Java: update "Unnecessarily escaped character" inspection for string literals (IDEA-326944)

GitOrigin-RevId: 49792b6510b8deaf20e49c509c948ba51f508de1

java/java-analysis-impl/src/com/siyeh/ig/PsiReplacementUtil.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.siyeh.ig;
 
 import com.intellij.openapi.project.Project;
@@ -15,6 +15,12 @@ import org.jetbrains.annotations.Nullable;
 
 public final class PsiReplacementUtil {
 
+  public static void replaceFragment(@NotNull PsiFragment fragment, @NotNull @NonNls String newFragmentText) {
+    final PsiElementFactory factory = JavaPsiFacade.getElementFactory(fragment.getProject());
+    final PsiFragment newFragment = factory.createStringTemplateFragment(newFragmentText, fragment.getTokenType(), fragment);
+    fragment.replace(newFragment);
+  }
+
   /**
    * Consider to use {@link #replaceExpression(PsiExpression, String, CommentTracker)} to preserve comments
    */

java/java-impl/src/com/siyeh/ig/redundancy/UnnecessaryStringEscapeInspection.java

@@ -3,7 +3,8 @@ package com.siyeh.ig.redundancy;
 
 import com.intellij.codeInsight.daemon.impl.HighlightInfo;
 import com.intellij.codeInsight.daemon.impl.analysis.HighlightUtil;
-import com.intellij.codeInspection.*;
+import com.intellij.codeInspection.CleanupLocalInspectionTool;
+import com.intellij.codeInspection.LocalQuickFix;
 import com.intellij.codeInspection.options.OptPane;
 import com.intellij.modcommand.ModPsiUpdater;
 import com.intellij.modcommand.PsiUpdateModCommandQuickFix;
@@ -12,6 +13,7 @@ import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.*;
+import com.intellij.psi.impl.source.tree.java.PsiFragmentImpl;
 import com.intellij.psi.util.PsiLiteralUtil;
 import com.intellij.psi.util.PsiUtil;
 import com.siyeh.InspectionGadgetsBundle;
@@ -69,71 +71,108 @@ public class UnnecessaryStringEscapeInspection extends BaseInspection implements
 
