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

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

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/*
 * Copyright 2009 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.jssrc.dsl.CodeChunk.fromExpr;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.template.soy.exprtree.Operator;
import com.google.template.soy.jssrc.dsl.CodeChunk.RequiresCollector;
import com.google.template.soy.jssrc.dsl.CodeChunk.WithValue;
import com.google.template.soy.jssrc.restricted.JsExpr;
import com.google.template.soy.jssrc.restricted.SoyJsSrcPrintDirective;
import com.google.template.soy.jssrc.restricted.SoyLibraryAssistedJsSrcPrintDirective;
import java.util.List;

/**
 * Convenience utilities for generating JS code from plugins (functions and directives).
 *
 * <p>The main code-generating classes of the JS backend understand {@link CodeChunk code chunks}
 * and have no need for these utilities. By contrast, plugins understand only {@link JsExpr}s. These
 * utilities are provided so that plugins do not needs to convert between code chunks and JsExprs
 * manually.
 *
 */
public final class SoyJsPluginUtils {

    private static final Function<WithValue, JsExpr> TO_JS_EXPR = new Function<WithValue, JsExpr>() {
        @Override
        public JsExpr apply(WithValue chunk) {
            return chunk.singleExprOrName();
        }
    };

    private SoyJsPluginUtils() {
    }

    /** Generates a JS expression for the given operator and operands. */
    public static JsExpr genJsExprUsingSoySyntax(Operator op, List<JsExpr> operandJsExprs) {
        List<CodeChunk.WithValue> operands = Lists.transform(operandJsExprs,
                new Function<JsExpr, CodeChunk.WithValue>() {
                    @Override
                    public CodeChunk.WithValue apply(JsExpr input) {
                        return fromExpr(input, ImmutableList.<GoogRequire>of());
                    }
                });
        return CodeChunk.operation(op, operands).assertExpr();
    }

    /**
     * Applies the given print directive to {@code expr} and returns the result.
     *
     * @param generator The CodeChunk generator to use.
     * @param expr The expression to apply the print directive to.
     * @param directive The print directive to apply.
     * @param args Print directive args, if any.
     */
    public static CodeChunk.WithValue applyDirective(CodeChunk.Generator generator, CodeChunk.WithValue expr,
            SoyJsSrcPrintDirective directive, List<CodeChunk.WithValue> args) {
        List<JsExpr> argExprs = Lists.transform(args, TO_JS_EXPR);
        JsExpr applied = directive.applyForJsSrc(expr.singleExprOrName(), argExprs);
        RequiresCollector.IntoImmutableSet collector = new RequiresCollector.IntoImmutableSet();
        expr.collectRequires(collector);
        for (CodeChunk.WithValue arg : args) {
            arg.collectRequires(collector);
        }
        if (directive instanceof SoyLibraryAssistedJsSrcPrintDirective) {
            for (String name : ((SoyLibraryAssistedJsSrcPrintDirective) directive).getRequiredJsLibNames()) {
                collector.add(GoogRequire.create(name));
            }
        }

        ImmutableList.Builder<CodeChunk> initialStatements = ImmutableList.<CodeChunk>builder()
                .addAll(expr.initialStatements());
        for (CodeChunk.WithValue arg : args) {
            initialStatements.addAll(arg.initialStatements());
        }
        return fromExpr(applied, collector.get()).withInitialStatements(initialStatements.build());
    }
}