Groovy example source code file (IndexedPropertyASTTransformation.java)

This example Groovy source code file (IndexedPropertyASTTransformation.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Groovy tags/keywords

annotatednode, annotatednode, annotationnode, binaryexpression, blockstatement, blockstatement, classnode, classnode, fieldnode, my_type_name, parameter, parameter, string, util, variableexpression

The Groovy IndexedPropertyASTTransformation.java source code

/*
 * Copyright 2008-2010 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 org.codehaus.groovy.transform;

import groovy.transform.IndexedProperty;
import org.codehaus.groovy.GroovyBugError;
import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.AnnotatedNode;
import org.codehaus.groovy.ast.AnnotationNode;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.FieldNode;
import org.codehaus.groovy.ast.Parameter;
import org.codehaus.groovy.ast.expr.BinaryExpression;
import org.codehaus.groovy.ast.expr.VariableExpression;
import org.codehaus.groovy.ast.stmt.BlockStatement;
import org.codehaus.groovy.ast.stmt.ExpressionStatement;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;
import org.codehaus.groovy.control.messages.SyntaxErrorMessage;
import org.codehaus.groovy.runtime.MetaClassHelper;
import org.codehaus.groovy.syntax.SyntaxException;
import org.codehaus.groovy.syntax.Token;
import org.objectweb.asm.Opcodes;

import java.util.Arrays;
import java.util.List;


/**
 * Handles generation of code for the {@code @}IndexedProperty annotation.
 *
 * @author Paul King
 */
@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
public class IndexedPropertyASTTransformation implements ASTTransformation, Opcodes {

    private static final Class MY_CLASS = IndexedProperty.class;
    private static final ClassNode MY_TYPE = ClassHelper.make(MY_CLASS);
    private static final String MY_TYPE_NAME = "@" + MY_TYPE.getNameWithoutPackage();
    private static final ClassNode LIST_TYPE = ClassHelper.makeWithoutCaching(List.class, false);
    private static final Token ASSIGN = Token.newSymbol("=", -1, -1);
    private static final Token INDEX = Token.newSymbol("[", -1, -1);

    public void visit(ASTNode[] nodes, SourceUnit source) {
        if (nodes.length != 2 || !(nodes[0] instanceof AnnotationNode) || !(nodes[1] instanceof AnnotatedNode)) {
            throw new GroovyBugError("Internal error: expecting [AnnotationNode, AnnotatedNode] but got: " + Arrays.asList(nodes));
        }

        AnnotatedNode parent = (AnnotatedNode) nodes[1];
        AnnotationNode node = (AnnotationNode) nodes[0];
        if (!MY_TYPE.equals(node.getClassNode())) return;

        if (parent instanceof FieldNode) {
            FieldNode fNode = (FieldNode) parent;
            ClassNode cNode = fNode.getDeclaringClass();
            if (cNode.getProperty(fNode.getName()) == null) {
                addError("Error during " + MY_TYPE_NAME + " processing. Field '" + fNode.getName() +
                        "' doesn't appear to be a property; incorrect visibility?", fNode, source);
                return;
            }
            ClassNode fType = fNode.getType();
            if (fType.isArray()) {
                addArraySetter(fNode);
                addArrayGetter(fNode);
            } else if (fType.isDerivedFrom(LIST_TYPE)) {
                addListSetter(fNode);
                addListGetter(fNode);
            } else {
                addError("Error during " + MY_TYPE_NAME + " processing. Non-Indexable property '" + fNode.getName() +
                        "' found. Type must be array or list but found " + fType.getName(), fNode, source);
            }
        }
    }

    private void addListGetter(FieldNode fNode) {
        addGetter(fNode, getComponentTypeForList(fNode.getType()));
    }

    private void addListSetter(FieldNode fNode) {
        addSetter(fNode, getComponentTypeForList(fNode.getType()));
    }

    private void addArrayGetter(FieldNode fNode) {
        addGetter(fNode, fNode.getType().getComponentType());
    }

    private void addArraySetter(FieldNode fNode) {
        addSetter(fNode, fNode.getType().getComponentType());
    }

    private void addGetter(FieldNode fNode, ClassNode componentType) {
        ClassNode cNode = fNode.getDeclaringClass();
        BlockStatement body = new BlockStatement();
        Parameter[] params = new Parameter[1];
        params[0] = new Parameter(ClassHelper.int_TYPE, "index");
        body.addStatement(new ExpressionStatement(
                new BinaryExpression(
                        new VariableExpression(fNode.getName()),
                        INDEX,
                        new VariableExpression(params[0]))
        ));
        cNode.addMethod(makeName(fNode, "get"), getModifiers(fNode), componentType, params, null, body);
    }

    private void addSetter(FieldNode fNode, ClassNode componentType) {
        ClassNode cNode = fNode.getDeclaringClass();
        BlockStatement body = new BlockStatement();
        Parameter[] params = new Parameter[2];
        params[0] = new Parameter(ClassHelper.int_TYPE, "index");
        params[1] = new Parameter(componentType, "value");
        body.addStatement(new ExpressionStatement(
                new BinaryExpression(
                        new BinaryExpression(
                                new VariableExpression(fNode.getName()),
                                INDEX,
                                new VariableExpression(params[0])),
                        ASSIGN,
                        new VariableExpression(params[1])
                )));
        cNode.addMethod(makeName(fNode, "set"), getModifiers(fNode), ClassHelper.VOID_TYPE, params, null, body);
    }

    private ClassNode getComponentTypeForList(ClassNode fType) {
        if (fType.isUsingGenerics() && fType.getGenericsTypes().length == 1) {
            return fType.getGenericsTypes()[0].getType();
        } else {
            return ClassHelper.OBJECT_TYPE;
        }
    }

    private int getModifiers(FieldNode fNode) {
        int mods = ACC_PUBLIC;
        if (fNode.isStatic()) mods |= ACC_STATIC;
        return mods;
    }

    private String makeName(FieldNode fNode, String prefix) {
        return prefix + MetaClassHelper.capitalize(fNode.getName());
    }

    private void addError(String msg, ASTNode expr, SourceUnit source) {
        int line = expr.getLineNumber();
        int col = expr.getColumnNumber();
        source.getErrorCollector().addErrorAndContinue(
                new SyntaxErrorMessage(new SyntaxException(msg + '\n', line, col), source)
        );
    }

}