45 lines
1.1 KiB
C
45 lines
1.1 KiB
C
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#include "parser_internal.h"
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typedef struct {
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const HParser *p1;
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const HParser *p2;
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} HTwoParsers;
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static HParseResult* parse_xor(void *env, HParseState *state) {
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HTwoParsers *parsers = (HTwoParsers*)env;
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// cache the initial state of the input stream
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HInputStream start_state = state->input_stream;
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HParseResult *r1 = h_do_parse(parsers->p1, state);
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HInputStream after_p1_state = state->input_stream;
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// reset input stream, parse again
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state->input_stream = start_state;
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HParseResult *r2 = h_do_parse(parsers->p2, state);
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if (NULL == r1) {
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if (NULL != r2) {
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return r2;
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} else {
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return NULL;
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}
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} else {
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if (NULL == r2) {
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state->input_stream = after_p1_state;
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return r1;
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} else {
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return NULL;
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}
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}
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}
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static const HParserVtable xor_vt = {
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.parse = parse_xor,
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};
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const HParser* h_xor(const HParser* p1, const HParser* p2) {
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HTwoParsers *env = g_new(HTwoParsers, 1);
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env->p1 = p1; env->p2 = p2;
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HParser *ret = g_new(HParser, 1);
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ret->vtable = &xor_vt; ret->env = (void*)env;
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return ret;
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}
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