IDEA-54829 When editing a resource bundle, IntelliJ generates spurious double backslashes

Corrected property values (un)escaping processing

plugins/properties/src/com/intellij/lang/properties/editor/ResourceBundleEditor.java

@@ -318,7 +318,14 @@ public class ResourceBundleEditor extends UserDataHolderBase implements FileEdit
             if (editor == null) continue;
             reinitSettings(editor);
             IProperty property = propertiesFile.findPropertyByKey(propertyName);
-            final String value = property == null ? "" : property.getValue();
+            final String value;
+            if (property == null) {
+              value = "";
+            }
+            else {
+              String rawValue = property.getValue();
+              value = rawValue == null ? "" : ResourceBundleUtil.fromPropertyValueToValueEditor(rawValue); 
+            }
             final Document document = editor.getDocument();
             CommandProcessor.getInstance().executeCommand(null, new Runnable() {
               public void run() {
@@ -362,7 +369,7 @@ public class ResourceBundleEditor extends UserDataHolderBase implements FileEdit
     else {
       myBackSlashPressed.remove(propertiesFile);
     }
-    String value = getPropertyValueFromText(text);
+    String value = ResourceBundleUtil.fromValueEditorToPropertyValue(text);
     IProperty property = propertiesFile.findPropertyByKey(propertyName);
     try {
       if (property == null) {
@@ -377,23 +384,6 @@ public class ResourceBundleEditor extends UserDataHolderBase implements FileEdit
     }
   }
 
-  private static String getPropertyValueFromText(final String text) {
-    StringBuilder value = new StringBuilder();
-    for (int i=0; i<text.length();i++) {
-      char c = text.charAt(i);
-      if (c == '\n') {
-        if (!PropertiesUtil.isUnescapedBackSlashAtTheEnd(value.toString())) {
-          value.append("\\");
-        }
-        value.append("\n");
-      }
-      else {
-        value.append(c);
-      }
-    }
-    return value.toString();
-  }
-
   private void installDocumentListeners() {
     List<PropertiesFile> propertiesFiles = myResourceBundle.getPropertiesFiles(myProject);
     for (final PropertiesFile propertiesFile : propertiesFiles) {

plugins/properties/src/com/intellij/lang/properties/editor/ResourceBundleUtil.java

@@ -0,0 +1,68 @@
+package com.intellij.lang.properties.editor;
+
+import gnu.trove.TIntHashSet;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.Reader;
+import java.util.Properties;
+
+/**
+ * @author Denis Zhdanov
+ * @since 10/5/11 2:35 PM
+ */
+public class ResourceBundleUtil {
+
+  private static final TIntHashSet SYMBOLS_TO_ESCAPE = new TIntHashSet(new int[]{'#', '!', '=', ':'});
+  private static final char        ESCAPE_SYMBOL     = '\\';
+  
+  private ResourceBundleUtil() {
+  }
+
+  /**
+   * Allows to map given 'raw' property value text to the 'user-friendly' text to show at the resource bundle editor.
+   * <p/>
+   * <b>Note:</b> please refer to {@link Properties#load(Reader)} contract for the property value escape rules.
+   * 
+   * @param text  'raw' property value text
+   * @return      'user-friendly' text to show at the resource bundle editor
+   */
+  @NotNull
+  public static String fromPropertyValueToValueEditor(@NotNull String text) {
+    StringBuilder buffer = new StringBuilder();
+    boolean escaped = false;
+    for (int i = 0; i < text.length(); i++) {
+      char c = text.charAt(i);
+      if (c == ESCAPE_SYMBOL && !escaped) {
+        escaped = true;
+        continue;
+      }
+      buffer.append(c);
+      escaped = false;
+    }
+    return buffer.toString();
+  }
+
+  /**
+   * Perform reverse operation to {@link #fromPropertyValueToValueEditor(String)}.
+   * 
+   * @param text  'user-friendly' text shown to the user at the resource bundle editor
+   * @return      'raw' value to store at the *.properties file
+   */
+  @NotNull
+  public static String fromValueEditorToPropertyValue(@NotNull String text) {
+    StringBuilder buffer = new StringBuilder();
+    for (int i = 0; i < text.length(); i++) {
+      char c = text.charAt(i);
+      
+      if ((i == 0 && (c == ' ' || c == '\t')) // Leading white space
+          || c == '\n'                        // Multi-line value
+          || c == ESCAPE_SYMBOL               // Escaped 'escape' symbol
+          || SYMBOLS_TO_ESCAPE.contains(c))   // Special symbol
+      {
+        buffer.append(ESCAPE_SYMBOL);
+      }
+      buffer.append(c);
+    }
+    return buffer.toString();
+  }
+}

plugins/properties/testSrc/com/intellij/lang/properties/editor/ResourceBundleUtilTest.java

@@ -0,0 +1,58 @@
+package com.intellij.lang.properties.editor;
+
+import gnu.trove.TIntHashSet;
+import org.jetbrains.annotations.NotNull;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author Denis Zhdanov
+ * @since 10/5/11 2:37 PM
+ */
+public class ResourceBundleUtilTest {
+
+  /**
+   * Holds pairs like <code>('property value'; 'value editor text')</code>.
+   */
+  private static final String[][] TEST_DATA = {
+    // Common.
+    { "", "" },
+    { "as-is", "as-is" },
+    { "with escaped escape symbol - \\\\", "with escaped escape symbol - \\" },
+    
+    // Special symbols.
+    { "special symbols - \\# and \\! and \\= and \\:", "special symbols - # and ! and = and :" },
+    
+    // White spaces.
+    { "trailing white space ", "trailing white space " },
+    { "trailing white spaces   ", "trailing white spaces   " },
+    { "trailing tab\t", "trailing tab\t" },
+    { "trailing tabs\t\t\t", "trailing tabs\t\t\t" },
+    { "\\\tstarting from tab", "\tstarting from tab" },
+    { "\\\t\t\tstarting from tabs", "\t\t\tstarting from tabs" },
+    { "\\ starting from white space", " starting from white space" },
+    { "\\   starting from white spaces", "   starting from white spaces" },
+    { "\\ \t  starting from white spaces and tabs", " \t  starting from white spaces and tabs" },
+    { "first line \\\nsecond line", "first line \nsecond line" },
+    
+    // All together.
+    { "\\\t text with \\\nspecial symbols\\:\\\n\\#", "\t text with \nspecial symbols:\n#" }
+  };
+  
+  @Test
+  public void checkAllTestData() {
+    for (String[] entry : TEST_DATA) {
+      assertEquals(
+        "Expected property value differs from the one converted from value editor text",
+        entry[0],
+        ResourceBundleUtil.fromValueEditorToPropertyValue(entry[1])
+      );
+      assertEquals(
+        "Expected value editor text differs from the one converted from property value",
+        entry[1],
+        ResourceBundleUtil.fromPropertyValueToValueEditor(entry[0])
+      );
+    }
+  }
+}