clang-format: Add option to break before non-assignment operators.

This will allow:
  int aaaaaaaaaaaaaa =
      bbbbbbbbbbbbbb
      + ccccccccccccccc;

llvm-svn: 217757

5 files changed, 76 insertions, 18 deletions

diff --git a/clang/docs/ClangFormatStyleOptions.rst b/clang/docs/ClangFormatStyleOptions.rst
index e0793e80a7d..84b3fc8202d 100644
--- a/clang/docs/ClangFormatStyleOptions.rst
+++ b/clang/docs/ClangFormatStyleOptions.rst
@@ -191,8 +191,18 @@ the configuration (without a prefix: ``Auto``).
   If ``false``, a function call's or function definition's parameters
   will either all be on the same line or will have one line each.
 
-**BreakBeforeBinaryOperators** (``bool``)
-  If ``true``, binary operators will be placed after line breaks.
+**BreakBeforeBinaryOperators** (``BinaryOperatorStyle``)
+  The way to wrap binary operators.
+
+  Possible values:
+
+  * ``BOS_None`` (in configuration: ``None``)
+    Break after operators.
+  * ``BOS_NonAssignment`` (in configuration: ``NonAssignment``)
+    Break before operators that aren't assignments.
+  * ``BOS_All`` (in configuration: ``All``)
+    Break before operators.
+
 
 **BreakBeforeBraces** (``BraceBreakingStyle``)
   The brace breaking style to use.
@@ -260,7 +270,7 @@ the configuration (without a prefix: ``Auto``).
 
 **DerivePointerAlignment** (``bool``)
   If ``true``, analyze the formatted file for the most common
-  alignment of & and ``*``. ``PointerAlignment`` is then used only as fallback.
+  alignment of & and *. ``PointerAlignment`` is then used only as fallback.
 
 **DisableFormat** (``bool``)
   Disables formatting at all.
diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
index abf505922ee..22a9ef606e5 100644
--- a/clang/include/clang/Format/Format.h
+++ b/clang/include/clang/Format/Format.h
@@ -266,8 +266,18 @@ struct FormatStyle {
   /// \brief The way to use tab characters in the resulting file.
   UseTabStyle UseTab;
 
-  /// \brief If \c true, binary operators will be placed after line breaks.
-  bool BreakBeforeBinaryOperators;
+  /// \brief The style of breaking before or after binary operators.
+  enum BinaryOperatorStyle {
+    /// Break after operators.
+    BOS_None,
+    /// Break before operators that aren't assignments.
+    BOS_NonAssignment,
+    /// Break before operators.
+    BOS_All,
+  };
+
+  /// \brief The way to wrap binary operators.
+  BinaryOperatorStyle BreakBeforeBinaryOperators;
 
   /// \brief If \c true, ternary operators will be placed after line breaks.
   bool BreakBeforeTernaryOperators;
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 36d0f62a854..5f9536dac8b 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -76,6 +76,16 @@ template <> struct ScalarEnumerationTraits<FormatStyle::ShortFunctionStyle> {
   }
 };
 
