clang-format: Make continuation indent width configurable.

Patch by Kim Gräsman. Thank you!

llvm-svn: 192964

4 files changed, 41 insertions, 12 deletions

diff --git a/clang/include/clang/Format/Format.h b/clang/include/clang/Format/Format.h
index 899087a1473..6745082546e 100644
--- a/clang/include/clang/Format/Format.h
+++ b/clang/include/clang/Format/Format.h
@@ -235,6 +235,9 @@ struct FormatStyle {
   /// \brief If \c false, spaces will be removed before assignment operators.
   bool SpaceBeforeAssignmentOperators;
 
+  /// \brief Indent width for line continuations.
+  unsigned ContinuationIndentWidth;
+
   bool operator==(const FormatStyle &R) const {
     return AccessModifierOffset == R.AccessModifierOffset &&
            ConstructorInitializerIndentWidth ==
@@ -282,7 +285,8 @@ struct FormatStyle {
            SpacesInCStyleCastParentheses == R.SpacesInCStyleCastParentheses &&
            SpaceAfterControlStatementKeyword ==
                R.SpaceAfterControlStatementKeyword &&
-           SpaceBeforeAssignmentOperators == R.SpaceBeforeAssignmentOperators;
+           SpaceBeforeAssignmentOperators == R.SpaceBeforeAssignmentOperators &&
+           ContinuationIndentWidth == R.ContinuationIndentWidth;
   }
 };
 
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 7632058199b..bbca06e6dfb 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -265,7 +265,7 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
   State.Column += Spaces;
   if (Current.is(tok::l_paren) && Previous.isOneOf(tok::kw_if, tok::kw_for))
     // Treat the condition inside an if as if it was a second function
-    // parameter, i.e. let nested calls have an indent of 4.
+    // parameter, i.e. let nested calls have a continuation indent.
     State.Stack.back().LastSpace = State.Column + 1; // 1 is length of "(".
   else if (Previous.is(tok::comma))
     State.Stack.back().LastSpace = State.Column;
@@ -303,9 +303,10 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
                                                  bool DryRun) {
   FormatToken &Current = *State.NextToken;
   const FormatToken &Previous = *State.NextToken->Previous;
-  // If we are continuing an expression, we want to indent an extra 4 spaces.
+  // If we are continuing an expression, we want to use the continuation indent.
   unsigned ContinuationIndent =
-      std::max(State.Stack.back().LastSpace, State.Stack.back().Indent) + 4;
+      std::max(State.Stack.back().LastSpace, State.Stack.back().Indent) +
+      Style.ContinuationIndentWidth;
   // Extra penalty that needs to be added because of the way certain line
   // breaks are chosen.
   unsigned Penalty = 0;
@@ -384,10 +385,10 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
     State.Column = State.Stack.back().Indent;
   } else {
     State.Column = State.Stack.back().Indent;
-    // Ensure that we fall back to indenting 4 spaces instead of just
+    // Ensure that we fall back to the continuation indent width instead of just
     // flushing continuations left.
     if (State.Column == State.FirstIndent)
-      State.Column += 4;
+      State.Column += Style.ContinuationIndentWidth;
   }
 
   if (Current.is(tok::question))
@@ -478,9 +479,10 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
   }
 
   // In ObjC method declaration we align on the ":" of parameters, but we need
-  // to ensure that we indent parameters on subsequent lines by at least 4.
+  // to ensure that we indent parameters on subsequent lines by at least our
+  // continuation indent width.
   if (Current.Type == TT_ObjCMethodSpecifier)
-    State.Stack.back().Indent += 4;
+    State.Stack.back().Indent += Style.ContinuationIndentWidth;
 
