bmharper removed rL LLVM as the repository for this revision.
bmharper updated this revision to Diff 60569.
bmharper added a comment.

diff with full context


http://reviews.llvm.org/D21279

Files:
  lib/Format/WhitespaceManager.cpp
  lib/Format/WhitespaceManager.h
  unittests/Format/FormatTest.cpp

Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -9242,12 +9242,11 @@
                "};",
                Alignment);
 
-  // FIXME: Should align all three assignments
   verifyFormat(
       "int i      = 1;\n"
       "SomeType a = SomeFunction(looooooooooooooooooooooongParameterA,\n"
       "                          loooooooooooooooooooooongParameterB);\n"
-      "int j = 2;",
+      "int j      = 2;",
       Alignment);
 
   verifyFormat("template <typename T, typename T_0 = very_long_type_name_0,\n"
@@ -9329,7 +9328,52 @@
                    "unsigned oneTwoThree = 123;\n"
                    "int oneTwo = 12;",
                    Alignment));
+  // Function prototype alignment
+  verifyFormat("int    a();\n"
+               "double b();",
+               Alignment);
+  verifyFormat("int    a(int x);\n"
+               "double b();",
+               Alignment);
+  unsigned OldColumnLimit = Alignment.ColumnLimit;
+  // We need to set ColumnLimit to zero, in order to stress nested alignments,
+  // otherwise the function parameters will be re-flowed onto a single line.
+  Alignment.ColumnLimit = 0;
+  EXPECT_EQ("int    a(int   x,\n"
+            "         float y);\n"
+            "double b(int    x,\n"
+            "         double y);",
+            format("int a(int x,\n"
+                   " float y);\n"
+                   "double b(int x,\n"
+                   " double y);",
+                   Alignment));
+  // This ensures that function parameters of function declarations are
+  // correctly indented when their owning functions are indented.
+  // The failure case here is for 'double y' to not be indented enough.
+  // This is the "split function parameter alignment" issue mentioned in
+  // WhitespaceManager.cpp
+  EXPECT_EQ("double a(int x);\n"
+            "int    b(int    x,\n"
+            "         double y);",
+            format("double a(int x);\n"
+                   "int b(int x,\n"
+                   " double y);",
+                   Alignment));
+  Alignment.ColumnLimit = OldColumnLimit;
+  // Ensure function pointers don't screw up recursive alignment
+  verifyFormat("int    a(int x, void (*fp)(int y));\n"
+               "double b();",
+               Alignment);
   Alignment.AlignConsecutiveAssignments = true;
+  // Ensure recursive alignment is broken by function braces, so that the
+  // "a = 1" does not align with subsequent assignments inside the function
+  // body.
+  verifyFormat("int func(int a = 1) {\n"
+               "  int b  = 2;\n"
+               "  int cc = 3;\n"
+               "}",
+               Alignment);
   verifyFormat("float      something = 2000;\n"
                "double     another   = 911;\n"
                "int        i = 1, j = 10;\n"
@@ -9440,17 +9484,16 @@
                Alignment);
   Alignment.AlignConsecutiveAssignments = false;
 
-  // FIXME: Should align all three declarations
   verifyFormat(
       "int      i = 1;\n"
       "SomeType a = SomeFunction(looooooooooooooooooooooongParameterA,\n"
       "                          loooooooooooooooooooooongParameterB);\n"
-      "int j = 2;",
+      "int      j = 2;",
       Alignment);
 
   // Test interactions with ColumnLimit and AlignConsecutiveAssignments:
   // We expect declarations and assignments to align, as long as it doesn't
-  // exceed the column limit, starting a new alignemnt sequence whenever it
+  // exceed the column limit, starting a new alignment sequence whenever it
   // happens.
   Alignment.AlignConsecutiveAssignments = true;
   Alignment.ColumnLimit = 30;
Index: lib/Format/WhitespaceManager.h
===================================================================
--- lib/Format/WhitespaceManager.h
+++ lib/Format/WhitespaceManager.h
@@ -108,7 +108,7 @@
     Change(bool CreateReplacement, SourceRange OriginalWhitespaceRange,
            unsigned IndentLevel, int Spaces, unsigned StartOfTokenColumn,
            unsigned NewlinesBefore, StringRef PreviousLinePostfix,
-           StringRef CurrentLinePrefix, tok::TokenKind Kind,
+           StringRef CurrentLinePrefix, tok::TokenKind Kind, TokenType Type,
            bool ContinuesPPDirective, bool IsStartOfDeclName,
            bool IsInsideToken);
 
