Space after '#' according to PEP8 (PY-11571).

python/src/META-INF/python-core.xml

@@ -18,6 +18,7 @@
     <lang.foldingBuilder language="Python" implementationClass="com.jetbrains.python.PythonFoldingBuilder"/>
     <lang.findUsagesProvider language="Python" implementationClass="com.jetbrains.python.findUsages.PythonFindUsagesProvider"/>
     <lang.formatter language="Python" implementationClass="com.jetbrains.python.formatter.PythonFormattingModelBuilder"/>
+    <preFormatProcessor implementation="com.jetbrains.python.formatter.PyPreFormatProcessor"/>
     <lang.whiteSpaceFormattingStrategy language="Python"
                                        implementationClass="com.jetbrains.python.formatter.PyWhiteSpaceFormattingStrategy"/>
     <lang.lineWrapStrategy language="Python" implementationClass="com.jetbrains.python.formatter.PyLineWrapPositionStrategy"/>

python/src/com/jetbrains/python/formatter/PyCodeStyleSettings.java

@@ -38,6 +38,8 @@ public class PyCodeStyleSettings extends CustomCodeStyleSettings {
   public boolean NEW_LINE_AFTER_COLON = false;
   public boolean NEW_LINE_AFTER_COLON_MULTI_CLAUSE = true;
 
+  public boolean SPACE_AFTER_NUMBER_SIGN = true;
+
   public PyCodeStyleSettings(CodeStyleSettings container) {
     super("Python", container);
   }

python/src/com/jetbrains/python/formatter/PyLanguageCodeStyleSettingsProvider.java

@@ -72,9 +72,11 @@ public class PyLanguageCodeStyleSettingsProvider extends LanguageCodeStyleSettin
       consumer.showCustomOption(PyCodeStyleSettings.class, "SPACE_AROUND_EQ_IN_KEYWORD_ARGUMENT", "Around = in keyword argument",
                                 SPACES_AROUND_OPERATORS);
       consumer.showCustomOption(PyCodeStyleSettings.class, "SPACE_WITHIN_BRACES", "Braces", SPACES_WITHIN);
-      consumer.showCustomOption(PyCodeStyleSettings.class, "SPACE_BEFORE_PY_COLON", ApplicationBundle.message("checkbox.spaces.before.colon"), SPACES_OTHER);
+      consumer.showCustomOption(PyCodeStyleSettings.class, "SPACE_BEFORE_PY_COLON",
+                                ApplicationBundle.message("checkbox.spaces.before.colon"), SPACES_OTHER);
       consumer.showCustomOption(PyCodeStyleSettings.class, "SPACE_AFTER_PY_COLON", ApplicationBundle.message("checkbox.spaces.after.colon"), SPACES_OTHER);
       consumer.showCustomOption(PyCodeStyleSettings.class, "SPACE_BEFORE_BACKSLASH", "Before '\\'", SPACES_OTHER);
+      consumer.showCustomOption(PyCodeStyleSettings.class, "SPACE_AFTER_NUMBER_SIGN", "After '#'", SPACES_OTHER);
     }
     else if (settingsType == SettingsType.BLANK_LINES_SETTINGS) {
       consumer.showStandardOptions("BLANK_LINES_AROUND_CLASS",
@@ -112,7 +114,7 @@ public class PyLanguageCodeStyleSettingsProvider extends LanguageCodeStyleSettin
     CommonCodeStyleSettings.IndentOptions indentOptions = defaultSettings.initIndentOptions();
     indentOptions.INDENT_SIZE = 4;
     defaultSettings.ALIGN_MULTILINE_PARAMETERS_IN_CALLS = true;
-    return defaultSettings; 
+    return defaultSettings;
   }
 
   @Override

python/src/com/jetbrains/python/formatter/PyPreFormatProcessor.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2000-2014 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.jetbrains.python.formatter;
+
+import com.intellij.lang.ASTNode;
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.openapi.util.text.StringUtil;
+import com.intellij.psi.PsiComment;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiFile;
+import com.intellij.psi.codeStyle.CodeStyleSettings;
+import com.intellij.psi.codeStyle.CodeStyleSettingsManager;
+import com.intellij.psi.impl.source.codeStyle.PreFormatProcessor;
+import com.jetbrains.python.PythonLanguage;
+import com.jetbrains.python.psi.LanguageLevel;
+import com.jetbrains.python.psi.PyElementGenerator;
+import com.jetbrains.python.psi.PyRecursiveElementVisitor;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author traff
+ */
+public class PyPreFormatProcessor implements PreFormatProcessor {
+  @NotNull
+  @Override
+  public TextRange process(@NotNull ASTNode element, @NotNull TextRange range) {
+    PsiElement psiElement = element.getPsi();
+    if (psiElement == null) return range;
+
+    if (!psiElement.getLanguage().is(PythonLanguage.getInstance())) return range;
+
+    PsiFile file = psiElement.isValid() ? psiElement.getContainingFile() : null;
+    if (file == null) return range;
+
+    Project project = psiElement.getProject();
+
+    return new PyCommentFormatter(project).process(psiElement, range);
+  }
+
+  /**
+   * @author traff
+   */
+  public static class PyCommentFormatter extends PyRecursiveElementVisitor {
+    private final Project myProject;
+    private final CodeStyleSettings mySettings;
+    private final PyCodeStyleSettings myPyCodeStyleSettings;
+    private TextRange myRange;
+
+    public PyCommentFormatter(Project project) {
+      myProject = project;
+      mySettings = CodeStyleSettingsManager.getSettings(project);
+      myPyCodeStyleSettings = mySettings.getCustomSettings(PyCodeStyleSettings.class);
+    }
+
+    public TextRange process(PsiElement element, TextRange range) {
+      if (!myPyCodeStyleSettings.SPACE_AFTER_NUMBER_SIGN) {
+        return range;
+      }
+      myRange = range;
+      element.accept(this);
+      return element.getTextRange();
+    }
+
+    @Override
+    public void visitComment(PsiComment element) {
+      if (!myRange.contains(element.getTextRange())) {
+        return;
+      }
+      String text = element.getText();
+      int commentStart = text.indexOf('#');
+      if (commentStart != -1 && (commentStart + 1) < text.length()) {
+        String commentText = StringUtil.trimLeading(text.substring(commentStart + 1));
+
+        String newText = "# " + commentText;
+        if (!newText.equals(text)) {
+          element.replace(
+            PyElementGenerator.getInstance(myProject).createFromText(LanguageLevel.getDefault(), PsiComment.class, newText));
+        }
+      }
+    }
+  }
+}