@parser-generator/core/lib/cjs/lr/automata.js

A Parser Generator that supports LL,SLR,LR1,LALR

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
const definition_1 = require("./definition");
const debug_1 = __importDefault(require("debug"));
let debug = debug_1.default("PG:automata");
/**
 * 构造一个由项集组成的状态机,(详见 #自动机的构造)
 * @param grammar
 * @param tools
 */
function getAutomata(grammar, tools) {
    //状态id计数
    let stateIdCounter = 1;
    // let I0 = new State(stateIdCounter++, closure(new ItemSet(new Item(grammar.prodOfStartNT))))
    let I0 = tools.getStartState(grammar);
    debug(`${I0}`);
    //存放状态集
    let stateSet = new definition_1.StateSet();
    stateSet.push(I0);
    //状态集中待处理的 状态的索引
    let procssedIdx = 0;
    //每一个状态集中尚未处理的状态
    while (procssedIdx < stateSet.length) {
        let curState = stateSet[procssedIdx++];
        //得到当前状态的后继符号集
        let nextSymbols = curState.getNextSymbols();
        //对当前状态输入 符号集 中的每个符号
        for (let nextSymbol of nextSymbols) {
            //生成当前状态对输入(nextSymbol)的后继状态
            let nextItemSet = tools.GOTO(curState, nextSymbol);
            //检查生成的状态是否已经存在 (判断状态相等标准见:ItemSet.equals())
            let nextState = stateSet.getExisting(nextItemSet);
            if (nextState == null) {
                nextState = new definition_1.State(stateIdCounter++, nextItemSet);
                stateSet.push(nextState);
                debug(`\n+Adding a new state:\n${nextState}\n`);
            }
            //记录当前状态 与 后继状态 的连接
            curState.addNextState(nextSymbol, nextState);
            debug(`mapping: ${curState.id} ----- ${nextSymbol} -----> ${nextState.id}`);
        }
    }
    return stateSet;
}
exports.getAutomata = getAutomata;
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