From 8b4f950405c7dac819f5befa7ce8e1f4bb61a59e Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Tue, 17 Jan 2017 11:34:30 +0700
Subject: [PATCH] CountingLoop extracted and used; IndexedContainer simplified

---
 .../UseBulkOperationInspection.java           |  33 +----
 .../StreamApiMigrationInspection.java         |  64 ++-------
 .../streamMigration/ToArrayMigration.java     |   4 +-
 .../com/siyeh/ig/psiutils/CountingLoop.java   | 131 ++++++++++++++++++
 .../siyeh/ig/psiutils/IndexedContainer.java   |  58 +-------
 5 files changed, 161 insertions(+), 129 deletions(-)
 create mode 100644 plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/CountingLoop.java

diff --git a/java/java-impl/src/com/intellij/codeInspection/bulkOperation/UseBulkOperationInspection.java b/java/java-impl/src/com/intellij/codeInspection/bulkOperation/UseBulkOperationInspection.java
index 1ae01e2c90bb..f2033424cde8 100644
--- a/java/java-impl/src/com/intellij/codeInspection/bulkOperation/UseBulkOperationInspection.java
+++ b/java/java-impl/src/com/intellij/codeInspection/bulkOperation/UseBulkOperationInspection.java
@@ -25,7 +25,6 @@ import com.intellij.psi.codeStyle.JavaCodeStyleManager;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtil;
 import com.intellij.refactoring.util.RefactoringUtil;
-import com.intellij.util.ObjectUtils;
 import com.siyeh.ig.psiutils.*;
 import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.Contract;
@@ -138,31 +137,13 @@ public class UseBulkOperationInspection extends BaseJavaBatchLocalInspectionTool
 
   @Nullable
   private static PsiExpression findIterableForIndexedLoop(PsiForStatement loop, PsiExpression getElementExpression) {
-    IndexedContainer container = IndexedContainer.fromGetExpression(getElementExpression);
-    if(container == null) return null;
-    PsiExpression indexExpression = container.extractIndexFromGetExpression(getElementExpression);
-
-    // Check that loop initialization is like `int idx = 0` and loop update is like `idx++`
-    PsiStatement initialization = loop.getInitialization();
-    if (!(initialization instanceof PsiDeclarationStatement)) return null;
-    PsiElement[] declaredElements = ((PsiDeclarationStatement)initialization).getDeclaredElements();
-    if (declaredElements.length != 1 || !(declaredElements[0] instanceof PsiLocalVariable)) return null;
-    PsiLocalVariable indexVariable = (PsiLocalVariable)declaredElements[0];
-    if (!ExpressionUtils.isReferenceTo(indexExpression, indexVariable) ||
-        !ExpressionUtils.isZero(indexVariable.getInitializer()) ||
-        !VariableAccessUtils.variableIsIncremented(indexVariable, loop.getUpdate())) {
-      return null;
-    }
-
-    // Check that loop condition is like `idx < arr.length` or `idx < list.size()`
-    PsiBinaryExpression condition = ObjectUtils.tryCast(loop.getCondition(), PsiBinaryExpression.class);
-    if (condition == null ||
-        !condition.getOperationTokenType().equals(JavaTokenType.LT) ||
-        !ExpressionUtils.isReferenceTo(condition.getLOperand(), indexVariable)) {
-      return null;
-    }
-    PsiExpression bound = condition.getROperand();
-    return container.extractQualifierFromLengthExpression(bound);
+    CountingLoop countingLoop = CountingLoop.from(loop);
+    if (countingLoop == null || countingLoop.isIncluding() || !ExpressionUtils.isZero(countingLoop.getInitializer())) return null;
+    IndexedContainer container = IndexedContainer.fromLengthExpression(countingLoop.getBound());
+    if (container == null) return null;
+    PsiExpression index = container.extractIndexFromGetExpression(getElementExpression);
+    if (!ExpressionUtils.isReferenceTo(index, countingLoop.getCounter())) return null;
+    return container.getQualifier();
   }
 
