stsys/lib/goalmgr.js

String rewriting system (semi-Thue system)

const strpair = require('./strpair');

class GoalManager
{
  constructor(prover)
  {
    this.prover = prover;
    this.goalsCount = 0;
    this.goals = [];
    this.unprovedGoalsCount = 0;
  }

  clearGoals()
  {
    this.goals.length = this.goalsCount = this.unprovedGoalsCount = 0;
  }

  addGoals(spec)
  {
    let goal;
    if (typeof spec === 'string')
    {
      this.goals.push(goal = new Goal(spec));
      goal.id = ++this.goalsCount;
      if (!goal.proved)
        this.unprovedGoalsCount++;
    }
    else if (spec instanceof Array)
      spec.forEach(gs => {
        this.goals.push(goal = new Goal(gs));
        goal.id = ++this.goalsCount;
        if (!goal.proved)
          this.unprovedGoalsCount++;
      });
    else if (spec)
      throw new Error('invalid specification of goals (illegal type: ' + typeof spec + ')');
  }

  getGoalsCount()
  {
    return this.goals.length;
  }

  getGoals()
  {
    return this.goals.map(g => {
      const r = {
        id: g.id,
        goal: g.original,
        proved: g.proved
      };
      if (g.proved)
        r.provedBy = g.modifiable.toString();
      return r;
    });
  }

  reduceAll(reducer, rule)
  {
    this.goals.forEach(goal => {
      if (!goal.proved)
      {
        goal.reduce(reducer, rule);
        if (goal.proved)
        {
          --this.unprovedGoalsCount;
          if (this.prover.isLoggable(2))
            this.prover.log('Goal proved: ' + goal.original);
        }
      }
    });
  }

  allGoalsProved()
  {
    return this.goals.length > 0 && this.unprovedGoalsCount === 0;
  }
}

class Goal
{
  constructor(spec)
  {
    this.modifiable = strpair.parseStrPair(spec);
    this.original = this.modifiable.toString();
    this.proved = this.modifiable.isTrivial();
    this.id = 0;
  }

  reduce(reducer, rule)
  {
    if (this.modifiable.reduce(reducer, rule) && !this.proved)
      this.proved = this.modifiable.isTrivial();
  }
}

module.exports.createGoalManager = function(prover)
{
  return new GoalManager(prover);
};