Xtext - 如何引用元素的元素 [英] Xtext - how to reference an element of an element

问题描述

使用简单实体示例 https://eclipse.org/Xtext/documentation/102_domainmodelwalkthrough.html

如何添加如下内容:

Map:
    'map' entityA=[Entity] '.' featureA=[Feature] '=>' entityZ=[Entity] '.' featureZ=[Feature]
;  

这样我就可以写了:

entity A {
  name:String
}
entity B {
  name:String
}
map A.name => B.name

以便我在编写 A 时获得内容帮助.仅适用于 A 的功能?

So that I get content assist when writing A. scoped to the features of A only?

谢谢

推荐答案

你通常通过调整范围"的概念来做这些事情.内容帮助通常尊重范围.所以像这样调整你的范围提供者

you usually do such things by adapting the concept of "scoping". the content assist ususally respects scoping. so adapt your scope provider like this

package org.xtext.example.mydsl1.scoping

import org.eclipse.emf.ecore.EObject
import org.eclipse.emf.ecore.EReference
import org.eclipse.xtext.scoping.IScope
import org.xtext.example.mydsl1.myDsl.Map
import org.xtext.example.mydsl1.myDsl.MyDslPackage
import org.eclipse.xtext.scoping.Scopes

class MyDslScopeProvider extends AbstractMyDslScopeProvider {

    override getScope(EObject context, EReference reference) {
        if (reference === MyDslPackage.Literals.MAP__FEATURE_A) {
            if (context instanceof Map) {
                return Scopes.scopeFor(context.entityA.features)
            }
            return IScope.NULLSCOPE
        }
        if (reference === MyDslPackage.Literals.MAP__FEATURE_Z) {
            if (context instanceof Map) {
                return Scopes.scopeFor(context.entityZ.features)
            }
            return IScope.NULLSCOPE
        }

        super.getScope(context, reference)

    }

}

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