@@ -125,6 +125,8 @@
     // FIXME: Currently this is not set correctly for breaks inside comments, as
     // the \c BreakableToken is still doing its own alignment.
     tok::TokenKind Kind;
+    // Same comment applies as for Kind
+    TokenType Type;
     bool ContinuesPPDirective;
     bool IsStartOfDeclName;
 
@@ -162,14 +164,24 @@
     // the alignment process.
     const Change *StartOfBlockComment;
     int IndentationOffset;
+    // This is the same concept as FormatToken::NestingLevel, but we give
+    // it a different name, to signify that it is computed independently of
+    // NestingLevel. Ideally, we could just use NestingLevel, but braces
+    // are currently ignored by the NestingLevel, which makes them unusable.
+    // This is easier to use when signed (vs unsigned), so that it can go
+    // down to -1.
+    int ScopeLevel;
   };
 
 private:
   /// \brief Calculate \c IsTrailingComment, \c TokenLength for the last tokens
   /// or token parts in a line and \c PreviousEndOfTokenColumn and
   /// \c EscapedNewlineColumn for the first tokens or token parts in a line.
   void calculateLineBreakInformation();
 
+  /// \brief Calculate \c ScopeLevel for all \c Changes.
+  void calculateScopeLevel();
+
   /// \brief Align consecutive assignments over all \c Changes.
   void alignConsecutiveAssignments();
 
Index: lib/Format/WhitespaceManager.cpp
===================================================================
--- lib/Format/WhitespaceManager.cpp
+++ lib/Format/WhitespaceManager.cpp
@@ -29,18 +29,18 @@
     bool CreateReplacement, SourceRange OriginalWhitespaceRange,
     unsigned IndentLevel, int Spaces, unsigned StartOfTokenColumn,
     unsigned NewlinesBefore, StringRef PreviousLinePostfix,
-    StringRef CurrentLinePrefix, tok::TokenKind Kind, bool ContinuesPPDirective,
-    bool IsStartOfDeclName, bool IsInsideToken)
+    StringRef CurrentLinePrefix, tok::TokenKind Kind, TokenType Type,
+    bool ContinuesPPDirective, bool IsStartOfDeclName, bool IsInsideToken)
     : CreateReplacement(CreateReplacement),
       OriginalWhitespaceRange(OriginalWhitespaceRange),
       StartOfTokenColumn(StartOfTokenColumn), NewlinesBefore(NewlinesBefore),
       PreviousLinePostfix(PreviousLinePostfix),
-      CurrentLinePrefix(CurrentLinePrefix), Kind(Kind),
+      CurrentLinePrefix(CurrentLinePrefix), Kind(Kind), Type(Type),
       ContinuesPPDirective(ContinuesPPDirective),
       IsStartOfDeclName(IsStartOfDeclName), IndentLevel(IndentLevel),
       Spaces(Spaces), IsInsideToken(IsInsideToken), IsTrailingComment(false),
       TokenLength(0), PreviousEndOfTokenColumn(0), EscapedNewlineColumn(0),
-      StartOfBlockComment(nullptr), IndentationOffset(0) {}
+      StartOfBlockComment(nullptr), IndentationOffset(0), ScopeLevel(0) {}
 
