IG: teach "Non-constant String should be StringBuilder" inspection about polyadic expressions

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/performance/StringVariableIsAppendedToVisitor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2008 Dave Griffith, Bas Leijdekkers
+ * Copyright 2003-2015 Dave Griffith, Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -81,16 +81,15 @@ class StringVariableIsAppendedToVisitor extends JavaRecursiveElementVisitor {
       return variable.equals(referent);
     }
     if (expression instanceof PsiParenthesizedExpression) {
-      final PsiExpression body =
-        ((PsiParenthesizedExpression)expression).getExpression();
+      final PsiParenthesizedExpression parenthesizedExpression = (PsiParenthesizedExpression)expression;
+      final PsiExpression body = parenthesizedExpression.getExpression();
       return isConcatenation(body);
     }
-    if (expression instanceof PsiBinaryExpression) {
-      final PsiBinaryExpression binaryExpression =
-        (PsiBinaryExpression)expression;
-      final PsiExpression lhs = binaryExpression.getLOperand();
-      final PsiExpression rhs = binaryExpression.getROperand();
-      return isConcatenation(lhs) || isConcatenation(rhs);
+    if (expression instanceof PsiPolyadicExpression) {
+      final PsiPolyadicExpression polyadicExpression = (PsiPolyadicExpression)expression;
+      for (PsiExpression operand : polyadicExpression.getOperands()) {
+        if (isConcatenation(operand)) return true;
+      }
     }
     return false;
   }

plugins/InspectionGadgets/test/com/siyeh/igtest/performance/StringReplaceableByStringBufferInspection.java

@@ -1,23 +0,0 @@
-package com.siyeh.igtest.performance;
-
-public class StringReplaceableByStringBufferInspection {
-    public void foo()
-    {
-        String buffer = "bar";
-        buffer += "foo";
-        System.out.println(buffer);
-    }
-
-    public void foobar()
-    {
-        String buffer = "bar";
-        buffer = buffer + "foo";
-        System.out.println(buffer);
-    }
-    
-    public void foobaz()
-    {
-        final String buffer = "bar";
-        System.out.println(buffer);
-    }
-}

plugins/InspectionGadgets/test/com/siyeh/igtest/performance/string_replaceable_by_string_buffer/StringReplaceableByStringBuffer.java

@@ -0,0 +1,41 @@
+package com.siyeh.igtest.performance.string_replaceable_by_string_buffer;
+
+public class StringReplaceableByStringBuffer {
+    public void foo()
+    {
+        String buffer = "bar";
+        buffer += "foo";
+        System.out.println(buffer);
+    }
+
+    public void foo2()
+    {
+        String <warning descr="Non-constant 'String buffer' should probably be declared as ''StringBuilder''">buffer</warning> = "bar";
+        for (int i = 0; i < 10; i++) {
+            buffer += "foo";
+        }
+        System.out.println(buffer);
+    }
+
+    public void foobar()
+    {
+        String buffer = "bar";
+        buffer = buffer + "foo" + buffer;
+        System.out.println(buffer);
+    }
+
+    public void foobar2()
+    {
+        String <warning descr="Non-constant 'String buffer' should probably be declared as ''StringBuilder''">buffer</warning> = "bar";
+        for (int i = 0; i < 10; i++) {
+            buffer = buffer + "foo" + buffer;
+        }
+        System.out.println(buffer);
+    }
+    
+    public void foobaz()
+    {
+        final String buffer = "bar";
+        System.out.println(buffer);
+    }
+}

plugins/InspectionGadgets/testsrc/com/siyeh/ig/performance/StringReplaceableByStringBufferInspectionTest.java

@@ -0,0 +1,36 @@
+/*
+ * 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.
+ * 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 com.siyeh.ig.performance;
+
+import com.intellij.codeInspection.InspectionProfileEntry;
+import com.siyeh.ig.LightInspectionTestCase;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class StringReplaceableByStringBufferInspectionTest extends LightInspectionTestCase {
+
+  public void testStringReplaceableByStringBuffer() {
+    doTest();
+  }
+
+  @Nullable
+  @Override
+  protected InspectionProfileEntry getInspection() {
+    return new StringReplaceableByStringBufferInspection();
+  }
+}