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Groovy example source code file (AnnotationVisitor.java)

This example Groovy source code file (AnnotationVisitor.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

annotationconstantexpression, annotationnode, classexpression, classnode, classnode, constantexpression, expression, expression, listexpression, listexpression, methodnode, propertyexpression, propertyexpression, reflection, string, util

The Groovy AnnotationVisitor.java source code

/*
 * Copyright 2003-2009 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.classgen;

import java.util.*;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

import org.codehaus.groovy.ast.*;
import org.codehaus.groovy.ast.stmt.ReturnStatement;
import org.codehaus.groovy.ast.expr.*;
import org.codehaus.groovy.control.ErrorCollector;
import org.codehaus.groovy.control.SourceUnit;
import org.codehaus.groovy.control.messages.SyntaxErrorMessage;
import org.codehaus.groovy.syntax.SyntaxException;
import org.codehaus.groovy.vmplugin.VMPluginFactory;

/**
 * An Annotation visitor responsible with:
 * - reading annotation metadata (@Retention, @Target, attribute types)
 * - verify that an <code>AnnotationNode conforms to annotation meta
 * - enhancing an <code>AnnotationNode AST to reflect real annotation meta
 *
 * @author <a href='mailto:the[dot]mindstorm[at]gmail[dot]com'>Alex Popescu
 */
public class AnnotationVisitor {
    private SourceUnit source;
    private ErrorCollector errorCollector;
    private AnnotationNode annotation;
    private ClassNode reportClass;

    public AnnotationVisitor(SourceUnit source, ErrorCollector errorCollector) {
        this.source = source;
        this.errorCollector = errorCollector;
    }

    public void setReportClass(ClassNode cn) {
        reportClass = cn;
    }

    public AnnotationNode visit(AnnotationNode node) {
        this.annotation = node;
        this.reportClass = node.getClassNode();

        if (!isValidAnnotationClass(node.getClassNode())) {
            addError("class " + node.getClassNode().getName() + " is not an annotation");
            return node;
        }

        // check if values have been passed for all annotation attributes that don't have defaults
        if (!checkIfMandatoryAnnotationValuesPassed(node)) {
            return node;
        }

        // if enum constants have been used, check if they are all valid
        if (!checkIfValidEnumConstsAreUsed(node)) {
            return node;
        }
        
        Map<String, Expression> attributes = node.getMembers();
        for (Map.Entry<String, Expression> entry : attributes.entrySet()) {
            String attrName = entry.getKey();
            Expression attrExpr = transformInlineConstants(entry.getValue());
            entry.setValue(attrExpr);
            ClassNode attrType = getAttributeType(node, attrName);
            visitExpression(attrName, attrExpr, attrType);
        }
        VMPluginFactory.getPlugin().configureAnnotation(node);
        return this.annotation;
    }
    
    private boolean checkIfValidEnumConstsAreUsed(AnnotationNode node) {
        boolean ok = true;
        Map<String, Expression> attributes = node.getMembers();
        for (Map.Entry<String, Expression> entry : attributes.entrySet()) {
            ok &= validateEnumConstant(entry.getValue());
        }
        return ok;
    }
    
    private boolean validateEnumConstant(Expression exp) {
        if (exp instanceof PropertyExpression) {
            PropertyExpression pe = (PropertyExpression) exp;
            String name = pe.getPropertyAsString();
            if (pe.getObjectExpression() instanceof ClassExpression && name != null) {
                ClassExpression ce = (ClassExpression) pe.getObjectExpression();
                ClassNode type = ce.getType();
                if (type.isEnum()) {
                    boolean ok = false;
                    try {
                        FieldNode enumField = type.getDeclaredField(name);
                        ok = enumField != null && enumField.getType().equals(type);
                    } catch(Exception ex) {
                        // ignore
                    }
                    if(!ok) {
                        addError("No enum const " + type.getName() + "." + name, pe);
                        return false;
                    }
                }
            }
        }
        return true;
    }

    private Expression transformInlineConstants(Expression exp) {
        if (exp instanceof PropertyExpression) {
            PropertyExpression pe = (PropertyExpression) exp;
            if (pe.getObjectExpression() instanceof ClassExpression) {
                ClassExpression ce = (ClassExpression) pe.getObjectExpression();
                ClassNode type = ce.getType();
                if (type.isEnum() || !type.isResolved())
                    return exp;

