Support GNU style rule to put a space before opening parenthesis.

Summary:
The rule from the GNU style states:
"We find it easier to read a program when it has spaces before the open-parentheses and after the commas."

http://www.gnu.org/prep/standards/standards.html#index-spaces-before-open_002dparen

This patch makes clang-format adds an option to put spaces before almost all open parentheses, except the cases, where different behavior is dictated by the style rules or language syntax:
  * preprocessor:
    ** function-like macro definitions can't have a space between the macro name and the parenthesis;
    ** `#if defined(...)` can have a space, but it seems, that it's more frequently used without a space in GCC, for example;
  * never add spaces after unary operators;
  * adding spaces between two opening parentheses is controlled with the `SpacesInParentheses` option;
  * never add spaces between `[` and `(` (there's no option yet).

Reviewers: djasper

Reviewed By: djasper

CC: cfe-commits, klimek

Differential Revision: http://llvm-reviews.chandlerc.com/D2326

llvm-svn: 196901

1 files changed, 27 insertions, 4 deletions

diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 26a320b05a0..60d323d2a9d 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -90,6 +90,24 @@ struct ScalarEnumerationTraits<
   }
 };
 
+template <>
+struct ScalarEnumerationTraits<
+    clang::format::FormatStyle::SpaceBeforeParensOptions> {
+  static void
+  enumeration(IO &IO,
+              clang::format::FormatStyle::SpaceBeforeParensOptions &Value) {
+    IO.enumCase(Value, "Never", clang::format::FormatStyle::SBPO_Never);
+    IO.enumCase(Value, "ControlStatements",
+                clang::format::FormatStyle::SBPO_ControlStatements);
+    IO.enumCase(Value, "Always", clang::format::FormatStyle::SBPO_Always);
+
+    // For backward compatibility.
+    IO.enumCase(Value, "false", clang::format::FormatStyle::SBPO_Never);
+    IO.enumCase(Value, "true",
+                clang::format::FormatStyle::SBPO_ControlStatements);
+  }
+};
+
 template <> struct MappingTraits<clang::format::FormatStyle> {
   static void mapping(llvm::yaml::IO &IO, clang::format::FormatStyle &Style) {
     if (IO.outputting()) {
@@ -179,11 +197,16 @@ template <> struct MappingTraits<clang::format::FormatStyle> {
     IO.mapOptional("SpaceInEmptyParentheses", Style.SpaceInEmptyParentheses);
     IO.mapOptional("SpacesInCStyleCastParentheses",
                    Style.SpacesInCStyleCastParentheses);
-    IO.mapOptional("SpaceAfterControlStatementKeyword",
-                   Style.SpaceAfterControlStatementKeyword);
     IO.mapOptional("SpaceBeforeAssignmentOperators",
                    Style.SpaceBeforeAssignmentOperators);
     IO.mapOptional("ContinuationIndentWidth", Style.ContinuationIndentWidth);
+
+    // For backward compatibility.
+    if (!IO.outputting()) {
+      IO.mapOptional("SpaceAfterControlStatementKeyword",
+                     Style.SpaceBeforeParens);
+    }
+    IO.mapOptional("SpaceBeforeParens", Style.SpaceBeforeParens);
   }
 };
 
@@ -266,7 +289,7 @@ FormatStyle getLLVMStyle() {
   LLVMStyle.SpacesInParentheses = false;
   LLVMStyle.SpaceInEmptyParentheses = false;
   LLVMStyle.SpacesInCStyleCastParentheses = false;
-  LLVMStyle.SpaceAfterControlStatementKeyword = true;
+  LLVMStyle.SpaceBeforeParens = FormatStyle::SBPO_ControlStatements;
   LLVMStyle.SpaceBeforeAssignmentOperators = true;
   LLVMStyle.ContinuationIndentWidth = 4;
   LLVMStyle.SpacesInAngles = false;
@@ -315,7 +338,7 @@ FormatStyle getGoogleStyle() {
   GoogleStyle.SpacesInParentheses = false;
   GoogleStyle.SpaceInEmptyParentheses = false;
   GoogleStyle.SpacesInCStyleCastParentheses = false;
-  GoogleStyle.SpaceAfterControlStatementKeyword = true;
+  GoogleStyle.SpaceBeforeParens = FormatStyle::SBPO_ControlStatements;
   GoogleStyle.SpaceBeforeAssignmentOperators = true;
   GoogleStyle.ContinuationIndentWidth = 4;
   GoogleStyle.SpacesInAngles = false;