ChainCallJoinLinesHandler: join chained calls; assignment/declaration+call

Fixes IDEA-54209 Join Lines should be able to merge multiple method calls into a chained call

java/java-impl/src/META-INF/JavaPlugin.xml

@@ -406,6 +406,7 @@
     <weigher key="proximity" implementationClass="com.intellij.psi.util.proximity.ReferenceListWeigher" id="referenceList"
              order="before samePsiMember"/>
     <joinLinesHandler implementation="com.intellij.codeInsight.editorActions.BlockJoinLinesHandler"/>
+    <joinLinesHandler implementation="com.intellij.codeInsight.editorActions.ChainCallJoinLinesHandler"/>
     <joinLinesHandler implementation="com.intellij.codeInsight.editorActions.DeclarationJoinLinesHandler"/>
     <joinLinesHandler implementation="com.intellij.codeInsight.editorActions.LiteralJoinLinesHandler"/>
     <editorSmartKeysConfigurable instance="com.intellij.application.options.JavadocOptionsProvider"

java/java-impl/src/com/intellij/codeInsight/editorActions/ChainCallJoinLinesHandler.java

@@ -0,0 +1,87 @@
+// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.codeInsight.editorActions;
+
+import com.intellij.codeInsight.PsiEquivalenceUtil;
+import com.intellij.openapi.editor.Document;
+import com.intellij.psi.*;
+import com.intellij.psi.util.PsiTreeUtil;
+import com.siyeh.ig.psiutils.ExpressionUtils;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import static com.intellij.util.ObjectUtils.tryCast;
+
+public class ChainCallJoinLinesHandler implements JoinLinesHandlerDelegate {
+  @Override
+  public int tryJoinLines(@NotNull final Document document, @NotNull final PsiFile psiFile, final int start, final int end) {
+    PsiJavaToken elementAtStartLineEnd = tryCast(psiFile.findElementAt(start), PsiJavaToken.class);
+    if (elementAtStartLineEnd == null) return CANNOT_JOIN;
+    PsiExpressionStatement secondStatement = PsiTreeUtil.getParentOfType(psiFile.findElementAt(end), PsiExpressionStatement.class);
+    if (secondStatement == null) return CANNOT_JOIN;
+    PsiMethodCallExpression secondCall = tryCast(secondStatement.getExpression(), PsiMethodCallExpression.class);
+    if (secondCall == null) return CANNOT_JOIN;
+    PsiElement firstStatement = elementAtStartLineEnd.getParent();
+
+    boolean result = false;
+    if (firstStatement instanceof PsiExpressionStatement) {
+      PsiExpression firstExpression = ((PsiExpressionStatement)firstStatement).getExpression();
+      if (firstExpression instanceof PsiMethodCallExpression) {
+        result = joinTwoCalls((PsiMethodCallExpression)firstExpression, secondCall);
+      } else if (firstExpression instanceof PsiAssignmentExpression) {
+        result = joinAssignmentAndCall((PsiAssignmentExpression)firstExpression, secondCall);
+      }
+    }
+    else if (firstStatement instanceof PsiLocalVariable) {
+      PsiLocalVariable var = (PsiLocalVariable)firstStatement;
+      result = joinExpressionAndCall(var, var.getInitializer(), secondCall);
+    }
+    if (!result) return CANNOT_JOIN;
+    secondStatement.delete();
+    return firstStatement.getTextRange().getEndOffset();
+  }
+
+  private static boolean joinAssignmentAndCall(PsiAssignmentExpression assignmentExpression, PsiMethodCallExpression nextCall) {
+    if (!assignmentExpression.getOperationTokenType().equals(JavaTokenType.EQ)) return false;
+    PsiLocalVariable var = ExpressionUtils.resolveLocalVariable(assignmentExpression.getLExpression());
+    if (var == null) return false;
+    return joinExpressionAndCall(var, assignmentExpression.getRExpression(), nextCall);
+  }
+
+  private static boolean joinExpressionAndCall(PsiLocalVariable var, PsiExpression initializer, PsiMethodCallExpression nextCall) {
+    if (initializer == null) return false;
+    PsiExpression qualifier = getDeepQualifier(nextCall);
+    if (!ExpressionUtils.isReferenceTo(qualifier, var)) return false;
+    PsiType type = nextCall.getType();
+    if (type == null || !type.equals(initializer.getType())) return false;
+    qualifier.replace(initializer);
+    initializer.replace(nextCall);
+    return true;
+  }
+
+  private static boolean joinTwoCalls(PsiMethodCallExpression firstCall,
+                                      @NotNull PsiMethodCallExpression secondCall) {
+
+    if (firstCall == null) return false;
+    PsiExpression firstQualifier = getDeepQualifier(firstCall);
+    if (firstQualifier == null) return false;
+    PsiExpression secondQualifier = getDeepQualifier(secondCall);
+    if (secondQualifier == null) return false;
+
+    if (!PsiEquivalenceUtil.areElementsEquivalent(firstQualifier, secondQualifier)) return false;
+    PsiType type = firstCall.getType();
+    if (type == null || !firstCall.getType().equals(firstQualifier.getType())) return false;
+
+    secondQualifier.replace(firstCall);
+    firstCall.replace(secondCall);
+    return true;
+  }
+
+  @Nullable
+  private static PsiExpression getDeepQualifier(PsiMethodCallExpression firstCall) {
+    PsiExpression firstQualifier = firstCall;
+    while (firstQualifier instanceof PsiMethodCallExpression) {
+      firstQualifier = ((PsiMethodCallExpression)firstQualifier).getMethodExpression().getQualifierExpression();
+    }
+    return firstQualifier;
+  }
+}

