IDEA-74544 Copy-Paste a string literal with '\n' character inserts actual line-feed instead of '\n'

StringLiteralCopyPasteProcessor handles string literals at the pasted text now

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

@@ -71,6 +71,9 @@ public class StringLiteralCopyPasteProcessor implements CopyPastePreProcessor {
       if (rawText != null && rawText.rawText != null) return rawText.rawText; // Copied from the string literal. Copy as is.
       return escapeCharCharacters(text);
     }
+    else {
+      text = escapePastedLiteral(text);
+    }
     return text;
   }
 
@@ -119,4 +122,38 @@ public class StringLiteralCopyPasteProcessor implements CopyPastePreProcessor {
     StringUtil.escapeStringCharacters(s.length(), s, "\'", buffer);
     return buffer.toString();
   }
+
+  /**
+   * There is a possible case that pasted string contains string literal. We need to escape problem symbols within it then
+   * (see IDEA-74544 for the problem example).
+   * 
+   * @param s  target string to paste
+   * @return   string that should be actually pasted
+   */
+  @SuppressWarnings("AssignmentToForLoopParameter")
+  public static String escapePastedLiteral(@NotNull String s) {
+    StringBuilder buffer = new StringBuilder();
+    int literalStart = -1;
+    int literalEnd = 0;
+    for (int i = 0; i < s.length(); i++) {
+      char c = s.charAt(i);
+      switch (c) {
+        case '\\': i++;break;
+        case '"':
+          if (literalStart < 0) {
+            literalStart = i + 1;
+            buffer.append(s, literalEnd, literalStart);
+          }
+          else {
+            literalEnd = i;
+            buffer.append(StringUtil.escapeStringCharacters(s.substring(literalStart, literalEnd)));
+            literalStart = -1;
+          }
+      }
+    }
+    if (literalEnd < s.length()) {
+      buffer.append(s.substring(Math.max(literalStart, literalEnd)));
+    } 
+    return buffer.toString();
+  }
 }

java/java-impl/testSrc/com/intellij/codeInsight/editorActions/StringLiteralCopyPasteProcessorTest.java

@@ -0,0 +1,25 @@
+package com.intellij.codeInsight.editorActions;
+
+import org.jetbrains.annotations.NotNull;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author Denis Zhdanov
+ * @since 10/4/11 1:28 PM
+ */
+public class StringLiteralCopyPasteProcessorTest {
+  
+  @Test
+  public void escapePastedStringLiteral() {
+    doEscapePastedStringLiteralTest("identity", "identity");
+    doEscapePastedStringLiteralTest("\"complete \n literal\"", "\"complete \\n literal\"");
+    doEscapePastedStringLiteralTest("\"incomplete \n literal", "\"incomplete \n literal");
+    doEscapePastedStringLiteralTest("partial \"string \n literal\"", "partial \"string \\n literal\"");
+  }
+
+  private static void doEscapePastedStringLiteralTest(@NotNull String initial, @NotNull String expected) {
+    assertEquals(expected, StringLiteralCopyPasteProcessor.escapePastedLiteral(initial));
+  }
+}