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Groovy example source code file (NewifyASTTransformation.java)

This example Groovy source code file (NewifyASTTransformation.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

classexpression, classexpression, classnode, classnode, declarationexpression, expression, expression, list, listexpression, listexpression, methodcallexpression, my_name, string, util, variableexpression

The Groovy NewifyASTTransformation.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.lang.Newify;
import org.codehaus.groovy.GroovyBugError;
import org.codehaus.groovy.ast.*;
import org.codehaus.groovy.ast.expr.*;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;

import java.util.HashSet;
import java.util.List;
import java.util.Arrays;
import java.util.Set;

/**
 * Handles generation of code for the @Newify annotation.
 *
 * @author Paul King
 */
@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
public class NewifyASTTransformation extends ClassCodeExpressionTransformer implements ASTTransformation {
    private static final ClassNode MY_TYPE = ClassHelper.make(Newify.class);
    private static final String MY_NAME = MY_TYPE.getNameWithoutPackage();
    private static final String BASE_BAD_PARAM_ERROR = "Error during @" + MY_NAME +
            " processing. Annotation parameter must be a class or list of classes but found ";
    private SourceUnit source;
    private ListExpression classesToNewify;
    private DeclarationExpression candidate;
    private boolean auto;

    public void visit(ASTNode[] nodes, SourceUnit source) {
        this.source = source;
        if (nodes.length != 2 || !(nodes[0] instanceof AnnotationNode) || !(nodes[1] instanceof AnnotatedNode)) {
            internalError("Expecting [AnnotationNode, AnnotatedClass] but got: " + Arrays.asList(nodes));
        }

        AnnotatedNode parent = (AnnotatedNode) nodes[1];
        AnnotationNode node = (AnnotationNode) nodes[0];
        if (!MY_TYPE.equals(node.getClassNode())) {
            internalError("Transformation called from wrong annotation: " + node.getClassNode().getName());
        }

        boolean autoFlag = determineAutoFlag(node.getMember("auto"));
        Expression value = node.getMember("value");

        if (parent instanceof ClassNode) {
            newifyClass((ClassNode) parent, autoFlag, determineClasses(value, false));
        } else if (parent instanceof MethodNode || parent instanceof FieldNode) {
            newifyMethodOrField(parent, autoFlag, determineClasses(value, false));
        } else if (parent instanceof DeclarationExpression) {
            newifyDeclaration((DeclarationExpression) parent, autoFlag, determineClasses(value, true));
        }
    }

    private void newifyDeclaration(DeclarationExpression de, boolean autoFlag, ListExpression list) {
        ClassNode cNode = de.getDeclaringClass();
        candidate = de;
        final ListExpression oldClassesToNewify = classesToNewify;
        final boolean oldAuto = auto;
        classesToNewify = list;
        auto = autoFlag;
        super.visitClass(cNode);
        classesToNewify = oldClassesToNewify;
        auto = oldAuto;
    }

    private boolean determineAutoFlag(Expression autoExpr) {
        return !(autoExpr instanceof ConstantExpression && ((ConstantExpression) autoExpr).getValue().equals(false));
    }

    /** allow non-strict mode in scripts because parsing not complete at that point */
    private ListExpression determineClasses(Expression expr, boolean searchSourceUnit) {
        ListExpression list = new ListExpression();
        if (expr instanceof ClassExpression) {
            list.addExpression(expr);
        } else if (expr instanceof VariableExpression && searchSourceUnit) {
            VariableExpression ve = (VariableExpression) expr;
            ClassNode fromSourceUnit = getSourceUnitClass(ve);
            if (fromSourceUnit != null) {
                ClassExpression found = new ClassExpression(fromSourceUnit);
                found.setSourcePosition(ve);
                list.addExpression(found);
            } else {
                addError(BASE_BAD_PARAM_ERROR + "an unresolvable reference to '" + ve.getName() + "'.", expr);
            }
        } else if (expr instanceof ListExpression) {
            list = (ListExpression) expr;
            final List<Expression> expressions = list.getExpressions();
            for (int i = 0; i < expressions.size(); i++) {
                Expression next = expressions.get(i);
                if (next instanceof VariableExpression && searchSourceUnit) {
                    VariableExpression ve = (VariableExpression) next;
                    ClassNode fromSourceUnit = getSourceUnitClass(ve);
                    if (fromSourceUnit != null) {
                        ClassExpression found = new ClassExpression(fromSourceUnit);
                        found.setSourcePosition(ve);
                        expressions.set(i, found);
                    } else {
                        addError(BASE_BAD_PARAM_ERROR + "a list containing an unresolvable reference to '" + ve.getName() + "'.", next);
                    }
                } else if (!(next instanceof ClassExpression)) {
                    addError(BASE_BAD_PARAM_ERROR + "a list containing type: " + next.getType().getName() + ".", next);
                }
            }
            checkDuplicateNameClashes(list);
        } else if (expr != null) {
            addError(BASE_BAD_PARAM_ERROR + "a type: " + expr.getType().getName() + ".", expr);
        }
        return list;
    }

    private ClassNode getSourceUnitClass(VariableExpression ve) {
        List<ClassNode> classes = source.getAST().getClasses();
        for (ClassNode classNode : classes) {
            if (classNode.getNameWithoutPackage().equals(ve.getName())) return classNode;
        }
        return null;
    }