java/java-tests/testData/codeInsight/joinLines/AssignmentAndCall.java

@@ -0,0 +1,9 @@
+class Foo {
+    void test() {
+        StringBuilder sb;
+        <caret>sb = new StringBuilder();
+        sb.append("foo");
+        sb.append("bar");
+        sb.append("baz");
+    }
+}

java/java-tests/testData/codeInsight/joinLines/AssignmentAndCall_after.java

@@ -0,0 +1,8 @@
+class Foo {
+    void test() {
+        StringBuilder sb;
+        sb = new StringBuilder().append("foo");<caret>
+        sb.append("bar");
+        sb.append("baz");
+    }
+}

java/java-tests/testData/codeInsight/joinLines/CallChain.java

@@ -0,0 +1,8 @@
+class Foo {
+    void test() {
+        StringBuilder sb = new StringBuilder();
+        <caret>sb.append("foo");
+        sb.append("bar");
+        sb.append("baz");
+    }
+}

java/java-tests/testData/codeInsight/joinLines/CallChain2.java

@@ -0,0 +1,7 @@
+class Foo {
+    void test() {
+        StringBuilder sb = new StringBuilder();
+        <caret>sb.append("foo").append("bar");
+        sb.append("baz");
+    }
+}

java/java-tests/testData/codeInsight/joinLines/CallChain2_after.java

@@ -0,0 +1,6 @@
+class Foo {
+    void test() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("foo").append("bar").append("baz");<caret>
+    }
+}

java/java-tests/testData/codeInsight/joinLines/CallChainWrong.java

@@ -0,0 +1,8 @@
+class Foo {
+    void test() {
+        StringBuilder sb = new StringBuilder();
+        <caret>sb.length();
+        sb.append("bar");
+        sb.append("baz");
+    }
+}

java/java-tests/testData/codeInsight/joinLines/CallChainWrong_after.java

@@ -0,0 +1,7 @@
+class Foo {
+    void test() {
+        StringBuilder sb = new StringBuilder();
+        sb.length();<caret>sb.append("bar");
+        sb.append("baz");
+    }
+}

java/java-tests/testData/codeInsight/joinLines/CallChain_after.java

@@ -0,0 +1,7 @@
+class Foo {
+    void test() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("foo").append("bar");<caret>
+        sb.append("baz");
+    }
+}

java/java-tests/testData/codeInsight/joinLines/DeclarationAndCall.java

@@ -0,0 +1,8 @@
+class Foo {
+    void test() {
+        <caret>StringBuilder sb = new StringBuilder();
+        sb.append("foo");
+        sb.append("bar");
+        sb.append("baz");
+    }
+}

java/java-tests/testData/codeInsight/joinLines/DeclarationAndCall_after.java

@@ -0,0 +1,7 @@
+class Foo {
+    void test() {
+        StringBuilder sb = new StringBuilder().append("foo");<caret>
+        sb.append("bar");
+        sb.append("baz");
+    }
+}

java/java-tests/testSrc/com/intellij/java/codeInsight/JoinLinesTest.java

@@ -40,6 +40,12 @@ public class JoinLinesTest extends LightCodeInsightTestCase {
   public void testStringLiteral() { doTest(); }
   public void testLiteralSCR4989() { doTest(); }
 
+  public void testCallChain() { doTest(); }
+  public void testCallChain2() { doTest(); }
+  public void testCallChainWrong() { doTest(); }
+  public void testDeclarationAndCall() { doTest(); }
+  public void testAssignmentAndCall() { doTest(); }
+
   public void testSCR3493() {
     CommonCodeStyleSettings settings = getJavaSettings();
     boolean use_tab_character = settings.getIndentOptions().USE_TAB_CHARACTER;
@@ -68,7 +74,7 @@ public class JoinLinesTest extends LightCodeInsightTestCase {
   }
   public void testSCR3493b() {
     CommonCodeStyleSettings settings = getJavaSettings();
-    boolean use_tab_character = settings.getIndentOptions().USE_TAB_CHARACTER;;
+    boolean use_tab_character = settings.getIndentOptions().USE_TAB_CHARACTER;
     boolean smart_tabs = settings.getIndentOptions().SMART_TABS;
     try {
       settings.getIndentOptions().USE_TAB_CHARACTER = true;
@@ -262,7 +268,7 @@ public class JoinLinesTest extends LightCodeInsightTestCase {
     checkResultByFile(path + getTestName(false) + "_after" + ext);
   }
 
-  private void performAction() {
+  private static void performAction() {
     EditorActionManager actionManager = EditorActionManager.getInstance();
     EditorActionHandler actionHandler = actionManager.getActionHandler(IdeActions.ACTION_EDITOR_JOIN_LINES);