src/main/org/codehaus/groovy/transform/ConditionalInterruptibleASTTransformation.groovy

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.ConditionalInterrupt
import org.codehaus.groovy.ast.*
import org.codehaus.groovy.ast.expr.*
import org.codehaus.groovy.ast.tools.ClosureUtils
import org.codehaus.groovy.control.CompilePhase

/**
 * Allows "interrupt-safe" executions of scripts by adding a custom conditional
 * check on loops (for, while, do) and first statement of closures. By default, also adds an interrupt check
 * statement on the beginning of method calls.
 *
 * @see groovy.transform.ConditionalInterrupt
 * @author Cedric Champeau
 * @author Hamlet D'Arcy
 * @author Paul King
 * @since 1.8.0
 */
@GroovyASTTransformation(phase = CompilePhase.CANONICALIZATION)
public class ConditionalInterruptibleASTTransformation extends AbstractInterruptibleASTTransformation {

  private static final ClassNode MY_TYPE = ClassHelper.make(ConditionalInterrupt)

  private ClosureExpression conditionNode
  private String conditionMethod
  private MethodCallExpression conditionCallExpression
  private ClassNode currentClass

  protected ClassNode type() {
    return MY_TYPE
  }

  protected void setupTransform(AnnotationNode node) {
    super.setupTransform(node)
    def member = node.getMember("value")
    if (!member || !(member instanceof ClosureExpression)) internalError("Expected closure value for annotation parameter 'value'. Found $member")
    conditionNode = member;
    conditionMethod = 'conditionalTransform' + node.hashCode() + '$condition'
    conditionCallExpression = new MethodCallExpression(new VariableExpression('this'), conditionMethod, new ArgumentListExpression())
  }

  protected String getErrorMessage() {
    'Execution interrupted. The following condition failed: ' + convertClosureToSource(conditionNode)
  }

  void visitClass(ClassNode type) {
    currentClass = type
    def method = type.addMethod(conditionMethod, ACC_PRIVATE | ACC_SYNTHETIC, ClassHelper.OBJECT_TYPE, Parameter.EMPTY_ARRAY, ClassNode.EMPTY_ARRAY, conditionNode.code)
    method.synthetic = true
    if (applyToAllMembers) {
      super.visitClass(type)
    }
  }

  protected Expression createCondition() {
    conditionCallExpression
  }

  @Override
  void visitAnnotations(AnnotatedNode node) {
    // this transformation does not apply on annotation nodes
    // visiting could lead to stack overflows
  }

  @Override
  void visitField(FieldNode node) {
    if (!node.isStatic() && !node.isSynthetic()) {
      super.visitField node
    }
  }

  @Override
  void visitProperty(PropertyNode node) {
    if (!node.isStatic() && !node.isSynthetic()) {
      super.visitProperty node
    }
  }

  @Override
  void visitClosureExpression(ClosureExpression closureExpr) {
    if (closureExpr == conditionNode) return // do not visit the closure from the annotation itself
    def code = closureExpr.code
    closureExpr.code = wrapBlock(code)
    super.visitClosureExpression closureExpr
  }

  @Override
  void visitMethod(MethodNode node) {
    if (node.name == conditionMethod && !node.isSynthetic()) return // do not visit the generated method
    if (node.name == 'run' && currentClass.isScript() && node.parameters.length == 0) {
      // the run() method should not have the statement added, otherwise the script binding won't be set before
      // the condition is actually tested
      super.visitMethod(node)
    } else {
      if (checkOnMethodStart && !node.isSynthetic() && !node.isStatic() && !node.isAbstract()) {
        def code = node.code
        node.code = wrapBlock(code);
      }
      if (!node.isSynthetic() && !node.isStatic()) super.visitMethod(node)
    }
  }

  /**
   * Converts a ClosureExpression into the String source.
   * @param expression a closure
   * @return the source the closure was created from
   */
  private String convertClosureToSource(ClosureExpression expression) {
    try {
        return ClosureUtils.convertClosureToSource(this.source.source, expression);
    } catch(Exception e) {
        return e.message
    }
  }
}