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The Aya proof assistant
There is a newer version: 0.33.0
// Copyright (c) 2020-2021 Yinsen (Tesla) Zhang.
// Use of this source code is governed by the MIT license that can be found in the LICENSE.md file.
package org.aya.core;

import kala.collection.SeqView;
import kala.collection.immutable.ImmutableSeq;
import kala.collection.mutable.DynamicSeq;
import kala.tuple.Tuple2;
import org.aya.api.ref.Var;
import org.aya.api.util.Arg;
import org.aya.core.term.CallTerm;
import org.aya.core.term.FormTerm;
import org.aya.core.term.Term;
import org.aya.core.visitor.Substituter;
import org.aya.generic.Constants;
import org.aya.tyck.TyckState;
import org.aya.util.error.SourcePos;
import org.jetbrains.annotations.NotNull;

/**
 * @author ice1000, re-xyr
 * @apiNote The object identity of this class is used at runtime
 * @implNote Do not override equals or hashCode
 */
public final class Meta implements Var {
  public final @NotNull ImmutableSeq contextTele;
  public final @NotNull ImmutableSeq telescope;
  public final @NotNull String name;
  public final @NotNull Term result;
  public final @NotNull SourcePos sourcePos;
  public final @NotNull DynamicSeq> conditions = DynamicSeq.create();

  public SeqView fullTelescope() {
    return contextTele.view().concat(telescope);
  }

  public boolean solve(@NotNull TyckState state, @NotNull Term t) {
    if (t.findUsages(this) > 0) return false;
    state.metas().put(this, t);
    return true;
  }

  private Meta(
    @NotNull ImmutableSeq contextTele,
    @NotNull ImmutableSeq telescope,
    @NotNull String name, @NotNull Term result,
    @NotNull SourcePos sourcePos
  ) {
    this.contextTele = contextTele;
    this.telescope = telescope;
    this.name = name;
    this.result = result;
    this.sourcePos = sourcePos;
  }

  public static @NotNull Meta from(
    @NotNull ImmutableSeq contextTele, @NotNull String name,
    @NotNull Term result, @NotNull SourcePos sourcePos
  ) {
    if (result instanceof FormTerm.Pi pi) {
      var buf = DynamicSeq.create();
      var r = pi.parameters(buf);
      return new Meta(contextTele, buf.toImmutableSeq(), name, r, sourcePos);
    } else return new Meta(contextTele, ImmutableSeq.empty(), name, result, sourcePos);
  }

  public @NotNull FormTerm.Pi asPi(
    @NotNull String domName, @NotNull String codName, boolean explicit,
    @NotNull ImmutableSeq> contextArgs
  ) {
    assert telescope.isEmpty();
    var domVar = Meta.from(contextTele, domName, result, sourcePos);
    var codVar = Meta.from(contextTele, codName, result, sourcePos);
    var dom = new CallTerm.Hole(domVar, contextArgs, ImmutableSeq.empty());
    var cod = new CallTerm.Hole(codVar, contextArgs, ImmutableSeq.empty());
    var domParam = new Term.Param(Constants.randomlyNamed(sourcePos), dom, explicit);
    return new FormTerm.Pi(domParam, cod);
  }

  @Override public @NotNull String name() {
    return name;
  }
}