iter: slice::Iter<'a, u8>
}
-// Return the initial codepoint accumulator for the first byte.
-// The first byte is special, only want bottom 5 bits for width 2, 4 bits
-// for width 3, and 3 bits for width 4
-macro_rules! utf8_first_byte {
- ($byte:expr, $width:expr) => (($byte & (0x7F >> $width)) as u32)
-}
+/// Return the initial codepoint accumulator for the first byte.
+/// The first byte is special, only want bottom 5 bits for width 2, 4 bits
+/// for width 3, and 3 bits for width 4.
+#[inline]
+fn utf8_first_byte(byte: u8, width: u32) -> u32 { (byte & (0x7F >> width)) as u32 }
-// return the value of $ch updated with continuation byte $byte
-macro_rules! utf8_acc_cont_byte {
- ($ch:expr, $byte:expr) => (($ch << 6) | ($byte & CONT_MASK) as u32)
-}
+/// Return the value of `ch` updated with continuation byte `byte`.
+#[inline]
+fn utf8_acc_cont_byte(ch: u32, byte: u8) -> u32 { (ch << 6) | (byte & CONT_MASK) as u32 }
-macro_rules! utf8_is_cont_byte {
- ($byte:expr) => (($byte & !CONT_MASK) == TAG_CONT_U8)
-}
+/// Checks whether the byte is a UTF-8 continuation byte (i.e. starts with the
+/// bits `10`).
+#[inline]
+fn utf8_is_cont_byte(byte: u8) -> bool { (byte & !CONT_MASK) == TAG_CONT_U8 }
#[inline]
fn unwrap_or_0(opt: Option<&u8>) -> u8 {
// Multibyte case follows
// Decode from a byte combination out of: [[[x y] z] w]
// NOTE: Performance is sensitive to the exact formulation here
- let init = utf8_first_byte!(x, 2);
+ let init = utf8_first_byte(x, 2);
let y = unwrap_or_0(bytes.next());
- let mut ch = utf8_acc_cont_byte!(init, y);
+ let mut ch = utf8_acc_cont_byte(init, y);
if x >= 0xE0 {
// [[x y z] w] case
// 5th bit in 0xE0 .. 0xEF is always clear, so `init` is still valid
let z = unwrap_or_0(bytes.next());
- let y_z = utf8_acc_cont_byte!((y & CONT_MASK) as u32, z);
+ let y_z = utf8_acc_cont_byte((y & CONT_MASK) as u32, z);
ch = init << 12 | y_z;
if x >= 0xF0 {
// [x y z w] case
// use only the lower 3 bits of `init`
let w = unwrap_or_0(bytes.next());
- ch = (init & 7) << 18 | utf8_acc_cont_byte!(y_z, w);
+ ch = (init & 7) << 18 | utf8_acc_cont_byte(y_z, w);
}
}
// Decode from a byte combination out of: [x [y [z w]]]
let mut ch;
let z = unwrap_or_0(bytes.next_back());
- ch = utf8_first_byte!(z, 2);
- if utf8_is_cont_byte!(z) {
+ ch = utf8_first_byte(z, 2);
+ if utf8_is_cont_byte(z) {
let y = unwrap_or_0(bytes.next_back());
- ch = utf8_first_byte!(y, 3);
- if utf8_is_cont_byte!(y) {
+ ch = utf8_first_byte(y, 3);
+ if utf8_is_cont_byte(y) {
let x = unwrap_or_0(bytes.next_back());
- ch = utf8_first_byte!(x, 4);
- ch = utf8_acc_cont_byte!(ch, y);
+ ch = utf8_first_byte(x, 4);
+ ch = utf8_acc_cont_byte(ch, y);
}
- ch = utf8_acc_cont_byte!(ch, z);
+ ch = utf8_acc_cont_byte(ch, z);
}
- ch = utf8_acc_cont_byte!(ch, w);
+ ch = utf8_acc_cont_byte(ch, w);
Some(ch)
}
// ASCII characters are always valid, so only large
// bytes need more examination.
if first >= 128 {
- let w = UTF8_CHAR_WIDTH[first as usize] as usize;
+ let w = UTF8_CHAR_WIDTH[first as usize];
let second = next!();
// 2-byte encoding is for codepoints \u{0080} to \u{07ff}
// first C2 80 last DF BF
i -= 1;
}
- let mut val = s.as_bytes()[i] as u32;
- let w = UTF8_CHAR_WIDTH[val as usize] as usize;
- assert!((w != 0));
+ let first= s.as_bytes()[i];
+ let w = UTF8_CHAR_WIDTH[first as usize];
+ assert!(w != 0);
- val = utf8_first_byte!(val, w);
- val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 1]);
- if w > 2 { val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 2]); }
- if w > 3 { val = utf8_acc_cont_byte!(val, s.as_bytes()[i + 3]); }
+ let mut val = utf8_first_byte(first, w as u32);
+ val = utf8_acc_cont_byte(val, s.as_bytes()[i + 1]);
+ if w > 2 { val = utf8_acc_cont_byte(val, s.as_bytes()[i + 2]); }
+ if w > 3 { val = utf8_acc_cont_byte(val, s.as_bytes()[i + 3]); }
return CharRange {ch: unsafe { mem::transmute(val) }, next: i};
}
// Multibyte case is a fn to allow char_range_at to inline cleanly
fn multibyte_char_range_at(bytes: &[u8], i: usize) -> (u32, usize) {
- let mut val = bytes[i] as u32;
- let w = UTF8_CHAR_WIDTH[val as usize] as usize;
- assert!((w != 0));
+ let first = bytes[i];
+ let w = UTF8_CHAR_WIDTH[first as usize];
+ assert!(w != 0);
- val = utf8_first_byte!(val, w);
- val = utf8_acc_cont_byte!(val, bytes[i + 1]);
- if w > 2 { val = utf8_acc_cont_byte!(val, bytes[i + 2]); }
- if w > 3 { val = utf8_acc_cont_byte!(val, bytes[i + 3]); }
+ let mut val = utf8_first_byte(first, w as u32);
+ val = utf8_acc_cont_byte(val, bytes[i + 1]);
+ if w > 2 { val = utf8_acc_cont_byte(val, bytes[i + 2]); }
+ if w > 3 { val = utf8_acc_cont_byte(val, bytes[i + 3]); }
- return (val, i + w);
+ return (val, i + w as usize);
}
multibyte_char_range_at(bytes, i)