Cleanup unused Source features (#335)

* Remove unused test_at method

* Simplify Source, read_unchecked is only ever used on single byte

logos-codegen/src/generator/context.rs

@@ -59,21 +59,12 @@ impl Context {
         self.available.saturating_sub(self.at)
     }
 
-    pub fn read_unchecked(&mut self, len: usize) -> TokenStream {
+    pub fn read_byte_unchecked(&mut self) -> TokenStream {
         let at = self.at;
 
-        match len {
-            0 => {
-                self.advance(1);
+        self.advance(1);
 
-                quote!(lex.read_unchecked::<u8>(#at))
-            }
-            l => {
-                self.advance(l);
-
-                quote!(lex.read_unchecked::<&[u8; #l]>(#at))
-            }
-        }
+        quote!(lex.read_byte_unchecked(#at))
     }
 
     pub fn read(&mut self, len: usize) -> TokenStream {

logos-codegen/src/generator/fork.rs

@@ -127,7 +127,7 @@ impl<'a> Generator<'a> {
         let min_read = self.meta[this].min_read;
 
         if ctx.remainder() >= max(min_read, 1) {
-            let read = ctx.read_unchecked(0);
+            let read = ctx.read_byte_unchecked();
 
             return (quote!(byte), quote!(let byte = unsafe { #read };));
         }

src/internal.rs

@@ -16,15 +16,12 @@ pub trait LexerInternal<'source> {
     /// Read a chunk at current position, offset by `n`.
     fn read_at<T: Chunk<'source>>(&self, n: usize) -> Option<T>;
 
-    /// Unchecked read a chunk at current position, offset by `n`.
-    unsafe fn read_unchecked<T: Chunk<'source>>(&self, n: usize) -> T;
+    /// Unchecked read a byte at current position, offset by `n`.
+    unsafe fn read_byte_unchecked(&self, n: usize) -> u8;
 
     /// Test a chunk at current position with a closure.
     fn test<T: Chunk<'source>, F: FnOnce(T) -> bool>(&self, test: F) -> bool;
 
-    /// Test a chunk at current position offset by `n` with a closure.
-    fn test_at<T: Chunk<'source>, F: FnOnce(T) -> bool>(&self, n: usize, test: F) -> bool;
-
     /// Bump the position by `size`.
     fn bump_unchecked(&mut self, size: usize);
 

src/lexer.rs

@@ -302,11 +302,8 @@ where
     }
 
     #[inline]
-    unsafe fn read_unchecked<Chunk>(&self, n: usize) -> Chunk
-    where
-        Chunk: source::Chunk<'source>,
-    {
-        self.source.read_unchecked(self.token_end + n)
+    unsafe fn read_byte_unchecked(&self, n: usize) -> u8 {
+        self.source.read_byte_unchecked(self.token_end + n)
     }
 
     /// Test a chunk at current position with a closure.
@@ -322,19 +319,6 @@ where
         }
     }
 
-    /// Test a chunk at current position offset by `n` with a closure.
-    #[inline]
-    fn test_at<T, F>(&self, n: usize, test: F) -> bool
-    where
-        T: source::Chunk<'source>,
-        F: FnOnce(T) -> bool,
-    {
-        match self.source.read::<T>(self.token_end + n) {
-            Some(chunk) => test(chunk),
-            None => false,
-        }
-    }
-
     /// Bump the position `Lexer` is reading from by `size`.
     #[inline]
     fn bump_unchecked(&mut self, size: usize) {

src/source.rs

@@ -43,14 +43,12 @@ pub trait Source {
     where
         Chunk: self::Chunk<'a>;
 
-    /// Read a chunk of bytes into an array without doing bounds checks.
+    /// Read a byte without doing bounds checks.
     ///
     /// # Safety
     ///
     /// Offset should not exceed bounds.
-    unsafe fn read_unchecked<'a, Chunk>(&'a self, offset: usize) -> Chunk
-    where
-        Chunk: self::Chunk<'a>;
+    unsafe fn read_byte_unchecked(&self, offset: usize) -> u8;
 
     /// Get a slice of the source at given range. This is analogous to
     /// `slice::get(range)`.
@@ -119,10 +117,7 @@ impl Source for str {
     }
 
     #[inline]
-    unsafe fn read_unchecked<'a, Chunk>(&'a self, offset: usize) -> Chunk
-    where
-        Chunk: self::Chunk<'a>,
-    {
+    unsafe fn read_byte_unchecked(&self, offset: usize) -> u8 {
         Chunk::from_ptr(self.as_ptr().add(offset))
     }
 
@@ -179,10 +174,7 @@ impl Source for [u8] {
     }
 
     #[inline]
-    unsafe fn read_unchecked<'a, Chunk>(&'a self, offset: usize) -> Chunk
-    where
-        Chunk: self::Chunk<'a>,
-    {
+    unsafe fn read_byte_unchecked(&self, offset: usize) -> u8 {
         Chunk::from_ptr(self.as_ptr().add(offset))
     }
 
@@ -232,11 +224,8 @@ where
         self.deref().read(offset)
     }
 
-    unsafe fn read_unchecked<'a, Chunk>(&'a self, offset: usize) -> Chunk
-    where
-        Chunk: self::Chunk<'a>,
-    {
-        self.deref().read_unchecked(offset)
+    unsafe fn read_byte_unchecked(&self, offset: usize) -> u8 {
+        self.deref().read_byte_unchecked(offset)
     }
 
     fn slice(&self, range: Range<usize>) -> Option<Self::Slice<'_>> {

tests/tests/source.rs

@@ -19,11 +19,8 @@ impl<'s, S: ?Sized + Source> Source for RefSource<'s, S> {
         self.0.read(offset)
     }
 
-    unsafe fn read_unchecked<'a, Chunk>(&'a self, offset: usize) -> Chunk
-    where
-        Chunk: logos::source::Chunk<'a>,
-    {
-        self.0.read_unchecked(offset)
+    unsafe fn read_byte_unchecked(&self, offset: usize) -> u8 {
+        self.0.read_byte_unchecked(offset)
     }
 
     fn slice(&self, range: Range<usize>) -> Option<Self::Slice<'_>> {