+template <> struct ScalarEnumerationTraits<FormatStyle::BinaryOperatorStyle> {
+  static void enumeration(IO &IO, FormatStyle::BinaryOperatorStyle &Value) {
+    IO.enumCase(Value, "All", FormatStyle::BOS_All);
+    IO.enumCase(Value, "true", FormatStyle::BOS_All);
+    IO.enumCase(Value, "None", FormatStyle::BOS_None);
+    IO.enumCase(Value, "false", FormatStyle::BOS_None);
+    IO.enumCase(Value, "NonAssignment", FormatStyle::BOS_NonAssignment);
+  }
+};
+
 template <> struct ScalarEnumerationTraits<FormatStyle::BraceBreakingStyle> {
   static void enumeration(IO &IO, FormatStyle::BraceBreakingStyle &Value) {
     IO.enumCase(Value, "Attach", FormatStyle::BS_Attach);
@@ -322,7 +332,7 @@ FormatStyle getLLVMStyle() {
   LLVMStyle.AlwaysBreakBeforeMultilineStrings = false;
   LLVMStyle.AlwaysBreakTemplateDeclarations = false;
   LLVMStyle.BinPackParameters = true;
-  LLVMStyle.BreakBeforeBinaryOperators = false;
+  LLVMStyle.BreakBeforeBinaryOperators = FormatStyle::BOS_None;
   LLVMStyle.BreakBeforeTernaryOperators = true;
   LLVMStyle.BreakBeforeBraces = FormatStyle::BS_Attach;
   LLVMStyle.BreakConstructorInitializersBeforeComma = false;
@@ -438,7 +448,7 @@ FormatStyle getWebKitStyle() {
   FormatStyle Style = getLLVMStyle();
   Style.AccessModifierOffset = -4;
   Style.AlignTrailingComments = false;
-  Style.BreakBeforeBinaryOperators = true;
+  Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
   Style.BreakBeforeBraces = FormatStyle::BS_Stroustrup;
   Style.BreakConstructorInitializersBeforeComma = true;
   Style.Cpp11BracedListStyle = false;
@@ -454,7 +464,7 @@ FormatStyle getWebKitStyle() {
 FormatStyle getGNUStyle() {
   FormatStyle Style = getLLVMStyle();
   Style.AlwaysBreakAfterDefinitionReturnType = true;
-  Style.BreakBeforeBinaryOperators = true;
+  Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
   Style.BreakBeforeBraces = FormatStyle::BS_GNU;
   Style.BreakBeforeTernaryOperators = true;
   Style.Cpp11BracedListStyle = false;
diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 4f3ec0b1996..4c18b72d3c6 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -1851,16 +1851,21 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
   if (Left.is(tok::greater) && Right.is(tok::greater) &&
       Left.Type != TT_TemplateCloser)
     return false;
-  if (Right.Type == TT_BinaryOperator && Style.BreakBeforeBinaryOperators)
+  if (Right.Type == TT_BinaryOperator &&
+      Style.BreakBeforeBinaryOperators != FormatStyle::BOS_None &&
+      (Style.BreakBeforeBinaryOperators == FormatStyle::BOS_All ||
+       Right.getPrecedence() != prec::Assignment))
     return true;
   if (Left.Type == TT_ArrayInitializerLSquare)
     return true;
   if (Right.is(tok::kw_typename) && Left.isNot(tok::kw_const))
     return true;
-  return (Left.isBinaryOperator() &&
-          !Left.isOneOf(tok::arrowstar, tok::lessless) &&
-          !Style.BreakBeforeBinaryOperators) ||
-         Left.isOneOf(tok::comma, tok::coloncolon, tok::semi, tok::l_brace,
+  if (Left.isBinaryOperator() && !Left.isOneOf(tok::arrowstar, tok::lessless) &&
+      Style.BreakBeforeBinaryOperators != FormatStyle::BOS_All &&
+      (Style.BreakBeforeBinaryOperators == FormatStyle::BOS_None ||
+       Left.getPrecedence() == prec::Assignment))
+    return true;
+  return Left.isOneOf(tok::comma, tok::coloncolon, tok::semi, tok::l_brace,
                       tok::kw_class, tok::kw_struct) ||
          Right.isMemberAccess() ||
          Right.isOneOf(tok::lessless, tok::colon, tok::l_square, tok::at) ||
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index dfa31085a96..2e358b4a3cb 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -3171,7 +3171,7 @@ TEST_F(FormatTest, ExpressionIndentationBreakingBeforeOperators) {
   // everything until something with the same indent as the operator is found.
   // FIXME: Is this a good system?
   FormatStyle Style = getLLVMStyle();
-  Style.BreakBeforeBinaryOperators = true;
+  Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
   verifyFormat(
       "bool value = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
       "             + aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
@@ -3224,6 +3224,15 @@ TEST_F(FormatTest, ExpressionIndentationBreakingBeforeOperators) {
                Style);
 }
 
