174 lines
3.1 KiB
Plaintext
174 lines
3.1 KiB
Plaintext
/* Simple expression parser */
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%{
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#include "util.h"
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#include "util/debug.h"
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#define IN_EXPR_Y 1
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#include "expr.h"
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#include <string.h>
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#define MAXIDLEN 256
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%}
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%pure-parser
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%parse-param { double *final_val }
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%parse-param { struct parse_ctx *ctx }
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%parse-param { const char **pp }
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%lex-param { const char **pp }
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%union {
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double num;
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char id[MAXIDLEN+1];
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}
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%token <num> NUMBER
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%token <id> ID
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%left '|'
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%left '^'
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%left '&'
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%left '-' '+'
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%left '*' '/' '%'
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%left NEG NOT
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%type <num> expr
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%{
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static int expr__lex(YYSTYPE *res, const char **pp);
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static void expr__error(double *final_val __maybe_unused,
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struct parse_ctx *ctx __maybe_unused,
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const char **pp __maybe_unused,
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const char *s)
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{
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pr_debug("%s\n", s);
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}
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static int lookup_id(struct parse_ctx *ctx, char *id, double *val)
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{
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int i;
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for (i = 0; i < ctx->num_ids; i++) {
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if (!strcasecmp(ctx->ids[i].name, id)) {
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*val = ctx->ids[i].val;
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return 0;
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}
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}
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return -1;
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}
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%}
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%%
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all_expr: expr { *final_val = $1; }
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;
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expr: NUMBER
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| ID { if (lookup_id(ctx, $1, &$$) < 0) {
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pr_debug("%s not found", $1);
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YYABORT;
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}
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}
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| expr '+' expr { $$ = $1 + $3; }
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| expr '-' expr { $$ = $1 - $3; }
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| expr '*' expr { $$ = $1 * $3; }
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| expr '/' expr { if ($3 == 0) YYABORT; $$ = $1 / $3; }
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| expr '%' expr { if ((long)$3 == 0) YYABORT; $$ = (long)$1 % (long)$3; }
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| '-' expr %prec NEG { $$ = -$2; }
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| '(' expr ')' { $$ = $2; }
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;
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%%
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static int expr__symbol(YYSTYPE *res, const char *p, const char **pp)
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{
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char *dst = res->id;
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const char *s = p;
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while (isalnum(*p) || *p == '_' || *p == '.') {
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if (p - s >= MAXIDLEN)
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return -1;
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*dst++ = *p++;
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}
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*dst = 0;
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*pp = p;
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return ID;
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}
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static int expr__lex(YYSTYPE *res, const char **pp)
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{
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int tok;
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const char *s;
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const char *p = *pp;
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while (isspace(*p))
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p++;
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s = p;
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switch (*p++) {
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case 'a' ... 'z':
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case 'A' ... 'Z':
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return expr__symbol(res, p - 1, pp);
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case '0' ... '9': case '.':
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res->num = strtod(s, (char **)&p);
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tok = NUMBER;
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break;
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default:
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tok = *s;
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break;
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}
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*pp = p;
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return tok;
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}
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/* Caller must make sure id is allocated */
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void expr__add_id(struct parse_ctx *ctx, const char *name, double val)
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{
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int idx;
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assert(ctx->num_ids < MAX_PARSE_ID);
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idx = ctx->num_ids++;
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ctx->ids[idx].name = name;
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ctx->ids[idx].val = val;
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}
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void expr__ctx_init(struct parse_ctx *ctx)
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{
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ctx->num_ids = 0;
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}
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int expr__find_other(const char *p, const char *one, const char ***other,
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int *num_otherp)
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{
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const char *orig = p;
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int err = -1;
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int num_other;
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*other = malloc((EXPR_MAX_OTHER + 1) * sizeof(char *));
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if (!*other)
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return -1;
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num_other = 0;
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for (;;) {
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YYSTYPE val;
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int tok = expr__lex(&val, &p);
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if (tok == 0) {
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err = 0;
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break;
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}
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if (tok == ID && strcasecmp(one, val.id)) {
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if (num_other >= EXPR_MAX_OTHER - 1) {
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pr_debug("Too many extra events in %s\n", orig);
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break;
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}
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(*other)[num_other] = strdup(val.id);
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if (!(*other)[num_other])
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return -1;
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num_other++;
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}
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}
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(*other)[num_other] = NULL;
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*num_otherp = num_other;
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if (err) {
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*num_otherp = 0;
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free(*other);
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*other = NULL;
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}
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return err;
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}
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