scanner/anchor: cache! before fetch

src/scanner/anchor.rs

@@ -1,5 +1,6 @@
 use super::{
     error::{ScanError, ScanResult as Result},
+    flag::Flags,
     stats::MStats,
     ALIAS, ANCHOR,
 };
@@ -8,6 +9,7 @@ use crate::token::Token;
 /// Scan an anchor or alias from the underlying .buffer
 /// returning the relevant Token
 pub(in crate::scanner) fn scan_anchor<'de>(
+    opts: Flags,
     buffer: &mut &'de str,
     stats: &mut MStats,
     kind: &AnchorKind,
@@ -17,7 +19,7 @@ pub(in crate::scanner) fn scan_anchor<'de>(
 
     // *anchor 'rest of the line'
     //  ^^^^^^
-    let anchor = take_while(buffer.as_bytes(), u8::is_ascii_alphanumeric);
+    let anchor = take_while(opts, buffer.as_bytes(), u8::is_ascii_alphanumeric)?;
 
     let anchor = advance!(<- *buffer, :stats, anchor.len());
 
@@ -33,6 +35,7 @@ pub(in crate::scanner) fn scan_anchor<'de>(
     // There does not necessarily need to be a whitespace so we
     // also check against a list of valid starting
     // tokens
+    cache!(~buffer, 1, opts)?;
     check!(~buffer
         => b' ' | b'\n' | b'?' | b',' | b']' | b'}' | b'%' | b'@' | b'`',
         else ScanError::InvalidAnchorName
@@ -73,7 +76,7 @@ impl AnchorKind
     }
 }
 
-fn take_while<F>(b: &[u8], f: F) -> &[u8]
+fn take_while<F>(opts: Flags, base: &[u8], f: F) -> Result<&[u8]>
 where
     F: Fn(&u8) -> bool,
 {
@@ -81,10 +84,12 @@ where
 
     loop
     {
-        match b.get(index)
+        let i = cache!(base, @index, 1, opts)?;
+
+        match base.get(index)
         {
-            Some(b) if f(b) => index += 1,
-            _ => return &b[..index],
+            Some(b) if f(b) => index += i,
+            _ => return Ok(&base[..index]),
         }
     }
 }

src/scanner/mod.rs

@@ -178,7 +178,7 @@ impl Scanner
             },
 
             // Is it an anchor or alias?
-            [ANCHOR, ..] | [ALIAS, ..] => self.fetch_anchor(base, tokens),
+            [ANCHOR, ..] | [ALIAS, ..] => self.fetch_anchor(opts, base, tokens),
 
             // Is it a tag?
             [TAG, ..] => self.fetch_tag(opts, base, tokens),
@@ -353,7 +353,12 @@ impl Scanner
         Ok(())
     }
 
-    fn fetch_anchor<'de>(&mut self, base: &mut &'de str, tokens: &mut Tokens<'de>) -> Result<()>
+    fn fetch_anchor<'de>(
+        &mut self,
+        opts: Flags,
+        base: &mut &'de str,
+        tokens: &mut Tokens<'de>,
+    ) -> Result<()>
     {
         let mut buffer = *base;
         let mut stats = MStats::new();
@@ -373,7 +378,7 @@ impl Scanner
         self.save_key(!REQUIRED)?;
 
         // Scan the token from the .buffer
-        let token = scan_anchor(&mut buffer, &mut stats, &kind)?;
+        let token = scan_anchor(opts, &mut buffer, &mut stats, &kind)?;
 
         // A key may not start after an anchor (only before)
         self.simple_key_allowed = false;