Introduce BalancedDelimiterTracker, to better track open/close

delimiter pairs and detect when we exceed the implementation limit for
nesting depth, from Aaron Ballman!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141782 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 70 insertions, 37 deletions

diff --git a/lib/Parse/Parser.cpp b/lib/Parse/Parser.cpp
index 05a2b15abf..c90964381f 100644
--- a/lib/Parse/Parser.cpp
+++ b/lib/Parse/Parser.cpp
@@ -122,34 +122,6 @@ void Parser::SuggestParentheses(SourceLocation Loc, unsigned DK,
     << FixItHint::CreateInsertion(EndLoc, ")");
 }
 
-/// MatchRHSPunctuation - For punctuation with a LHS and RHS (e.g. '['/']'),
-/// this helper function matches and consumes the specified RHS token if
-/// present.  If not present, it emits a corresponding diagnostic indicating
-/// that the parser failed to match the RHS of the token at LHSLoc.
-SourceLocation Parser::MatchRHSPunctuation(tok::TokenKind RHSTok,
-                                           SourceLocation LHSLoc) {
-
-  if (Tok.is(RHSTok))
-    return ConsumeAnyToken();
-
-  SourceLocation R = Tok.getLocation();
-  const char *LHSName = "unknown";
-  diag::kind DID = diag::err_parse_error;
-  switch (RHSTok) {
-  default: break;
-  case tok::r_paren : LHSName = "("; DID = diag::err_expected_rparen; break;
-  case tok::r_brace : LHSName = "{"; DID = diag::err_expected_rbrace; break;
-  case tok::r_square: LHSName = "["; DID = diag::err_expected_rsquare; break;
-  case tok::greater:  LHSName = "<"; DID = diag::err_expected_greater; break;
-  case tok::greatergreatergreater:
-                      LHSName = "<<<"; DID = diag::err_expected_ggg; break;
-  }
-  Diag(Tok, DID);
-  Diag(LHSLoc, diag::note_matching) << LHSName;
-  SkipUntil(RHSTok);
-  return R;
-}
-
 static bool IsCommonTypo(tok::TokenKind ExpectedTok, const Token &Tok) {
   switch (ExpectedTok) {
   case tok::semi: return Tok.is(tok::colon); // : for ;
@@ -1147,13 +1119,12 @@ Parser::ExprResult Parser::ParseSimpleAsm(SourceLocation *EndLoc) {
     ConsumeToken();
   }
 
-  if (Tok.isNot(tok::l_paren)) {
+  BalancedDelimiterTracker T(*this, tok::l_paren);
+  if (T.consumeOpen()) {
     Diag(Tok, diag::err_expected_lparen_after) << "asm";
     return ExprError();
   }
 
-  Loc = ConsumeParen();
-
   ExprResult Result(ParseAsmStringLiteral());
 
   if (Result.isInvalid()) {
@@ -1162,9 +1133,10 @@ Parser::ExprResult Parser::ParseSimpleAsm(SourceLocation *EndLoc) {
       *EndLoc = Tok.getLocation();
     ConsumeAnyToken();
   } else {
-    Loc = MatchRHSPunctuation(tok::r_paren, Loc);
+    // Close the paren and get the location of the end bracket
+    T.consumeClose();
     if (EndLoc)
-      *EndLoc = Loc;
+      *EndLoc = T.getCloseLocation();
   }
 
   return move(Result);
@@ -1489,13 +1461,12 @@ bool Parser::ParseMicrosoftIfExistsCondition(bool& Result) {
   Token Condition = Tok;
   SourceLocation IfExistsLoc = ConsumeToken();
 
-  SourceLocation LParenLoc = Tok.getLocation();
-  if (Tok.isNot(tok::l_paren)) {
+  BalancedDelimiterTracker T(*this, tok::l_paren);
+  if (T.consumeOpen()) {
     Diag(Tok, diag::err_expected_lparen_after) << IfExistsLoc;
     SkipUntil(tok::semi);
     return true;
   }
-  ConsumeParen(); // eat the '('.
   
   // Parse nested-name-specifier.
   CXXScopeSpec SS;
@@ -1514,7 +1485,8 @@ bool Parser::ParseMicrosoftIfExistsCondition(bool& Result) {
     return true;
   }
 
-  if (MatchRHSPunctuation(tok::r_paren, LParenLoc).isInvalid())
+  T.consumeClose();
+  if (T.getCloseLocation().isInvalid())
     return true;
 
   // Check if the symbol exists.
@@ -1581,3 +1553,64 @@ Parser::DeclGroupPtrTy Parser::ParseModuleImport() {
   
   return Actions.ConvertDeclToDeclGroup(Import.get());
 }
+
+bool Parser::BalancedDelimiterTracker::consumeOpen() {
+  // Try to consume the token we are holding
+  if (P.Tok.is(Kind)) {
+    P.QuantityTracker.push(Kind);
+    Cleanup = true;
+    if (P.QuantityTracker.getDepth(Kind) < MaxDepth) {
+      LOpen = P.ConsumeAnyToken();
+      return false;
+    } else {
+      P.Diag(P.Tok, diag::err_parser_impl_limit_overflow);
+      P.SkipUntil(tok::eof);
+    }
+  }
+  return true;
+}
+
+bool Parser::BalancedDelimiterTracker::expectAndConsume(unsigned DiagID, 
+                                            const char *Msg,
+                                            tok::TokenKind SkipToToc ) {
+  LOpen = P.Tok.getLocation();
+  if (!P.ExpectAndConsume(Kind, DiagID, Msg, SkipToToc)) {
+    P.QuantityTracker.push(Kind);
+    Cleanup = true;
+    if (P.QuantityTracker.getDepth(Kind) < MaxDepth) {
+      return false;
+    } else {
+      P.Diag(P.Tok, diag::err_parser_impl_limit_overflow);
+      P.SkipUntil(tok::eof);
+    }
+  }
+  return true;
+}
+
+bool Parser::BalancedDelimiterTracker::consumeClose() {
+  if (P.Tok.is(Close)) {
+    LClose = P.ConsumeAnyToken();
+    if (Cleanup)
+      P.QuantityTracker.pop(Kind);
+
+    Cleanup = false;
+    return false;
+  } else {
+    const char *LHSName = "unknown";
+    diag::kind DID = diag::err_parse_error;
+    switch (Close) {
+    default: break;
+    case tok::r_paren : LHSName = "("; DID = diag::err_expected_rparen; break;
+    case tok::r_brace : LHSName = "{"; DID = diag::err_expected_rbrace; break;
+    case tok::r_square: LHSName = "["; DID = diag::err_expected_rsquare; break;
+    case tok::greater:  LHSName = "<"; DID = diag::err_expected_greater; break;
+    case tok::greatergreatergreater:
+                        LHSName = "<<<"; DID = diag::err_expected_ggg; break;
+    }
+    P.Diag(P.Tok, DID);
+    P.Diag(LOpen, diag::note_matching) << LHSName;
+    if (P.SkipUntil(Close))
+      LClose = P.Tok.getLocation();
+  }
+  return true;
+}