将Xtext 2.21.0 Eclipse项目迁移至Maven时的语法引用问题

问题背景 #

将Eclipse 2020-03环境下的Xtext 2.21.0项目迁移至Maven后，自定义DSL出现语法引用解析失败问题，原项目在Eclipse中运行正常。尝试升级至Eclipse 2023-09、Java 17及Xtext 2.32.0时，出现注入变量为空的问题，同时不确定是否需要在Mwe2工作流中处理Eclipse的plugin.xml配置。

报错信息 #

529  ERROR XtextGeneratorLanguage - [XtextLinkingDiagnostic: null:1 无法解析对Grammar 'abc.generator.ServiceGenerator'的引用。, XtextLinkingDiagnostic: null:4 无法解析对EPackage 'http://www.generator.abc/ServiceGenerator'的引用。, XtextLinkingDiagnostic: null:117 STRING无法解析为规则, XtextLinkingDiagnostic: null:249 INT无法解析为规则, TransformationDiagnostic: null:248 数据类型规则只能使用其他数据类型规则、词法分析器规则和关键字。(错误代码: InvalidDatatypeRule)]
531  ERROR Mwe2Launcher       - 运行工作流abc.generator.GenerateRawNotificationGenerator时出现问题: 解析'file:/C:/Users/xxx/Desktop/eclipse_plugin_pom/abc.generator/../abc.generator/src/abc/generator/VarDefinitionGenerator.xtext'时出错:
XtextLinkingDiagnostic: null:1 无法解析对Grammar 'abc.generator.ServiceGenerator'的引用。
XtextLinkingDiagnostic: null:4 无法解析对EPackage 'http://www.generator.abc/ServiceGenerator'的引用。
XtextLinkingDiagnostic: null:117 STRING无法解析为规则
XtextLinkingDiagnostic: null:249 INT无法解析为规则
TransformationDiagnostic: null:248 数据类型规则只能使用其他数据类型规则、词法分析器规则和关键字。(错误代码: InvalidDatatypeRule)

关键配置文件 #

1. Mwe2工作流文件 #

module abc.generator.GenerateRawNotificationGenerator

import org.eclipse.xtext.xtext.generator.*
import org.eclipse.emf.mwe.utils.StandaloneSetup
import org.eclipse.xtext.xtext.generator.model.project.*

var rootPath = ".."

Workflow {
    
    component = XtextGenerator 
    {
        configuration = 
        {
            project = StandardProjectConfig 
            {
                baseName = "abc.generator"
                rootPath = rootPath
                runtimeTest = 
                {
                    enabled = true
                }
                
                eclipsePlugin = 
                {
                    enabled = true
                }
                
                eclipsePluginTest = 
                {
                    enabled = true
                }
                
                createEclipseMetaData = true
            }
            code = 
            {
                encoding = "windows-1252"
                lineDelimiter = "\r\n"
                fileHeader = "/*\n * generated by Xtext \${version}\n */"
            }
        }
        
        language = StandardLanguage 
        {
            name = "abc.generator.ServiceGenerator"
            fileExtensions = "services"

            serializer = 
            {
                generateStub = false
            }
            
            validator = 
            {
                composedCheck = "org.eclipse.xtext.validation.NamesAreUniqueValidator"
            }
        }

        language = StandardLanguage 
        {
            name = "abc.generator.VarDefinitionGenerator"
            fileExtensions = "vardefinition"

            serializer = 
            {
                generateStub = false
            }
            
            validator = 
            {
                composedCheck = "org.eclipse.xtext.validation.NamesAreUniqueValidator"
            }
        }
    }
}

2. ServiceGenerator语法头 #

grammar abc.generator.ServiceGenerator with org.eclipse.xtext.common.Terminals
generate serviceGenerator "http://www.generator.abc/ServiceGenerator"
import "http://www.eclipse.org/emf/2002/Ecore" as ecore

3. VarDefinitionGenerator语法头 #

grammar abc.generator.VarDefinitionGenerator with abc.generator.ServiceGenerator
generate varDefinitionGenerator "http://www.generator.abc/VarDefinitionGenerator"

import "http://www.generator.abc/ServiceGenerator"
import "http://www.eclipse.org/emf/2002/Ecore" as ecore

4. Eclipse plugin.xml #

<?xml version="1.0" encoding="windows-1252"?>
<?eclipse version="3.0"?>
<plugin>
    <extension point="org.eclipse.emf.ecore.generated_package">
        <package 
            uri = "http://www.generator.abc/ServiceGenerator"
            class = "abc.generator.serviceGenerator.ServiceGeneratorPackage"
            genModel = "model/generated/ServiceGenerator.genmodel" />
    </extension>
    <extension point="org.eclipse.emf.ecore.generated_package">
        <package 
            uri = "http://www.generator.abc/VarDefinitionGenerator"
            class = "abc.generator.varDefinitionGenerator.VarDefinitionGeneratorPackage"
            genModel = "model/generated/VarDefinitionGenerator.genmodel" />
    </extension>
</plugin>

解决方案 #

1. 明确Mwe2中的语言依赖关系 #

由于VarDefinitionGenerator继承自ServiceGenerator，需在Mwe2工作流中为后者添加依赖声明，确保生成顺序与依赖解析正确。修改第二个StandardLanguage配置：

language = StandardLanguage 
{
    name = "abc.generator.VarDefinitionGenerator"
    fileExtensions = "vardefinition"

    // 添加依赖，指定依赖的语言
    dependencies = {
        language = "abc.generator.ServiceGenerator"
    }

    serializer = 
    {
        generateStub = false
    }
    
    validator = 
    {
        composedCheck = "org.eclipse.xtext.validation.NamesAreUniqueValidator"
    }
}

2. 配置StandaloneSetup加载EPackage #

在Workflow开头添加StandaloneSetup组件，确保EPackage和生成的类能被正确扫描加载：

Workflow {
    // 添加StandaloneSetup组件，放在XtextGenerator之前
    component = StandaloneSetup {
        scanClassPath = true
        platformUri = rootPath
        registerGeneratedPackages = true
    }

    component = XtextGenerator 
    {
        // 原XtextGenerator配置保持不变
        // ...
    }
}

3. 确保EPackage自动注册 #

在两个StandardLanguage配置中添加ecoreGenerator配置，让生成的Package类自动注册EPackage：

language = StandardLanguage 
{
    name = "abc.generator.ServiceGenerator"
    fileExtensions = "services"

    serializer = 
    {
        generateStub = false
    }
    
    validator = 
    {
        composedCheck = "org.eclipse.xtext.validation.NamesAreUniqueValidator"
    }

    // 添加EPackage自动注册配置
    ecoreGenerator = {
        registerPackage = true
    }
}

4. 处理plugin.xml生成逻辑 #

由于Mwe2中createEclipseMetaData = true，会自动生成Eclipse插件相关的plugin.xml，包括EPackage注册。不需要手动维护plugin.xml，删除手动添加的文件，让Mwe2自动生成即可。若需自定义，可通过Mwe2的eclipsePlugin配置调整。

5. 验证Maven构建顺序 #

执行Maven命令时，先清理并生成源码：

mvn clean generate-sources

确保ServiceGenerator的代码先于VarDefinitionGenerator生成，类路径包含所有生成的类文件。

关于版本升级的注入变量问题 #

若升级至Xtext 2.32.0 + Java 17：

• 替换依赖中的javax.inject为jakarta.inject
• 确保Xtext Maven插件版本与Xtext版本匹配
• 检查代码中@Inject注解的导入路径，改为jakarta.inject.Inject

内容的提问来源于stack exchange，提问作者Cosmin Polifronie