Do not ignore empty value of template expressions

java/java-tests/testSrc/com/intellij/codeInsight/template/LiveTemplateTest.groovy

@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 package com.intellij.codeInsight.template
-
 import com.intellij.JavaTestUtil
 import com.intellij.codeInsight.CodeInsightSettings
 import com.intellij.codeInsight.lookup.Lookup
@@ -38,7 +37,6 @@ import com.intellij.util.ui.UIUtil
 import org.jetbrains.annotations.NotNull
 
 import static com.intellij.codeInsight.template.Template.Property.USE_STATIC_IMPORT_IF_POSSIBLE
-
 /**
  * @author spleaner
  */
@@ -474,6 +472,8 @@ class Foo {
   @Override
   protected void invokeTestRunnable(@NotNull final Runnable runnable) throws Exception {
     if (name in ["testNavigationActionsDontTerminateTemplate", "testTemplateWithEnd", "testDisappearingVar",
+                 "test do replace macro value with empty result",
+                 "test do not replace macro value with null result",
                  "test escape string characters in soutv", "test do not replace macro value with empty result"]) {
       runnable.run();
       return;
@@ -835,7 +835,7 @@ class Foo {
 """
   }
 
-  public void "test do not replace macro value with empty result"() {
+  public void "test do not replace macro value with null result"() {
     myFixture.configureByText "a.java", """\
 class Foo {
   {
@@ -868,6 +868,77 @@ class Foo {
 }
 """
   }
+  
+  public void "test do replace macro value with empty result"() {
+    myFixture.configureByText "a.java", """\
+class Foo {
+  {
+    <caret>
+  }
+}
+"""
+    final TemplateManager manager = TemplateManager.getInstance(getProject());
+    final Template template = manager.createTemplate("xxx", "user", '$VAR1$ $VAR2$');
+    template.addVariable("VAR1", "", "", true)
+    template.addVariable("VAR2", new MacroCallNode(new MyMirrorMacro("VAR1")), null, true)
+    ((TemplateImpl)template).templateContext.setEnabled(contextType(JavaCodeContextType.class), true)
+    addTemplate(template, testRootDisposable)
+
+    writeCommand { startTemplate(template); }
+    myFixture.checkResult """\
+class Foo {
+  {
+    <caret> 
+  }
+}
+"""
+    writeCommand { myFixture.type '42' }
+    myFixture.checkResult """\
+class Foo {
+  {
+    42<caret> 42
+  }
+}
+"""
+
+    writeCommand { myFixture.type '\b\b' }
+    myFixture.checkResult """\
+class Foo {
+  {
+    <caret> 
+  }
+}
+"""
+  }
+
+  private static class MyMirrorMacro extends Macro {
+    private final String myVariableName
+
+    MyMirrorMacro(String variableName) {
+      this.myVariableName = variableName
+    }
+
+    @Override
+    String getName() {
+      return "mirror"
+    }
+
+    @Override
+    String getPresentableName() {
+      return getName();
+    }
+
+    @Override
+    Result calculateResult(@NotNull Expression[] params, ExpressionContext context) {
+      def state = TemplateManagerImpl.getTemplateState(context.editor)
+      return state != null ? state.getVariableValue(myVariableName) : null 
+    }
+
+    @Override
+    Result calculateQuickResult(@NotNull Expression[] params, ExpressionContext context) {
+      return calculateResult(params, context)
+    }
+  }
 
   public void "test multicaret expanding with space"() {
     myFixture.configureByText "a.java", """\

platform/lang-impl/src/com/intellij/codeInsight/template/impl/TemplateState.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2015 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.
@@ -742,10 +742,10 @@ public class TemplateState implements Disposable {
 
     ExpressionContext context = createExpressionContext(start);
     Result result = isQuick ? expressionNode.calculateQuickResult(context) : expressionNode.calculateResult(context);
-    if (isQuick && isEmptyResult(result, element) && !oldValue.isEmpty()) {
+    if (isQuick && result == null && !oldValue.isEmpty()) {
       return;
     }
-    if (isEmptyResult(result, element) && defaultValue != null) {
+    if (defaultValue != null && (result == null || result.equalsToText("", element))) {
       result = defaultValue.calculateResult(context);
     }
     if (element != null) {
@@ -765,10 +765,6 @@ public class TemplateState implements Disposable {
     }
   }
 
-  private static boolean isEmptyResult(Result result, PsiElement context) {
-    return result == null || result.equalsToText("", context);
-  }
-
   private void replaceString(String newValue, int start, int end, int segmentNumber) {
     String oldText = myDocument.getCharsSequence().subSequence(start, end).toString();