[uast] UInjectionHost introduced (KT-27283)

uast/uast-common/src/org/jetbrains/uast/expressions/UInjectionHost.kt

@@ -0,0 +1,25 @@
+// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.jetbrains.uast.expressions
+
+import com.intellij.psi.PsiLanguageInjectionHost
+import org.jetbrains.annotations.ApiStatus
+import org.jetbrains.uast.UExpression
+
+/**
+ * Represents a "string-like" elements in the host language (String literals, interpolated strings, comments)
+ * where other languages could be injected by [com.intellij.psi.LanguageInjector]
+ * or references contributed by [com.intellij.psi.PsiReferenceProvider]
+ *
+ * @see com.intellij.psi.UastReferenceProvider
+ */
+@ApiStatus.Experimental
+interface UInjectionHost : UExpression {
+
+  val isString: Boolean
+    get() = evaluateToString() != null
+
+  fun evaluateToString(): String? = evaluate() as? String
+
+  val psiLanguageInjectionHost: PsiLanguageInjectionHost
+
+}

uast/uast-java/src/org/jetbrains/uast/java/JavaUastLanguagePlugin.kt

@@ -19,6 +19,7 @@ package org.jetbrains.uast.java
 import com.intellij.lang.Language
 import com.intellij.lang.java.JavaLanguage
 import com.intellij.psi.*
+import com.intellij.psi.impl.source.tree.java.PsiLiteralExpressionImpl
 import com.intellij.psi.util.PsiTreeUtil
 import org.jetbrains.uast.*
 import org.jetbrains.uast.java.expressions.JavaUAnnotationCallExpression
@@ -241,7 +242,7 @@ internal object JavaConverter {
         is PsiParenthesizedExpression -> expr<UParenthesizedExpression>(build(::JavaUParenthesizedExpression))
         is PsiPrefixExpression -> expr<UPrefixExpression>(build(::JavaUPrefixExpression))
         is PsiPostfixExpression -> expr<UPostfixExpression>(build(::JavaUPostfixExpression))
-        is PsiLiteralExpression -> expr<ULiteralExpression>(build(::JavaULiteralExpression))
+        is PsiLiteralExpressionImpl -> expr<ULiteralExpression>(build(::JavaULiteralExpression))
         is PsiMethodReferenceExpression -> expr<UCallableReferenceExpression>(build(::JavaUCallableReferenceExpression))
         is PsiReferenceExpression -> convertReference(el, givenParent, requiredType)
         is PsiThisExpression -> expr<UThisExpression>(build(::JavaUThisExpression))

uast/uast-java/src/org/jetbrains/uast/java/expressions/JavaULiteralExpression.kt

@@ -15,14 +15,23 @@
  */
 package org.jetbrains.uast.java
 
-import com.intellij.psi.PsiLiteralExpression
+import com.intellij.psi.PsiLanguageInjectionHost
+import com.intellij.psi.impl.source.tree.java.PsiLiteralExpressionImpl
 import org.jetbrains.uast.UElement
 import org.jetbrains.uast.ULiteralExpression
+import org.jetbrains.uast.expressions.UInjectionHost
 
 class JavaULiteralExpression(
-  override val psi: PsiLiteralExpression,
+  override val psi: PsiLiteralExpressionImpl,
   givenParent: UElement?
-) : JavaAbstractUExpression(givenParent), ULiteralExpression {
+) : JavaAbstractUExpression(givenParent), ULiteralExpression, UInjectionHost {
   override fun evaluate(): Any? = psi.value
   override val value: Any? by lz { evaluate() }
+
+  override val isString: Boolean
+    get() = super<UInjectionHost>.isString
+
+  override val psiLanguageInjectionHost: PsiLanguageInjectionHost
+    get() = psi
+
 }