   // Insert scopes created by fake parenthesis.
   const FormatToken *Previous = Current.getPreviousNonComment();
@@ -521,7 +523,7 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
     if (*I == prec::Conditional ||
         (!SkipFirstExtraIndent && *I > prec::Assignment &&
          !Style.BreakBeforeBinaryOperators))
-      NewParenState.Indent += 4;
+      NewParenState.Indent += Style.ContinuationIndentWidth;
     if (Previous && !Previous->opensScope())
       NewParenState.BreakBeforeParameter = false;
     State.Stack.push_back(NewParenState);
@@ -558,7 +560,7 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
       } else {
         NewIndent = State.Stack.back().LastSpace;
         if (Style.Cpp11BracedListStyle)
-          NewIndent += 4;
+          NewIndent += Style.ContinuationIndentWidth;
         else {
           NewIndent += Style.IndentWidth;
           ++NewIndentLevel;
@@ -569,8 +571,9 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
                         (NextNoComment &&
                          NextNoComment->Type == TT_DesignatedInitializerPeriod);
     } else {
-      NewIndent = 4 + std::max(State.Stack.back().LastSpace,
-                               State.Stack.back().StartOfFunctionCall);
+      NewIndent = Style.ContinuationIndentWidth +
+                  std::max(State.Stack.back().LastSpace,
+                           State.Stack.back().StartOfFunctionCall);
       AvoidBinPacking = !Style.BinPackParameters ||
                         (Style.ExperimentalAutoDetectBinPacking &&
                          (Current.PackingKind == PPK_OnePerLine ||
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index ff857676272..3496712e3cf 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -163,6 +163,7 @@ template <> struct MappingTraits<clang::format::FormatStyle> {
                    Style.SpaceAfterControlStatementKeyword);
     IO.mapOptional("SpaceBeforeAssignmentOperators",
                    Style.SpaceBeforeAssignmentOperators);
+    IO.mapOptional("ContinuationIndentWidth", Style.ContinuationIndentWidth);
   }
 };
 }
@@ -214,6 +215,7 @@ FormatStyle getLLVMStyle() {
   LLVMStyle.SpacesInCStyleCastParentheses = false;
   LLVMStyle.SpaceAfterControlStatementKeyword = true;
   LLVMStyle.SpaceBeforeAssignmentOperators = true;
+  LLVMStyle.ContinuationIndentWidth = 4;
 
   setDefaultPenalties(LLVMStyle);
   LLVMStyle.PenaltyReturnTypeOnItsOwnLine = 60;
@@ -257,6 +259,7 @@ FormatStyle getGoogleStyle() {
   GoogleStyle.SpacesInCStyleCastParentheses = false;
   GoogleStyle.SpaceAfterControlStatementKeyword = true;
   GoogleStyle.SpaceBeforeAssignmentOperators = true;
+  GoogleStyle.ContinuationIndentWidth = 4;
 
   setDefaultPenalties(GoogleStyle);
   GoogleStyle.PenaltyReturnTypeOnItsOwnLine = 200;
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 5a8b5d6f52b..1e898d8f721 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -6495,6 +6495,7 @@ TEST_F(FormatTest, ParsesConfiguration) {
   CHECK_PARSE("SpacesBeforeTrailingComments: 1234",
               SpacesBeforeTrailingComments, 1234u);
   CHECK_PARSE("IndentWidth: 32", IndentWidth, 32u);
+  CHECK_PARSE("ContinuationIndentWidth: 11", ContinuationIndentWidth, 11u);
 
   Style.Standard = FormatStyle::LS_Auto;
   CHECK_PARSE("Standard: Cpp03", Standard, FormatStyle::LS_Cpp03);
@@ -6876,5 +6877,23 @@ TEST_F(FormatTest, MunchSemicolonAfterBlocks) {
                "};");
 }
 
+TEST_F(FormatTest, ConfigurableContinuationIndentWidth) {
+  FormatStyle TwoIndent = getLLVMStyleWithColumns(15);
+  TwoIndent.ContinuationIndentWidth = 2;
+
+  EXPECT_EQ("int i =\n"
+            "  longFunction(\n"
+            "    arg);",
+            format("int i = longFunction(arg);", TwoIndent));
+
+  FormatStyle SixIndent = getLLVMStyleWithColumns(20);
+  SixIndent.ContinuationIndentWidth = 6;
+
+  EXPECT_EQ("int i =\n"
+            "      longFunction(\n"
+            "            arg);",
+            format("int i = longFunction(arg);", SixIndent));
+}
+
 } // end namespace tooling
 } // end namespace clang