[clang-format][NFC] Clean up tryMergeLessLess()

[curdeius]

LGTM.

clang/lib/Format/FormatTokenLexer.cpp

433–434

To go a bit further, could we move First[1]->isNot(tok::less) || First[0]->isNot(tok::less) into its own if around the top of the function?
Sth like:

if (Tokens.size() < 3)
  return false;

auto First = Tokens.end() - 3;
if (First[0]->isNot(tok::less) || First[1]->isNot(tok::less))
  return false;

?

[owenpan]

Further cleanup.

[owenpan]

clang/lib/Format/FormatTokenLexer.cpp

433–434

Good idea.

[curdeius]

Great! Thanks.

[MyDeveloperDay]

LGTM, at first my head was confused with First[-1] but I think its ok.

clang/lib/Format/FormatTokenLexer.cpp

 }
 
 bool FormatTokenLexer::tryMergeLessLess() {
   // Merge X,less,less,Y into X,lessless,Y unless X or Y is less.
   if (Tokens.size() < 3)
     return false;
 
   auto First = Tokens.end() - 3;
-  bool FourthTokenIsLess = false;
-
-  if (Tokens.size() > 3) {
-    auto Fourth = (Tokens.end() - 4)[0];
-    FourthTokenIsLess = Fourth->is(tok::less);
+  if (First[0]->isNot(tok::less) || First[1]->isNot(tok::less))
+    return false;
 
-    // Do not remove a whitespace between the two "<" e.g. "operator< <>".
-    if (First[2]->is(tok::greater) && Fourth->is(tok::kw_operator))
-      return false;
-  }
+  // Only merge if there currently is no whitespace between the two "<".
+  if (First[1]->hasWhitespaceBefore())
 
-  if (First[2]->is(tok::less) || First[1]->isNot(tok::less) ||
-      First[0]->isNot(tok::less) || FourthTokenIsLess)
+  auto X = Tokens.size() > 3 ? First[-1] : nullptr;
+  auto Y = First[2];
+  if ((X && X->is(tok::less)) || Y->is(tok::less))
     return false;
 
-  // Only merge if there currently is no whitespace between the two "<".
-  if (First[1]->hasWhitespaceBefore())
+  // Do not remove a whitespace between the two "<" e.g. "operator< <>".
+  if (X && X->is(tok::kw_operator) && Y->is(tok::greater))
     return false;
 
   First[0]->Tok.setKind(tok::lessless);
   First[0]->TokenText = "<<";
   First[0]->ColumnWidth += 1;
   Tokens.erase(Tokens.end() - 2);
   return true;
 }