                try {
                    Field field = type.getTypeClass().getField(pe.getPropertyAsString());
                    if (field != null && Modifier.isStatic(field.getModifiers()) && Modifier.isFinal(field.getModifiers())) {
                        return new ConstantExpression(field.get(null));
                    }
                } catch(Exception e) {
                    // ignore, leave property expression in place and we'll report later
                }
            }
        } else if (exp instanceof ListExpression) {
            ListExpression le = (ListExpression) exp;
            ListExpression result = new ListExpression();
            for (Expression e : le.getExpressions()) {
                result.addExpression(transformInlineConstants(e));
            }
            return result;
        }
        return exp;
    }

    private boolean checkIfMandatoryAnnotationValuesPassed(AnnotationNode node) {
        boolean ok = true;
        Map attributes = node.getMembers();
        ClassNode classNode = node.getClassNode();
        for (MethodNode mn : classNode.getMethods()) {
            String methodName = mn.getName();
            // if the annotation attribute has a default, getCode() returns a ReturnStatement with the default value
            if (mn.getCode() == null && !attributes.containsKey(methodName)) {
                addError("No explicit/default value found for annotation attribute '" + methodName + "' in annotation " + classNode, node);
                ok = false;
            }
        }
        return ok;
    }

    private ClassNode getAttributeType(AnnotationNode node, String attrName) {
        ClassNode classNode = node.getClassNode();
        List methods = classNode.getMethods(attrName);
        // if size is >1, then the method was overwritten or something, we ignore that
        // if it is an error, we have to test it at another place. But size==0 is
        // an error, because it means that no such attribute exists.
        if (methods.size() == 0) {
            addError("'" + attrName + "'is not part of the annotation " + classNode, node);
            return ClassHelper.OBJECT_TYPE;
        }
        MethodNode method = (MethodNode) methods.get(0);
        return method.getReturnType();
    }

    private boolean isValidAnnotationClass(ClassNode node) {
        return node.implementsInterface(ClassHelper.Annotation_TYPE);
    }

    protected void visitExpression(String attrName, Expression attrExp, ClassNode attrType) {
        if (attrType.isArray()) {
            // check needed as @Test(attr = {"elem"}) passes through the parser
            if (attrExp instanceof ListExpression) {
                ListExpression le = (ListExpression) attrExp;
                visitListExpression(attrName, le, attrType.getComponentType());
            } else if (attrExp instanceof ClosureExpression) {
                addError("Annotation list attributes must use Groovy notation [el1, el2]", attrExp);
            } else {
                // treat like a singleton list as per Java
                ListExpression listExp = new ListExpression();
                listExp.addExpression(attrExp);
                if (annotation != null) {
                    annotation.setMember(attrName, listExp);
                }
                visitExpression(attrName, listExp, attrType);
            }
        } else if (ClassHelper.isPrimitiveType(attrType)) {
            visitConstantExpression(attrName, getConstantExpression(attrExp, attrType), ClassHelper.getWrapper(attrType));
        } else if (ClassHelper.STRING_TYPE.equals(attrType)) {
            visitConstantExpression(attrName, getConstantExpression(attrExp, attrType), ClassHelper.STRING_TYPE);
        } else if (ClassHelper.CLASS_Type.equals(attrType)) {
            if (!(attrExp instanceof ClassExpression || attrExp instanceof ClosureExpression)) {
                addError("Only classes and closures can be used for attribute '" + attrName + "'", attrExp);
            }
        } else if (attrType.isDerivedFrom(ClassHelper.Enum_Type)) {
            if (attrExp instanceof PropertyExpression) {
                visitEnumExpression(attrName, (PropertyExpression) attrExp, attrType);
            } else {
                addError("Expected enum value for attribute " + attrName, attrExp);
            }
        } else if (isValidAnnotationClass(attrType)) {
            if (attrExp instanceof AnnotationConstantExpression) {
                visitAnnotationExpression(attrName, (AnnotationConstantExpression) attrExp, attrType);
            } else {
                addError("Expected annotation of type '" + attrType.getName() + "' for attribute " + attrName, attrExp);
            }
        } else {
            addError("Unexpected type " + attrType.getName(), attrExp);
        }
    }