   @Nullable
diff --git a/java/java-impl/src/com/intellij/codeInspection/streamMigration/StreamApiMigrationInspection.java b/java/java-impl/src/com/intellij/codeInspection/streamMigration/StreamApiMigrationInspection.java
index 05d4e6f115ef..9934a9ba4102 100644
--- a/java/java-impl/src/com/intellij/codeInspection/streamMigration/StreamApiMigrationInspection.java
+++ b/java/java-impl/src/com/intellij/codeInspection/streamMigration/StreamApiMigrationInspection.java
@@ -32,7 +32,6 @@ import com.intellij.psi.controlFlow.*;
 import com.intellij.psi.search.GlobalSearchScope;
 import com.intellij.psi.search.LocalSearchScope;
 import com.intellij.psi.search.searches.ReferencesSearch;
-import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.InheritanceUtil;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtil;
@@ -688,7 +687,7 @@ public class StreamApiMigrationInspection extends BaseJavaBatchLocalInspectionTo
 
   @Nullable
   static PsiLocalVariable extractArray(TerminalBlock tb) {
-    CountingLoop loop = tb.getLastOperation(CountingLoop.class);
+    CountingLoopSource loop = tb.getLastOperation(CountingLoopSource.class);
     if(loop == null || loop.myIncluding) return null;
     PsiAssignmentExpression assignment = tb.getSingleExpression(PsiAssignmentExpression.class);
     if(assignment == null || !assignment.getOperationTokenType().equals(JavaTokenType.EQ)) return null;
@@ -945,7 +944,7 @@ public class StreamApiMigrationInspection extends BaseJavaBatchLocalInspectionTo
     @Contract("null -> null")
     static StreamSource tryCreate(PsiLoopStatement statement) {
       if(statement instanceof PsiForStatement) {
-        return CountingLoop.from((PsiForStatement)statement);
+        return CountingLoopSource.from((PsiForStatement)statement);
       }
       if(statement instanceof PsiForeachStatement) {
         ArrayStream source = ArrayStream.from((PsiForeachStatement)statement);
@@ -1073,15 +1072,15 @@ public class StreamApiMigrationInspection extends BaseJavaBatchLocalInspectionTo
     }
   }
 
-  static class CountingLoop extends StreamSource {
+  static class CountingLoopSource extends StreamSource {
     final PsiExpression myBound;
     final boolean myIncluding;
 
-    private CountingLoop(PsiLoopStatement loop,
-                         PsiVariable counter,
-                         PsiExpression initializer,
-                         PsiExpression bound,
-                         boolean including) {
+    private CountingLoopSource(PsiLoopStatement loop,
+                               PsiVariable counter,
+                               PsiExpression initializer,
+                               PsiExpression bound,
+                               boolean including) {
       super(loop, counter, initializer);
       myBound = bound;
       myIncluding = including;
@@ -1099,8 +1098,8 @@ public class StreamApiMigrationInspection extends BaseJavaBatchLocalInspectionTo
       return className+"."+methodName+"("+myExpression.getText()+", "+myBound.getText()+")";
     }
 
-    CountingLoop withBound(PsiExpression bound) {
-      return new CountingLoop(getLoop(), getVariable(), getExpression(), bound, myIncluding);
+    CountingLoopSource withBound(PsiExpression bound) {
+      return new CountingLoopSource(getLoop(), getVariable(), getExpression(), bound, myIncluding);
     }
 
     @Override
@@ -1115,45 +1114,10 @@ public class StreamApiMigrationInspection extends BaseJavaBatchLocalInspectionTo
     }
 
