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Groovy: A powerful, dynamic language for the JVM
There is a newer version: 3.0.22
/*
 * Copyright 2003-2013 the original author or authors.
 *
 * 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 groovy.transform.stc;

import antlr.RecognitionException;
import antlr.TokenStreamException;
import org.codehaus.groovy.antlr.AntlrParserPlugin;
import org.codehaus.groovy.antlr.parser.GroovyLexer;
import org.codehaus.groovy.antlr.parser.GroovyRecognizer;
import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.GenericsType;
import org.codehaus.groovy.ast.MethodNode;
import org.codehaus.groovy.ast.ModuleNode;
import org.codehaus.groovy.ast.Parameter;
import org.codehaus.groovy.ast.stmt.EmptyStatement;
import org.codehaus.groovy.control.CompilationUnit;
import org.codehaus.groovy.control.ResolveVisitor;
import org.codehaus.groovy.control.SourceUnit;
import org.codehaus.groovy.syntax.ParserException;
import org.codehaus.groovy.syntax.Reduction;

import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;


/**
 * A closure parameter hint class that is convenient if you want to use a String representation
 * of the signature. It makes use of the {@link ClosureParams#options() option strings}, where
 * each string corresponds to a single signature.
 *
 * The following example describes a closure as accepting a single signature (List<T> list ->):
 *
 * public <T> T apply(T src, @ClosureParams(value=FromString.class, options="List<T>" Closure<T> cl)
 *
 * The next example describes a closure as accepting two signatures (List<T> list ->) and (T t ->):
 *
 * public <T> T apply(T src, @ClosureParams(value=FromString.class, options={"List<T>","T"} Closure<T> cl)
 *
 * It is advisable not to use this hint as a replacement for the various {@link FirstParam}, {@link SimpleType},
 * ... hints because it is actually much slower. Using this hint should therefore be limited
 * to cases where it's not possible to express the signature using the existing hints.
 *
 * @author Cédric Champeau
 * @since 2.3.0
 */
public class FromString extends ClosureSignatureHint {

    @Override
    public List getClosureSignatures(final MethodNode node, final SourceUnit sourceUnit, final CompilationUnit compilationUnit, final String[] options, final ASTNode usage) {
        List list = new ArrayList(options.length);
        for (String option : options) {
            list.add(parseOption(option, sourceUnit, compilationUnit, node, usage));
        }
        return list;
    }

    /**
     * Parses a string representing a type, that must be aligned with the current context.
     * For example, "List<T>" must be converted into the appropriate ClassNode
     * for which T matches the appropriate placeholder.
     *
     *
     * @param option a string representing a type
     * @param sourceUnit the source unit (of the file being compiled)
     * @param compilationUnit the compilation unit (of the file being compiled)
     * @param mn the method node
     * @param usage
     * @return a class node if it could be parsed and resolved, null otherwise
     */
    private ClassNode[] parseOption(final String option, final SourceUnit sourceUnit, final CompilationUnit compilationUnit, final MethodNode mn, final ASTNode usage) {
        GroovyLexer lexer = new GroovyLexer(new StringReader("DummyNode<"+option+">"));
        final GroovyRecognizer rn = GroovyRecognizer.make(lexer);
        try {
            rn.classOrInterfaceType(true);
            final AtomicReference ref = new AtomicReference();
            AntlrParserPlugin plugin = new AntlrParserPlugin() {
                @Override
                public ModuleNode buildAST(final SourceUnit sourceUnit, final ClassLoader classLoader, final Reduction cst) throws ParserException {
                    ref.set(makeTypeWithArguments(rn.getAST()));
                    return null;
                }
            };
            plugin.buildAST(null, null, null);
            ClassNode parsedNode = ref.get();
            // the returned node is DummyNode