 void WhitespaceManager::reset() {
   Changes.clear();
@@ -57,7 +57,7 @@
   Changes.push_back(
       Change(/*CreateReplacement=*/true, Tok.WhitespaceRange, IndentLevel,
              Spaces, StartOfTokenColumn, Newlines, "", "", Tok.Tok.getKind(),
-             InPPDirective && !Tok.IsFirst,
+             Tok.Type, InPPDirective && !Tok.IsFirst,
              Tok.is(TT_StartOfName) || Tok.is(TT_FunctionDeclarationName),
              /*IsInsideToken=*/false));
 }
@@ -69,7 +69,7 @@
   Changes.push_back(Change(
       /*CreateReplacement=*/false, Tok.WhitespaceRange, /*IndentLevel=*/0,
       /*Spaces=*/0, Tok.OriginalColumn, Tok.NewlinesBefore, "", "",
-      Tok.Tok.getKind(), InPPDirective && !Tok.IsFirst,
+      Tok.Tok.getKind(), Tok.Type, InPPDirective && !Tok.IsFirst,
       Tok.is(TT_StartOfName) || Tok.is(TT_FunctionDeclarationName),
       /*IsInsideToken=*/false));
 }
@@ -85,7 +85,7 @@
       true, SourceRange(Start, Start.getLocWithOffset(ReplaceChars)),
       IndentLevel, Spaces, std::max(0, Spaces), Newlines, PreviousPostfix,
       CurrentPrefix, Tok.is(TT_LineComment) ? tok::comment : tok::unknown,
-      InPPDirective && !Tok.IsFirst,
+      Tok.Type, InPPDirective && !Tok.IsFirst,
       Tok.is(TT_StartOfName) || Tok.is(TT_FunctionDeclarationName),
       /*IsInsideToken=*/Newlines == 0));
 }
@@ -95,6 +95,7 @@
     return Replaces;
 
   std::sort(Changes.begin(), Changes.end(), Change::IsBeforeInFile(SourceMgr));
+  calculateScopeLevel();
   calculateLineBreakInformation();
   alignConsecutiveDeclarations();
   alignConsecutiveAssignments();
@@ -160,59 +161,153 @@
   }
 }
 
+static tok::TokenKind OppositeNestingToken(tok::TokenKind t) {
+  switch (t) {
+  case tok::l_paren:
+    return tok::r_paren;
+  case tok::l_brace:
+    return tok::r_brace;
+  case tok::l_square:
+    return tok::r_square;
+  default:
+    assert(false && "Not a nesting token");
+    return tok::unknown;
+  }
+}
+
+struct TokenTypeAndLevel {
+  TokenType Type;
+  int ScopeLevel;
+};
+
+// See comment in Change::ScopeLevel for an explanation of why we need
+// to run this function instead of just using FormatToken::NestingLevel
+void WhitespaceManager::calculateScopeLevel() {
+  SmallVector<tok::TokenKind, 16> ScopeStack;
+  for (auto &Change : Changes) {
+    Change.ScopeLevel = ScopeStack.size();
+
+    if (ScopeStack.size() != 0 && Change.Kind == ScopeStack.back())
+      ScopeStack.pop_back();
+
+    switch (Change.Kind) {
+    case tok::l_paren:
+    case tok::l_square:
+    case tok::l_brace:
+      ScopeStack.push_back(OppositeNestingToken(Change.Kind));
+      break;
+    case tok::less:
+      if (Change.Type == TT_TemplateOpener)
+        ScopeStack.push_back(tok::greater);
+      break;
+    default:
+      break;
+    }
+  }
+}
+
 // Align a single sequence of tokens, see AlignTokens below.
 template <typename F>
 static void
 AlignTokenSequence(unsigned Start, unsigned End, unsigned Column, F &&Matches,
                    SmallVector<WhitespaceManager::Change, 16> &Changes) {
   bool FoundMatchOnLine = false;
   int Shift = 0;
+
+  // ScopeStack keeps track of the current scope depth (aka NestingLevel).
+  // We only run the "Matches" function on tokens from the outer-most scope.
+  // However, we do need to adjust some special tokens within the entire
+  // Start..End range, regardless of their scope. This special rule applies
+  // only to function parameters which are split across multiple lines, and
+  // who's function names have been shifted for declaration alignment's sake.
+  // See "split function parameter alignment" in FormatTest.cpp for an example.
+  SmallVector<TokenTypeAndLevel, 16> ScopeStack;
+
   for (unsigned i = Start; i != End; ++i) {
-    if (Changes[i].NewlinesBefore > 0) {
-      FoundMatchOnLine = false;
+    if (ScopeStack.size() != 0 &&
+        Changes[i].ScopeLevel < ScopeStack.back().ScopeLevel)
+      ScopeStack.pop_back();
+
+    if (i != Start) {
+      if (Changes[i].ScopeLevel > Changes[i - 1].ScopeLevel) {
+        ScopeStack.push_back({Changes[i - 1].Type, Changes[i].ScopeLevel});
+        if (i > Start + 1 && Changes[i - 2].Type == TT_FunctionDeclarationName)
+          ScopeStack.back().Type = Changes[i - 2].Type;
+      }
+    }
+
+    bool InsideNestedScope = ScopeStack.size() != 0;
+
+    if (Changes[i].NewlinesBefore > 0 && !InsideNestedScope) {
       Shift = 0;
+      FoundMatchOnLine = false;
     }
 
