com.google.template.soy.jssrc.dsl.ConditionalBuilder.java Source code

Introduction

Here is the source code for com.google.template.soy.jssrc.dsl.ConditionalBuilder.java

Source

/*
 * 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 com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.template.soy.jssrc.dsl.CodeChunk.WithValue;
import javax.annotation.CheckReturnValue;
import javax.annotation.Nullable;

/** Builds a single {@link Conditional}. */
public final class ConditionalBuilder {

    private final ImmutableList.Builder<IfThenPair> conditions = ImmutableList.builder();

    @Nullable
    private CodeChunk trailingElse = null;

    ConditionalBuilder(CodeChunk.WithValue predicate, CodeChunk consequent) {
        conditions.add(new IfThenPair(predicate, consequent));
    }

    /**
     * Adds an {@code else if} clause with the given predicate and consequent to this conditional.
     */
    public ConditionalBuilder elseif_(CodeChunk.WithValue predicate, CodeChunk consequent) {
        conditions.add(new IfThenPair(predicate, consequent));
        return this;
    }

    /** Adds an {@code else} clause encapsulating the given chunk to this conditional. */
    public ConditionalBuilder else_(CodeChunk trailingElse) {
        Preconditions.checkState(this.trailingElse == null);
        this.trailingElse = trailingElse;
        return this;
    }

    /** Finishes building this conditional. */
    @CheckReturnValue
    public CodeChunk build() {
        ImmutableList<IfThenPair> pairs = conditions.build();
        if (isRepresentableAsTernaryExpression(pairs)) {
            return Ternary.create(pairs.get(0).predicate, (CodeChunk.WithValue) pairs.get(0).consequent,
                    (CodeChunk.WithValue) trailingElse);
        } else {
            return Conditional.create(pairs, trailingElse);
        }
    }

    private boolean isRepresentableAsTernaryExpression(ImmutableList<IfThenPair> pairs) {
        if (pairs.size() != 1 || trailingElse == null) {
            return false;
        }

        IfThenPair ifThen = Iterables.getOnlyElement(pairs);
        CodeChunk.WithValue predicate = ifThen.predicate;
        CodeChunk consequent = ifThen.consequent;
        return consequent instanceof CodeChunk.WithValue && trailingElse instanceof CodeChunk.WithValue
                && predicate.initialStatements().containsAll(((WithValue) consequent).initialStatements())
                && predicate.initialStatements().containsAll(((WithValue) trailingElse).initialStatements());
    }
}