Auto merge of servo#193 - servo:…, r=SimonSapin

Use an array instead of `match` for hexadecimal digits.

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Author: bors-servo

src/parser.rs

@@ -788,10 +788,10 @@ pub fn parse_until_before<'i: 't, 't, F, T, E>(parser: &mut Parser<'i, 't>,
     }
     // FIXME: have a special-purpose tokenizer method for this that does less work.
     loop {
-        if delimiters.contains(Delimiters::from_byte((parser.input.tokenizer).next_byte())) {
+        if delimiters.contains(Delimiters::from_byte(parser.input.tokenizer.next_byte())) {
             break
         }
-        if let Ok(token) = (parser.input.tokenizer).next() {
+        if let Ok(token) = parser.input.tokenizer.next() {
             if let Some(block_type) = BlockType::opening(&token) {
                 consume_until_end_of_block(block_type, &mut parser.input.tokenizer);
             }
@@ -808,11 +808,11 @@ pub fn parse_until_after<'i: 't, 't, F, T, E>(parser: &mut Parser<'i, 't>,
                                               -> Result <T, ParseError<'i, E>>
     where F: for<'tt> FnOnce(&mut Parser<'i, 'tt>) -> Result<T, ParseError<'i, E>> {
     let result = parser.parse_until_before(delimiters, parse);
-    let next_byte = (parser.input.tokenizer).next_byte();
+    let next_byte = parser.input.tokenizer.next_byte();
     if next_byte.is_some() && !parser.stop_before.contains(Delimiters::from_byte(next_byte)) {
         debug_assert!(delimiters.contains(Delimiters::from_byte(next_byte)));
         // We know this byte is ASCII.
-        (parser.input.tokenizer).advance(1);
+        parser.input.tokenizer.advance(1);
         if next_byte == Some(b'{') {
             consume_until_end_of_block(BlockType::CurlyBracket, &mut parser.input.tokenizer);
         }

src/serializer.rs

@@ -132,23 +132,17 @@ impl<'a> ToCss for Token<'a> {
     }
 }
 
-fn to_hex_byte(value: u8) -> u8 {
-    match value {
-        0...9 => value + b'0',
-        _ => value - 10 + b'a',
-    }
-}
-
 fn hex_escape<W>(ascii_byte: u8, dest: &mut W) -> fmt::Result where W:fmt::Write {
-    let high = ascii_byte >> 4;
+    static HEX_DIGITS: &'static [u8; 16] = b"0123456789abcdef";
     let b3;
     let b4;
-    let bytes = if high > 0 {
-        let low = ascii_byte & 0x0F;
-        b4 = [b'\\', to_hex_byte(high), to_hex_byte(low), b' '];
+    let bytes = if ascii_byte > 0x0F {
+        let high = (ascii_byte >> 4) as usize;
+        let low = (ascii_byte & 0x0F) as usize;
+        b4 = [b'\\', HEX_DIGITS[high], HEX_DIGITS[low], b' '];
         &b4[..]
     } else {
-        b3 = [b'\\', to_hex_byte(ascii_byte), b' '];
+        b3 = [b'\\', HEX_DIGITS[ascii_byte as usize], b' '];
         &b3[..]
     };
     dest.write_str(unsafe { str::from_utf8_unchecked(&bytes) })