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/* See LICENSE file for copyright and license details. */
#include "libparser.h"
#include <stdlib.h>
#include <string.h>
struct context {
const struct libparser_rule *const *rules;
struct libparser_unit *cache;
const char *data;
size_t length;
size_t position;
char done;
char exception;
char error;
};
static void
free_unit(struct libparser_unit *unit, struct context *ctx)
{
struct libparser_unit *prev;
while (unit) {
free_unit(unit->in, ctx);
prev = unit;
unit = unit->next;
prev->next = ctx->cache;
ctx->cache = prev;
}
}
static void
dealloc_unit(struct libparser_unit *unit)
{
struct libparser_unit *next;
for (; unit; unit = next) {
dealloc_unit(unit->in);
next = unit->next;
free(unit);
}
}
static struct libparser_unit *
try_match(const char *rule, const union libparser_sentence *sentence, struct context *ctx)
{
struct libparser_unit *unit, *next;
struct libparser_unit **head;
unsigned char c;
size_t i;
if (!ctx->cache) {
unit = calloc(1, sizeof(*unit));
if (!unit) {
ctx->done = 1;
ctx->error = 1;
return NULL;
}
} else {
unit = ctx->cache;
ctx->cache = unit->next;
unit->in = unit->next = NULL;
}
unit->rule = rule;
unit->start = ctx->position;
switch (sentence->type) {
case LIBPARSER_SENTENCE_TYPE_CONCATENATION:
unit->in = try_match(NULL, sentence->binary.left, ctx);
if (!unit->in)
goto mismatch;
if (ctx->done)
break;
unit->in->next = try_match(NULL, sentence->binary.right, ctx);
if (!unit->in->next) {
free_unit(unit->in, ctx);
goto mismatch;
}
if (!unit->in->next->rule || unit->in->next->rule[0] == '_') {
unit->in->next->next = ctx->cache;
ctx->cache = unit->in->next;
unit->in->next = unit->in->next->in;
}
if (!unit->in->rule || unit->in->rule[0] == '_') {
next = unit->in->next;
unit->in->next = ctx->cache;
ctx->cache = unit->in;
unit->in = unit->in->in;
if (unit->in) {
for (head = &unit->in->next; *head; head = &(*head)->next);
*head = next;
} else {
unit->in = next;
}
}
break;
case LIBPARSER_SENTENCE_TYPE_ALTERNATION:
unit->in = try_match(NULL, sentence->binary.left, ctx);
if (!unit->in) {
unit->in = try_match(NULL, sentence->binary.right, ctx);
if (!unit->in)
goto mismatch;
}
prone:
if (unit->in && (!unit->in->rule || unit->in->rule[0] == '_')) {
unit->in->next = ctx->cache;
ctx->cache = unit->in;
unit->in = unit->in->in;
}
break;
case LIBPARSER_SENTENCE_TYPE_OPTIONAL:
unit->in = try_match(NULL, sentence->unary.sentence, ctx);
goto prone;
case LIBPARSER_SENTENCE_TYPE_REPEATED:
head = &unit->in;
while ((*head = try_match(NULL, sentence->unary.sentence, ctx))) {
if (!(*head)->rule || (*head)->rule[0] == '_') {
(*head)->next = ctx->cache;
ctx->cache = *head;
*head = (*head)->in;
while (*head)
head = &(*head)->next;
} else {
head = &(*head)->next;
}
if (ctx->done)
break;
}
break;
case LIBPARSER_SENTENCE_TYPE_STRING:
if (sentence->string.length > ctx->length - ctx->position)
goto mismatch;
if (memcmp(&ctx->data[ctx->position], sentence->string.string, sentence->string.length))
goto mismatch;
ctx->position += sentence->string.length;
break;
case LIBPARSER_SENTENCE_TYPE_CHAR_RANGE:
if (ctx->position == ctx->length)
goto mismatch;
c = ((const unsigned char *)ctx->data)[ctx->position];
if (sentence->char_range.low > c || c > sentence->char_range.high)
goto mismatch;
ctx->position += 1;
break;
case LIBPARSER_SENTENCE_TYPE_RULE:
for (i = 0; ctx->rules[i]; i++)
if (!strcmp(ctx->rules[i]->name, sentence->rule.rule))
break;
if (!ctx->rules[i])
abort();
unit->in = try_match(ctx->rules[i]->name, ctx->rules[i]->sentence, ctx);
if (!unit->in)
goto mismatch;
goto prone;
case LIBPARSER_SENTENCE_TYPE_EXCEPTION:
ctx->done = 1;
ctx->exception = 1;
break;
case LIBPARSER_SENTENCE_TYPE_EOF:
if (ctx->position != ctx->length)
goto mismatch;
ctx->done = 1;
break;
default:
abort();
}
unit->end = ctx->position;
return unit;
mismatch:
ctx->position = unit->start;
unit->next = ctx->cache;
ctx->cache = unit;
return NULL;
}
int
libparser_parse_file(const struct libparser_rule *const rules[], const char *data, size_t length, struct libparser_unit **rootp)
{
struct libparser_unit *ret, *t;
struct context ctx;
size_t i;
ctx.rules = rules;
ctx.cache = NULL;
ctx.data = data;
ctx.length = length;
ctx.position = 0;
ctx.done = 0;
ctx.error = 0;
ctx.exception = 0;
for (i = 0; rules[i]; i++)
if (!strcmp(rules[i]->name, "@start"))
break;
if (!rules[i])
abort();
ret = try_match(rules[i]->name, rules[i]->sentence, &ctx);
while (ctx.cache) {
t = ctx.cache;
ctx.cache = t->next;
free(t);
}
if (ctx.error) {
dealloc_unit(ret);
*rootp = NULL;
return -1;
}
*rootp = ret;
return !ctx.exception;
}
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