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https://github.com/stedolan/jq.git
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90 lines
2.6 KiB
C
90 lines
2.6 KiB
C
#include <stdio.h>
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#include <assert.h>
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#include "jv_unicode.h"
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#include "jv_utf8_tables.h"
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const char* jvp_utf8_next(const char* in, const char* end, int* codepoint_ret) {
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assert(in <= end);
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if (in == end) {
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return 0;
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}
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int codepoint = -1;
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unsigned char first = (unsigned char)in[0];
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int length = utf8_coding_length[first];
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if ((first & 0x80) == 0) {
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/* Fast-path for ASCII */
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codepoint = first;
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length = 1;
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} else if (length == 0 || length == UTF8_CONTINUATION_BYTE) {
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/* Bad single byte - either an invalid byte or an out-of-place continuation byte */
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length = 1;
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} else if (in + length > end) {
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/* String ends before UTF8 sequence ends */
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length = end - in;
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} else {
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codepoint = ((unsigned)in[0]) & utf8_coding_bits[first];
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for (int i=1; i<length; i++) {
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unsigned ch = (unsigned char)in[i];
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if (utf8_coding_length[ch] != UTF8_CONTINUATION_BYTE){
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/* Invalid UTF8 sequence - not followed by the right number of continuation bytes */
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codepoint = -1;
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length = i;
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break;
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}
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codepoint = (codepoint << 6) | (ch & 0x3f);
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}
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if (codepoint < utf8_first_codepoint[length]) {
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/* Overlong UTF8 sequence */
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codepoint = -1;
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}
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if (0xD800 <= codepoint && codepoint <= 0xDFFF) {
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/* Surrogate codepoints can't be encoded in UTF8 */
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codepoint = -1;
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}
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if (codepoint > 0x10FFFF) {
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/* Outside Unicode range */
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codepoint = -1;
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}
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}
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assert(length > 0);
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*codepoint_ret = codepoint;
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return in + length;
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}
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int jvp_utf8_is_valid(const char* in, const char* end) {
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int codepoint;
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while ((in = jvp_utf8_next(in, end, &codepoint))) {
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if (codepoint == -1) return 0;
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}
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return 1;
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}
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int jvp_utf8_encode_length(int codepoint) {
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if (codepoint <= 0x7F) return 1;
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else if (codepoint <= 0x7FF) return 2;
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else if (codepoint <= 0xFFFF) return 3;
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else return 4;
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}
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int jvp_utf8_encode(int codepoint, char* out) {
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assert(codepoint >= 0 && codepoint <= 0x10FFFF);
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char* start = out;
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if (codepoint <= 0x7F) {
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*out++ = codepoint;
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} else if (codepoint <= 0x7FF) {
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*out++ = 0xC0 + ((codepoint & 0x7C0) >> 6);
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*out++ = 0x80 + ((codepoint & 0x03F));
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} else if(codepoint <= 0xFFFF) {
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*out++ = 0xE0 + ((codepoint & 0xF000) >> 12);
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*out++ = 0x80 + ((codepoint & 0x0FC0) >> 6);
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*out++ = 0x80 + ((codepoint & 0x003F));
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} else {
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*out++ = 0xF0 + ((codepoint & 0x1C0000) >> 18);
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*out++ = 0x80 + ((codepoint & 0x03F000) >> 12);
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*out++ = 0x80 + ((codepoint & 0x000FC0) >> 6);
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*out++ = 0x80 + ((codepoint & 0x00003F));
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}
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assert(out - start == jvp_utf8_encode_length(codepoint));
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return out - start;
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}
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