src/spec/test/metaprogramming/ASTMatcherTestingTest.groovy

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 *  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,
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 *  "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
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package metaprogramming


import org.codehaus.groovy.ast.ASTNode
import org.codehaus.groovy.ast.ClassNode
import org.codehaus.groovy.ast.MethodNode
import org.codehaus.groovy.ast.expr.BinaryExpression
import org.codehaus.groovy.ast.expr.Expression
import org.codehaus.groovy.control.CompilePhase
import org.codehaus.groovy.control.SourceUnit
import org.codehaus.groovy.macro.matcher.ASTMatcher
import org.codehaus.groovy.macro.transform.MacroClass
import org.codehaus.groovy.transform.AbstractASTTransformation
import org.codehaus.groovy.transform.GroovyASTTransformation
import org.codehaus.groovy.transform.GroovyASTTransformationClass
import org.junit.jupiter.api.Test

import java.lang.annotation.ElementType
import java.lang.annotation.Retention
import java.lang.annotation.RetentionPolicy
import java.lang.annotation.Target

import static groovy.test.GroovyAssert.assertScript
import static org.codehaus.groovy.ast.tools.GeneralUtils.varX

class ASTMatcherTestingTest {

    // tag::testexpression[]
    @Test
    void testTestingSumExpression() {
        use(ASTMatcher) {                 // <1>
            TwiceASTTransformation sample = new TwiceASTTransformation()
            Expression referenceNode = macro {
                a + a                     // <2>
            }.withConstraints {           // <3>
                placeholder 'a'           // <4>
            }

            assert sample
                .sumExpression
                .matches(referenceNode)   // <5>
        }
    }
    // end::testexpression[]

    // tag::executiontesting[]
    @Test
    void testASTBehavior() {
        assertScript '''
        package metaprogramming

        @Twice
        class AAA {

        }

        assert new AAA().giveMeTwo(1) == 2
        '''
    }
    // end::executiontesting[]
}

@Retention(RetentionPolicy.SOURCE)
@Target([ElementType.TYPE])
@GroovyASTTransformationClass(["metaprogramming.TwiceASTTransformation"])
@interface Twice { }

// tag::twiceasttransformation[]
@GroovyASTTransformation(phase = CompilePhase.INSTRUCTION_SELECTION)
class TwiceASTTransformation extends AbstractASTTransformation {

    static final String VAR_X = 'x'

    @Override
    void visit(ASTNode[] nodes, SourceUnit source) {
        ClassNode classNode = (ClassNode) nodes[1]
        MethodNode giveMeTwo = getTemplateClass(sumExpression)
            .getDeclaredMethods('giveMeTwo')
            .first()

        classNode.addMethod(giveMeTwo)                  // <1>
    }

    BinaryExpression getSumExpression() {               // <2>
        return macro {
            $v{ varX(VAR_X) } +
            $v{ varX(VAR_X) }
        }
    }

    ClassNode getTemplateClass(Expression expression) { // <3>
        return new MacroClass() {
            class Template {
                java.lang.Integer giveMeTwo(java.lang.Integer x) {
                    return $v { expression }
                }
            }
        }
    }
}
// end::twiceasttransformation[]