Strip trailing spaces line filter API [IDEA-CR-8203]

platform/core-api/src/com/intellij/openapi/editor/StripTrailingSpacesLineFilter.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2000-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.editor;
+
+import com.intellij.openapi.extensions.ExtensionPointName;
+import com.intellij.openapi.project.Project;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.*;
+
+/**
+ * Allows to suppress stripping spaces from some lines when a document is being saved and "Strip spaces on Save" option is not "None".
+ */
+public abstract class StripTrailingSpacesLineFilter {
+  public static final ExtensionPointName<StripTrailingSpacesLineFilter> LINE_FILTER_EXTENSION_POINT 
+    = new ExtensionPointName<StripTrailingSpacesLineFilter>("com.intellij.stripTrailingSpacesLineFilter");
+
+  /**
+   * Tells if spaces can be stripped from the document. Returns <code>false</code> if trailing spaces should be preserved regardless of
+   * the editor settings and other filters.
+   * 
+   * @param project  The current project or <code>null</code> if there is no project context.
+   * @param document The document.
+   * @return True if it's OK to strip spaces, false otherwise.
+   */
+  public abstract boolean isStripSpacesAllowed(@Nullable Project project, @NotNull Document document);
+
+  /**
+   * Processes a document and sets bits to 1 (true) for lines which should remain untouched when trailing spaces are removed.
+   * 
+   * @param project   The current project or null if there is no project context.
+   * @param document  The document to process.
+   * @param disabledLinesBitSet The bit set which can be modified by the <code>apply()</code> method. Each bit index corresponds to a line
+   *
+   * @return True if successful, false if can't be applied now, probably later. 
+   */
+  public abstract boolean apply(@Nullable Project project, @NotNull Document document, @NotNull BitSet disabledLinesBitSet);
+  
+}

platform/core-impl/src/com/intellij/openapi/editor/impl/DocumentImpl.java

@@ -51,8 +51,11 @@ import java.beans.PropertyChangeListener;
 import java.beans.PropertyChangeSupport;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.BitSet;
 import java.util.List;
 
+import static com.intellij.openapi.editor.StripTrailingSpacesLineFilter.LINE_FILTER_EXTENSION_POINT;
+
 public class DocumentImpl extends UserDataHolderBase implements DocumentEx {
   private static final Logger LOG = Logger.getInstance("#com.intellij.openapi.editor.impl.DocumentImpl");
 
@@ -196,6 +199,14 @@ public class DocumentImpl extends UserDataHolderBase implements DocumentEx {
     if (!isStripTrailingSpacesEnabled) {
       return true;
     }
+    StripTrailingSpacesLineFilter[] filters = LINE_FILTER_EXTENSION_POINT.getExtensions(); 
+    for (StripTrailingSpacesLineFilter filter : filters) {
+      if (!filter.isStripSpacesAllowed(project, this)) return true;
+    }
+    BitSet disabledLinesBitSet = new BitSet(getLineCount());
+    for (StripTrailingSpacesLineFilter filter : filters) {
+      if (!filter.apply(project, this, disabledLinesBitSet)) return false;
+    }
 
     boolean markAsNeedsStrippingLater = false;
     CharSequence text = myText;
@@ -219,7 +230,7 @@ public class DocumentImpl extends UserDataHolderBase implements DocumentEx {
       lineLoop:
       for (int line = 0; line < getLineCount(); line++) {
         LineSet lineSet = getLineSet();
-        if (inChangedLinesOnly && !lineSet.isModified(line)) continue;
+        if (inChangedLinesOnly && !lineSet.isModified(line) || disabledLinesBitSet.get(line)) continue;
         int whiteSpaceStart = -1;
         final int lineEnd = lineSet.getLineEnd(line) - lineSet.getSeparatorLength(line);
         int lineStart = lineSet.getLineStart(line);

platform/core-impl/src/com/intellij/openapi/editor/impl/PsiBasedStripTrailingSpacesLineFilter.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2000-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.editor.impl;
+
+import com.intellij.lang.Language;
+import com.intellij.lang.LanguageUtil;
+import com.intellij.openapi.editor.Document;
+import com.intellij.openapi.editor.StripTrailingSpacesLineFilter;
+import com.intellij.openapi.fileEditor.FileDocumentManager;
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.psi.PsiDocumentManager;
+import com.intellij.psi.PsiFile;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.BitSet;
+
+public abstract class PsiBasedStripTrailingSpacesLineFilter extends StripTrailingSpacesLineFilter {
+  @Override
+  public boolean isStripSpacesAllowed(@Nullable Project project, @NotNull Document document) {
+    return true;
+  }
+
+  @Override
+  public final boolean apply(@Nullable Project project, @NotNull Document document, @NotNull BitSet disabledLinesBitSet) {
+    Language language = getDocumentLanguage(document);
+    if (language != null && isApplicableTo(language)) {
+      PsiFile psiFile = getPsiFile(project, document);
+      if (psiFile != null) {
+        return apply(document, psiFile, disabledLinesBitSet);
+      }
+      return false;
+    }
+    return true;
+  }
+  
+  protected abstract boolean isApplicableTo(@NotNull Language language);
+  
+  protected abstract boolean apply(@NotNull Document document, @NotNull PsiFile psiFile, BitSet disabledLinesBitSet);
+
+  @Nullable
+  private static Language getDocumentLanguage(@NotNull Document document) {
+    FileDocumentManager manager = FileDocumentManager.getInstance();
+    VirtualFile file = manager.getFile(document);
+    if (file != null && file.isValid()) {
+      return LanguageUtil.getFileLanguage(file);
+    }
+    return null;
+  }
+  
+  @Nullable
+  private static PsiFile getPsiFile(@Nullable Project project, @NotNull Document document) {
+    if (project != null) {
+      PsiDocumentManager documentManager = PsiDocumentManager.getInstance(project);
+      if (documentManager.isCommitted(document)) {
+        return documentManager.getCachedPsiFile(document);
+      }
+    }
+    return null;
+  }
+}

platform/platform-resources/src/META-INF/PlatformExtensionPoints.xml

@@ -262,5 +262,6 @@
     <extensionPoint name="remote.credentialsType" interface="com.intellij.remote.ext.CredentialsTypeEx"/>
     <extensionPoint name="remote.credentialsLanguageContribution"
                     interface="com.intellij.remote.ext.CredentialsLanguageContribution"/>
+    <extensionPoint name="stripTrailingSpacesLineFilter" interface="com.intellij.openapi.editor.StripTrailingSpacesLineFilter"/>
   </extensionPoints>
 </idea-plugin>