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• Overview
• Example

Overview

⚠️ cparse is still under development and code is unpolished.

cparse is an LR(1) and LALR(1) parser generator for C.

cparse uses clex lexer generator for lexical analysis purposes.

Note that LR(1) parsers are memory-intensive (and there are memory leaks...), so something like full C grammar can require up to 4GBs of free RAM. If you don't have RAM to spare then use the LALR(1) parser, which also happens to get constructed faster but might not support some of the grammars that LR(1) does (though in practice most programming language grammars are LALR(1)-compatible).

Example

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

// Create an enum for token types
typedef enum TokenKind {
  RETURN,
  SEMICOL,
  IDENTIFIER,
} TokenKind;

// Provide a string representation for each token type to be used in the grammar
const char * const tokenKindStr[] = {
  [RETURN] = "RETURN",
  [SEMICOL] = "SEMICOL",
  [IDENTIFIER] = "IDENTIFIER",
};

int main(int argc, char *argv[]) {
  // Register your token types with `clex`
  clexRegisterKind("return", RETURN);
  clexRegisterKind(";", SEMICOL);
  clexRegisterKind("[a-zA-Z_]([a-zA-Z_]|[0-9])*", IDENTIFIER);

  // Write your grammar
  char grammarString[] =
    "S -> A IDENTIFIER SEMICOL\n"
    "A -> RETURN";

  // Parse your grammar
  Grammar *grammar = cparseGrammar(grammarString);
  // Construct an LALR(1) parser
  LALR1Parser *parser = cparseCreateLALR1Parser(grammar, tokenKindStr);

  // Or construct an LR(1) parser
  //LR1Parser *parser = cparseCreateLR1Parser(grammar, tokenKindStr);

  // Test if given input is valid within the grammar
  assert(cparseAccept(parser, "return id1;") == true);

  // Parse a given input and get a parse tree
  ParseTreeNode *node = cparse(parser, "return id1;");

  // Use your parse tree
  assert(strcmp(node->value, "S") == 0);
  assert(strcmp(node->children[0]->value, "SEMICOL") == 0);
  assert(node->children[0]->token.kind == SEMICOL);
  assert(strcmp(node->children[0]->token.lexeme, ";") == 0);
  assert(strcmp(node->children[1]->value, "IDENTIFIER") == 0);
  assert(node->children[1]->token.kind == IDENTIFIER);
  assert(strcmp(node->children[1]->token.lexeme, "id1") == 0);
  assert(strcmp(node->children[2]->value, "A") == 0);
  assert(strcmp(node->children[2]->children[0]->value, "RETURN") == 0);
  assert(node->children[2]->children[0]->token.kind == RETURN);
  assert(strcmp(node->children[2]->children[0]->token.lexeme, "return") == 0);
}