+TEST_F(FormatTest, BreakingBeforeNonAssigmentOperators) {
+  FormatStyle Style = getLLVMStyle();
+  Style.BreakBeforeBinaryOperators = FormatStyle::BOS_NonAssignment;
+  verifyFormat("int aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa =\n"
+               "    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
+               "    + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb;", Style);
+
+}
+
 TEST_F(FormatTest, ConstructorInitializers) {
   verifyFormat("Constructor() : Initializer(FitsOnTheLine) {}");
   verifyFormat("Constructor() : Inttializer(FitsOnTheLine) {}",
@@ -8368,7 +8377,6 @@ TEST_F(FormatTest, ParsesConfigurationBools) {
   CHECK_PARSE_BOOL(AlwaysBreakAfterDefinitionReturnType);
   CHECK_PARSE_BOOL(AlwaysBreakTemplateDeclarations);
   CHECK_PARSE_BOOL(BinPackParameters);
-  CHECK_PARSE_BOOL(BreakBeforeBinaryOperators);
   CHECK_PARSE_BOOL(BreakBeforeTernaryOperators);
   CHECK_PARSE_BOOL(BreakConstructorInitializersBeforeComma);
   CHECK_PARSE_BOOL(ConstructorInitializerAllOnOneLineOrOnePerLine);
@@ -8415,9 +8423,12 @@ TEST_F(FormatTest, ParsesConfiguration) {
   CHECK_PARSE("ContinuationIndentWidth: 11", ContinuationIndentWidth, 11u);
 
   Style.PointerAlignment = FormatStyle::PAS_Middle;
-  CHECK_PARSE("PointerAlignment: Left", PointerAlignment, FormatStyle::PAS_Left);
-  CHECK_PARSE("PointerAlignment: Right", PointerAlignment, FormatStyle::PAS_Right);
-  CHECK_PARSE("PointerAlignment: Middle", PointerAlignment, FormatStyle::PAS_Middle);
+  CHECK_PARSE("PointerAlignment: Left", PointerAlignment,
+              FormatStyle::PAS_Left);
+  CHECK_PARSE("PointerAlignment: Right", PointerAlignment,
+              FormatStyle::PAS_Right);
+  CHECK_PARSE("PointerAlignment: Middle", PointerAlignment,
+              FormatStyle::PAS_Middle);
 
   Style.Standard = FormatStyle::LS_Auto;
   CHECK_PARSE("Standard: Cpp03", Standard, FormatStyle::LS_Cpp03);
@@ -8426,6 +8437,18 @@ TEST_F(FormatTest, ParsesConfiguration) {
   CHECK_PARSE("Standard: C++11", Standard, FormatStyle::LS_Cpp11);
   CHECK_PARSE("Standard: Auto", Standard, FormatStyle::LS_Auto);
 
+  Style.BreakBeforeBinaryOperators = FormatStyle::BOS_All;
+  CHECK_PARSE("BreakBeforeBinaryOperators: false", BreakBeforeBinaryOperators,
+              FormatStyle::BOS_None);
+  CHECK_PARSE("BreakBeforeBinaryOperators: NonAssignment",
+              BreakBeforeBinaryOperators, FormatStyle::BOS_NonAssignment);
+  CHECK_PARSE("BreakBeforeBinaryOperators: true", BreakBeforeBinaryOperators,
+              FormatStyle::BOS_All);
+  CHECK_PARSE("BreakBeforeBinaryOperators: None", BreakBeforeBinaryOperators,
+              FormatStyle::BOS_None);
+  CHECK_PARSE("BreakBeforeBinaryOperators: All", BreakBeforeBinaryOperators,
+              FormatStyle::BOS_All);
+
   Style.UseTab = FormatStyle::UT_ForIndentation;
   CHECK_PARSE("UseTab: false", UseTab, FormatStyle::UT_Never);
   CHECK_PARSE("UseTab: true", UseTab, FormatStyle::UT_Always);