v/builtin/utf8.v

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// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
// 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
pub fn utf8_char_len(b byte) int {
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 {
icode := int(code) //Prevents doing casts everywhere
mut buffer := malloc(5)
if icode <= 127 /* 0x7F */ {
buffer[0] = icode
return tos(buffer, 1)
}
if (icode <= 2047 /* 0x7FF */) {
buffer[0] = 192 /*0xC0*/ | (icode >> 6) /* 110xxxxx */
buffer[1] = 128 /*0x80*/ | (icode & 63 /*0x3F*/) /* 10xxxxxx */
return tos(buffer, 2)
}
if (icode <= 65535 /* 0xFFFF */) {
buffer[0] = 224 /*0xE0*/ | (icode >> 12) /* 1110xxxx */
buffer[1] = 128 /*0x80*/ | ((icode >> 6) & 63 /*0x3F*/) /* 10xxxxxx */
buffer[2] = 128 /*0x80*/ | (icode & 63 /*0x3F*/) /* 10xxxxxx */
return tos(buffer, 3)
}
if (icode <= 1114111 /* 0x10FFFF */) {
buffer[0] = 240 /*0xF0*/ | (icode >> 18) /* 11110xxx */
buffer[1] = 128 /*0x80*/ | ((icode >> 12) & 63 /*0x3F*/) /* 10xxxxxx */
buffer[2] = 128 /*0x80*/ | ((icode >> 6) & 63 /*0x3F*/) /* 10xxxxxx */
buffer[3] = 128 /*0x80*/ | (icode & 63 /*0x3F*/) /* 10xxxxxx */
return tos(buffer, 4)
}
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return ''
}
// TODO copypasta
pub fn utf32_to_str_no_malloc(code u32, buf voidptr) string {
icode := int(code) //Prevents doing casts everywhere
mut buffer := byteptr(buf)
if icode <= 127 /* 0x7F */ {
buffer[0] = icode
return tos(buffer, 1)
}
if (icode <= 2047 /* 0x7FF */) {
buffer[0] = 192 /*0xC0*/ | (icode >> 6) /* 110xxxxx */
buffer[1] = 128 /*0x80*/ | (icode & 63 /*0x3F*/) /* 10xxxxxx */
return tos(buffer, 2)
}
if (icode <= 65535 /* 0xFFFF */) {
buffer[0] = 224 /*0xE0*/ | (icode >> 12) /* 1110xxxx */
buffer[1] = 128 /*0x80*/ | ((icode >> 6) & 63 /*0x3F*/) /* 10xxxxxx */
buffer[2] = 128 /*0x80*/ | (icode & 63 /*0x3F*/) /* 10xxxxxx */
return tos(buffer, 3)
}
if (icode <= 1114111 /* 0x10FFFF */) {
buffer[0] = 240 /*0xF0*/ | (icode >> 18) /* 11110xxx */
buffer[1] = 128 /*0x80*/ | ((icode >> 12) & 63 /*0x3F*/) /* 10xxxxxx */
buffer[2] = 128 /*0x80*/ | ((icode >> 6) & 63 /*0x3F*/) /* 10xxxxxx */
buffer[3] = 128 /*0x80*/ | (icode & 63 /*0x3F*/) /* 10xxxxxx */
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)
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])
res = res << shift
res |= c & 63 /* 0x3f */
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shift = 6
}
return res
}