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Add a parser combinator to parse a delimited list

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omicron 2025-04-01 23:39:48 +02:00
parent 333991e05e
commit c3fcb917fc
2 changed files with 56 additions and 3 deletions
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55
src/parser_combinators.c
View File

@ -1,5 +1,54 @@
#include "parser_combinators.h"
// Parse a list of the given parser delimited by the given token id. Does not
// store the delimiters in the parent node
parse_result_t parse_list(tokenlist_entry_t *current, node_id_t id,
bool allow_none, lexer_token_id_t delimiter_id,
parser_t parser) {
ast_node_t *many;
error_t *err = ast_node_alloc(&many);
parse_result_t result;
if (err)
return parse_error(err);
many->id = id;
while (current) {
// Skip beyond the delimiter on all but the first iteration
if (many->len > 0) {
if (current->token.id != delimiter_id)
break;
current = tokenlist_next(current);
if (current == nullptr) {
// FIXME: this isn't quite right, we can't consume the delimiter
// if the next element will fail to parse but it's late and I
// must think this through tomorrow
break;
}
}
result = parser(current);
if (result.err == err_parse_no_match)
break;
if (result.err) {
ast_node_free(many);
return result;
}
err = ast_node_add_child(many, result.node);
if (err) {
ast_node_free(many);
ast_node_free(result.node);
return parse_error(err);
}
current = result.next;
}
if (!allow_none && many->len == 0) {
ast_node_free(many);
return parse_no_match();
}
return parse_success(many, current);
}
parse_result_t parse_any(tokenlist_entry_t *current, parser_t parsers[]) {
for (parser_t parser = *parsers; parser; parser = *parsers++) {
parse_result_t result = parser(current);
@ -9,9 +58,9 @@ parse_result_t parse_any(tokenlist_entry_t *current, parser_t parsers[]) {
return parse_no_match();
}
// parse as many of the giver parsers objects in a row as possible, potentially
// allowing none wraps the found objects in a new ast node with the given note
// id
// parse as many of the giver parsers objects in a row as possible,
// potentially allowing none wraps the found objects in a new ast node with
// the given note id
parse_result_t parse_many(tokenlist_entry_t *current, node_id_t id,
bool allow_none, parser_t parser) {
ast_node_t *many;

4
src/parser_combinators.h
View File

@ -10,6 +10,10 @@ parse_result_t parse_any(tokenlist_entry_t *current, parser_t parsers[]);
parse_result_t parse_many(tokenlist_entry_t *current, node_id_t id,
bool allow_none, parser_t parser);
parse_result_t parse_list(tokenlist_entry_t *current, node_id_t id,
bool allow_none, lexer_token_id_t delimiter_id,
parser_t parser);
// Parse all tries to parse all parsers consecutively and if it succeeds it
// wraps the parsed nodes in a new parent node.
parse_result_t parse_consecutive(tokenlist_entry_t *current, node_id_t id,