PerCederberg.Grammatica.Runtime.ReaderBuffer Class Reference

A character buffer that automatically reads from an input source stream when needed. More...

Public Member Functions
	ReaderBuffer (TextReader input)
	Creates a new tokenizer character buffer. More...
void	Dispose ()
	Discards all resources used by this buffer. More...
string	Substring (int index, int length)
	Returns a substring already in the buffer. More...
override string	ToString ()
	Returns the current content of the buffer as a string. More...
int	Peek (int offset)
	Returns a character relative to the current position. More...
string	Read (int offset)
	Reads the specified number of characters from the current position. More...

Public Attributes
const int	BLOCK_SIZE = 1024
	The stream reading block size. More...

Properties
int	Position [get]
	The current buffer position property (read-only).
int	LineNumber [get]
	The current line number property (read-only). More...
int	ColumnNumber [get]
	The current column number property (read-only). More...
int	Length [get]
	The current character buffer length property (read-only). More...

Detailed Description

A character buffer that automatically reads from an input source stream when needed.

This class keeps track of the current position in the buffer and its line and column number in the original input source. It allows unlimited look-ahead of characters in the input, reading and buffering the required data internally. As the position is advanced, the buffer content prior to the current position is subject to removal to make space for reading new content. A few characters before the current position are always kept to enable boundary condition checks.

Author

Per Cederberg

Version

1.5

Since

1.5

Constructor & Destructor Documentation

PerCederberg.Grammatica.Runtime.ReaderBuffer.ReaderBuffer ( TextReader  input )

inline

Creates a new tokenizer character buffer.

Parameters

input

the input source character reader

Member Function Documentation

void PerCederberg.Grammatica.Runtime.ReaderBuffer.Dispose ( )

inline

Discards all resources used by this buffer.

This will also close the source input stream. Disposing a previously disposed buffer has no effect.

int PerCederberg.Grammatica.Runtime.ReaderBuffer.Peek ( int  offset )

inline

Returns a character relative to the current position.

This method may read from the input source and may also trim the buffer content prior to the current position. The result of calling this method may therefore be that the buffer length and content have been modified.

The character offset must be positive, but is allowed to span the entire size of the input source stream. Note that the internal buffer must hold all the intermediate characters, which may be wasteful if the offset is too large.

Parameters

offset

the character offset, from 0 and up

Returns

the character found as an integer in the range 0 to 65535 (0x00-0xffff), or -1 if the end of the stream was reached

Exceptions

IOException

if an I/O error occurred

string PerCederberg.Grammatica.Runtime.ReaderBuffer.Read ( int  offset )

inline

Reads the specified number of characters from the current position.

This will also move the current position forward. This method will not attempt to move beyond the end of the input source stream. When reaching the end of file, the returned string might be shorter than requested. Any remaining characters will always be returned before returning null.

Parameters

offset

the character offset, from 0 and up

Returns

the string containing the characters read, or null no more characters remain in the buffer

Exceptions

IOException

if an I/O error occurred

string PerCederberg.Grammatica.Runtime.ReaderBuffer.Substring ( int  index, int  length  )

inline

Returns a substring already in the buffer.

Note that this method may behave in unexpected ways when performing operations that modifies the buffer content.

Parameters

index	the start index, inclusive
length	the substring length

Returns

the substring specified

Exceptions

IndexOutOfBoundsException

if one of the indices were negative or not less than (or equal) than length()

override string PerCederberg.Grammatica.Runtime.ReaderBuffer.ToString ( )

inline

Returns the current content of the buffer as a string.

Note that content before the current position will also be returned.

Returns

the current buffer content

Member Data Documentation

const int PerCederberg.Grammatica.Runtime.ReaderBuffer.BLOCK_SIZE = 1024

The stream reading block size.

All reads from the underlying character stream will be made in multiples of this block size. Also the character buffer size will always be a multiple of this factor.

Property Documentation

int PerCederberg.Grammatica.Runtime.ReaderBuffer.ColumnNumber

get

The current column number property (read-only).

This number is the column number of the next character to read.

int PerCederberg.Grammatica.Runtime.ReaderBuffer.Length

get

The current character buffer length property (read-only).

Note that the length may increase (and decrease) as more characters are read from the input source or removed to free up space.

int PerCederberg.Grammatica.Runtime.ReaderBuffer.LineNumber

get

The current line number property (read-only).

This number is the line number of the next character to read.

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The documentation for this class was generated from the following file:

• src/csharp/PerCederberg.Grammatica.Runtime/ReaderBuffer.cs