Group.java

/*
 * Copyright 2016 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.template.soy.jssrc.dsl;

import static com.google.template.soy.exprtree.Operator.Associativity.LEFT;

import com.google.auto.value.AutoValue;
import com.google.common.collect.ImmutableSet;
import com.google.errorprone.annotations.Immutable;
import com.google.template.soy.exprtree.Operator.Associativity;
import com.google.template.soy.jssrc.restricted.JsExpr;

/**
 * Represents a JavaScript grouping ({@code (...)}).
 *
 * <p>The CodeChunk DSL parenthesizes subexpressions only where required for correctness. This class
 * should therefore be rarely needed. The intended use case is for defensively parenthesizing a
 * {@link JsExpr} that may have come from a plugin, and whose precedence may be untrustworthy.
 */
@AutoValue
@Immutable
abstract class Group extends Operation {
  abstract CodeChunk.WithValue underlying();

  static Group create(WithValue underlying) {
    return new AutoValue_Group(underlying);
  }

  @Override
  int precedence() {
    // grouping is the highest-precedence JS operator
    return Integer.MAX_VALUE;
  }

  @Override
  Associativity associativity() {
    return LEFT; // irrelevant
  }

  @Override
  void doFormatInitialStatements(FormattingContext ctx) {
    ctx.appendInitialStatements(underlying());
  }

  @Override
  void doFormatOutputExpr(FormattingContext ctx) {
    ctx.append('(').appendOutputExpression(underlying()).append(')');
  }

  @Override
  public void collectRequires(RequiresCollector collector) {
    underlying().collectRequires(collector);
  }

  @Override
  public ImmutableSet<CodeChunk> initialStatements() {
    return underlying().initialStatements();
  }
}