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      1 //===--- RAIIObjectsForParser.h - RAII helpers for the parser ---*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file defines and implements the some simple RAII objects that are used
     11 // by the parser to manage bits in recursion.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_CLANG_PARSE_RAII_OBJECTS_FOR_PARSER_H
     16 #define LLVM_CLANG_PARSE_RAII_OBJECTS_FOR_PARSER_H
     17 
     18 #include "clang/Parse/ParseDiagnostic.h"
     19 
     20 namespace clang {
     21   // TODO: move ParsingDeclRAIIObject here.
     22   // TODO: move ParsingClassDefinition here.
     23   // TODO: move TentativeParsingAction here.
     24 
     25 
     26   /// ExtensionRAIIObject - This saves the state of extension warnings when
     27   /// constructed and disables them.  When destructed, it restores them back to
     28   /// the way they used to be.  This is used to handle __extension__ in the
     29   /// parser.
     30   class ExtensionRAIIObject {
     31     void operator=(const ExtensionRAIIObject &);     // DO NOT IMPLEMENT
     32     ExtensionRAIIObject(const ExtensionRAIIObject&); // DO NOT IMPLEMENT
     33     DiagnosticsEngine &Diags;
     34   public:
     35     ExtensionRAIIObject(DiagnosticsEngine &diags) : Diags(diags) {
     36       Diags.IncrementAllExtensionsSilenced();
     37     }
     38 
     39     ~ExtensionRAIIObject() {
     40       Diags.DecrementAllExtensionsSilenced();
     41     }
     42   };
     43 
     44   /// ColonProtectionRAIIObject - This sets the Parser::ColonIsSacred bool and
     45   /// restores it when destroyed.  This says that "foo:" should not be
     46   /// considered a possible typo for "foo::" for error recovery purposes.
     47   class ColonProtectionRAIIObject {
     48     Parser &P;
     49     bool OldVal;
     50   public:
     51     ColonProtectionRAIIObject(Parser &p, bool Value = true)
     52       : P(p), OldVal(P.ColonIsSacred) {
     53       P.ColonIsSacred = Value;
     54     }
     55 
     56     /// restore - This can be used to restore the state early, before the dtor
     57     /// is run.
     58     void restore() {
     59       P.ColonIsSacred = OldVal;
     60     }
     61 
     62     ~ColonProtectionRAIIObject() {
     63       restore();
     64     }
     65   };
     66 
     67   /// \brief RAII object that makes '>' behave either as an operator
     68   /// or as the closing angle bracket for a template argument list.
     69   class GreaterThanIsOperatorScope {
     70     bool &GreaterThanIsOperator;
     71     bool OldGreaterThanIsOperator;
     72   public:
     73     GreaterThanIsOperatorScope(bool &GTIO, bool Val)
     74     : GreaterThanIsOperator(GTIO), OldGreaterThanIsOperator(GTIO) {
     75       GreaterThanIsOperator = Val;
     76     }
     77 
     78     ~GreaterThanIsOperatorScope() {
     79       GreaterThanIsOperator = OldGreaterThanIsOperator;
     80     }
     81   };
     82 
     83   class InMessageExpressionRAIIObject {
     84     bool &InMessageExpression;
     85     bool OldValue;
     86 
     87   public:
     88     InMessageExpressionRAIIObject(Parser &P, bool Value)
     89       : InMessageExpression(P.InMessageExpression),
     90         OldValue(P.InMessageExpression) {
     91       InMessageExpression = Value;
     92     }
     93 
     94     ~InMessageExpressionRAIIObject() {
     95       InMessageExpression = OldValue;
     96     }
     97   };
     98 
     99   /// \brief RAII object that makes sure paren/bracket/brace count is correct
    100   /// after declaration/statement parsing, even when there's a parsing error.
    101   class ParenBraceBracketBalancer {
    102     Parser &P;
    103     unsigned short ParenCount, BracketCount, BraceCount;
    104   public:
    105     ParenBraceBracketBalancer(Parser &p)
    106       : P(p), ParenCount(p.ParenCount), BracketCount(p.BracketCount),
    107         BraceCount(p.BraceCount) { }
    108 
    109     ~ParenBraceBracketBalancer() {
    110       P.ParenCount = ParenCount;
    111       P.BracketCount = BracketCount;
    112       P.BraceCount = BraceCount;
    113     }
    114   };
    115 
    116   class PoisonSEHIdentifiersRAIIObject {
    117     PoisonIdentifierRAIIObject Ident_AbnormalTermination;
    118     PoisonIdentifierRAIIObject Ident_GetExceptionCode;
    119     PoisonIdentifierRAIIObject Ident_GetExceptionInfo;
    120     PoisonIdentifierRAIIObject Ident__abnormal_termination;
    121     PoisonIdentifierRAIIObject Ident__exception_code;
    122     PoisonIdentifierRAIIObject Ident__exception_info;
    123     PoisonIdentifierRAIIObject Ident___abnormal_termination;
    124     PoisonIdentifierRAIIObject Ident___exception_code;
    125     PoisonIdentifierRAIIObject Ident___exception_info;
    126   public:
    127     PoisonSEHIdentifiersRAIIObject(Parser &Self, bool NewValue)
    128       : Ident_AbnormalTermination(Self.Ident_AbnormalTermination, NewValue),
    129         Ident_GetExceptionCode(Self.Ident_GetExceptionCode, NewValue),
    130         Ident_GetExceptionInfo(Self.Ident_GetExceptionInfo, NewValue),
    131         Ident__abnormal_termination(Self.Ident__abnormal_termination, NewValue),
    132         Ident__exception_code(Self.Ident__exception_code, NewValue),
    133         Ident__exception_info(Self.Ident__exception_info, NewValue),
    134         Ident___abnormal_termination(Self.Ident___abnormal_termination, NewValue),
    135         Ident___exception_code(Self.Ident___exception_code, NewValue),
    136         Ident___exception_info(Self.Ident___exception_info, NewValue) {
    137     }
    138   };
    139 
    140 } // end namespace clang
    141 
    142 #endif
    143