optional space before backslash (on by default) in python code style settings (PY-5674)

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

@@ -13,6 +13,7 @@ public class PyCodeStyleSettings extends CustomCodeStyleSettings {
   public boolean SPACE_BEFORE_LBRACKET = false;
   public boolean SPACE_AROUND_EQ_IN_NAMED_PARAMETER = false;
   public boolean SPACE_AROUND_EQ_IN_KEYWORD_ARGUMENT = false;
+  public boolean SPACE_BEFORE_BACKSLASH = true;
 
   public int BLANK_LINES_AROUND_TOP_LEVEL_CLASSES_FUNCTIONS = 2;
 

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

@@ -58,6 +58,7 @@ public class PyLanguageCodeStyleSettingsProvider extends LanguageCodeStyleSettin
       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_AFTER_PY_COLON", ApplicationBundle.message("checkbox.spaces.after.colon"), SPACES_OTHER);
+      consumer.showCustomOption(PyCodeStyleSettings.class, "SPACE_BEFORE_BACKSLASH", "Before \\", SPACES_OTHER);
     }
     else if (settingsType == SettingsType.BLANK_LINES_SETTINGS) {
       consumer.showStandardOptions("BLANK_LINES_AROUND_CLASS",

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

@@ -1,5 +1,6 @@
 package com.jetbrains.python.formatter;
 
+import com.intellij.psi.codeStyle.CodeStyleSettings;
 import com.intellij.psi.formatter.StaticSymbolWhiteSpaceDefinitionStrategy;
 import gnu.trove.TIntIntHashMap;
 import gnu.trove.TIntProcedure;
@@ -21,10 +22,12 @@ public class PyWhiteSpaceFormattingStrategy extends StaticSymbolWhiteSpaceDefini
    * <p/>
    * Hence, we need to preserve them during white space manipulation.
    *
+   *
    * @param whiteSpaceText    white space text to use by default for replacing sub-sequence of the given text
    * @param text              target text which region is to be replaced by the given white space symbols
    * @param startOffset       start offset to use with the given text (inclusive)
    * @param endOffset         end offset to use with the given text (exclusive)
+   * @param codeStyleSettings the code style settings
    * @return                  symbols to use for replacing <code>[startOffset; endOffset)</code> sub-sequence of the given text
    */
   @NotNull
@@ -32,7 +35,8 @@ public class PyWhiteSpaceFormattingStrategy extends StaticSymbolWhiteSpaceDefini
   public CharSequence adjustWhiteSpaceIfNecessary(@NotNull CharSequence whiteSpaceText,
                                                   @NotNull CharSequence text,
                                                   int startOffset,
-                                                  int endOffset)
+                                                  int endOffset,
+                                                  CodeStyleSettings codeStyleSettings)
   {
     // The general idea is that '\' symbol before line feed should be preserved.
     TIntIntHashMap initialBackSlashes = countBackSlashes(text, startOffset, endOffset);
@@ -56,6 +60,7 @@ public class PyWhiteSpaceFormattingStrategy extends StaticSymbolWhiteSpaceDefini
       return whiteSpaceText;
     }
 
+    PyCodeStyleSettings settings = codeStyleSettings.getCustomSettings(PyCodeStyleSettings.class);
     StringBuilder result = new StringBuilder();
     int line = 0;
     for (int i = 0; i < whiteSpaceText.length(); i++) {
@@ -65,6 +70,9 @@ public class PyWhiteSpaceFormattingStrategy extends StaticSymbolWhiteSpaceDefini
         continue;
       }
       if (!newBackSlashes.contains(line++)) {
+        if ((i == 0 || (i > 0 && whiteSpaceText.charAt(i - 1) != ' ')) && settings.SPACE_BEFORE_BACKSLASH) {
+          result.append(' ');
+        }
         result.append('\\');
       }
       result.append(c);

python/testData/formatter/alignInBinaryExpression_after.py

@@ -1,2 +1,2 @@
-if isintance(True, bool) and\
+if isintance(True, bool) and \
    isinstance(1, int): pass

python/testData/formatter/alignInBinaryExpressions_after.py

@@ -1,3 +1,3 @@
-term1 = BNF.lpar + expr + BNF.rpar\
-        | if_expr\
+term1 = BNF.lpar + expr + BNF.rpar \
+        | if_expr \
         | numeric_value

python/testData/formatter/alignInStringLiteral_after.py

@@ -1,2 +1,2 @@
-a = "a"\
+a = "a" \
     "b"

python/testData/formatter/indentAfterBackslash_after.py

@@ -1,2 +1,2 @@
-foo = bar\
+foo = bar \
     if bar is not None else None

python/testData/formatter/spaceAfterCommaWrappedLine_after.py

@@ -1,2 +1,2 @@
-import contextlib,\
+import contextlib, \
     math, decimal

python/testData/formatter/spaceBeforeBackslash.py

@@ -0,0 +1,2 @@
+import contextlib,\
+    math,decimal

python/testData/formatter/spaceBeforeBackslash_after.py

@@ -0,0 +1,2 @@
+import contextlib,\
+    math, decimal

python/testData/intentions/afterConvertFormatOperatorToMethodMulti.py

@@ -1,13 +1,13 @@
 n = 8
-a = "{n:d} bottles of {what:s} on the {where:s}"\
+a = "{n:d} bottles of {what:s} on the {where:s}" \
     """
     {n:d} bottles
     of {what:s}
-    """\
-    r'\n/ take {howmuch!r:s} down \n/'\
-    ur"pass it {how:>8s}"\
-    "{new_n:#d} {{that is, {percent:+3.2f}% less}} "\
-    "bottles of {what:>6s} on the {where:s}"\
+    """ \
+    r'\n/ take {howmuch!r:s} down \n/' \
+    ur"pass it {how:>8s}" \
+    "{new_n:#d} {{that is, {percent:+3.2f}% less}} " \
+    "bottles of {what:>6s} on the {where:s}" \
     .format(n=n, where="wall", howmuch=u'one', how="'round\t", new_n=(n - 1), percent=100 * (1 - ((n - 1.0) / n)),
             what="beer")
 print a

python/testData/refactoring/introduceVariable/multipartString.after.py

@@ -1,3 +1,3 @@
-a = "foo"\
+a = "foo" \
     "bar"
 x(a)

python/testSrc/com/jetbrains/python/PyFormatterTest.java

@@ -268,6 +268,11 @@ public class PyFormatterTest extends PyTestCase {
     doTest();
   }
 
+  public void testSpaceBeforeBackslash() {
+    settings().getCustomSettings(PyCodeStyleSettings.class).SPACE_BEFORE_BACKSLASH = false;
+    doTest();
+  }
+
   private void doTest() {
     myFixture.configureByFile("formatter/" + getTestName(true) + ".py");
     ApplicationManager.getApplication().runWriteAction(new Runnable() {