[java] Join Lines in text blocks: automatically remove \s on the joined line boundaries (IDEA-349062)

GitOrigin-RevId: 97f4885283f6da2bb06c46df6ea19ee6cd8caa7c

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

@@ -37,12 +37,25 @@ public final class TextBlockJoinLinesHandler implements JoinRawLinesHandlerDeleg
                           && lineNumber == doc.getLineNumber(tokenRange.getStartOffset());
     boolean atEmptyStartLine = atStartLine && TEXT_BLOCK_START.matcher(token.getText()).find();
     boolean singleSlash = false;
-    if (text.charAt(start) == '\\') {
+    int numSpaces = 0;
+    char charAtStart = text.charAt(start);
+    if (charAtStart == '\\') {
       int startOffset = Math.max(tokenRange.getStartOffset(), doc.getLineStartOffset(lineNumber));
       String substring = doc.getText(TextRange.create(startOffset, start)) + "\\\n";
       CharSequence parsed = CodeInsightUtilCore.parseStringCharacters(substring, null);
       singleSlash = parsed != null && parsed.charAt(parsed.length() - 1) != '\n';
     }
+    else if (charAtStart == 's' && text.charAt(start - 1) == '\\') {
+      int startOffset = Math.max(tokenRange.getStartOffset(), doc.getLineStartOffset(lineNumber));
+      String substring = doc.getText(TextRange.create(startOffset, start + 1));
+      CharSequence parsed = CodeInsightUtilCore.parseStringCharacters(substring, null);
+      if (parsed != null) {
+        while (text.charAt(start - numSpaces * 2) == 's' && text.charAt(start - numSpaces * 2 - 1) == '\\' &&
+               parsed.charAt(parsed.length() - 1 - numSpaces) == ' ') {
+          numSpaces++;
+        }
+      }
+    }
     if (!singleSlash) {
       start++;
     }
@@ -61,7 +74,8 @@ public final class TextBlockJoinLinesHandler implements JoinRawLinesHandlerDeleg
       doc.deleteString(start, end);
       endOffset += start - end;
     } else {
-      doc.replaceString(start, end, "\\n");
+      doc.replaceString(start - numSpaces * 2, end, " ".repeat(numSpaces) + "\\n");
+      start -= numSpaces;
       endOffset += start - end + 2;
     }
     if (fromStartTillEnd) {

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

@@ -0,0 +1,7 @@
+class A {
+  void test() {
+    String s = STR."""
+       <caret>Hello\s
+       World""";
+  }
+}

java/java-tests/testData/codeInsight/joinLines/JoinTextBlockSlashS2.java

@@ -0,0 +1,7 @@
+class A {
+  void test() {
+    String s = STR."""
+       <caret>Hello\s\s
+       World""";
+  }
+}

java/java-tests/testData/codeInsight/joinLines/JoinTextBlockSlashS2_after.java

@@ -0,0 +1,6 @@
+class A {
+  void test() {
+    String s = STR."""
+       Hello  <caret>\nWorld""";
+  }
+}

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

@@ -0,0 +1,7 @@
+class A {
+  void test() {
+    String s = <selection>STR."""
+       Hello\s\s\s
+       World"""</selection>;
+  }
+}

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

@@ -0,0 +1,5 @@
+class A {
+  void test() {
+    String s = <selection>STR."Hello   \nWorld"<caret></selection>;
+  }
+}

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

@@ -0,0 +1,7 @@
+class A {
+  void test() {
+    String s = STR."""
+       <caret>Hello\\s
+       World""";
+  }
+}

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

@@ -0,0 +1,6 @@
+class A {
+  void test() {
+    String s = STR."""
+       Hello\\s<caret>\nWorld""";
+  }
+}

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

@@ -0,0 +1,6 @@
+class A {
+  void test() {
+    String s = STR."""
+       Hello <caret>\nWorld""";
+  }
+}

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

@@ -311,6 +311,10 @@ public class JoinLinesTest extends LightJavaCodeInsightTestCase {
   public void testJoinTextBlockBackTripleSlash() {doTest();}
   public void testJoinTextBlockBackSlashEmptyLineAfter() {doTest();}
   public void testJoinTextBlockBackSlashLastLine() {doTest();}
+  public void testJoinTextBlockSlashS() {doTest();}
+  public void testJoinTextBlockSlashSFake() {doTest();}
+  public void testJoinTextBlockSlashS2() {doTest();}
+  public void testJoinTextBlockSlashSComplete() {doTest();}
   public void testJoinStringTemplateBackSlash() {doTest();}
   public void testJoinStringTemplateBackSlash2() {doTest();}