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Added optional parser

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This commit is contained in:
Dan Hirsch 2012-05-12 23:24:39 +01:00
parent 0954feba89
commit 0e9bcb31ca
1 changed files with 21 additions and 2 deletions
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23
src/hammer.c
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@ -461,8 +461,27 @@ const parser_t* xor(const parser_t* p1, const parser_t* p2) {
const parser_t* repeat0(const parser_t* p) { return &unimplemented; }
const parser_t* repeat1(const parser_t* p) { return &unimplemented; }
const parser_t* repeat_n(const parser_t* p, const size_t n) { return &unimplemented; }
const parser_t* optional(const parser_t* p) { return &unimplemented; }
static parse_result_t* parse_optional(void* env, parse_state_t* state) {
input_stream_t bak = state->input_stream;
parse_result_t *res0 = do_parse((parser_t*)env, state);
if (res0)
return res0;
state->input_stream = bak;
parsed_token_t *ast = a_new(parsed_token_t, 1);
ast->token_type = TT_NONE;
return make_result(state, ast);
}
const parser_t* optional(const parser_t* p) {
parser_t *ret = g_new(parser_t, 1);
ret->fn = parse_optional;
ret->env = (void*)p;
return ret;
}
static parse_result_t* parse_ignore(void* env, parse_state_t* state) {
parse_result_t *res0 = do_parse((parser_t*)env, state);
@ -734,7 +753,7 @@ static void test_optional(void) {
g_check_parse_ok(optional_, "abd", 3, "(s0x61 s0x62 s0x64)");
g_check_parse_ok(optional_, "acd", 3, "(s0x61 s0x63 s0x64)");
g_check_parse_ok(optional_, "ad", 2, "(s0x61 s0x64)");
g_check_parse_ok(optional_, "ad", 2, "(s0x61 null s0x64)");
g_check_parse_failed(optional_, "aed", 3);
g_check_parse_failed(optional_, "ab", 2);
g_check_parse_failed(optional_, "ac", 2);