    public void checkReturnType(ClassNode attrType, ASTNode node) {
        if (attrType.isArray()) {
            checkReturnType(attrType.getComponentType(), node);
        } else if (ClassHelper.isPrimitiveType(attrType)) {
            return;
        } else if (ClassHelper.STRING_TYPE.equals(attrType)) {
            return;
        } else if (ClassHelper.CLASS_Type.equals(attrType)) {
            return;
        } else if (attrType.isDerivedFrom(ClassHelper.Enum_Type)) {
            return;
        } else if (isValidAnnotationClass(attrType)) {
            return;
        } else {
            addError("Unexpected return type " + attrType.getName(), node);
        }
    }

    private ConstantExpression getConstantExpression(Expression exp, ClassNode attrType) {
        if (exp instanceof ConstantExpression) {
            return (ConstantExpression) exp;
        } else {
            String base = "expected '" + exp.getText() + "' to be an inline constant of type " + attrType.getName();
            if (exp instanceof PropertyExpression) {
                addError(base + " not a property expression", exp);
            } else if (exp instanceof VariableExpression && ((VariableExpression)exp).getAccessedVariable() instanceof FieldNode) {
                addError(base + " not a field expression", exp);
            } else {
                addError(base, exp);
            }
            return ConstantExpression.EMPTY_EXPRESSION;
        }
    }

    /**
     * @param attrName   the name
     * @param expression the expression
     * @param attrType   the type
     */
    protected void visitAnnotationExpression(String attrName, AnnotationConstantExpression expression, ClassNode attrType) {
        AnnotationNode annotationNode = (AnnotationNode) expression.getValue();
        AnnotationVisitor visitor = new AnnotationVisitor(this.source, this.errorCollector);
        // TODO track Deprecated usage and give a warning?
        visitor.visit(annotationNode);
    }

    protected void visitListExpression(String attrName, ListExpression listExpr, ClassNode elementType) {
        for (Expression expression : listExpr.getExpressions()) {
            visitExpression(attrName, expression, elementType);
        }
    }

    protected void visitConstantExpression(String attrName, ConstantExpression constExpr, ClassNode attrType) {
        ClassNode type = ClassHelper.getWrapper(constExpr.getType());
        if (!type.isDerivedFrom(attrType)) {
            addError("Attribute '" + attrName + "' should have type '" + attrType.getName() + "'; "
                    + "but found type '" + constExpr.getType().getName() + "'",
                    constExpr);
        }
    }

    protected void visitEnumExpression(String attrName, PropertyExpression propExpr, ClassNode attrType) {
        if (!propExpr.getObjectExpression().getType().isDerivedFrom(attrType)) {
            addError("Attribute '" + attrName + "' should have type '" + attrType.getName() + "' (Enum), but found "
                    + propExpr.getObjectExpression().getType().getName(),
                    propExpr);
        }
    }

    protected void addError(String msg) {
        addError(msg, this.annotation);
    }

    protected void addError(String msg, ASTNode expr) {
        this.errorCollector.addErrorAndContinue(
                new SyntaxErrorMessage(new SyntaxException(
                        msg + " in @" + this.reportClass.getName() + '\n',
                        expr.getLineNumber(),
                        expr.getColumnNumber()), this.source)
        );
    }

    public void checkCircularReference(ClassNode searchClass, ClassNode attrType, Expression startExp) {
        if (!isValidAnnotationClass(attrType)) return;
        if (!(startExp instanceof AnnotationConstantExpression)) {
            addError("Found '" + startExp.getText() + "' when expecting an Annotation Constant", startExp);
            return;
        }
        AnnotationConstantExpression ace = (AnnotationConstantExpression) startExp;
        AnnotationNode annotationNode = (AnnotationNode) ace.getValue();
        if (annotationNode.getClassNode().equals(searchClass)) {
            addError("Circular reference discovered in " + searchClass.getName(), startExp);
            return;
        }
        ClassNode cn = annotationNode.getClassNode();
        for (MethodNode method : cn.getMethods()) {
            if (method.getReturnType().equals(searchClass)) {
                addError("Circular reference discovered in " + cn.getName(), startExp);
            }
            ReturnStatement code = (ReturnStatement) method.getCode();
            if (code == null) continue;
            checkCircularReference(searchClass, method.getReturnType(), code.getExpression());
        }
    }

}

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