utf8CountCodepoints
Returns the length of a supplied UTF-8 string literal in terms of unicode codepoints.
Function parameters
Parameters
- s:[]const u8
Utf8View iterates the code points of a utf-8 encoded string.
Types
- Utf8View
- Utf8View iterates the code points of a utf-8 encoded string.
- Wtf8View
- Wtf8View iterates the code points of a WTF-8 encoded string,
- Wtf8Iterator
- Asserts that `bytes` is valid WTF-8
Returns how many bytes the UTF-8 representation would require
Functions
- utf8CodepointSequenceLength
- Returns how many bytes the UTF-8 representation would require
- utf8ByteSequenceLength
- Given the first byte of a UTF-8 codepoint,
- utf8Encode
- Encodes the given codepoint into a UTF-8 byte sequence.
- utf8Decode
- Deprecated.
- utf8ValidCodepoint
- Returns true if the given unicode codepoint can be encoded in UTF-8.
- utf8CountCodepoints
- Returns the length of a supplied UTF-8 string literal in terms of unicode
- utf8ValidateSlice
- Returns true if the input consists entirely of UTF-8 codepoints
- utf16CodepointSequenceLength
- Returns how many code units the UTF-16 representation would require
- utf16CodeUnitSequenceLength
- Given the first code unit of a UTF-16 codepoint, returns a number 1-2
- utf16DecodeSurrogatePair
- Decodes the codepoint encoded in the given pair of UTF-16 code units.
- utf16CountCodepoints
- Returns the length of a supplied UTF-16 string literal in terms of unicode
- fmtUtf8
- Return a Formatter for a (potentially ill-formed) UTF-8 string.
- utf16LeToUtf8Alloc
- Caller owns returned memory.
- utf16LeToUtf8AllocZ
- Caller owns returned memory.
- utf8ToUtf16Le
- Returns index of next character.
- utf8ToUtf16LeStringLiteral
- Converts a UTF-8 string literal into a UTF-16LE string literal.
- wtf8ToWtf16LeStringLiteral
- Converts a WTF-8 string literal into a WTF-16LE string literal.
- calcUtf16LeLen
- Returns length in UTF-16LE of UTF-8 slice as length of []u16.
- calcWtf16LeLen
- Returns length in WTF-16LE of WTF-8 slice as length of []u16.
- fmtUtf16Le
- Return a Formatter for a (potentially ill-formed) UTF-16 LE string,
- isSurrogateCodepoint
- Returns true if the codepoint is a surrogate (U+DC00 to U+DFFF)
- wtf8Encode
- Encodes the given codepoint into a WTF-8 byte sequence.
- wtf8Decode
- Deprecated.
- wtf8ValidateSlice
- Returns true if the input consists entirely of WTF-8 codepoints
- wtf16LeToWtf8Alloc
- Caller must free returned memory.
- wtf16LeToWtf8AllocZ
- Caller must free returned memory.
- wtf8ToWtf16Le
- Returns index of next character.
- checkUtf8ToUtf16LeOverflow
- Checks if calling `utf8ToUtf16Le` would overflow.
- checkWtf8ToWtf16LeOverflow
- Checks if calling `utf8ToUtf16Le` would overflow.
- wtf8ToUtf8Lossy
- Surrogate codepoints (U+D800 to U+DFFF) are replaced by the Unicode replacement
- calcWtf8Len
- Returns the length, in bytes, that would be necessary to encode the
Error sets in this namespace
Error Sets
Use this to replace an unknown, unrecognized, or unrepresentable character.
Values
- replacement_character
- Use this to replace an unknown, unrecognized, or unrepresentable character.
- replacement_character_utf8
- = utf8EncodeComptime(replacement_character)
Source
Implementation
pub fn utf8CountCodepoints(s: []const u8) !usize {
var len: usize = 0;
const N = @sizeOf(usize);
const MASK = 0x80 * (std.math.maxInt(usize) / 0xff);
var i: usize = 0;
while (i < s.len) {
// Fast path for ASCII sequences
while (i + N <= s.len) : (i += N) {
const v = mem.readInt(usize, s[i..][0..N], native_endian);
if (v & MASK != 0) break;
len += N;
}
if (i < s.len) {
const n = try utf8ByteSequenceLength(s[i]);
if (i + n > s.len) return error.TruncatedInput;
switch (n) {
1 => {}, // ASCII, no validation needed
else => _ = try utf8Decode(s[i..][0..n]),
}
i += n;
len += 1;
}
}
return len;
}