A complete parsing toolkit for C.
From source text to parse trees in minutes.

#include "clex.h"
#include <stdio.h>
#include <stdlib.h>

typedef enum TokenKind { INT, OPARAN, CPARAN, IDENTIFIER, CONSTANT, SEMICOL } TokenKind;

int main() {
    clexLexer *lexer = clexInit();

    clexRegisterKind(lexer, "int",                                   INT);
    clexRegisterKind(lexer, "\\(",                                   OPARAN);
    clexRegisterKind(lexer, "\\)",                                   CPARAN);
    clexRegisterKind(lexer, "[1-9][0-9]*",                           CONSTANT);
    clexRegisterKind(lexer, ";",                                     SEMICOL);
    clexRegisterKind(lexer, "[a-zA-Z_]([a-zA-Z_]|[0-9])*",           IDENTIFIER);

    clexReset(lexer, "int main()");

    clexToken tok;
    clexTokenInit(&tok);
    while (1) {
        clexStatus st = clex(lexer, &tok);
        if (st == CLEX_STATUS_EOF) break;
        if (st != CLEX_STATUS_OK) {
            const clexError *err = clexGetLastError(lexer);
            fprintf(stderr, "lexical error at %zu:%zu near '%s'\n",
                    err->position.line, err->position.column,
                    err->offending_lexeme ? err->offending_lexeme : "");
            break;
        }
        printf("kind=%d lexeme='%s' @ %zu:%zu\n", tok.kind, tok.lexeme,
               tok.span.start.line, tok.span.start.column);
    }
    clexTokenClear(&tok);

    clexLexerDestroy(lexer);
}

#include "cparse.h"
#include "clex/clex.h"
#include <stdio.h>

int main(void) {
    /* ── Step 1: Set up the lexer ─────────────────────────────── */
    clexLexer *lexer = clexInit();
    clexRegisterKind(lexer, "[0-9]+",  0);   /* NUMBER */
    clexRegisterKind(lexer, "\\+",     1);   /* PLUS   */
    clexRegisterKind(lexer, "\\*",     2);   /* STAR   */
    clexRegisterKind(lexer, "\\(",     3);   /* LPAREN */
    clexRegisterKind(lexer, "\\)",     4);   /* RPAREN */

    /* ── Step 2: Define the grammar ──────────────────────────── */
    const char *grammar_src =
        "Expr     -> Term ExprTail\n"
        "ExprTail -> PLUS Term ExprTail | epsilon\n"
        "Term     -> Factor TermTail\n"
        "TermTail -> STAR Factor TermTail | epsilon\n"
        "Factor   -> NUMBER | LPAREN Expr RPAREN";

    Grammar *grammar = cparseGrammar(grammar_src);

    /* ── Step 3: Build the parser ───────────────────────────── */
    const char *names[] = {"NUMBER", "PLUS", "STAR", "LPAREN", "RPAREN"};
    LALR1Parser *parser = cparseCreateLALR1Parser(
        grammar, lexer, names, sizeof(names) / sizeof(names[0]));

    /* ── Step 4: Parse input ───────────────────────────────── */
    const char *input = "8 + 5 * 2";

    if (cparseAccept(parser, input) == CPARSE_STATUS_OK) {
        ParseTreeNode *tree = NULL;
        if (cparse(parser, input, &tree) == CPARSE_STATUS_OK) {
            /* ... traverse or inspect the parse tree ... */
        }
        cparseFreeParseTree(tree);
    } else {
        const cparseError *err = cparseGetLastError(parser);
        /* err->position, err->expected_tokens, err->offending_lexeme */
    }

    /* ── Cleanup ────────────────────────────────────────────── */
    cparseFreeParser(parser);
    cparseFreeGrammar(grammar);
    clexLexerDestroy(lexer);
}