Loyc.Syntax.BaseParserNoBacktracking< Token, Enumerator > Class Template Reference

An base class designed for parsers that use LLLPG (Loyc LL(k) Parser Generator) and receive tokens from any IEnumerator{Token}. More...

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Source file:

• /Core/Loyc.Syntax/Parsing/BaseParserNoBacktracking.cs

Inheritance diagram for Loyc.Syntax.BaseParserNoBacktracking< Token, Enumerator >:

Remarks

An base class designed for parsers that use LLLPG (Loyc LL(k) Parser Generator) and receive tokens from any IEnumerator{Token}.

This base class for LLLPG parsers simply requires an enumerator to work, and it has a small buffer to hold lookahead tokens. Old tokens are forgotten, so this base class does not support backtracking (i.e. syntactic predicates), but it can save memory. Please use BaseParserForList{Tok,La} if your input sequence comes in the form of a list.

This version of BaseParser has Enumerator as a generic parameter. Compared to using IEnumerator{Token} directly, this can increase performance in case Enumerator is a value type (e.g. List<Token>.Enumerator).

(I wrote this class by mistake... I actually forgot about backtracking!)

Type Constraints

Token	:	ISimpleToken
Enumerator	:	IEnumerator<Token>

Properties
sealed override Int32	LA0Int [get]
new int	InputPosition [get, set]
	Cumulative index of the next token to be parsed. More...
Properties inherited from Loyc.Syntax.BaseParser< Token, MatchType >
IMessageSink	ErrorSink [get, set]
	Gets or sets the object to which error messages are sent. The default object is FormatExceptionErrorSink, which throws FormatException if an error occurs. More...
ISourceFile	SourceFile [get]
	The ISourceFile object that was provided to the constructor, if any. More...
Token	LT0 [get]
	Next token to parse (cached; is set to LT(0) whenever InputPosition is changed). More...
int	InputPosition [get, set]
	Current position of the next token to be parsed. More...
abstract MatchType	LA0Int [get]
	Returns the token type of _lt0 (normally _lt0.TypeInt) More...

Protected Member Functions
	BaseParserNoBacktracking (Enumerator sequence, Token eofToken, ISourceFile file, int startIndex=0)
	Initializes this object to begin parsing the specified tokens. More...
void	Reset (Enumerator sequence, Token eofToken, ISourceFile file, int startIndex=0)
sealed override Int32	EofInt ()
	Returns the value used for EOF (normally 0) More...
sealed override Token	LT (int i)
	Returns the Token at lookahead i, where 0 is the next token. This class does not support negative lookahead because old tokens from the IEnumerator are discarded. More...
abstract override string	ToString (Int32 tokenType)
	Returns a string representation of the specified token type. These strings are used in error messages. More...
Protected Member Functions inherited from Loyc.Syntax.BaseParser< Token >
	BaseParser (ISourceFile file=null, int startIndex=0)
Protected Member Functions inherited from Loyc.Syntax.BaseParser< Token, MatchType >
	BaseParser (ISourceFile file=null, int startIndex=0)
abstract string	ToString (MatchType tokenType)
	Returns a string representation of the specified token type. These strings are used in error messages. More...
virtual int	LaIndexToCharIndex (int lookaheadIndex)
	Converts a lookahead token index to a character index (used for error reporting). More...
virtual object	LaIndexToSourcePos (int lookaheadIndex)
	Converts a lookahead token index to a SourcePos object using LaIndexToCharIndex and SourceFile. More...
virtual void	Error (int lookaheadIndex, string message)
	Records an error or throws an exception. More...
virtual void	Error (int lookaheadIndex, string format, params object[] args)
void	Skip ()
Token	MatchAny ()
Token	Match (HashSet< MatchType > set, bool inverted=false)
Token	Match (MatchType a)
Token	Match (MatchType a, MatchType b)
Token	Match (MatchType a, MatchType b, MatchType c)
Token	Match (MatchType a, MatchType b, MatchType c, MatchType d)
Token	MatchExcept ()
Token	MatchExcept (MatchType a)
Token	MatchExcept (MatchType a, MatchType b)
Token	MatchExcept (MatchType a, MatchType b, MatchType c)
Token	MatchExcept (MatchType a, MatchType b, MatchType c, MatchType d)
Token	MatchExcept (HashSet< MatchType > set)
bool	TryMatch (HashSet< MatchType > set, bool inverted=false)
bool	TryMatch (MatchType a)
bool	TryMatch (MatchType a, MatchType b)
bool	TryMatch (MatchType a, MatchType b, MatchType c)
bool	TryMatch (MatchType a, MatchType b, MatchType c, MatchType d)
bool	TryMatchExcept ()
bool	TryMatchExcept (MatchType a)
bool	TryMatchExcept (MatchType a, MatchType b)
bool	TryMatchExcept (MatchType a, MatchType b, MatchType c)
bool	TryMatchExcept (MatchType a, MatchType b, MatchType c, MatchType d)
bool	TryMatchExcept (HashSet< MatchType > set)
void	Error (bool inverted, params MatchType[] expected)
virtual void	Error (bool inverted, IEnumerable< MatchType > expected)
virtual string	ToString (bool inverted, IEnumerable< MatchType > expected)
virtual void	Check (bool expectation, string expectedDescr="")

