org.exolab.castor.xml.dtd.parser
Class InputCharStream
java.lang.Object
org.exolab.castor.xml.dtd.parser.InputCharStream
- CharStream
public final class InputCharStream
extends java.lang.Object
An implementation of interface
CharStream
.
Implements input character stream
that maintains line and column number positions of the characters.
It also has the capability to backup the stream to some extent.
The object of this class is constructed using
java.io.Reader
reader and it is left to
constructor of the
reader to set up character encoding correctly.
This means that method
read of
the
reader is used to get next characters, assuming it returns
appropriate values. It is recommended to use class
java.io.InputStreamReader
as a
reader, which allows to set desired character encoding.
This class is an intermediate component between input
character reader and the parser.
The code of this class is based on the class
ASCII_CharStream - implementation
of interface
CharStream
,
that JavaCC would have generated with
the following options set in a JavaCC grammar file:
JAVA_UNICODE_ESCAPE = false;
UNICODE_INPUT = false;
USER_CHAR_STREAM = false;
Note that this class is not fully JavaCC generated.
$Revision: 5962 $ $Date: 2003-03-03 00:05:44 -0700 (Mon, 03 Mar 2003) $
InputCharStream(java.io.Reader dstream) - Constructor, instantiating the char stream to begin at 1-st line and
1-st column of dstream.
|
InputCharStream(java.io.Reader dstream, int startline, int startcolumn) - Constructor, allowing to specify start line and start column
of the char stream.
|
InputCharStream(java.io.Reader dstream, int startline, int startcolumn, int buffersize) - Constructor, allowing to specify start line and start column of the char
stream, and buffer size as well.
|
char | BeginToken() - Returns the next character that marks the beginning of the next token.
|
void | Done() - The lexer calls this function to indicate that it is done with the stream
and hence implementations can free any resources held by this class.
|
String | GetImage() - Returns a string made up of characters from the marked token beginning
to the current buffer position.
|
char[] | GetSuffix(int len) - Returns an array of characters that make up the suffix of length 'len' for
the currently matched token.
|
void | ReInit(java.io.Reader dstream) - Reinitialization of the char stream, instantiating the char stream
to begin at 1-st line and 1-st column of dstream.
|
void | ReInit(java.io.Reader dstream, int startline, int startcolumn) - Reinitialization of the char stream, allowing to specify start line
and start column of the char stream.
|
void | ReInit(java.io.Reader dstream, int startline, int startcolumn, int buffersize) - Reinitialization of the char stream, allowing to specify start line
and start column of the char stream, and buffer size as well.
|
void | adjustBeginLineColumn(int newLine, int newCol) - Method to adjust line and column numbers for the start of a token.
|
void | backup(int amount) - Backs up the input stream by amount steps.
|
int | getBeginColumn() - Returns the column number of the first character for current token (being
matched after the last call to BeginTOken).
|
int | getBeginLine() - Returns the line number of the first character for current token (being
matched after the last call to BeginTOken).
|
int | getColumn()
|
int | getEndColumn() - Returns the column number of the last character for current token (being
matched after the last call to BeginTOken).
|
int | getEndLine() - Returns the line number of the last character for current token (being
matched after the last call to BeginTOken).
|
int | getLine()
|
char | readChar() - Returns the next character from the input stream.
|
available
(package private) int available
bufsize
(package private) int bufsize
staticFlag
public static final boolean staticFlag
tokenBegin
(package private) int tokenBegin
InputCharStream
public InputCharStream(java.io.Reader dstream)
Constructor, instantiating the char stream to begin at 1-st line and
1-st column of dstream.
InputCharStream
public InputCharStream(java.io.Reader dstream,
int startline,
int startcolumn)
Constructor, allowing to specify start line and start column
of the char stream.
InputCharStream
public InputCharStream(java.io.Reader dstream,
int startline,
int startcolumn,
int buffersize)
Constructor, allowing to specify start line and start column of the char
stream, and buffer size as well.
BeginToken
public final char BeginToken()
throws java.io.IOException
Returns the next character that marks the beginning of the next token.
All characters must remain in the buffer between two successive calls
to this method to implement backup correctly.
- BeginToken in interface CharStream
Done
public void Done()
The lexer calls this function to indicate that it is done with the stream
and hence implementations can free any resources held by this class.
Again, the body of this function can be just empty and it will not
affect the lexer's operation.
- Done in interface CharStream
GetImage
public final String GetImage()
Returns a string made up of characters from the marked token beginning
to the current buffer position. Implementations have the choice of returning
anything that they want to. For example, for efficiency, one might decide
to just return null, which is a valid implementation.
- GetImage in interface CharStream
GetSuffix
public final char[] GetSuffix(int len)
Returns an array of characters that make up the suffix of length 'len' for
the currently matched token. This is used to build up the matched string
for use in actions in the case of MORE. A simple and inefficient
implementation of this is as follows :
{
String t = GetImage();
return t.substring(t.length() - len, t.length()).toCharArray();
}
- GetSuffix in interface CharStream
ReInit
public void ReInit(java.io.Reader dstream)
Reinitialization of the char stream, instantiating the char stream
to begin at 1-st line and 1-st column of dstream.
ReInit
public void ReInit(java.io.Reader dstream,
int startline,
int startcolumn)
Reinitialization of the char stream, allowing to specify start line
and start column of the char stream.
ReInit
public void ReInit(java.io.Reader dstream,
int startline,
int startcolumn,
int buffersize)
Reinitialization of the char stream, allowing to specify start line
and start column of the char stream, and buffer size as well.
adjustBeginLineColumn
public void adjustBeginLineColumn(int newLine,
int newCol)
Method to adjust line and column numbers for the start of a token.
backup
public final void backup(int amount)
Backs up the input stream by amount steps. Lexer calls this method if it
had already read some characters, but could not use them to match a
(longer) token. So, they will be used again as the prefix of the next
token and it is the implemetation's responsibility to do this right.
- backup in interface CharStream
getBeginColumn
public final int getBeginColumn()
Returns the column number of the first character for current token (being
matched after the last call to BeginTOken).
- getBeginColumn in interface CharStream
getBeginLine
public final int getBeginLine()
Returns the line number of the first character for current token (being
matched after the last call to BeginTOken).
- getBeginLine in interface CharStream
getEndColumn
public final int getEndColumn()
Returns the column number of the last character for current token (being
matched after the last call to BeginTOken).
- getEndColumn in interface CharStream
getEndLine
public final int getEndLine()
Returns the line number of the last character for current token (being
matched after the last call to BeginTOken).
- getEndLine in interface CharStream
readChar
public final char readChar()
throws java.io.IOException
Returns the next character from the input stream. The only method whose
implementation is different from its original in the ASCII_CharStream class.
- readChar in interface CharStream
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