64 lines
1.4 KiB
C++
64 lines
1.4 KiB
C++
/** @license 2022 Neil Edelman, distributed under the terms of the
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[MIT License](https://opensource.org/licenses/MIT).
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Lexer for journal entries.
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@std C89/90 */
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#include <stdlib.h>
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#include <stdio.h>
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#include <assert.h>
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#include <limits.h>
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#include <errno.h>
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static int parse_uint(const char *s, const char *e, unsigned *u) {
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uint32_t n = 0;
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for ( ; s < e; ++s) {
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unsigned digit = (unsigned)(*s - '0');
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assert(digit < 10);
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if(n > (UINT_MAX - digit) / 10) return errno = ERANGE, 0; /* check */
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n = n * 10 + digit;
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}
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*u = n;
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return 1;
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}
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static int lex_line(const char *YYCURSOR, unsigned *const u) {
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const char *YYMARKER, *o1, *o2, *o3, *o4;
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/*!stags:re2c format = 'const char *@@;\n'; */
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/*!re2c
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re2c:yyfill:enable = 0;
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re2c:flags:tags = 1;
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re2c:define:YYCTYPE = char;
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octet = [0-9] | [1-9][0-9] | [1][0-9][0-9] | [2][0-4][0-9] | [2][5][0-5];
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dot = [.];
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end = [\x00];
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@o1 octet dot @o2 octet dot @o3 octet dot @o4 octet end {
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unsigned u1, u2, u3, u4;
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if(!parse_uint(o1, o2 - 1, &u1)
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|| !parse_uint(o2, o3 - 1, &u2)
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|| !parse_uint(o3, o4 - 1, &u3)
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|| !parse_uint(o4, YYCURSOR - 1, &u4)) return 0;
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*u = u4 + (u3 << 8) + (u2 << 16) + (u1 << 24);
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return 1;
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}
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* { return 0; }
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*/
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}
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int main(int argc, char **argv) {
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unsigned u;
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int success;
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success = lex_line("1.2.3.4", &u);
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assert(success);
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printf("%x\n", u);
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return EXIT_SUCCESS;
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}
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