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94 lines
2.2 KiB
94 lines
2.2 KiB
2 years ago
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/**
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* UTF-8 string parsing and character iteration
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*
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* Created on 2020/01/04.
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*/
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#ifndef LIQUIDTYPE_UTF8_H
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#define LIQUIDTYPE_UTF8_H
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#include <stddef.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include "progmem.h"
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/**
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* UTF-8 encoded character.
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*/
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struct Utf8Char {
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union {
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/** character bytes; padded by zero bytes if shorter than 4 */
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uint8_t bytes[4];
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/** u32 view of the bytes */
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uint32_t uint;
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};
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};
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/** UTF8 string parser internal state */
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struct Utf8Parser {
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/** UTF-8 bytes buffer */
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struct Utf8Char buffer;
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/** Currently collected UTF-8 character length */
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uint8_t utf_len;
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/** Position in the current character */
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uint8_t utf_j;
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};
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static inline void Utf8Parser_Clear(struct Utf8Parser *self) {
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self->buffer.uint = 0;
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self->utf_j = 0;
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self->utf_len = 0;
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}
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/**
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* Utf8 character iterator.
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*
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* Usage:
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* struct Utf8Iterator iter;
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* Utf8Iterator_Init(&iter, myString);
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*
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* union Utf8Char uchar;
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* while ((uchar = Utf8Iterator_Next(&iter)).uint) {
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* // do something with the char
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* }
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*
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* // Free myString if needed, it is not mutated.
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*/
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struct Utf8Iterator {
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/* Characters to parse. The pointer is advanced as the iterator progresses. */
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const char *source;
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struct Utf8Parser parser;
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bool is_progmem;
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};
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static inline void Utf8Iterator_Init(struct Utf8Iterator *self, const char *source) {
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Utf8Parser_Clear(&self->parser);
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self->source = source;
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self->is_progmem = false;
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}
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static inline void Utf8Iterator_Init_P(struct Utf8Iterator *self, const char *source) {
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Utf8Iterator_Init(self, source);
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self->is_progmem = true;
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}
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size_t utf8_strlen(const char *text);
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/**
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* Get the next character from the iterator; Returns empty character if there are no more characters to parse.
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*
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* Invalid characters are skipped.
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*/
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struct Utf8Char Utf8Iterator_Next(struct Utf8Iterator *self);
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/**
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* Parse a character.
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*
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* The returned struct contains NIL (uint == 0) if no character is yet available.
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*
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* ASCII is passed through, utf-8 is collected and returned in one piece.
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*/
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struct Utf8Char Utf8Parser_Handle(struct Utf8Parser *self, char c);
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#endif //LIQUIDTYPE_UTF8_H
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