Protected fields
Token	EofToken
new int	_inputPosition
Protected fields inherited from Loyc.Syntax.BaseParser< Token, MatchType >
ISourceFile	_sourceFile
Token	_lt0
int	_inputPosition
MatchType	EOF

Additional Inherited Members
Public static fields inherited from Loyc.Syntax.BaseParser< Token, MatchType >
static readonly IMessageSink	FormatExceptionErrorSink
	Throws FormatException when it receives an error. Non-errors are sent to MessageSink.Current. More...
Static Protected Member Functions inherited from Loyc.Syntax.BaseParser< Token, MatchType >
static HashSet< MatchType >	NewSet (params MatchType[] items)

Constructor & Destructor Documentation

Loyc.Syntax.BaseParserNoBacktracking< Token, Enumerator >.BaseParserNoBacktracking ( Enumerator  sequence, Token  eofToken, ISourceFile  file, int  startIndex = 0  )

inlineprotected

Initializes this object to begin parsing the specified tokens.

Parameters

sequence	A list of tokens to be parsed.
eofToken	A token value to return when the input position reaches the end of the token list.
file	A source file object that will be returned by the SourceFile property. By default, this object is used to get the file name, line number and column number shown in parser errors. If you are using BaseLexer, you can get this object from the BaseLexer{C}.SourceFile property. The SourceFile. property (in this class) will return this value. It can be null, which means that default error messages will show the character index instead of the file, line number and column number.
startIndex	The initial value of the InputPosition property. This is informational only, and has no effect on the behavior of this class.

Member Function Documentation

sealed override Int32 Loyc.Syntax.BaseParserNoBacktracking< Token, Enumerator >.EofInt ( )

inlineprotectedvirtual

Returns the value used for EOF (normally 0)

Implements Loyc.Syntax.BaseParser< Token, MatchType >.

sealed override Token Loyc.Syntax.BaseParserNoBacktracking< Token, Enumerator >.LT ( int  i )

inlineprotectedvirtual

Returns the Token at lookahead i, where 0 is the next token. This class does not support negative lookahead because old tokens from the IEnumerator are discarded.

Implements Loyc.Syntax.BaseParser< Token, MatchType >.

abstract override string Loyc.Syntax.BaseParserNoBacktracking< Token, Enumerator >.ToString ( Int32  tokenType )

protectedpure virtual

Returns a string representation of the specified token type. These strings are used in error messages.

Property Documentation

new int Loyc.Syntax.BaseParserNoBacktracking< Token, Enumerator >.InputPosition

getsetprotected

Cumulative index of the next token to be parsed.

This class doesn't care what the absolute InputPosition is, since it reads from an IEnumerator{Token}. This property is constrained to always increase, since old tokens are forgotten.