ReaderBuffer (Grammatica 1.6 Documentation)

java.lang.Object
- net.percederberg.grammatica.parser.ReaderBuffer

All Implemented Interfaces:

java.lang.CharSequence
```
public class ReaderBuffer
extends java.lang.Object
implements java.lang.CharSequence
```
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.

Since:

1.5

Field Summary

Fields
Modifier and Type Field and Description

static int BLOCK_SIZE
The stream reading block size.

Fields
Modifier and Type	Field and Description
`static int`	`BLOCK_SIZE` The stream reading block size.

Constructor Summary

Constructors
Constructor and Description

ReaderBuffer(java.io.Reader input)
Creates a new tokenizer character buffer.

Constructors
Constructor and Description
`ReaderBuffer(java.io.Reader input)` Creates a new tokenizer character buffer.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`char`	`charAt(int index)` Returns a character already in the buffer.
`int`	`columnNumber()` Returns the current column number.
`void`	`dispose()` Discards all resources used by this buffer.
`int`	`length()` Returns the current character buffer length.
`int`	`lineNumber()` Returns the current line number.
`int`	`peek(int offset)` Returns a character relative to the current position.
`int`	`position()` Returns the current position in the buffer.
`java.lang.String`	`read(int offset)` Reads the specified number of characters from the current position.
`java.lang.CharSequence`	`subSequence(int start, int end)` Returns a character sequence already in the buffer.
`java.lang.String`	`toString()` Returns the current content of the buffer as a string.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.CharSequence
chars, codePoints

- Field Detail
  - BLOCK_SIZE
```
public static final int BLOCK_SIZE
```
    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.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - ReaderBuffer
```
public ReaderBuffer(java.io.Reader input)
```
    Creates a new tokenizer character buffer.
    
    Parameters:
    
    input - the input source character reader
- Method Detail
  - dispose
```
public void dispose()
```
    Discards all resources used by this buffer. This will also close the source input stream. Disposing a previously disposed buffer has no effect.
  - position
```
public int position()
```
    Returns the current position in the buffer.
    
    Returns:
    
    the current position in the buffer
  - lineNumber
```
public int lineNumber()
```
    Returns the current line number. This number is the input source line number of the current position.
    
    Returns:
    
    the current position line number
  - columnNumber
```
public int columnNumber()
```
    Returns the current column number. This number is the input source column number of the current position.
    
    Returns:
    
    the current position column number
  - length
```
public int length()
```
    Returns the current character buffer length. Note that the length may increase (and decrease) as more characters are read from the input source or removed to free up space.
    
    Specified by:
    
    length in interface java.lang.CharSequence
  - charAt
```
public char charAt(int index)
            throws java.lang.IndexOutOfBoundsException
```
    Returns a character already in the buffer. Note that this method may behave in unexpected ways when performing operations that modifies the buffer content.
    
    Specified by:
    
    charAt in interface java.lang.CharSequence
    
    Parameters:
    
    index - the char index, starting at 0
    
    Returns:
    
    the character at the specified index
    
    Throws:
    
    java.lang.IndexOutOfBoundsException - if the index is negative or not less than length()
  - subSequence
```
public java.lang.CharSequence subSequence(int start,
                                          int end)
                                   throws java.lang.IndexOutOfBoundsException
```
    Returns a character sequence already in the buffer. Note that this method may behave in unexpected ways when performing operations that modifies the buffer content.
    
    Specified by:
    
    subSequence in interface java.lang.CharSequence
    
    Parameters:
    
    start - the start index, inclusive
    
    end - the end index, exclusive
    
    Returns:
    
    the character sequence specified
    
    Throws:
    
    java.lang.IndexOutOfBoundsException - if one of the indices were negative or not less than (or equal) than length()
  - toString
```
public java.lang.String toString()
```
    Returns the current content of the buffer as a string. Note that content before the current position will also be returned.
    
    Specified by:
    
    toString in interface java.lang.CharSequence
    
    Overrides:
    
    toString in class java.lang.Object
    
    Returns:
    
    the current buffer content
  - peek
```
public int peek(int offset)
         throws java.io.IOException
```
    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
    
    Throws:
    
    java.io.IOException - if an I/O error occurred
  - read
```
public java.lang.String read(int offset)
                      throws java.io.IOException
```
    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
    
    Throws:
    
    java.io.IOException - if an I/O error occurred

Class ReaderBuffer

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.CharSequence

Field Detail

BLOCK_SIZE

Constructor Detail

ReaderBuffer

Method Detail

dispose

position

lineNumber

columnNumber

length

charAt

subSequence

toString

peek

read