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Groovy example source code file (FieldASTTransformation.java)

This example Groovy source code file (FieldASTTransformation.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, annotationnode, annotationnode, classnode, closureexpression, declarationexpression, declarationexpression, error, my_type_name, my_type_name, override, override, sourceunit, util, variableexpression

The Groovy FieldASTTransformation.java source code

/*
 * Copyright 2008-2011 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.Field;
import org.codehaus.groovy.GroovyBugError;
import org.codehaus.groovy.ast.*;
import org.codehaus.groovy.ast.expr.BinaryExpression;
import org.codehaus.groovy.ast.expr.ClosureExpression;
import org.codehaus.groovy.ast.expr.ConstantExpression;
import org.codehaus.groovy.ast.expr.DeclarationExpression;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.expr.VariableExpression;
import org.codehaus.groovy.ast.stmt.ExpressionStatement;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;
import org.objectweb.asm.Opcodes;

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

/**
 * Handles transformation for the @Field annotation.
 * This is experimental, use at your own risk.
 *
 * @author Paul King
 * @author Cedric Champeau
 */
@GroovyASTTransformation(phase = CompilePhase.SEMANTIC_ANALYSIS)
public class FieldASTTransformation extends ClassCodeExpressionTransformer implements ASTTransformation, Opcodes {

    private static final Class MY_CLASS = Field.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 ASTTRANSFORM_TYPE = ClassHelper.make(GroovyASTTransformationClass.class);
    private SourceUnit sourceUnit;
    private DeclarationExpression candidate;
    private boolean insideScriptBody;
    private String variableName;
    private FieldNode fieldNode;
    private ClosureExpression currentClosure;

    public void visit(ASTNode[] nodes, SourceUnit source) {
        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 DeclarationExpression) {
            DeclarationExpression de = (DeclarationExpression) parent;
            ClassNode cNode = de.getDeclaringClass();
            if (!cNode.isScript()) {
                addError("Error: annotation " + MY_TYPE_NAME + " can only be used within a Script.", parent);
                return;
            }
            candidate = de;
            // GROOVY-4548: temp fix to stop CCE until proper support is added
            if (de.isMultipleAssignmentDeclaration()) {
                addError("Error: annotation " + MY_TYPE_NAME + " not supported with multiple assignment notation.", parent);
                return;
            }
            VariableExpression ve = de.getVariableExpression();
            variableName = ve.getName();
            // set owner null here, it will be updated by addField
            fieldNode = new FieldNode(variableName, ve.getModifiers(), ve.getType(), null, de.getRightExpression());
            fieldNode.setSourcePosition(de);
            cNode.addField(fieldNode);

            // GROOVY-4833 : annotations that are not Groovy transforms should be transfered to the generated field
            final List<AnnotationNode> annotations = de.getAnnotations();
            for (AnnotationNode annotation : annotations) {
                final ClassNode annotationClassNode = annotation.getClassNode();
                if (annotationClassNode.getAnnotations(ASTTRANSFORM_TYPE).isEmpty()) {
                    fieldNode.addAnnotation(annotation);
                }
            }

            super.visitClass(cNode);
        }
    }

    @Override
    public Expression transform(Expression expr) {
        if (expr == null) return null;
        if (expr instanceof DeclarationExpression) {
            DeclarationExpression de = (DeclarationExpression) expr;
            if (de.getLeftExpression() == candidate.getLeftExpression()) {
                if (insideScriptBody) {
                    // TODO make EmptyExpression work
                    // partially works but not if only thing in script
                    // return EmptyExpression.INSTANCE;
                    return new ConstantExpression(null);
                }
                addError("Error: annotation " + MY_TYPE_NAME + " can only be used within a Script body.", expr);
                return expr;
            }
        } else if (insideScriptBody && expr instanceof VariableExpression && currentClosure != null) {
            VariableExpression ve = (VariableExpression) expr;
            if (ve.getName().equals(variableName)) {
                // we may only check the variable name because the Groovy compiler
                // already fails if a variable with the same name already exists in the scope.
                // this means that a closure cannot shadow a class variable
                ve.setAccessedVariable(fieldNode);
                final VariableScope variableScope = currentClosure.getVariableScope();
                final Iterator<Variable> iterator = variableScope.getReferencedLocalVariablesIterator();
                while (iterator.hasNext()) {
                    Variable next = iterator.next();
                    if (next.getName().equals(variableName)) iterator.remove();
                }
                variableScope.putReferencedClassVariable(fieldNode);
                return ve;
            }
        }
        return expr.transformExpression(this);
    }

    @Override
    public void visitClosureExpression(final ClosureExpression expression) {
        ClosureExpression old = currentClosure;
        currentClosure = expression;
        super.visitClosureExpression(expression);
        currentClosure = old;
    }

    @Override
    public void visitMethod(MethodNode node) {
        Boolean oldInsideScriptBody = insideScriptBody;
        if (node.isScriptBody()) insideScriptBody = true;
        super.visitMethod(node);
        insideScriptBody = oldInsideScriptBody;
    }

    @Override
    public void visitExpressionStatement(ExpressionStatement es) {
        Expression exp = es.getExpression();
        if (exp instanceof BinaryExpression) {
            exp.visit(this);
        }
        super.visitExpressionStatement(es);
    }

    protected SourceUnit getSourceUnit() {
        return sourceUnit;
    }
}

Other Groovy examples (source code examples)

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