     // If this is the first matching token to be aligned, remember by how many
     // spaces it has to be shifted, so the rest of the changes on the line are
     // shifted by the same amount
-    if (!FoundMatchOnLine && Matches(Changes[i])) {
+    if (!FoundMatchOnLine && !InsideNestedScope && Matches(Changes[i])) {
       FoundMatchOnLine = true;
       Shift = Column - Changes[i].StartOfTokenColumn;
       Changes[i].Spaces += Shift;
     }
 
+    // This is for function parameters that are split across multiple lines,
+    // as mentioned in the ScopeStack comment.
+    if (InsideNestedScope && Changes[i].NewlinesBefore > 0 &&
+        ScopeStack.back().Type == TT_FunctionDeclarationName)
+      Changes[i].Spaces += Shift;
+
     assert(Shift >= 0);
     Changes[i].StartOfTokenColumn += Shift;
     if (i + 1 != Changes.size())
       Changes[i + 1].PreviousEndOfTokenColumn += Shift;
   }
 }
 
-// Walk through all of the changes and find sequences of matching tokens to
-// align. To do so, keep track of the lines and whether or not a matching token
-// was found on a line. If a matching token is found, extend the current
-// sequence. If the current line cannot be part of a sequence, e.g. because
-// there is an empty line before it or it contains only non-matching tokens,
-// finalize the previous sequence.
+// Walk through a subset of the changes, starting at StartAt, and find
+// sequences of matching tokens to align. To do so, keep track of the lines and
+// whether or not a matching token was found on a line. If a matching token is
+// found, extend the current sequence. If the current line cannot be part of a
+// sequence, e.g. because there is an empty line before it or it contains only
+// non-matching tokens, finalize the previous sequence.
+// The value returned is the token on which we stopped, either because we
+// exhausted all items inside Changes, or because we hit a scope level higher
+// than our initial scope.
+// This function is recursive. Each invocation processes only the nesting level
+// (aka ScopeLevel) equal to the initial level, which is the level of
+// Changes[StartAt].
+// If we encounter a nesting level greater than the initial level, then we call
+// ourselves recursively, thereby avoiding the pollution of the current state
+// with the alignment requirements of the nested sub-level. This recursive
+// behavior is necessary for aligning function prototypes that have one or more
+// arguments.
+// If this function encounters a nesting level less than the initial level,
+// it exits.
+// There is a non-obvious subtlety in the recursive behavior: Even though we
+// defer processing of nested levels to recursive invocations of this
+// function, when it comes time to align a sequence of tokens, we run the
+// alignment on the entire sequence, including the nested levels.
+// When doing so, most of the nested tokens are skipped, because their
+// alignment was already handled by the recursive invocations of this function.
+// However, the special exception is that we do NOT skip function parameters
+// that are split across multiple lines. See the test case in FormatTest.cpp
+// that mentions "split function parameter alignment" for an example of this.
 template <typename F>
-static void AlignTokens(const FormatStyle &Style, F &&Matches,
-                        SmallVector<WhitespaceManager::Change, 16> &Changes) {
+static unsigned
+AlignTokens(const FormatStyle &Style, F &&Matches,
+            SmallVector<WhitespaceManager::Change, 16> &Changes,
+            unsigned StartAt) {
   unsigned MinColumn = 0;
   unsigned MaxColumn = UINT_MAX;
 
