JS: decomposition of ternary operator

js/js.inliner/src/org/jetbrains/kotlin/js/inline/ExpressionDecomposer.kt

@@ -97,6 +97,35 @@ class ExpressionDecomposer private (
         index = accept(index)
     }
 
+    override fun visit(x: JsConditional, ctx: JsContext<*>): Boolean {
+        x.process(ctx)
+        return false
+    }
+
+    private fun JsConditional.process(ctx: JsContext<*>) {
+        test = accept(test)
+        if (then !in containsExtractable && otherwise !in containsExtractable) return
+
+        val tmp = Temporary()
+        addStatement(tmp.variable)
+
+        val thenBlock = withNewAdditionalStatements {
+            then = accept(then)
+            addStatement(tmp.assign(then))
+            additionalStatements.toStatement()
+        }
+
+        val elseBlock = withNewAdditionalStatements {
+            otherwise = accept(otherwise)
+            addStatement(tmp.assign(otherwise))
+            additionalStatements.toStatement()
+        }
+
+        val lazyEval = JsIf(test, thenBlock, elseBlock)
+        addStatement(lazyEval)
+        ctx.replaceMe(tmp.nameRef)
+    }
+
     override fun visit(x: JsInvocation, ctx: JsContext<*>): Boolean {
         CallableInvocationAdapter(x).process()
         return false
@@ -153,9 +182,21 @@ class ExpressionDecomposer private (
         }
     }
 
+    inline
+    private fun withNewAdditionalStatements<T>(fn: ()->T): T {
+        val backup = additionalStatements
+        additionalStatements = SmartList<JsStatement>()
+        val result = fn()
+        additionalStatements = backup
+        return result
+    }
+
     private fun addStatement(statement: JsStatement) =
             additionalStatements.add(statement)
 
+    private fun addStatements(statements: List<JsStatement>) =
+            additionalStatements.addAll(statements)
+
     private fun JsExpression.extractToTemporary(): JsExpression {
         val tmp = Temporary(this)
         addStatement(tmp.variable)
@@ -294,3 +335,10 @@ private fun JsNode.withParentsOfNodes(nodes: Set<JsNode>): Set<JsNode> {
     visitor.accept(this)
     return visitor.matched
 }
+
+private fun List<JsStatement>.toStatement(): JsStatement =
+        when (size()) {
+            0 -> JsEmpty
+            1 -> get(0)
+            else -> JsBlock(this)
+        }

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/astUtils.kt

@@ -63,3 +63,15 @@ public var JsArrayAccess.index: JsExpression
 public var JsArrayAccess.array: JsExpression
     get() = getArrayExpression()
     set(value) = setArrayExpression(value)
+
+public var JsConditional.test: JsExpression
+    get() = getTestExpression()
+    set(value) = setTestExpression(value)
+
+public var JsConditional.then: JsExpression
+    get() = getThenExpression()
+    set(value) = setThenExpression(value)
+
+public var JsConditional.otherwise: JsExpression
+    get() = getElseExpression()
+    set(value) = setElseExpression(value)

js/js.translator/testData/inlineEvaluationOrder/cases/conditional.kt

@@ -0,0 +1,13 @@
+package foo
+
+fun test(x: Boolean): Boolean =
+        if (fizz(x)) buzz(true) else buzz(false)
+
+fun box(): String {
+    assertEquals(true, test(true))
+    assertEquals("fizz(true);buzz(true);", pullLog())
+    assertEquals(false, test(false))
+    assertEquals("fizz(false);buzz(false);", pullLog())
+
+    return "OK"
+}

js/js.translator/testData/inlineEvaluationOrder/cases/conditionalElvis.kt

@@ -0,0 +1,14 @@
+package foo
+
+fun test(x: Boolean?): Boolean = fizz(x) ?: buzz(true)
+
+fun box(): String {
+    assertEquals(true, test(null))
+    assertEquals("fizz(null);buzz(true);", pullLog())
+    assertEquals(false, test(false))
+    assertEquals("fizz(false);", pullLog())
+    assertEquals(true, test(true))
+    assertEquals("fizz(true);", pullLog())
+
+    return "OK"
+}

js/js.translator/testData/inlineEvaluationOrder/cases/conditionalNested.kt

@@ -0,0 +1,23 @@
+package foo
+
+fun test(x: Boolean, y: Boolean): Int =
+        if (fizz(x))
+            if (fizz(y)) buzz(1) else buzz(2)
+        else
+            if (fizz(y)) buzz(3) else buzz(4)
+
+fun box(): String {
+    assertEquals(1, test(true, true))
+    assertEquals("fizz(true);fizz(true);buzz(1);", pullLog())
+
+    assertEquals(2, test(true, false))
+    assertEquals("fizz(true);fizz(false);buzz(2);", pullLog())
+
+    assertEquals(3, test(false, true))
+    assertEquals("fizz(false);fizz(true);buzz(3);", pullLog())
+
+    assertEquals(4, test(false, false))
+    assertEquals("fizz(false);fizz(false);buzz(4);", pullLog())
+
+    return "OK"
+}

js/js.translator/testData/inlineEvaluationOrder/cases/conditionalTestExpression.kt

@@ -0,0 +1,13 @@
+package foo
+
+fun test(x: Boolean): Boolean =
+        if (buzz(x)) buzz(true) else fizz(false)
+
+fun box(): String {
+    assertEquals(true, test(true))
+    assertEquals("buzz(true);buzz(true);", pullLog())
+    assertEquals(false, test(false))
+    assertEquals("buzz(false);fizz(false);", pullLog())
+
+    return "OK"
+}

js/js.translator/testData/inlineEvaluationOrder/cases/conditionalTestExpressionElvis.kt

@@ -0,0 +1,14 @@
+package foo
+
+fun test(x: Boolean?): Boolean = buzz(x) ?: fizz(true)
+
+fun box(): String {
+    assertEquals(true, test(null))
+    assertEquals("buzz(null);fizz(true);", pullLog())
+    assertEquals(false, test(false))
+    assertEquals("buzz(false);", pullLog())
+    assertEquals(true, test(true))
+    assertEquals("buzz(true);", pullLog())
+
+    return "OK"
+}