Groovy example source code file (OptimizerVisitor.java)

This example Groovy source code file (OptimizerVisitor.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

classcodeexpressiontransformer, fieldnode, fieldnode, hashmap, list, map, number, object, object, optimizervisitor, optimizervisitor, sourceunit, sourceunit, string, util

The Groovy OptimizerVisitor.java source code

/*
 * Copyright 2003-2007 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.control;

import org.codehaus.groovy.ast.ClassCodeExpressionTransformer;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.FieldNode;
import org.codehaus.groovy.ast.expr.ClosureExpression;
import org.codehaus.groovy.ast.expr.ConstantExpression;
import org.codehaus.groovy.ast.expr.Expression;
import org.objectweb.asm.Opcodes;

import java.util.*;

/**
 * Visitor to produce several optimizations
 *  - to replace numbered constants with references to static fields
 *
 * @author Alex Tkachman
 */
public class OptimizerVisitor extends ClassCodeExpressionTransformer {
    private ClassNode currentClass;
    private SourceUnit source;

    private Map const2Var = new HashMap();
    private List<FieldNode> missingFields = new LinkedList();

    public OptimizerVisitor(CompilationUnit cu) {
    }

    public void visitClass(ClassNode node, SourceUnit source) {
        this.currentClass = node;
        this.source = source;
        const2Var.clear();
        missingFields.clear();
        super.visitClass(node);
        addMissingFields();
    }

    private void addMissingFields() {
        for (Object missingField : missingFields) {
            FieldNode f = (FieldNode) missingField;
            currentClass.addField(f);
        }
    }

    private void setConstField(ConstantExpression constantExpression) {
        final Object n = constantExpression.getValue();
        if (!(n instanceof Number || n instanceof Character)) return;
        if (n instanceof Integer) return;
        FieldNode field = (FieldNode) const2Var.get(n);
        if (field!=null) {
            constantExpression.setConstantName(field.getName());
            return;
        }
        final String name = "$const$" + const2Var.size();
        //TODO: this part here needs a bit of rethinking. If it can happen that the field is defined already,
        //      then is this code still valid?
        field = currentClass.getDeclaredField(name);
        if (field==null) {
            field = new FieldNode(name,
                    Opcodes.ACC_PRIVATE|Opcodes.ACC_STATIC|Opcodes.ACC_SYNTHETIC| Opcodes.ACC_FINAL,
                    constantExpression.getType(),
                    currentClass,
                    constantExpression
                    );
            field.setSynthetic(true);
            missingFields.add(field);
        }
        constantExpression.setConstantName(field.getName());
        const2Var.put(n, field);
    }

    public Expression transform(Expression exp) {
        if (exp == null) return null;
        if (!currentClass.isInterface() && exp.getClass() == ConstantExpression.class) {
            setConstField((ConstantExpression)exp);
        }
        return exp.transformExpression(this);
    }

    protected SourceUnit getSourceUnit() {
        return source;
    }

    public void visitClosureExpression(ClosureExpression expression) {
        /*
         * GROOVY-3339 - do nothing - so that numbers don't get replaced by cached constants in closure classes
         */
    }
}