C99

The C target generates portable C99 source with an explicit ownership API. Generated parsers use the standard C library and require no additional runtime.

Minimal working example

Create the following two files in an empty directory. parser.c is generated by pegtool.

identifier.peg

Start = Identifier !. {
    return pegtool_value_string_n(c->text, c->text_length);
}

Identifier = [\pL_] [\pL\p{Nd}_]*

main.c

#include "parser.c"

int main(void) {
    PegtoolResult result = pegtool_parse("name_世界");
    if (!result.ok) {
        fprintf(stderr, "%s\n", result.error);
        pegtool_result_free(&result);
        return 1;
    }
    printf("%s\n", result.value.as.string.data);
    pegtool_result_free(&result);
    return 0;
}

Generate and compile it:

pegtool -t c -o parser.c identifier.peg
gcc -std=c99 -Wall -Wextra -Werror -pedantic-errors main.c -o identifier
.\identifier.exe

Output:

name_世界

Public API

Function	Purpose
pegtool_parse	Parse a NUL-terminated string
pegtool_parse_n	Parse an explicit byte length, which may contain NUL
pegtool_parse_with_options	Use PegtoolParserOptions
pegtool_parse_with_options_n	Combine options with an explicit length
pegtool_result_free	Free memory owned by the success value or error result

Call pegtool_result_free after every parse, whether it succeeds or fails.

Actions and ownership

word = [\p{L}]+ {
    return pegtool_value_string_n(c->text, c->text_length);
}

Labels are const PegtoolValue *, and actions return an owned PegtoolValue. Call pegtool_value_clone when retaining a label value. Build arrays with pegtool_value_array and pegtool_value_array_push. Failure paths must free temporary values whose ownership they have acquired.

Labels that conflict with internal parameters or C99 keywords are generated as _pegtool_label_<name>. Use -receiver-name to change the default c name of the current-match object.

Options

PegtoolParserOptions supports filename, entrypoint, custom_data, and max_expressions. The C target currently has no memoization switch, and -optimize-parser has no C-specific effect.