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Groovy example source code file (StaticVerifier.java)

This example Groovy source code file (StaticVerifier.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

classcodevisitorsupport, dynamicvariable, expression, methodnode, override, override, propertyexpression, sourceunit, sourceunit, variable, variableexpression, variableexpression, you, you

The Groovy StaticVerifier.java source code

/*
 * Copyright 2003-2010 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.control;

import org.codehaus.groovy.ast.*;
import org.codehaus.groovy.ast.expr.*;

/**
 * Verifier to check non-static access in static contexts
 *
 * @author Jochen Theodorou
 * @author Paul King
 * @author <a href="mailto:roshandawrani@codehaus.org">Roshan Dawrani
 */
public class StaticVerifier extends ClassCodeVisitorSupport {
    private boolean inSpecialConstructorCall;
    private boolean inPropertyExpression;
    private boolean inClosure;
    private MethodNode currentMethod;
    private SourceUnit source;

    public void visitClass(ClassNode node, SourceUnit source) {
        this.source = source;
        super.visitClass(node);
    }

    @Override
    public void visitVariableExpression(VariableExpression ve) {
        Variable v = ve.getAccessedVariable();
        if (v != null && v instanceof DynamicVariable) {
            if (!inPropertyExpression || inSpecialConstructorCall) addStaticVariableError(ve);
        }
    }

    @Override
    public void visitClosureExpression(ClosureExpression ce) {
        boolean oldInClosure = inClosure;
        inClosure = true;
        super.visitClosureExpression(ce);
        inClosure = oldInClosure;
    }

    @Override
    public void visitConstructorCallExpression(ConstructorCallExpression cce) {
        boolean oldIsSpecialConstructorCall = inSpecialConstructorCall;
        inSpecialConstructorCall = cce.isSpecialCall();
        super.visitConstructorCallExpression(cce);
        inSpecialConstructorCall = oldIsSpecialConstructorCall;
    }

    @Override
    public void visitConstructorOrMethod(MethodNode node, boolean isConstructor) {
        MethodNode oldCurrentMethod = currentMethod;
        currentMethod = node;
        super.visitConstructorOrMethod(node, isConstructor);
        currentMethod = oldCurrentMethod;
    }

    @Override
    public void visitMethodCallExpression(MethodCallExpression mce) {
        checkSuperAccess(mce, mce.getObjectExpression());
        super.visitMethodCallExpression(mce);
    }

    @Override
    public void visitPropertyExpression(PropertyExpression pe) {
        boolean oldInPropertyExpression = inPropertyExpression;
        inPropertyExpression = true;
        checkSuperAccess(pe, pe.getObjectExpression());
        inPropertyExpression = oldInPropertyExpression;
        if (!inSpecialConstructorCall) checkStaticScope(pe);
    }

    @Override
    protected SourceUnit getSourceUnit() {
        return source;
    }

    private void checkSuperAccess(Expression expr, Expression object) {
        if (object instanceof VariableExpression) {
            VariableExpression ve = (VariableExpression) object;
            boolean isExplicitSuper = ve.getName().equals("super");
            if (isExplicitSuper && currentMethod != null && currentMethod.isStatic()) {
                addError("'super' cannot be used in a static context, use the explicit class instead.", expr);
            }
        }
    }

    private void checkStaticScope(PropertyExpression pe) {
        if (inClosure) return;
        for (Expression it = pe; it != null; it = ((PropertyExpression) it).getObjectExpression()) {
            if (it instanceof PropertyExpression) continue;
            if (it instanceof VariableExpression) {
                addStaticVariableError((VariableExpression) it);
            }
            return;
        }
    }

    private void addStaticVariableError(VariableExpression ve) {
        // closures are always dynamic
        // propertyExpressions will handle the error a bit differently
        if (!inSpecialConstructorCall && (inClosure || !ve.isInStaticContext())) return;
        if (ve.isThisExpression() || ve.isSuperExpression()) return;
        Variable v = ve.getAccessedVariable();
        if (currentMethod != null && currentMethod.isStatic()) {
            FieldNode fieldNode = currentMethod.getDeclaringClass().getField(ve.getName());
            if (fieldNode != null && fieldNode.isStatic()) return;
        }
        if (v != null && !(v instanceof DynamicVariable) && v.isInStaticContext()) return;
        addError("Apparent variable '" + ve.getName() + "' was found in a static scope but doesn't refer" +
                " to a local variable, static field or class. Possible causes:\n" +
                "You attempted to reference a variable in the binding or an instance variable from a static context.\n" +
                "You misspelled a classname or statically imported field. Please check the spelling.\n" +
                "You attempted to use a method '" + ve.getName() +
                "' but left out brackets in a place not allowed by the grammar.", ve);
    }
}

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