clang-format: Add option to allow short blocks on a single line.

With AllowShortBlocksOnASingleLine, clang-format allows:
  if (a) { return; }

Based on patch by Gonzalo BG, thank you!

llvm-svn: 208765

1 files changed, 29 insertions, 10 deletions

diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 60706b1b3be..e0b2961af35 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -151,6 +151,8 @@ template <> struct MappingTraits<FormatStyle> {
     IO.mapOptional("AlignTrailingComments", Style.AlignTrailingComments);
     IO.mapOptional("AllowAllParametersOfDeclarationOnNextLine",
                    Style.AllowAllParametersOfDeclarationOnNextLine);
+    IO.mapOptional("AllowShortBlocksOnASingleLine",
+                   Style.AllowShortBlocksOnASingleLine);
     IO.mapOptional("AllowShortIfStatementsOnASingleLine",
                    Style.AllowShortIfStatementsOnASingleLine);
     IO.mapOptional("AllowShortLoopsOnASingleLine",
@@ -263,6 +265,7 @@ FormatStyle getLLVMStyle() {
   LLVMStyle.AlignTrailingComments = true;
   LLVMStyle.AllowAllParametersOfDeclarationOnNextLine = true;
   LLVMStyle.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_All;
+  LLVMStyle.AllowShortBlocksOnASingleLine = false;
   LLVMStyle.AllowShortIfStatementsOnASingleLine = false;
   LLVMStyle.AllowShortLoopsOnASingleLine = false;
   LLVMStyle.AlwaysBreakBeforeMultilineStrings = false;
@@ -609,7 +612,7 @@ private:
       return 0;
     if ((Style.BreakBeforeBraces == FormatStyle::BS_Allman ||
          Style.BreakBeforeBraces == FormatStyle::BS_GNU) &&
-        I[1]->First->is(tok::l_brace))
+        (I[1]->First->is(tok::l_brace) && !Style.AllowShortBlocksOnASingleLine))
       return 0;
     if (I[1]->InPPDirective != (*I)->InPPDirective ||
         (I[1]->InPPDirective && I[1]->First->HasUnescapedNewline))
@@ -635,16 +638,31 @@ private:
   tryMergeSimpleBlock(SmallVectorImpl<AnnotatedLine *>::const_iterator I,
                       SmallVectorImpl<AnnotatedLine *>::const_iterator E,
                       unsigned Limit) {
-    // First, check that the current line allows merging. This is the case if
-    // we're not in a control flow statement and the last token is an opening
-    // brace.
     AnnotatedLine &Line = **I;
-    if (Line.First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_do, tok::r_brace,
-                            tok::kw_else, tok::kw_try, tok::kw_catch,
-                            tok::kw_for, tok::kw_case,
-                            // This gets rid of all ObjC @ keywords and methods.
-                            tok::at, tok::minus, tok::plus))
+
+    // Don't merge ObjC @ keywords and methods.
+    if (Line.First->isOneOf(tok::at, tok::minus, tok::plus))
+      return 0;
+
+    // Check that the current line allows merging. This depends on whether we
+    // are in a control flow statements as well as several style flags.
+    if (Line.First->isOneOf(tok::kw_else, tok::kw_case))
       return 0;
+    if (Line.First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_do, tok::kw_try,
+                            tok::kw_catch, tok::kw_for, tok::r_brace)) {
+      if (!Style.AllowShortBlocksOnASingleLine)
+        return 0;
+      if (!Style.AllowShortIfStatementsOnASingleLine &&
+          Line.First->is(tok::kw_if))
+        return 0;
+      if (!Style.AllowShortLoopsOnASingleLine &&
+          Line.First->isOneOf(tok::kw_while, tok::kw_do, tok::kw_for))
+        return 0;
+      // FIXME: Consider an option to allow short exception handling clauses on
+      // a single line.
+      if (Line.First->isOneOf(tok::kw_try, tok::kw_catch))
+        return 0;
+    }
 
     FormatToken *Tok = I[1]->First;
     if (Tok->is(tok::r_brace) && !Tok->MustBreakBefore &&
@@ -672,7 +690,8 @@ private:
       if (I[1]->Last->Type == TT_LineComment)
         return 0;
       do {
-        if (Tok->isOneOf(tok::l_brace, tok::r_brace))
+        if (Tok->isOneOf(tok::l_brace, tok::r_brace) &&
+            !Style.AllowShortBlocksOnASingleLine)
           return 0;
         Tok = Tok->Next;
       } while (Tok);