Added IfThenUtils

idea/src/org/jetbrains/jet/plugin/intentions/branchedTransformations/IfThenUtils.kt

@@ -0,0 +1,143 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.plugin.intentions.branchedTransformations
+
+import org.jetbrains.jet.lang.psi.JetExpression
+import org.jetbrains.jet.lang.psi.JetBlockExpression
+import org.jetbrains.jet.lang.psi.JetBinaryExpression
+import org.jetbrains.jet.lang.psi.JetIfExpression
+import org.jetbrains.jet.lang.psi.JetPsiUtil
+import org.jetbrains.jet.lexer.JetTokens
+import org.jetbrains.jet.lang.psi.JetPsiFactory
+import com.intellij.openapi.editor.Editor
+import org.jetbrains.jet.plugin.refactoring.introduceVariable.JetIntroduceVariableHandler
+import org.jetbrains.jet.lang.psi.JetSafeQualifiedExpression
+import org.jetbrains.jet.lang.resolve.BindingContext
+import org.jetbrains.jet.plugin.project.AnalyzerFacadeWithCache
+import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns
+import com.intellij.psi.PsiElement
+import org.jetbrains.jet.plugin.refactoring.inline.KotlinInlineValHandler
+import org.jetbrains.jet.lang.psi.JetSimpleNameExpression
+import org.jetbrains.jet.lang.resolve.calls.autocasts.DataFlowValueFactory
+import org.jetbrains.jet.lang.resolve.BindingContextUtils
+import org.jetbrains.jet.lang.descriptors.VariableDescriptor
+import com.intellij.psi.search.searches.ReferencesSearch
+import com.intellij.psi.search.LocalSearchScope
+import org.jetbrains.jet.lang.psi.JetDeclaration
+
+fun JetBinaryExpression.comparesNonNullToNull(): Boolean {
+    val operationToken = this.getOperationToken()
+    val rhs = this.getRight()
+    val lhs = this.getLeft()
+    if (rhs == null || lhs == null) return false
+
+    val rightIsNull = rhs.isNullExpression()
+    val leftIsNull = lhs.isNullExpression()
+    return leftIsNull != rightIsNull && (operationToken == JetTokens.EQEQ || operationToken == JetTokens.EXCLEQ)
+}
+
+fun JetExpression.extractExpressionIfSingle(): JetExpression? {
+    val innerExpression = JetPsiUtil.deparenthesize(this)
+    if (innerExpression is JetBlockExpression) {
+        return if (innerExpression.getStatements().size() == 1)
+                   JetPsiUtil.deparenthesize(innerExpression.getStatements().first as? JetExpression)
+               else
+                   null
+    }
+
+    return innerExpression
+}
+
+fun JetSafeQualifiedExpression.isStatement(): Boolean {
+    val context = AnalyzerFacadeWithCache.getContextForElement(this)
+
+    val expectedType = context.get(BindingContext.EXPECTED_EXPRESSION_TYPE, this);
+    val isUnit = expectedType != null && KotlinBuiltIns.getInstance().isUnit(expectedType);
+
+    // Some "statements" are actually expressions returned from lambdas, their expected types are non-null
+    val isStatement = context.get(BindingContext.STATEMENT, this) == true && expectedType == null;
+
+    return isStatement || isUnit
+}
+
+fun JetBinaryExpression.getNonNullExpression(): JetExpression? = when {
+    this.getLeft()?.isNullExpression() == false ->
+        this.getLeft()
+    this.getRight()?.isNullExpression() == false ->
+        this.getRight()
+    else ->
+        null
+}
+
+fun JetExpression.isNullExpression(): Boolean = this.extractExpressionIfSingle()?.getText() == "null"
+
+fun JetExpression.isNullExpressionOrEmptyBlock(): Boolean = this.isNullExpression() || this is JetBlockExpression && this.getStatements().empty
+
+fun JetExpression.isNotNullExpression(): Boolean {
+    val innerExpression = this.extractExpressionIfSingle()
+    return innerExpression != null && innerExpression.getText() != "null"
+}
+
+fun JetExpression.evaluatesTo(other: JetExpression): Boolean {
+    return this.extractExpressionIfSingle()?.getText() == other.getText()
+}
+
+fun JetExpression.convertToIfNotNullExpression(conditionLhs: JetExpression, thenClause: JetExpression, elseClause: JetExpression?): JetIfExpression {
+    val elseBranch = if (elseClause == null) "" else " else ${elseClause.getText()}"
+    val conditionalString = "if (${conditionLhs.getText()} != null) ${thenClause.getText()}$elseBranch"
+
+    val st = this.replace(conditionalString) as JetExpression
+    return JetPsiUtil.deparenthesize(st) as JetIfExpression
+}
+
+fun JetIfExpression.introduceValueForCondition(occurrenceInThenClause: JetExpression, editor: Editor) {
+    val project = this.getProject()
+    val occurrenceInConditional = (this.getCondition() as JetBinaryExpression).getLeft()!!
+    JetIntroduceVariableHandler.doRefactoring(project, editor, occurrenceInConditional, listOf(occurrenceInConditional, occurrenceInThenClause))
+}
+
+fun PsiElement.replace(expressionAsString: String): PsiElement =
+        this.replace(JetPsiFactory.createExpression(this.getProject(), expressionAsString))
+
+fun JetSimpleNameExpression.inlineIfDeclaredLocallyAndOnlyUsedOnceWithPrompt(editor: Editor) {
+    val declaration = this.getReference()?.resolve() as JetDeclaration
+
+    val enclosingElement = JetPsiUtil.getEnclosingElementForLocalDeclaration(declaration)
+    val isLocal = enclosingElement != null
+    if (!isLocal) return
+
+    val scope = LocalSearchScope(enclosingElement!!)
+
+    val references = ReferencesSearch.search(declaration, scope).findAll()
+    if (references.size() == 1) {
+        KotlinInlineValHandler().inlineElement(this.getProject(), editor, declaration)
+    }
+}
+
+fun JetSafeQualifiedExpression.inlineReceiverIfApplicableWithPrompt(editor: Editor) {
+    (this.getReceiverExpression() as? JetSimpleNameExpression)?.inlineIfDeclaredLocallyAndOnlyUsedOnceWithPrompt(editor)
+}
+
+fun JetBinaryExpression.inlineLeftSideIfApplicableWithPrompt(editor: Editor) {
+    (this.getLeft() as? JetSimpleNameExpression)?.inlineIfDeclaredLocallyAndOnlyUsedOnceWithPrompt(editor)
+}
+
+fun JetExpression.isStableVariable(): Boolean {
+    val context = AnalyzerFacadeWithCache.getContextForElement(this)
+    val descriptor = BindingContextUtils.extractVariableDescriptorIfAny(context, this, false)
+    return descriptor is VariableDescriptor && DataFlowValueFactory.isStableVariable(descriptor)
+}