如何进行AST转换？

debugcn 发表于 Dev

蝙蝠侠

我正在尝试从此示例运行AST转换：

http://melix.github.io/ast-workshop/exercise1-hints.html

但是，当我运行测试时，我的断言失败了。

我需要先编译类AuthorAdderASTTransformation吗？我什至也这样做，添加了main方法并对其进行了编译。但是仍然测试失败说：

groovy.lang.MissingPropertyException: No such property: $AUTHOR for class: org.gr8conf.AuthorAdderASTTransformationTest
    at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:50)
    at org.codehaus.groovy.runtime.callsite.GetEffectivePogoPropertySite.getProperty(GetEffectivePogoPropertySite.java:86)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGroovyObjectGetProperty(AbstractCallSite.java:231)
    at org.gr8conf.AuthorAdderASTTransformationTest.testThatAuthorExists(AuthorAdderASTTransformationTest.groovy:5)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:84)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:74)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:202)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:65)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)


groovy.lang.MissingPropertyException: No such property: $AUTHOR for class: Foo
    at groovy.lang.MetaClassImpl.invokeStaticMissingProperty(MetaClassImpl.java:900)
    at groovy.lang.MetaClassImpl.getProperty(MetaClassImpl.java:1729)
    at groovy.lang.MetaClassImpl.getProperty(MetaClassImpl.java:1705)
    at groovy.lang.MetaClassImpl.getProperty(MetaClassImpl.java:3458)
    at org.codehaus.groovy.runtime.callsite.ClassMetaClassGetPropertySite.getProperty(ClassMetaClassGetPropertySite.java:48)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGetProperty(AbstractCallSite.java:227)
    at TestScripttestASTTransformationShouldBeDebuggableFromIDE0.run(TestScripttestASTTransformationShouldBeDebuggableFromIDE0.groovy:4)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:518)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:556)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:537)
    at groovy.util.GroovyTestCase.assertScript(GroovyTestCase.java:203)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:272)
    at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:52)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:49)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:141)
    at org.gr8conf.AuthorAdderASTTransformationTest.testASTTransformationShouldBeDebuggableFromIDE(AuthorAdderASTTransformationTest.groovy:9)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:84)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:74)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:202)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:65)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

我在哪里犯错？

黑拖

异常表明您的测试尝试读取属性$ AUTHOR，但未找到。假设转换本身是正确的，并且您实际上要求的是正确的类，则意味着该转换未运行。我只能假设这两点，因为您没有提供任何信息。

那么接下来为什么不运行它。编译Foo时，需要预编译AuthorAdderASTTransformation。但这还不够，还需要有元数据。http://www.groovy-lang.org/metaprogramming.html#developing-ast-xforms页面建议为此创建一个jar。尽管这不是严格要求的，但是它可以防止您在编译常规源代码时正确地忘记元数据文件服务。

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