com.google.gwt.sample.hellorebinding.rebind.JsniSnippetGenerator.java Source code

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Here is the source code for com.google.gwt.sample.hellorebinding.rebind.JsniSnippetGenerator.java

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/*
 * Copyright 2013 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.gwt.sample.hellorebinding.rebind;

import com.google.gwt.core.ext.GeneratorContext;
import com.google.gwt.core.ext.ParameterizedGenerator;
import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.core.ext.arguments.JArgument;
import com.google.gwt.core.ext.arguments.JArguments;
import com.google.gwt.core.ext.arguments.JStringArgument;
import com.google.gwt.core.ext.typeinfo.JClassType;
import com.google.gwt.core.ext.typeinfo.JMethod;
import com.google.gwt.sample.hellorebinding.client.util.JsniSnippet;

import java.io.PrintWriter;

/**
 * Generates {@link JsniSnippet} implementations depending on {@link JArgument}s.
 */
public class JsniSnippetGenerator extends ParameterizedGenerator {

    private int argumentsCount(JClassType type) {
        for (JMethod m : type.getMethods()) {
            if (m.getName().equals("execute")) {
                return m.getParameters().length;
            }
        }
        return -1;
    }

    @Override
    public String generate(TreeLogger logger, GeneratorContext context, String typeName, JArgument[] arguments)
            throws UnableToCompleteException {

        JClassType snippetType = context.getTypeOracle().findType(typeName);

        if (snippetType == null) {
            logger.log(TreeLogger.ERROR, "Rebinding type not found");
            throw new UnableToCompleteException();
        }

        if (arguments.length < 1) {
            logger.log(TreeLogger.ERROR, "Missing JSNI literal argument");
            throw new UnableToCompleteException();
        }

        JArgument arg0 = arguments[0];

        if (!(arg0 instanceof JStringArgument)) {
            logger.log(TreeLogger.ERROR, "JSNI literal argument must be a String literal");
            throw new UnableToCompleteException();
        }

        String argumentsKey = JArguments.getKey(arguments);

        String packageName = snippetType.getPackage().getName();
        String snippetTypeName = snippetType.getSimpleSourceName() + "_impl_" + argumentsKey;
        String qualifiedSnippetTypeName = packageName + "." + snippetTypeName;

        PrintWriter pw = context.tryCreate(logger, packageName, snippetTypeName);

        if (pw != null) {

            int argCount = argumentsCount(snippetType);

            if (argCount < 0) {
                logger.log(TreeLogger.ERROR, "execute() method not found");
                throw new UnableToCompleteException();
            }

            String jsniTemplate = ((JStringArgument) arg0).getValue();
            String[] parts = jsniTemplate.split("#", -1);

            if (parts.length != (argCount + 1)) {
                logger.log(TreeLogger.ERROR, "wrong number of snippet arguments");
                throw new UnableToCompleteException();
            }

            pw.printf("package %s;\n\n", packageName);
            pw.printf("public class %s implements %s {\n\n", snippetTypeName, snippetType.getSimpleSourceName());
            pw.printf("  public %s(String jsniLiteral) {}\n", snippetTypeName);
            pw.println();

            pw.print("  @Override public native <T> T execute(");

            boolean hasSeparator = false;

            for (int i = 0; i < argCount; i++) {
                if (hasSeparator) {
                    pw.print(", ");
                } else {
                    hasSeparator = true;
                }
                pw.printf("Object a%d", i);
            }

            pw.println(") /*-{");
            pw.print("    return ");

            if (argCount == 0) {
                pw.print(jsniTemplate);
            } else {
                for (int i = 0; i < argCount; i++) {
                    pw.printf("%sa%d", parts[i], i);
                }
                pw.print(parts[argCount]);
            }
            pw.println(";");

            pw.println("  }-*/;");
            pw.println("}");
            context.commit(logger, pw);
        }

        return qualifiedSnippetTypeName;
    }
}