UAST: Implement getFunctionalInterfaceType for KotlinULambdaExpression

plugins/uast-kotlin/src/org/jetbrains/uast/kotlin/expressions/KotlinULambdaExpression.kt

@@ -16,6 +16,7 @@
 
 package org.jetbrains.uast.kotlin
 
+import com.intellij.psi.PsiType
 import org.jetbrains.kotlin.psi.KtLambdaExpression
 import org.jetbrains.uast.UBlockExpression
 import org.jetbrains.uast.UElement
@@ -27,6 +28,9 @@ class KotlinULambdaExpression(
         override val psi: KtLambdaExpression,
         override val uastParent: UElement?
 ) : KotlinAbstractUExpression(), ULambdaExpression, KotlinUElementWithType {
+    val functionalInterfaceType: PsiType?
+        get() = getFunctionalInterfaceType()
+
     override val body by lz { KotlinConverter.convertOrEmpty(psi.bodyExpression, this) }
     
     override val valueParameters by lz {
@@ -43,6 +47,6 @@ class KotlinULambdaExpression(
         val expressions = (body as? UBlockExpression)?.expressions
                                   ?.joinToString("\n") { it.asRenderString().withMargin } ?: body.asRenderString()
 
-        return "{ " + renderedValueParameters + "\n" + expressions + "\n}"
+        return "{ $renderedValueParameters\n$expressions\n}"
     }
 }

plugins/uast-kotlin/src/org/jetbrains/uast/kotlin/expressions/LocalFunction.kt

@@ -1,5 +1,6 @@
 package org.jetbrains.uast.kotlin.expressions
 
+import com.intellij.psi.PsiType
 import com.intellij.psi.PsiVariable
 import org.jetbrains.kotlin.psi.KtFunction
 import org.jetbrains.uast.*
@@ -29,6 +30,8 @@ private class KotlinLocalFunctionULambdaExpression(
         override val psi: KtFunction,
         override val uastParent: UElement?
 ): KotlinAbstractUExpression(), ULambdaExpression {
+    val functionalInterfaceType: PsiType?
+        get() = null
 
     override val body by lz { KotlinConverter.convertOrEmpty(psi.bodyExpression, this) }
 

plugins/uast-kotlin/src/org/jetbrains/uast/kotlin/internal/kotlinInternalUastUtils.kt

@@ -30,11 +30,13 @@ import com.intellij.psi.search.GlobalSearchScope
 import com.intellij.psi.util.PsiTypesUtil
 import org.jetbrains.kotlin.asJava.toLightClass
 import org.jetbrains.kotlin.asJava.toLightElements
+import org.jetbrains.kotlin.builtins.isBuiltinFunctionalTypeOrSubtype
 import org.jetbrains.kotlin.codegen.signature.BothSignatureWriter
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.descriptors.PropertyDescriptor
+import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.load.kotlin.TypeMappingMode
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.resolve.BindingContext
@@ -43,6 +45,7 @@ import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.isError
+import org.jetbrains.kotlin.types.typeUtil.isInterface
 import org.jetbrains.uast.*
 import java.lang.ref.WeakReference
 import java.text.StringCharacterIterator
@@ -180,3 +183,18 @@ internal inline fun <reified T : UDeclaration, reified P : PsiElement> unwrap(el
     assert(unwrapped !is UElement)
     return unwrapped as P
 }
+
+internal fun KtExpression.getExpectedType(): KotlinType? = analyze()[BindingContext.EXPECTED_EXPRESSION_TYPE, this]
+
+internal fun KtTypeReference.getType(): KotlinType? = analyze()[BindingContext.TYPE, this]
+
+internal fun KotlinType.getFunctionalInterfaceType(source: UElement, element: KtElement): PsiType? =
+        takeIf { it.isInterface() && !it.isBuiltinFunctionalTypeOrSubtype }?.toPsiType(source, element, false)
+
+internal fun KotlinULambdaExpression.getFunctionalInterfaceType(): PsiType? {
+    val parent = psi.parent
+    return when(parent) {
+        is KtBinaryExpressionWithTypeRHS -> parent.right?.getType()?.getFunctionalInterfaceType(this, psi)
+        else -> psi.getExpectedType()?.getFunctionalInterfaceType(this, psi)
+    }
+}

plugins/uast-kotlin/testData/SAM.kt

@@ -0,0 +1,11 @@
+
+val notSam = { /* Not SAM */ }
+var foo: java.lang.Runnable = {/* Variable */}
+fun bar(): java.lang.Runnable {
+    foo = {/* Assignment */}
+    val a = {/* Type Cast */} as java.lang.Runnable
+    runRunnable {/* Argument */}
+    return {/* Return */}
+}
+
+fun runRunnable(r: java.lang.Runnable) = r()