     @Nullable
-    public static CountingLoop from(PsiForStatement forStatement) {
-      // check that initialization is for(int/long i = <initial_value>;...;...)
-      PsiDeclarationStatement initialization = tryCast(forStatement.getInitialization(), PsiDeclarationStatement.class);
-      if (initialization == null || initialization.getDeclaredElements().length != 1) return null;
-      PsiLocalVariable counter = tryCast(initialization.getDeclaredElements()[0], PsiLocalVariable.class);
-      if(counter == null) return null;
-      if(!counter.getType().equals(PsiType.INT) && !counter.getType().equals(PsiType.LONG)) return null;
-
-      PsiExpression initializer = counter.getInitializer();
-      if(initializer == null) return null;
-
-      // check that increment is like for(...;...;i++)
-      if(!VariableAccessUtils.variableIsIncremented(counter, forStatement.getUpdate())) return null;
-
-      // check that condition is like for(...;i<bound;...) or for(...;i<=bound;...)
-      PsiBinaryExpression condition = tryCast(forStatement.getCondition(), PsiBinaryExpression.class);
-      if(condition == null) return null;
-      IElementType type = condition.getOperationTokenType();
-      boolean closed = false;
-      PsiExpression bound;
-      PsiExpression ref;
-      if(type.equals(JavaTokenType.LE)) {
-        bound = condition.getROperand();
-        ref = condition.getLOperand();
-        closed = true;
-      } else if(type.equals(JavaTokenType.LT)) {
-        bound = condition.getROperand();
-        ref = condition.getLOperand();
-      } else if(type.equals(JavaTokenType.GE)) {
-        bound = condition.getLOperand();
-        ref = condition.getROperand();
-        closed = true;
-      } else if(type.equals(JavaTokenType.GT)) {
-        bound = condition.getLOperand();
-        ref = condition.getROperand();
-      } else return null;
-      if(bound == null || !ExpressionUtils.isReferenceTo(ref, counter)) return null;
-      if(!TypeConversionUtil.areTypesAssignmentCompatible(counter.getType(), bound)) return null;
-      return new CountingLoop(forStatement, counter, initializer, bound, closed);
+    public static CountingLoopSource from(PsiForStatement forStatement) {
+      CountingLoop loop = CountingLoop.from(forStatement);
+      if (loop == null) return null;
+      return new CountingLoopSource(forStatement, loop.getCounter(), loop.getInitializer(), loop.getBound(), loop.isIncluding());
     }
   }
 }
diff --git a/java/java-impl/src/com/intellij/codeInspection/streamMigration/ToArrayMigration.java b/java/java-impl/src/com/intellij/codeInspection/streamMigration/ToArrayMigration.java
index 1343b9e30947..ea3d442c73c4 100644
--- a/java/java-impl/src/com/intellij/codeInspection/streamMigration/ToArrayMigration.java
+++ b/java/java-impl/src/com/intellij/codeInspection/streamMigration/ToArrayMigration.java
@@ -15,7 +15,7 @@
  */
 package com.intellij.codeInspection.streamMigration;
 
