Better formatting of conditional expressions.

In conditional expressions, if the condition is split over multiple
lines, also break before both operands.

This prevents formattings like:

  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ==
      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ? b : c;

Which are bad, because they suggestion incorrect operator precedence:

  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ==
      (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ? b : c);

This lead to the discovery that the expression parser incorrectly
handled conditional operators and that it could also handle semicolons
(which in turn reduced the amount of special casing for for-loops). As a
side-effect, we can now apply the bin-packing configuration to the
sections of for-loops.

llvm-svn: 175973

1 files changed, 24 insertions, 8 deletions

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index 80780185c0e..b7f43d52edf 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -724,7 +724,7 @@ public:
   ExpressionParser(AnnotatedLine &Line) : Current(&Line.First) {}
 
   /// \brief Parse expressions with the given operatore precedence.
-  void parse(prec::Level Precedence = prec::Unknown) {
+  void parse(int Precedence = 0) {
     if (Precedence > prec::PointerToMember || Current == NULL)
       return;
 
@@ -740,18 +740,27 @@ public:
     AnnotatedToken *Start = Current;
     bool OperatorFound = false;
 
-    while (Current != NULL) {
+    while (Current) {
       // Consume operators with higher precedence.
       parse(prec::Level(Precedence + 1));
 
+      int CurrentPrecedence = 0;
+      if (Current) {
+        if (Current->Type == TT_ConditionalExpr)
+          CurrentPrecedence = 1 + (int) prec::Conditional;
+        else if (Current->is(tok::semi))
+          CurrentPrecedence = 1;
+        else if (Current->Type == TT_BinaryOperator || Current->is(tok::comma))
+          CurrentPrecedence = 1 + (int) getPrecedence(*Current);
+      }
+
       // At the end of the line or when an operator with higher precedence is
       // found, insert fake parenthesis and return.
-      if (Current == NULL || Current->is(tok::semi) || closesScope(*Current) ||
-          ((Current->Type == TT_BinaryOperator || Current->is(tok::comma)) &&
-           getPrecedence(*Current) < Precedence)) {
+      if (Current == NULL || closesScope(*Current) ||
+          (CurrentPrecedence != 0 && CurrentPrecedence < Precedence)) {
         if (OperatorFound) {
           ++Start->FakeLParens;
-          if (Current != NULL)
+          if (Current)
             ++Current->Parent->FakeRParens;
         }
         return;
@@ -759,14 +768,21 @@ public:
 
       // Consume scopes: (), [], <> and {}
       if (opensScope(*Current)) {
-        while (Current != NULL && !closesScope(*Current)) {
+        AnnotatedToken *Left = Current;
+        while (Current && !closesScope(*Current)) {
           next();
           parse();
         }
+        // Remove fake parens that just duplicate the real parens.
+        if (Current && Left->Children[0].FakeLParens > 0 &&
+            Current->Parent->FakeRParens > 0) {
+          --Left->Children[0].FakeLParens;
+          --Current->Parent->FakeRParens;
+        }
         next();
       } else {
         // Operator found.
-        if (getPrecedence(*Current) == Precedence)
+        if (CurrentPrecedence == Precedence)
           OperatorFound = true;
 
         next();