     @Override
     protected void applyFix(@NotNull Project project, @NotNull PsiElement element, @NotNull ModPsiUpdater updater) {
-      if (!(element instanceof PsiLiteralExpression literalExpression)) {
-        return;
-      }
-      final PsiType type = literalExpression.getType();
-      if (type == null) {
-        return;
-      }
-      final String text = literalExpression.getText();
+      final String text = element.getText();
       if (!myText.equals(text)) {
         return;
       }
-      if (type.equalsToText(CommonClassNames.JAVA_LANG_STRING)) {
-        final StringBuilder newExpression = new StringBuilder();
-        if (literalExpression.isTextBlock()) {
-          int offset = 0;
-          int start = findUnnecessaryTextBlockEscapes(text, 4);
-          while (start >= 0) {
-            newExpression.append(text, offset, start);
-            offset = start + 2;
-            @NonNls final String escape = text.substring(start, offset);
-            if ("\\n".equals(escape)) {
-              final int indent = PsiLiteralUtil.getTextBlockIndent(literalExpression);
-              if (indent < 0) return;
-              newExpression.append('\n').append(StringUtil.repeatSymbol(' ', indent));
-            }
-            else {
-              newExpression.append(escape.charAt(1));
-            }
-            start = findUnnecessaryTextBlockEscapes(text, offset);
-          }
-          newExpression.append(text.substring(offset));
-          final Document document = element.getContainingFile().getViewProvider().getDocument();
-          assert document != null;
-          final TextRange replaceRange = element.getTextRange();
-          document.replaceString(replaceRange.getStartOffset(), replaceRange.getEndOffset(), newExpression.toString());
-          return;
+      if (element instanceof PsiFragment fragment) {
+        if (fragment.isTextBlock()) {
+          int indent = PsiFragmentImpl.getTextBlockFragmentIndent(fragment);
+          PsiReplacementUtil.replaceFragment(fragment, buildNewTextBlockText(text, indent));
         }
         else {
-          boolean escaped = false;
-          final int length = text.length();
-          for (int i = 0; i < length; i++) {
-            final char c = text.charAt(i);
-            if (escaped) {
-              if (c != '\'') newExpression.append('\\');
-              newExpression.append(c);
-              escaped = false;
-            }
-            else if (c == '\\') escaped = true;
-            else newExpression.append(c);
+          PsiReplacementUtil.replaceFragment(fragment, buildNewStringText(text));
+        }
+      }
+      else if (element instanceof PsiLiteralExpression literalExpression) {
+        final PsiType type = literalExpression.getType();
+        if (type == null) {
+          return;
+        }
+
+        if (type.equalsToText(CommonClassNames.JAVA_LANG_STRING)) {
+          if (literalExpression.isTextBlock()) {
+            final int indent = PsiLiteralUtil.getTextBlockIndent(literalExpression);
+            if (indent < 0)  return;
+            final String newTextBlockTest = buildNewTextBlockText(text, indent);
+            final Document document = element.getContainingFile().getViewProvider().getDocument();
+            assert document != null;
+            final TextRange replaceRange = element.getTextRange();
+            document.replaceString(replaceRange.getStartOffset(), replaceRange.getEndOffset(), newTextBlockTest);
+          }
+          else {
+            PsiReplacementUtil.replaceExpression(literalExpression, buildNewStringText(text));
           }
         }
-        PsiReplacementUtil.replaceExpression(literalExpression, newExpression.toString());
+        else if (PsiTypes.charType().equals(type) && text.equals("'\\\"'")) {
+          PsiReplacementUtil.replaceExpression(literalExpression, "'\"'");
+        }
       }
-      else if (PsiTypes.charType().equals(type) && text.equals("'\\\"'")) {
-        PsiReplacementUtil.replaceExpression(literalExpression, "'\"'");
+    }
+
+    private static String buildNewStringText(String text) {
+      final StringBuilder newExpression = new StringBuilder();
+      boolean escaped = false;
+      final int length = text.length();
+      for (int i = 0; i < length; i++) {
+        final char c = text.charAt(i);
+        if (escaped) {
+          if (c != '\'') newExpression.append('\\');
+          newExpression.append(c);
+          escaped = false;
+        }
+        else if (c == '\\') {
+          escaped = true;
+        }
+        else {
+          newExpression.append(c);
+        }
       }
+      return newExpression.toString();
+    }
+
+    @NotNull
+    private static String buildNewTextBlockText(String text, int indent) {
+      final StringBuilder newExpression = new StringBuilder();
+      int offset = 0;
+      int end = text.endsWith("\"\"\"") ? text.length() - 3 : text.length() - 2;
+      int start = findUnnecessaryTextBlockEscapes(text, text.startsWith("\"\"\"") ? 4 : 1, end);
+      while (start >= 0) {
+        newExpression.append(text, offset, start);
+        offset = start + 2;
+        @NonNls final String escape = text.substring(start, offset);
+        if ("\\n".equals(escape)) {
+          newExpression.append('\n').append(StringUtil.repeatSymbol(' ', indent));
+        }
+        else {
+          newExpression.append(escape.charAt(1));
+        }
+        start = findUnnecessaryTextBlockEscapes(text, offset, end);
+      }
+      newExpression.append(text.substring(offset));
+      return newExpression.toString();
     }
   }
 
