@fauton/cfg/dist/extractTerminalsFromCfg.js

A package to work with context free grammars and LL1 parsers

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.extractTerminalsFromCfg = void 0;
/**
 * Extract terminals from cfg rules
 * @param cfg Cfg object
 * @returns An array of terminals
 */
function extractTerminalsFromCfg(inputCfg) {
    if (!inputCfg.variables) {
        inputCfg.variables = Object.keys(inputCfg.productionRules);
    }
    const terminals = [];
    // Creating a set of variables initially to improve search performance
    const variablesSet = new Set(inputCfg.variables);
    Object.values(inputCfg.productionRules).forEach((rules) => {
        rules.forEach((rule) => {
            const tokens = rule.split(' ');
            // Loop through each of the tokens to see which of them are terminals
            tokens.forEach((token) => {
                // If the token is not a variable and not empty string, its a terminal
                if (!variablesSet.has(token) && token) {
                    terminals.push(token);
                }
            });
        });
    });
    return Array.from(new Set(terminals));
}
exports.extractTerminalsFromCfg = extractTerminalsFromCfg;