[clang-format] Add style option AllowShortLambdasOnASingleLine

Summary:
This option `AllowShortLambdasOnASingleLine` similar to the other `AllowShort*` options, but applied to C++ lambdas.

Reviewers: djasper, klimek

Reviewed By: klimek

Subscribers: MyDeveloperDay, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D57687

llvm-svn: 357027

4 files changed, 35 insertions, 6 deletions

diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 2d1adb58e4a..39651ab74d6 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -119,6 +119,17 @@ template <> struct ScalarEnumerationTraits<FormatStyle::ShortIfStyle> {
   }
 };
 
+template <> struct ScalarEnumerationTraits<FormatStyle::ShortLambdaStyle> {
+  static void enumeration(IO &IO, FormatStyle::ShortLambdaStyle &Value) {
+    IO.enumCase(Value, "None", FormatStyle::SLS_None);
+    IO.enumCase(Value, "false", FormatStyle::SLS_None);
+    IO.enumCase(Value, "Empty", FormatStyle::SLS_Empty);
+    IO.enumCase(Value, "Inline", FormatStyle::SLS_Inline);
+    IO.enumCase(Value, "All", FormatStyle::SLS_All);
+    IO.enumCase(Value, "true", FormatStyle::SLS_All);
+  }
+};
+
 template <> struct ScalarEnumerationTraits<FormatStyle::BinPackStyle> {
   static void enumeration(IO &IO, FormatStyle::BinPackStyle &Value) {
     IO.enumCase(Value, "Auto", FormatStyle::BPS_Auto);
@@ -347,6 +358,8 @@ template <> struct MappingTraits<FormatStyle> {
                    Style.AllowShortCaseLabelsOnASingleLine);
     IO.mapOptional("AllowShortFunctionsOnASingleLine",
                    Style.AllowShortFunctionsOnASingleLine);
+    IO.mapOptional("AllowShortLambdasOnASingleLine",
+                   Style.AllowShortLambdasOnASingleLine);
     IO.mapOptional("AllowShortIfStatementsOnASingleLine",
                    Style.AllowShortIfStatementsOnASingleLine);
     IO.mapOptional("AllowShortLoopsOnASingleLine",
@@ -653,6 +666,7 @@ FormatStyle getLLVMStyle(FormatStyle::LanguageKind Language) {
   LLVMStyle.AllowShortBlocksOnASingleLine = false;
   LLVMStyle.AllowShortCaseLabelsOnASingleLine = false;
   LLVMStyle.AllowShortIfStatementsOnASingleLine = FormatStyle::SIS_Never;
+  LLVMStyle.AllowShortLambdasOnASingleLine = FormatStyle::SLS_All;
   LLVMStyle.AllowShortLoopsOnASingleLine = false;
   LLVMStyle.AlwaysBreakAfterReturnType = FormatStyle::RTBS_None;
   LLVMStyle.AlwaysBreakAfterDefinitionReturnType = FormatStyle::DRTBS_None;
diff --git a/clang/lib/Format/FormatToken.h b/clang/lib/Format/FormatToken.h
index 461e0704a3f..f54ffe9d54c 100644
--- a/clang/lib/Format/FormatToken.h
+++ b/clang/lib/Format/FormatToken.h
@@ -65,6 +65,7 @@ namespace format {
   TYPE(JsTypeOperator)                                                         \
   TYPE(JsTypeOptionalQuestion)                                                 \
   TYPE(LambdaArrow)                                                            \
+  TYPE(LambdaLBrace)                                                           \
   TYPE(LambdaLSquare)                                                          \
   TYPE(LeadingJavaAnnotation)                                                  \
   TYPE(LineComment)                                                            \
diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 04fc3a64f55..c7b148c7909 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -1191,11 +1191,11 @@ private:
 
     // Reset token type in case we have already looked at it and then
     // recovered from an error (e.g. failure to find the matching >).
-    if (!CurrentToken->isOneOf(TT_LambdaLSquare, TT_ForEachMacro,
-                               TT_FunctionLBrace, TT_ImplicitStringLiteral,
-                               TT_InlineASMBrace, TT_JsFatArrow, TT_LambdaArrow,
-                               TT_OverloadedOperator, TT_RegexLiteral,
-                               TT_TemplateString, TT_ObjCStringLiteral))
+    if (!CurrentToken->isOneOf(
+            TT_LambdaLSquare, TT_LambdaLBrace, TT_ForEachMacro,
+            TT_FunctionLBrace, TT_ImplicitStringLiteral, TT_InlineASMBrace,
+            TT_JsFatArrow, TT_LambdaArrow, TT_OverloadedOperator,
+            TT_RegexLiteral, TT_TemplateString, TT_ObjCStringLiteral))
       CurrentToken->Type = TT_Unknown;
     CurrentToken->Role.reset();
     CurrentToken->MatchingParen = nullptr;
@@ -2896,7 +2896,7 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
 // Returns 'true' if 'Tok' is a brace we'd want to break before in Allman style.
 static bool isAllmanBrace(const FormatToken &Tok) {
   return Tok.is(tok::l_brace) && Tok.BlockKind == BK_Block &&
-         !Tok.isOneOf(TT_ObjCBlockLBrace, TT_DictLiteral);
+         !Tok.isOneOf(TT_ObjCBlockLBrace, TT_LambdaLBrace, TT_DictLiteral);
 }
 
 bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
@@ -3024,6 +3024,19 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
   if (Left.is(TT_ObjCBlockLBrace) && !Style.AllowShortBlocksOnASingleLine)
     return true;
 
+  if (Left.is(TT_LambdaLBrace)) {
+    if (Left.MatchingParen && Left.MatchingParen->Next &&
+        Left.MatchingParen->Next->isOneOf(tok::comma, tok::r_paren) &&
+        Style.AllowShortLambdasOnASingleLine == FormatStyle::SLS_Inline)
+      return false;
+
+    if (Style.AllowShortLambdasOnASingleLine == FormatStyle::SLS_None ||
+        Style.AllowShortLambdasOnASingleLine == FormatStyle::SLS_Inline ||
+        (!Left.Children.empty() &&
+         Style.AllowShortLambdasOnASingleLine == FormatStyle::SLS_Empty))
+      return true;
+  }
+
   // Put multiple C# attributes on a new line.
   if (Style.isCSharp() &&
       ((Left.is(TT_AttributeSquare) && Left.is(tok::r_square)) ||
diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 5c7ab1240c4..010b086587e 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -1475,6 +1475,7 @@ bool UnwrappedLineParser::tryToParseLambda() {
       return true;
     }
   }
+  FormatTok->Type = TT_LambdaLBrace;
   LSquare.Type = TT_LambdaLSquare;
   parseChildBlock();
   return true;