-  static int findUnnecessaryTextBlockEscapes(String text, int start) {
+  static int findUnnecessaryStringEscapes(String text, int start) {
+    boolean slash = false;
+    final int max = text.length() - 1; // skip closing "
+    for (int i = start; i < max; i++) {
+      final char c = text.charAt(i);
+      if (slash) {
+        slash = false;
+        if (c == '\'') return i - 1;
+      }
+      else if (c == '\\') slash = true;
+    }
+    return -1;
+  }
+
+  static int findUnnecessaryTextBlockEscapes(String text, int start, int end) {
     boolean slash = false;
     boolean ws = false;
     int doubleQuotes = 0;
-    final int max = text.length() - 3; // skip closing """
-    for (int i = start; i < max; i++) {
+    for (int i = start; i < end; i++) {
       final char ch = text.charAt(i);
       if (ch == '\\') slash = !slash;
       else if (ch == ' ' || ch == '\t') ws = true;
@@ -146,9 +185,9 @@ public class UnnecessaryStringEscapeInspection extends BaseInspection implements
             return i - 1;
           }
           else if (ch == '"' && doubleQuotes < 2) {
-            if (i == max - 1) return -1;
-            if (i == max - 2) return i - 1;
-            if (i < max - 2 && text.charAt(i + 1) == '"') {
+            if (i == end - 1) return -1;
+            if (i == end - 2) return i - 1;
+            if (i < end - 2 && text.charAt(i + 1) == '"') {
               if (doubleQuotes != 1 && text.charAt(i + 2) != '"') return i - 1;
             }
             else {
@@ -173,6 +212,32 @@ public class UnnecessaryStringEscapeInspection extends BaseInspection implements
 
   private class RedundantStringEscapeVisitor extends BaseInspectionVisitor {
 
+    @Override
+    public void visitFragment(@NotNull PsiFragment fragment) {
+      super.visitFragment(fragment);
+      HighlightInfo.Builder error = HighlightUtil.checkFragmentError(fragment);
+      if (error != null) {
+        return;
+      }
+
+      final String text = fragment.getText();
+      if (fragment.isTextBlock()) {
+        int end = fragment.getTokenType() == JavaTokenType.TEXT_BLOCK_TEMPLATE_END ? text.length() - 3 : text.length() - 2;
+        int start = findUnnecessaryTextBlockEscapes(text, 1, end);
+        while (start >= 0) {
+          registerErrorAtOffset(fragment, start, 2, text);
+          start = findUnnecessaryTextBlockEscapes(text, start + 2, end);
+        }
+      }
+      else {
+        int start = findUnnecessaryStringEscapes(text, 1);
+        while (start >= 0) {
+          registerErrorAtOffset(fragment, start, 2, text);
+          start = findUnnecessaryStringEscapes(text, start + 2);
+        }
+      }
+    }
+
     @Override
     public void visitLiteralExpression(@NotNull PsiLiteralExpression expression) {
       super.visitLiteralExpression(expression);
@@ -180,31 +245,26 @@ public class UnnecessaryStringEscapeInspection extends BaseInspection implements
       if (type == null) {
         return;
       }
-      HighlightInfo.Builder
-        parsingError = HighlightUtil.checkLiteralExpressionParsingError(expression, PsiUtil.getLanguageLevel(expression), null, null);
+      HighlightInfo.Builder parsingError =
+        HighlightUtil.checkLiteralExpressionParsingError(expression, PsiUtil.getLanguageLevel(expression), null, null);
       if (parsingError != null) {
         return;
       }
       if (type.equalsToText(CommonClassNames.JAVA_LANG_STRING)) {
+        final String text = expression.getText();
         if (expression.isTextBlock()) {
-          final String text = expression.getText();
-          int start = findUnnecessaryTextBlockEscapes(text, 4);
+          int end = text.length() - 3;
+          int start = findUnnecessaryTextBlockEscapes(text, 4, end);
           while (start >= 0) {
             registerErrorAtOffset(expression, start, 2, text);
-            start = findUnnecessaryTextBlockEscapes(text, start + 2);
+            start = findUnnecessaryTextBlockEscapes(text, start + 2, end);
           }
         }
         else {
-          final String text = expression.getText();
-          boolean slash = false;
-          final int max = text.length() - 1; // skip closing "
-          for (int i = 1; i < max; i++) {
-            final char c = text.charAt(i);
-            if (slash) {
-              slash = false;
-              if (c == '\'') registerErrorAtOffset(expression, i - 1, 2, text);
-            }
-            else if (c == '\\') slash = true;
+          int start = findUnnecessaryStringEscapes(text, 1);
+          while (start >= 0) {
+            registerErrorAtOffset(expression, start, 2, text);
+            start = findUnnecessaryStringEscapes(text, start + 2);
           }
         }
       }

