100644
index 0000000..38ace17
--- /dev/null
+++ b/compiler/cl-structures/src/arena/string_arena.rs
@@ -0,0 +1,48 @@
+//! Compactly stores a set of immutable strings, producing a [Symbol] for each one
+use super::symbol::Symbol;
+use std::marker::PhantomData;
+/// Compactly stores a set of immutable strings, producing a [Symbol] for each one
+#[derive(Debug)]
+pub struct StringArena<T: Symbol> {
+    ends: Vec<usize>,
+    buf: String,
+    _t: PhantomData<fn(T)>,
+}
+
+impl<T: Symbol> StringArena<T> {
+    pub fn new() -> Self {
+        Default::default()
+    }
+    /// # May panic
+    /// Panics if Symbol::from_usize would panic
+    fn next_key(&self) -> T {
+        Symbol::from_usize(self.ends.len())
+    }
+
+    fn get_span(&self, key: T) -> Option<(usize, usize)> {
+        let key = key.into_usize();
+        Some((*self.ends.get(key - 1)?, *self.ends.get(key)?))
+    }
+
+    pub fn get(&self, key: T) -> Option<&str> {
+        let (start, end) = self.get_span(key)?;
+        // Safety: start and end offsets were created by push_string
+        Some(unsafe { self.buf.get_unchecked(start..end) })
+    }
+
+    pub fn push_string(&mut self, s: &str) -> T {
+        if self.ends.is_empty() {
+            self.ends.push(self.buf.len())
+        }
+        let key = self.next_key();
+        self.buf.push_str(s);
+        self.ends.push(self.buf.len());
+        key
+    }
+}
+
+impl<T: Symbol> Default for StringArena<T> {
+    fn default() -> Self {
+        Self { ends: Default::default(), buf: Default::default(), _t: PhantomData }
+    }
+}