如何运行 AST 转换？答案

【问题标题】：How to run AST transformation?如何运行 AST 转换？
【发布时间】：2015-11-20 18:38:30
【问题描述】：

我正在尝试运行此示例中的 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？我什至也这样做了，添加了一个 main 方法并编译了它。但仍然测试失败说：

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)

我哪里出错了？

【问题讨论】：

标签： groovy abstract-syntax-tree

【解决方案1】：

异常表示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，并且您实际上询问了正确的类，这意味着它没有运行。我只能假设这两点，因为你没有提供任何信息。

那么接下来是为什么它没有运行。编译 Foo 时需要预编译 AuthorAdderASTTransformation。但即使这样还不够，还需要有元数据。 http://www.groovy-lang.org/metaprogramming.html#developing-ast-xforms 页面建议为它创建一个 jar。虽然这不是严格要求，但它可以很好地防止您在编译正常源代码时正确忘记元数据文件服务。

【讨论】：