java/java-impl/src/inspectionDescriptions/UnnecessaryStringEscape.html

@@ -1,7 +1,7 @@
 <html>
 <body>
 Reports unnecessarily escaped characters in <code>String</code> and optionally <code>char</code> literals.
-<p>The escaped tab character <code>\t</code> is not reported, because otherwise it will be invisible.</p>
+<p>Escaped tab characters <code>\t</code> are not reported, because tab characters are invisible.</p>
 <p>Examples:</p>
 <pre><code>
   String s = "\'Scare\' quotes";

java/java-psi-api/src/com/intellij/psi/PsiElementFactory.java

@@ -363,6 +363,11 @@ public interface PsiElementFactory extends PsiJavaParserFacade, JVMElementFactor
                                              @Nullable PsiExpression initializer,
                                              @Nullable PsiElement context);
 
+  /**
+   * Creates a string template fragment with the specified text of the specified token type.
+   */
+  @NotNull PsiFragment createStringTemplateFragment(@NotNull String newText, @NotNull IElementType tokenType, @Nullable PsiElement context);
+
   /**
    * Creates a PSI element for the "@param" JavaDoc tag.
    *

java/java-psi-impl/src/com/intellij/psi/impl/PsiElementFactoryImpl.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.psi.impl;
 
 import com.intellij.lang.*;
@@ -734,6 +734,45 @@ public final class PsiElementFactoryImpl extends PsiJavaParserFacadeImpl impleme
     return catchSection;
   }
 
+  @Override
+  @NotNull
+  public PsiFragment createStringTemplateFragment(@NotNull String newText, @NotNull IElementType tokenType, @Nullable PsiElement context) {
+    int index;
+    if (tokenType == JavaTokenType.TEXT_BLOCK_TEMPLATE_BEGIN) {
+      newText += "}\"\"\"";
+      index = 0;
+    }
+    else if (tokenType == JavaTokenType.TEXT_BLOCK_TEMPLATE_MID) {
+      newText = "\"\"\"\n\\{" + newText + "}\"\"\"";
+      index = 1;
+    }
+    else if (tokenType == JavaTokenType.TEXT_BLOCK_TEMPLATE_END) {
+      newText = "\"\"\"\n\\{" + newText;
+      index = 1;
+    }
+    else if (tokenType == JavaTokenType.STRING_TEMPLATE_BEGIN) {
+      newText += "}\"";
+      index = 0;
+    }
+    else if (tokenType == JavaTokenType.STRING_TEMPLATE_MID) {
+      newText = "\"\\{" + newText + "}\"";
+      index = 1;
+    }
+    else if (tokenType == JavaTokenType.STRING_TEMPLATE_END) {
+      newText = "\"\\{" + newText;
+      index = 1;
+    }
+    else {
+      throw new IllegalArgumentException();
+    }
+    PsiTemplateExpression expression = (PsiTemplateExpression)createExpressionFromText(newText, context);
+    PsiTemplate template = expression.getTemplate();
+    assert template != null;
+    PsiFragment fragment = template.getFragments().get(index);
+    GeneratedMarkerVisitor.markGenerated(fragment);
+    return fragment;
+  }
+
   @Override
   public boolean isValidClassName(@NotNull String name) {
     return isIdentifier(name);

java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiFragmentImpl.java

@@ -116,7 +116,7 @@ public final class PsiFragmentImpl extends LeafPsiElement implements PsiFragment
     return result.toString();
   }
 
-  private static int getTextBlockFragmentIndent(PsiFragment fragment) {
+  public static int getTextBlockFragmentIndent(PsiFragment fragment) {
     final PsiElement parent = fragment.getParent();
     if (!(parent instanceof PsiTemplate)) {
       return -1;

java/java-tests/testData/ig/com/siyeh/igtest/redundancy/unnecessary_string_escape/EscapedNewLine.after.java

@@ -0,0 +1,12 @@
+class EscapedNewLine {
+  public static void main(String[] args) {
+    String s = """
+                first line
+                          a
+                |
+                third line
+                """;
+    System.out.println(s.replace(' ', '.'));
+    System.out.println("123");
+  }
+}

java/java-tests/testData/ig/com/siyeh/igtest/redundancy/unnecessary_string_escape/EscapedNewLine.java