    public Expression transform(Expression expr) {
        if (expr == null) return null;
        if (expr instanceof MethodCallExpression && candidate == null) {
            MethodCallExpression mce = (MethodCallExpression) expr;
            Expression args = transform(mce.getArguments());
            if (isNewifyCandidate(mce)) {
                Expression transformed = transformMethodCall(mce, args);
                transformed.setSourcePosition(mce);
                return transformed;
            }
            Expression method = transform(mce.getMethod());
            Expression object = transform(mce.getObjectExpression());
            MethodCallExpression transformed = new MethodCallExpression(object, method, args);
            transformed.setSourcePosition(mce);
            return transformed;
        } else if (expr instanceof DeclarationExpression) {
            DeclarationExpression de = (DeclarationExpression) expr;
            if (de == candidate) {
                candidate = null;
                Expression left = de.getLeftExpression();
                Expression right = transform(de.getRightExpression());
                DeclarationExpression newDecl = new DeclarationExpression(left, de.getOperation(), right);
                newDecl.addAnnotations(de.getAnnotations());
                return newDecl;
            }
            return de;
        }
        return expr.transformExpression(this);
    }

    private void newifyClass(ClassNode cNode, boolean autoFlag, ListExpression list) {
        String cName = cNode.getName();
        if (cNode.isInterface()) {
            addError("Error processing interface '" + cName + "'. @"
                    + MY_NAME + " not allowed for interfaces.", cNode);
        }
        final ListExpression oldClassesToNewify = classesToNewify;
        final boolean oldAuto = auto;
        classesToNewify = list;
        auto = autoFlag;
        super.visitClass(cNode);
        classesToNewify = oldClassesToNewify;
        auto = oldAuto;
    }

    private void newifyMethodOrField(AnnotatedNode parent, boolean autoFlag, ListExpression list) {
        final ListExpression oldClassesToNewify = classesToNewify;
        final boolean oldAuto = auto;
        checkClassLevelClashes(list);
        checkAutoClash(autoFlag, parent);
        classesToNewify = list;
        auto = autoFlag;
        if (parent instanceof FieldNode) {
            super.visitField((FieldNode) parent);
        } else {
            super.visitMethod((MethodNode) parent);
        }
        classesToNewify = oldClassesToNewify;
        auto = oldAuto;
    }

    private void checkDuplicateNameClashes(ListExpression list) {
        final Set<String> seen = new HashSet();
        @SuppressWarnings("unchecked")
        final List<ClassExpression> classes = (List)list.getExpressions();
        for (ClassExpression ce : classes) {
            final String name = ce.getType().getNameWithoutPackage();
            if (seen.contains(name)) {
                addError("Duplicate name '" + name + "' found during @" + MY_NAME + " processing.", ce);
            }
            seen.add(name);
        }
    }

    private void checkAutoClash(boolean autoFlag, AnnotatedNode parent) {
        if (auto && !autoFlag) {
            addError("Error during @" + MY_NAME + " processing. The 'auto' flag can't be false at " +
                    "method/constructor/field level if it is true at the class level.", parent);
        }
    }

    private void checkClassLevelClashes(ListExpression list) {
        @SuppressWarnings("unchecked")
        final List<ClassExpression> classes = (List)list.getExpressions();
        for (ClassExpression ce : classes) {
            final String name = ce.getType().getNameWithoutPackage();
            if (findClassWithMatchingBasename(name)) {
                addError("Error during @" + MY_NAME + " processing. Class '" + name + "' can't appear at " +
                        "method/constructor/field level if it already appears at the class level.", ce);
            }
        }
    }

    private boolean findClassWithMatchingBasename(String nameWithoutPackage) {
        if (classesToNewify == null) return false;
        @SuppressWarnings("unchecked")
        final List<ClassExpression> classes = (List)classesToNewify.getExpressions();
        for (ClassExpression ce : classes) {
            if (ce.getType().getNameWithoutPackage().equals(nameWithoutPackage)) {
                return true;
            }
        }
        return false;
    }

    private boolean isNewifyCandidate(MethodCallExpression mce) {
        return mce.getObjectExpression() == VariableExpression.THIS_EXPRESSION
                || (auto && isNewMethodStyle(mce));
    }

    private boolean isNewMethodStyle(MethodCallExpression mce) {
        final Expression obj = mce.getObjectExpression();
        final Expression meth = mce.getMethod();
        return (obj instanceof ClassExpression && meth instanceof ConstantExpression
                && ((ConstantExpression) meth).getValue().equals("new"));
    }

    private Expression transformMethodCall(MethodCallExpression mce, Expression args) {
        ClassNode classType;
        if (isNewMethodStyle(mce)) {
            classType = mce.getObjectExpression().getType();
        } else {
            classType = findMatchingCandidateClass(mce);
        }
        if (classType != null) {
            return new ConstructorCallExpression(classType, args);
        }
        // set the args as they might have gotten Newify transformed GROOVY-3491
        mce.setArguments(args);
        return mce;
    }

    private ClassNode findMatchingCandidateClass(MethodCallExpression mce) {
        if (classesToNewify == null) return null;
        @SuppressWarnings("unchecked")
        List<ClassExpression> classes = (List)classesToNewify.getExpressions();
        for (ClassExpression ce : classes) {
            final ClassNode type = ce.getType();
            if (type.getNameWithoutPackage().equals(mce.getMethodAsString())) {
                return type;
            }
        }
        return null;
    }

    private void internalError(String message) {
        throw new GroovyBugError("Internal error: " + message);
    }

    protected SourceUnit getSourceUnit() {
        return source;
    }
}

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