com.google.gwt.resources.gss.ResourceUrlFunction.java Source code

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Here is the source code for com.google.gwt.resources.gss.ResourceUrlFunction.java

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/*
 * Copyright 2013 Julien Dramaix.
 *
 * 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.gwt.resources.gss;

import com.google.common.collect.ImmutableList;
import com.google.common.css.SourceCodeLocation;
import com.google.common.css.compiler.ast.CssFunctionArgumentsNode;
import com.google.common.css.compiler.ast.CssFunctionNode;
import com.google.common.css.compiler.ast.CssValueNode;
import com.google.common.css.compiler.ast.ErrorManager;
import com.google.common.css.compiler.ast.GssError;
import com.google.common.css.compiler.ast.GssFunction;
import com.google.common.css.compiler.ast.GssFunctionException;
import com.google.common.css.compiler.gssfunctions.GssFunctions;
import com.google.gwt.core.ext.typeinfo.JClassType;
import com.google.gwt.core.ext.typeinfo.JType;
import com.google.gwt.core.ext.typeinfo.NotFoundException;
import com.google.gwt.resources.client.DataResource;
import com.google.gwt.resources.client.ImageResource;
import com.google.gwt.resources.ext.ResourceContext;
import com.google.gwt.resources.ext.ResourceGeneratorUtil;
import com.google.gwt.resources.gss.ast.CssDotPathNode;
import com.google.gwt.resources.gss.ast.CssJavaExpressionNode;

import java.util.List;

public class ResourceUrlFunction implements GssFunction {
    private final ResourceContext context;
    private final JClassType dataResourceType;
    private final JClassType imageResourceType;

    public ResourceUrlFunction(ResourceContext context) {
        this.context = context;
        this.dataResourceType = context.getGeneratorContext().getTypeOracle()
                .findType(DataResource.class.getCanonicalName());
        this.imageResourceType = context.getGeneratorContext().getTypeOracle()
                .findType(ImageResource.class.getCanonicalName());
    }

    public static String getName() {
        return "resourceUrl";
    }

    @Override
    public Integer getNumExpectedArguments() {
        return 1;
    }

    @Override
    public List<CssValueNode> getCallResultNodes(List<CssValueNode> cssValueNodes, ErrorManager errorManager)
            throws GssFunctionException {
        CssValueNode functionToEval = cssValueNodes.get(0);
        String value = functionToEval.getValue();
        SourceCodeLocation location = functionToEval.getSourceCodeLocation();

        String javaExpression = buildJavaExpression(value, location, errorManager);

        CssFunctionNode urlNode = buildUrlNode(javaExpression, location);

        return ImmutableList.<CssValueNode>of(urlNode);
    }

    @Override
    public String getCallResultString(List<String> strings) throws GssFunctionException {
        return strings.get(0);
    }

    private String buildJavaExpression(String value, SourceCodeLocation location, ErrorManager errorManager)
            throws GssFunctionException {
        CssDotPathNode dotPathValue = new CssDotPathNode(value, "", "", location);

        assertMethodIsValidResource(location, dotPathValue.getPathElements(), errorManager);

        return context.getImplementationSimpleSourceName() + ".this." + dotPathValue.getValue()
                + ".getSafeUri().asString()";
    }

    private void assertMethodIsValidResource(SourceCodeLocation location, List<String> pathElements,
            ErrorManager errorManager) throws GssFunctionException {
        JType methodType;

        try {
            methodType = ResourceGeneratorUtil.getMethodByPath(context.getClientBundleType(), pathElements, null)
                    .getReturnType();
        } catch (NotFoundException e) {
            String message = e.getMessage();
            errorManager.report(new GssError(message, location));
            throw new GssFunctionException(message, e);
        }

        if (!dataResourceType.isAssignableFrom((JClassType) methodType)
                && !imageResourceType.isAssignableFrom((JClassType) methodType)) {
            String message = "Invalid method type for url substitution: " + methodType + ". "
                    + "Only DataResource and ImageResource are supported.";
            errorManager.report(new GssError(message, location));
            throw new GssFunctionException(message);
        }
    }

    private CssFunctionNode buildUrlNode(String javaExpression, SourceCodeLocation location) {
        CssFunctionNode urlNode = GssFunctions.createUrlNode("", location);
        CssJavaExpressionNode cssJavaExpressionNode = new CssJavaExpressionNode(javaExpression);
        CssFunctionArgumentsNode arguments = new CssFunctionArgumentsNode(
                ImmutableList.<CssValueNode>of(cssJavaExpressionNode));
        urlNode.setArguments(arguments);

        return urlNode;
    }
}