@@ -2,7 +2,7 @@ class EscapedNewLine {
   public static void main(String[] args) {
     String s = """
                 first line
-                          a<warning descr="'\n' is unnecessarily escaped"><caret>\n</warning>
+                          a<warning descr="'\n' is unnecessarily escaped"><caret>\n</warning>|
                 third line
                 """;
     System.out.println(s.replace(' ', '.'));

java/java-tests/testData/ig/com/siyeh/igtest/redundancy/unnecessary_string_escape/StringTemplate1.after.java

@@ -0,0 +1,6 @@
+class StringTemplate1 {
+
+  String x(int i) {
+    return STR." '\{i}''\{i}'''";
+  }
+}

java/java-tests/testData/ig/com/siyeh/igtest/redundancy/unnecessary_string_escape/StringTemplate1.java

@@ -0,0 +1,6 @@
+class StringTemplate1 {
+
+  String x(int i) {
+    return STR." <warning descr="'\'' is unnecessarily escaped"><caret>\'</warning>\{i}<warning descr="'\'' is unnecessarily escaped">\'</warning><warning descr="'\'' is unnecessarily escaped">\'</warning>\{i}<warning descr="'\'' is unnecessarily escaped">\'</warning><warning descr="'\'' is unnecessarily escaped">\'</warning><warning descr="'\'' is unnecessarily escaped">\'</warning>";
+  }
+}

java/java-tests/testData/ig/com/siyeh/igtest/redundancy/unnecessary_string_escape/StringTemplate2.after.java

@@ -0,0 +1,8 @@
+class StringTemplate2 {
+
+  String x(int i) {
+    return STR."""
+      '\{i}'
+      '\{i}'""";
+  }
+}

java/java-tests/testData/ig/com/siyeh/igtest/redundancy/unnecessary_string_escape/StringTemplate2.java

@@ -0,0 +1,8 @@
+class StringTemplate2 {
+
+  String x(int i) {
+    return STR."""
+      <warning descr="'\'' is unnecessarily escaped"><caret>\'</warning>\{i}<warning descr="'\'' is unnecessarily escaped">\'</warning>
+      <warning descr="'\'' is unnecessarily escaped">\'</warning>\{i}<warning descr="'\'' is unnecessarily escaped">\'</warning>""";
+  }
+}

java/java-tests/testSrc/com/siyeh/ig/redundancy/UnnecessaryStringEscapeInspectionTest.java

@@ -1,8 +1,10 @@
-// Copyright 2000-2021 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.siyeh.ig.redundancy;
 
 import com.intellij.codeInspection.InspectionProfileEntry;
+import com.intellij.testFramework.LightProjectDescriptor;
 import com.siyeh.ig.LightJavaInspectionTestCase;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 /**
@@ -15,12 +17,25 @@ public class UnnecessaryStringEscapeInspectionTest extends LightJavaInspectionTe
   public void testDoubleQuoteInChar() { doQuickFixTest(); }
   public void testSingleQuoteInString() { doQuickFixTest(); }
   public void testMultipleProblemsInSingleString() { doQuickFixTest(); }
-  public void testEscapedNewLine() { doTest(); }
+  public void testEscapedNewLine() { doQuickFixTest(); }
+  public void testStringTemplate1() { doQuickFixTest(); }
+  public void testStringTemplate2() { doQuickFixTest(); }
 
   public void testEscapedNewLineNotUnnecessary() { doTest(); }
   public void testBrokenCode() { doTest(); }
 
   protected void doQuickFixTest() {
+    myFixture.addClass("""
+      package java.lang;
+      public interface StringTemplate {
+        Processor<String, RuntimeException> STR = null;
+        
+        @PreviewFeature(feature=PreviewFeature.Feature.STRING_TEMPLATES)
+        @FunctionalInterface
+        interface Processor<R, E extends Throwable> {
+          R process(StringTemplate stringTemplate) throws E;
+        }
+      }""");
     doTest();
     checkQuickFixAll();
   }
@@ -38,4 +53,8 @@ public class UnnecessaryStringEscapeInspectionTest extends LightJavaInspectionTe
     return inspection;
   }
 
+  @Override
+  protected @NotNull LightProjectDescriptor getProjectDescriptor() {
+    return JAVA_21;
+  }
 }