v/vlib/builtin/utf8.v

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// Copyright (c) 2019-2020 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
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module builtin
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pub fn utf8_char_len(b byte) int {
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return ((0xe5000000>>((b>>3) & 0x1e)) & 3) + 1
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}
// Convert utf32 to utf8
// utf32 == Codepoint
pub fn utf32_to_str(code u32) string {
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mut buffer := malloc(5)
return utf32_to_str_no_malloc(code, buffer)
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}
pub fn utf32_to_str_no_malloc(code u32, buf voidptr) string {
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icode := int(code) // Prevents doing casts everywhere
unsafe {
mut buffer := byteptr(buf)
if icode <= 127/* 0x7F */ {
buffer[0] = byte(icode)
return tos(buffer, 1)
}
if icode <= 2047/* 0x7FF */ {
buffer[0] = 192/*0xC0*/ | byte(icode>>6)/* 110xxxxx */
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buffer[1] = 128/*0x80*/ | byte(icode & 63/*0x3F*/)/* 10xxxxxx */
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return tos(buffer, 2)
}
if icode <= 65535/* 0xFFFF */ {
buffer[0] = 224/*0xE0*/ | byte(icode>>12)/* 1110xxxx */
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buffer[1] = 128/*0x80*/ | (byte(icode>>6) & 63/*0x3F*/)/* 10xxxxxx */
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buffer[2] = 128/*0x80*/ | byte(icode & 63/*0x3F*/)/* 10xxxxxx */
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return tos(buffer, 3)
}
if icode <= 1114111/* 0x10FFFF */ {
buffer[0] = 240/*0xF0*/ | byte(icode>>18)/* 11110xxx */
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buffer[1] = 128/*0x80*/ | (byte(icode>>12) & 63/*0x3F*/)/* 10xxxxxx */
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buffer[2] = 128/*0x80*/ | (byte(icode>>6) & 63/*0x3F*/)/* 10xxxxxx */
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buffer[3] = 128/*0x80*/ | byte(icode & 63/*0x3F*/)/* 10xxxxxx */
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return tos(buffer, 4)
}
}
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return ''
}
// Convert utf8 to utf32
pub fn (_rune string) utf32_code() int {
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if _rune.len == 0 {
return 0
}
// save ASC symbol as is
if _rune.len == 1 {
return int(_rune[0])
}
mut b := byte(int(_rune[0]))
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// TODO should be
// res := int( rune[0] << rune.len)
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b = b<<_rune.len
mut res := int(b)
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mut shift := 6 - _rune.len
for i := 1; i < _rune.len; i++ {
c := int(_rune[i])
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res = res<<shift
res |= c & 63 // 0x3f
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shift = 6
}
return res
}
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const (
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cp_utf8 = 65001
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)
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pub fn (_str string) to_wide() &u16 {
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$if windows {
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num_chars := (C.MultiByteToWideChar(cp_utf8, 0, charptr(_str.str), _str.len, 0, 0))
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mut wstr := &u16(malloc((num_chars + 1) * 2)) // sizeof(wchar_t)
if wstr != 0 {
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C.MultiByteToWideChar(cp_utf8, 0, charptr(_str.str), _str.len, wstr, num_chars)
unsafe {
C.memset(&byte(wstr) + num_chars * 2, 0, 2)
}
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}
return wstr
} $else {
return 0
}
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}
pub fn string_from_wide(_wstr &u16) string {
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$if windows {
wstr_len := C.wcslen(_wstr)
return string_from_wide2(_wstr, wstr_len)
} $else {
return ''
}
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}
pub fn string_from_wide2(_wstr &u16, len int) string {
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$if windows {
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num_chars := C.WideCharToMultiByte(cp_utf8, 0, _wstr, len, 0, 0, 0, 0)
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mut str_to := malloc(num_chars + 1)
if str_to != 0 {
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C.WideCharToMultiByte(cp_utf8, 0, _wstr, len, charptr(str_to), num_chars, 0, 0)
unsafe {
C.memset(str_to + num_chars, 0, 1)
}
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}
return tos2(str_to)
} $else {
return ''
}
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}
// Calculate length to read from the first byte
fn utf8_len(c byte) int {
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mut b := 0
mut x := c
if (x & 240) != 0 {
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// 0xF0
x >>= 4
}
else {
b += 4
}
if (x & 12) != 0 {
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// 0x0C
x >>= 2
}
else {
b += 2
}
if (x & 2) == 0 {
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// 0x02
b++
}
return b
}
// Calculate string length for in number of codepoints
fn utf8_str_len(s string) int {
mut l := 0
for i := 0; i < s.len; i++ {
l++
c := unsafe {s.str[i]}
if (c & (1 << 7)) != 0 {
for t := byte(1 << 6); (c & t) != 0; t >>= 1 {
i++
}
}
}
return l
}
// Calculate string length for formatting, i.e. number of "characters"
fn utf8_str_visible_length(s string) int {
mut l := 0
mut ul := 1
for i := 0; i < s.len; i+=ul {
ul = 1
c := unsafe {s.str[i]}
if (c & (1 << 7)) != 0 {
for t := byte(1 << 6); (c & t) != 0; t >>= 1 {
ul++
}
}
if i + ul > s.len { // incomplete UTF-8 sequence
return l
}
l++
// recognize combining characters
if c == 0xcc || c == 0xcd {
r := (u16(c) << 8) | unsafe {s.str[i+1]}
if r >= 0xcc80 && r < 0xcdb0 { // diacritical marks
l--
}
} else if c == 0xe1 || c == 0xe2 || c == 0xef {
r := (u32(c) << 16) | unsafe {(u32(s.str[i+1]) << 8) | s.str[i+2]}
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if (r >= 0xe1aab0 && r < 0xe1ac80) // diacritical marks extended
|| (r >= 0xe1b780 && r < 0xe1b880) // diacritical marks supplement
|| (r >= 0xe28390 && r < 0xe28480) // diacritical marks for symbols
|| (r >= 0xefb8a0 && r < 0xefb8b0) { // half marks
l--
}
}
}
return l
}
// Reads an utf8 character from standard input
pub fn utf8_getchar() int {
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c := C.getchar()
len := utf8_len(byte(~c))
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if c < 0 {
return 0
}
else if len == 0 {
return c
}
else if len == 1 {
return -1
}
else {
mut uc := c & ((1<<(7 - len)) - 1)
for i := 0; i + 1 < len; i++ {
c2 := C.getchar()
if c2 != -1 && (c2>>6) == 2 {
uc <<= 6
uc |= (c2 & 63)
}
else if c2 == -1 {
return 0
}
else {
return -1
}
}
return uc
}
}