   // Line number of the start and the end of the current token sequence.
   unsigned StartOfSequence = 0;
   unsigned EndOfSequence = 0;
 
-  // Keep track of the nesting level of matching tokens, i.e. the number of
-  // surrounding (), [], or {}. We will only align a sequence of matching
-  // token that share the same scope depth.
-  //
-  // FIXME: This could use FormatToken::NestingLevel information, but there is
-  // an outstanding issue wrt the brace scopes.
-  unsigned NestingLevelOfLastMatch = 0;
-  unsigned NestingLevel = 0;
+  // Measure the ScopeLevel (i.e. depth of (), [], {}) of the first token, and abort
+  // when we hit any token in a higher scope than the starting one.
+  int ScopeLevel = StartAt < Changes.size() ? Changes[StartAt].ScopeLevel : -1;
 
   // Keep track of the number of commas before the matching tokens, we will only
   // align a sequence of matching tokens if they are preceded by the same number
@@ -240,7 +335,10 @@
     EndOfSequence = 0;
   };
 
-  for (unsigned i = 0, e = Changes.size(); i != e; ++i) {
+  unsigned i = StartAt;
+  for (unsigned e = Changes.size();
+       i != e && Changes[i].ScopeLevel >= ScopeLevel; ++i) {
+
     if (Changes[i].NewlinesBefore != 0) {
       CommasBeforeMatch = 0;
       EndOfSequence = i;
@@ -254,31 +352,23 @@
 
     if (Changes[i].Kind == tok::comma) {
       ++CommasBeforeMatch;
-    } else if (Changes[i].Kind == tok::r_brace ||
-               Changes[i].Kind == tok::r_paren ||
-               Changes[i].Kind == tok::r_square) {
-      --NestingLevel;
-    } else if (Changes[i].Kind == tok::l_brace ||
-               Changes[i].Kind == tok::l_paren ||
-               Changes[i].Kind == tok::l_square) {
-      // We want sequences to skip over child scopes if possible, but not the
-      // other way around.
-      NestingLevelOfLastMatch = std::min(NestingLevelOfLastMatch, NestingLevel);
-      ++NestingLevel;
+    } else if (Changes[i].ScopeLevel != ScopeLevel) {
+      // Call AlignTokens recursively, skipping over this scope block.
+      unsigned StoppedAt = AlignTokens(Style, Matches, Changes, i);
+      i = StoppedAt - 1;
+      continue;
     }
 
     if (!Matches(Changes[i]))
       continue;
 
     // If there is more than one matching token per line, or if the number of
     // preceding commas, or the scope depth, do not match anymore, end the
     // sequence.
-    if (FoundMatchOnLine || CommasBeforeMatch != CommasBeforeLastMatch ||
-        NestingLevel != NestingLevelOfLastMatch)
+    if (FoundMatchOnLine || CommasBeforeMatch != CommasBeforeLastMatch)
       AlignCurrentSequence();
 
     CommasBeforeLastMatch = CommasBeforeMatch;
-    NestingLevelOfLastMatch = NestingLevel;
     FoundMatchOnLine = true;
 
     if (StartOfSequence == 0)
@@ -301,8 +391,10 @@
     MaxColumn = std::min(MaxColumn, ChangeMaxColumn);
   }
 
-  EndOfSequence = Changes.size();
+  unsigned StoppedAt = i;
+  EndOfSequence = i;
   AlignCurrentSequence();
+  return StoppedAt;
 }
 
 void WhitespaceManager::alignConsecutiveAssignments() {
@@ -321,7 +413,7 @@
 
                 return C.Kind == tok::equal;
               },
-              Changes);
+              Changes, 0);
 }
 
 void WhitespaceManager::alignConsecutiveDeclarations() {
@@ -334,9 +426,8 @@
   //   const char* const* v1;
   //   float const* v2;
   //   SomeVeryLongType const& v3;
-
   AlignTokens(Style, [](Change const &C) { return C.IsStartOfDeclName; },
-              Changes);
+              Changes, 0);
 }
 
 void WhitespaceManager::alignTrailingComments() {
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