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111 lines
3.1 KiB
111 lines
3.1 KiB
#include <stdint.h>
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#include "utf8.h"
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//
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// Created by MightyPork on 2017/08/20.
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//
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// UTF-8 parser - collects bytes of a code point before writing them
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// into a screen cell.
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//
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const struct Utf8Char EMPTY_CHAR = (struct Utf8Char) {.uint = 0};
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// Code Points First Byte Second Byte Third Byte Fourth Byte
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// U+0000 - U+007F 00 - 7F
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// U+0080 - U+07FF C2 - DF 80 - BF
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// U+0800 - U+0FFF E0 *A0 - BF 80 - BF
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// U+1000 - U+CFFF E1 - EC 80 - BF 80 - BF
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// U+D000 - U+D7FF ED 80 - *9F 80 - BF
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// U+E000 - U+FFFF EE - EF 80 - BF 80 - BF
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// U+10000 - U+3FFFF F0 *90 - BF 80 - BF 80 - BF
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// U+40000 - U+FFFFF F1 - F3 80 - BF 80 - BF 80 - BF
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// U+100000 - U+10FFFF F4 80 - *8F 80 - BF 80 - BF
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/**
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* Handle a received character
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*/
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struct Utf8Char Utf8Parser_Handle(struct Utf8Parser *self, char c)
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{
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uint8_t *bytes = self->buffer.bytes;
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uint8_t uc = (uint8_t) c;
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// collecting unicode glyphs...
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if (uc & 0x80) {
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if (self->utf_len == 0) {
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bytes[0] = uc;
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self->utf_j = 1;
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// start
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if (uc == 0xC0 || uc == 0xC1 || uc > 0xF4) {
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// forbidden start codes
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goto fail;
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}
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if ((uc & 0xE0) == 0xC0) {
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self->utf_len = 2;
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}
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else if ((uc & 0xF0) == 0xE0) {
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self->utf_len = 3;
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}
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else if ((uc & 0xF8) == 0xF0) {
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self->utf_len = 4;
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}
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else {
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// chars over 127 that don't start unicode sequences
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goto fail;
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}
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}
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else {
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if ((uc & 0xC0) != 0x80) {
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bytes[self->utf_j++] = uc;
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goto fail;
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}
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else {
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bytes[self->utf_j++] = uc;
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if (self->utf_j >= self->utf_len) {
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// check for bad sequences - overlong or some other problem
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if (bytes[0] == 0xF4 && bytes[1] > 0x8F) goto fail;
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if (bytes[0] == 0xF0 && bytes[1] < 0x90) goto fail;
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if (bytes[0] == 0xED && bytes[1] > 0x9F) goto fail;
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if (bytes[0] == 0xE0 && bytes[1] < 0xA0) goto fail;
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// trap for surrogates - those break javascript
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if (bytes[0] == 0xED && bytes[1] >= 0xA0 && bytes[1] <= 0xBF) goto fail;
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goto success;
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}
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}
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}
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}
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else {
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bytes[0] = uc;
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goto success;
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}
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return EMPTY_CHAR;
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success:;
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struct Utf8Char result = self->buffer;
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self->buffer.uint = 0; // erase the buffer
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self->utf_len = 0;
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return result;
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fail:
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self->buffer.uint = 0; // erase the buffer
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self->utf_len = 0;
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return EMPTY_CHAR;
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}
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struct Utf8Char Utf8Iterator_Next(struct Utf8Iterator *self)
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{
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char c;
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struct Utf8Char uchar;
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while ((c = *self->source++) != 0) {
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uchar = Utf8Parser_Handle(&self->parser, c);
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if (uchar.uint) {
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return uchar;
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}
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}
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return EMPTY_CHAR;
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}
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