-import com.intellij.codeInspection.streamMigration.StreamApiMigrationInspection.CountingLoop;
+import com.intellij.codeInspection.streamMigration.StreamApiMigrationInspection.CountingLoopSource;
 import com.intellij.codeInspection.streamMigration.StreamApiMigrationInspection.InitializerUsageStatus;
 import com.intellij.codeInspection.streamMigration.StreamApiMigrationInspection.MapOp;
 import com.intellij.openapi.project.Project;
@@ -45,7 +45,7 @@ public class ToArrayMigration extends BaseStreamApiMigration {
     if(initializer == null) return null;
     PsiExpression dimension = ArrayUtil.getFirstElement(initializer.getArrayDimensions());
     if(dimension == null) return null;
-    CountingLoop loop = tb.getLastOperation(CountingLoop.class);
+    CountingLoopSource loop = tb.getLastOperation(CountingLoopSource.class);
     if(loop == null) return null;
     PsiArrayType arrayType = tryCast(initializer.getType(), PsiArrayType.class);
     if(arrayType == null) return null;
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/CountingLoop.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/CountingLoop.java
new file mode 100644
index 000000000000..87eb545f2d31
--- /dev/null
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/CountingLoop.java
@@ -0,0 +1,131 @@
+/*
+ * Copyright 2000-2017 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.psiutils;
+
+import com.intellij.psi.*;
+import com.intellij.psi.tree.IElementType;
+import com.intellij.psi.util.PsiUtil;
+import com.intellij.psi.util.TypeConversionUtil;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import static com.intellij.util.ObjectUtils.tryCast;
+
+/**
+ * Represents a loop of form {@code for(int/long counter = initializer; counter </<= bound; counter++)}
+ *
+ * @author Tagir Valeev
+ */
+public class CountingLoop {
+  final @NotNull PsiLocalVariable myCounter;
+  final @NotNull PsiLoopStatement myLoop;
+  final @NotNull PsiExpression myInitializer;
+  final @NotNull PsiExpression myBound;
+  final boolean myIncluding;
+
+  private CountingLoop(@NotNull PsiLoopStatement loop,
+                       @NotNull PsiLocalVariable counter,
+                       @NotNull PsiExpression initializer,
+                       @NotNull PsiExpression bound,
+                       boolean including) {
+    myInitializer = initializer;
+    myCounter = counter;
+    myLoop = loop;
+    myBound = bound;
+    myIncluding = including;
+  }
+
+  /**
+   * @return loop counter variable
+   */
+  @NotNull
+  public PsiLocalVariable getCounter() {
+    return myCounter;
+  }
+
+  /**
+   * @return loop statement
+   */
+  @NotNull
+  public PsiLoopStatement getLoop() {
+    return myLoop;
+  }
+
+  /**
+   * @return counter variable initial value
+   */
+  @NotNull
+  public PsiExpression getInitializer() {
+    return myInitializer;
+  }
+
+  /**
+   * @return loop bound
+   */
+  @NotNull
+  public PsiExpression getBound() {
+    return myBound;
+  }
+
+  /**
+   * @return true if bound is including
+   */
+  public boolean isIncluding() {
+    return myIncluding;
+  }
+
+  @Nullable
+  public static CountingLoop from(PsiForStatement forStatement) {
+    // check that initialization is for(int/long i = <initial_value>;...;...)
+    PsiDeclarationStatement initialization = tryCast(forStatement.getInitialization(), PsiDeclarationStatement.class);
+    if (initialization == null || initialization.getDeclaredElements().length != 1) return null;
+    PsiLocalVariable counter = tryCast(initialization.getDeclaredElements()[0], PsiLocalVariable.class);
+    if(counter == null) return null;
+    if(!counter.getType().equals(PsiType.INT) && !counter.getType().equals(PsiType.LONG)) return null;
+
+    PsiExpression initializer = PsiUtil.skipParenthesizedExprDown(counter.getInitializer());
+    if(initializer == null) return null;
+
+    // check that increment is like for(...;...;i++)
+    if(!VariableAccessUtils.variableIsIncremented(counter, forStatement.getUpdate())) return null;
+
+    // check that condition is like for(...;i<bound;...) or for(...;i<=bound;...)
+    PsiBinaryExpression condition = tryCast(forStatement.getCondition(), PsiBinaryExpression.class);
+    if(condition == null) return null;
+    IElementType type = condition.getOperationTokenType();
+    boolean closed = false;
+    PsiExpression bound;
+    PsiExpression ref;
+    if(type.equals(JavaTokenType.LE)) {
+      bound = condition.getROperand();
+      ref = condition.getLOperand();
+      closed = true;
+    } else if(type.equals(JavaTokenType.LT)) {
+      bound = condition.getROperand();
+      ref = condition.getLOperand();
+    } else if(type.equals(JavaTokenType.GE)) {
+      bound = condition.getLOperand();
+      ref = condition.getROperand();
+      closed = true;
+    } else if(type.equals(JavaTokenType.GT)) {
+      bound = condition.getLOperand();
+      ref = condition.getROperand();
+    } else return null;
+    if(bound == null || !ExpressionUtils.isReferenceTo(ref, counter)) return null;
+    if(!TypeConversionUtil.areTypesAssignmentCompatible(counter.getType(), bound)) return null;
+    return new CountingLoop(forStatement, counter, initializer, bound, closed);
+  }
+}
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/IndexedContainer.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/IndexedContainer.java
index 807b39ec851d..2f749476ea95 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/IndexedContainer.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/IndexedContainer.java
@@ -42,15 +42,6 @@ public abstract class IndexedContainer {
    */
   public abstract boolean isGetMethodReference(PsiMethodReferenceExpression methodReference);
 
-  /**
-   * Extracts the qualifier if the supplied expression obtains the container length (either array.length or list.size())
-   *
-   * @param expression expression to extract the qualifier from
-   * @return the extracted qualifier or null if the supplied expression is not a length expression. The extracted qualifier might be
-   * non-physical if it was implicit in the original code (e.g. "this" could be returned if original call was simply "size()")
-   */
-  public abstract PsiExpression extractQualifierFromLengthExpression(@Nullable PsiExpression expression);
-
   /**
    * Returns an ancestor element retrieval expression if the supplied expression is the index used in it
    * (e.g. index in arr[index] or in list.get(index))
@@ -76,6 +67,10 @@ public abstract class IndexedContainer {
     return myQualifier;
   }
 
+  public boolean isQualifierEquivalent(@Nullable PsiExpression candidate) {
+    return candidate != null && PsiEquivalenceUtil.areElementsEquivalent(myQualifier, candidate);
+  }
+
   /**
    * @return type of the elements in the container or null if cannot be determined
    */
@@ -103,28 +98,6 @@ public abstract class IndexedContainer {
     return null;
   }
 
