99 lines
2.3 KiB
C++
99 lines
2.3 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 parse_double(const char *s0, const char *s1, double *d) {
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char *finish;
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assert(d && s0 && s0 < s1);
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*d = strtod(s0, &finish);
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return !errno && ((finish == s1) || (errno = EDOM, 0));
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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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double d;
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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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keyword = [a-z][a-z0-9_-]{0,64}; // uppercase is lame
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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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eol = [\n];
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w = [ \t]*;
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double = [0-9]* "." [0-9]+ | [0-9]+;
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*/
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errno = 0; /* For accuracy detecting errors. */
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text:
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/*!re2c
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"\\[" | "\\![" { goto text; }
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"[" { goto custom; }
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"![" { goto image; }
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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 errno = EILSEQ, 0; }
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*/
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image:
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/*!re2c
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"osm" "](" @o1 double @o2 "," @o3 double @o4 ")" {
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printf("Got a map.\n");
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if(!parse_double(o1, o2, &d)) return 0;
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printf("Latitude %f.\n", d);
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if(!parse_double(o3, o4, &d)) return 0;
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printf("Longitude %f.\n", d);
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goto text;
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}
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* { return errno = EILSEQ, 0; }
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*/
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custom:
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/*!re2c
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glider = "glider" ":" ;
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flight = "flight" ":" ;
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* { return errno = EILSEQ, 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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if(!lex_line("1.2.3.4", &u)) goto catch;
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printf("0x%x\n", u);
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if(!lex_line("1.2.3.49999999999999999", &u)) goto catch;
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return EXIT_SUCCESS;
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catch:
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perror("interpret");
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return EXIT_FAILURE;
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}
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