-  /**
-   * Creates an IndexedContainer from element retrieval expression (like array[idx] or list.get(idx))
-   *
-   * @param expression expression to create an IndexedContainer from
-   * @return newly created IndexedContainer or null if the supplied expression is not element retrieval expression
-   */
-  @Nullable
-  public static IndexedContainer fromGetExpression(PsiExpression expression) {
-    expression = PsiUtil.skipParenthesizedExprDown(expression);
-    if (expression instanceof PsiArrayAccessExpression) {
-      PsiArrayAccessExpression arrayAccess = (PsiArrayAccessExpression)expression;
-      return new ArrayIndexedContainer(arrayAccess.getArrayExpression());
-    }
-    if (expression instanceof PsiMethodCallExpression) {
-      PsiMethodCallExpression call = (PsiMethodCallExpression)expression;
-      PsiExpression[] args = call.getArgumentList().getExpressions();
-      if (args.length != 1 || !ListIndexedContainer.isGetCall(call)) return null;
-      return new ListIndexedContainer(ExpressionUtils.getQualifierOrThis(call.getMethodExpression()));
-    }
-    return null;
-  }
-
   static class ArrayIndexedContainer extends IndexedContainer {
     ArrayIndexedContainer(PsiExpression qualifier) {
       super(qualifier);
@@ -135,13 +108,6 @@ public abstract class IndexedContainer {
       return false;
     }
 
-    @Override
-    public PsiExpression extractQualifierFromLengthExpression(@Nullable PsiExpression expression) {
-      expression = PsiUtil.skipParenthesizedExprDown(expression);
-      PsiExpression lengthQualifier = ExpressionUtils.getArrayFromLengthExpression(expression);
-      return lengthQualifier != null && PsiEquivalenceUtil.areElementsEquivalent(getQualifier(), lengthQualifier) ? lengthQualifier : null;
-    }
-
     @Override
     public PsiExpression extractGetExpressionFromIndex(@Nullable PsiExpression indexExpression) {
       if (indexExpression != null) {
@@ -159,7 +125,7 @@ public abstract class IndexedContainer {
       expression = PsiUtil.skipParenthesizedExprDown(expression);
       if (expression instanceof PsiArrayAccessExpression) {
         PsiArrayAccessExpression arrayAccess = (PsiArrayAccessExpression)expression;
-        if (PsiEquivalenceUtil.areElementsEquivalent(getQualifier(), arrayAccess.getArrayExpression())) {
+        if (isQualifierEquivalent(arrayAccess.getArrayExpression())) {
           return arrayAccess.getIndexExpression();
         }
       }
@@ -181,20 +147,11 @@ public abstract class IndexedContainer {
     @Override
     public boolean isGetMethodReference(PsiMethodReferenceExpression methodReference) {
       if (!"get".equals(methodReference.getReferenceName())) return false;
-      PsiExpression qualifier = methodReference.getQualifierExpression();
-      if (qualifier == null || !PsiEquivalenceUtil.areElementsEquivalent(getQualifier(), qualifier)) return false;
+      if (!isQualifierEquivalent(ExpressionUtils.getQualifierOrThis(methodReference))) return false;
       PsiMethod method = ObjectUtils.tryCast(methodReference.resolve(), PsiMethod.class);
       return method != null && MethodUtils.methodMatches(method, CommonClassNames.JAVA_UTIL_LIST, null, "get", PsiType.INT);
     }
 
-    @Override
-    public PsiExpression extractQualifierFromLengthExpression(@Nullable PsiExpression expression) {
-      PsiMethodCallExpression call = ObjectUtils.tryCast(PsiUtil.skipParenthesizedExprDown(expression), PsiMethodCallExpression.class);
-      if (call == null || !isSizeCall(call)) return null;
-      PsiExpression lengthQualifier = ExpressionUtils.getQualifierOrThis(call.getMethodExpression());
-      return PsiEquivalenceUtil.areElementsEquivalent(getQualifier(), lengthQualifier) ? lengthQualifier : null;
-    }
-
     @Override
     public PsiExpression extractGetExpressionFromIndex(@Nullable PsiExpression indexExpression) {
       if (indexExpression != null) {
@@ -215,8 +172,7 @@ public abstract class IndexedContainer {
       PsiMethodCallExpression call = ObjectUtils.tryCast(PsiUtil.skipParenthesizedExprDown(expression), PsiMethodCallExpression.class);
       if (call == null) return null;
       PsiExpression[] args = call.getArgumentList().getExpressions();
-      if (args.length == 1 && isGetCall(call) &&
-          PsiEquivalenceUtil.areElementsEquivalent(getQualifier(), ExpressionUtils.getQualifierOrThis(call.getMethodExpression()))) {
+      if (args.length == 1 && isGetCall(call) && isQualifierEquivalent(ExpressionUtils.getQualifierOrThis(call.getMethodExpression()))) {
         return args[0];
       }
       return null;