tribble.io
Class CharInputStreamDfl

java.lang.Object
  tribble.io.CharInputStreamDfl

All Implemented Interfaces:

CharInputStreamI, DiagnosticWriterI

public class CharInputStreamDfl
extends java.lang.Object
implements CharInputStreamI, DiagnosticWriterI

Default generic character input stream.

This is a default implementation of an input stream that is capable of reading a single character at a time. Such a stream can be used as the underlying character input stream for classes implementing the LexerI interface.

This character stream handles various combinations of newline termination characters (LF, CR, and CR/LF pairs), returning a single newline character ('\n') for any given combination.

This also handles formfeed (FF) and null (NUL) characters, treating them as spaces (SP).

Tab (HT) characters are replaced with one or more spaces, to align on tabbed columns. By default, tabs are replaced with the appropriate number of spaces so as to align on 8-character columns, but this can be changed to a different width or disabled altogether.

Since:

2001-05-18

Version:

$Revision: 1.2 $ $Date: 2003/01/25 18:40:45 $

Author:

David R. Tribble, david@tribble.com.
Copyright ©2001-2003 by David R. Tribble, all rights reserved.
Permission is granted to freely use and distribute this source code provided that the original copyright and authorship notices remain intact.

See Also:

LexerI

Field Summary

static int	DFL_TABSIZE Default tab width.
static int	EOF End of file character code.
protected int	m_colNo Column position (of the last character read).
protected java.io.Reader	m_in Input stream.
protected DiagnosticOutputI	m_out Diagnostic output stream.
protected int	m_tabSp Pending tab (HT) character replacement.
protected int	m_tabSz Tab (HT) column width.
protected int	m_ungetc Pushed-back (unread) character.
(package private) static java.lang.String	REV Revision information.

Constructor Summary

CharInputStreamDfl()
Default constructor.

CharInputStreamDfl(java.io.Reader in)
Constructor.

CharInputStreamDfl(java.io.Reader in, DiagnosticOutputI out)
Constructor.

Method Summary

void	close() Close the input stream.
protected void	finalize() Finalization.
int	readChar() Read the next character from the input stream.
void	setInput(java.io.Reader in) Establish the input stream from which to read characters.
void	setOutput(DiagnosticOutputI out) Establish the output stream to which diagnostic messages (warning and error messages) are written during parsing.
void	setTabSize(int n) Establish the tab (HT) column width.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

REV

static final java.lang.String REV

Revision information.

See Also:

Constant Field Values

EOF

public static final int EOF

End of file character code.

See Also:

Constant Field Values

DFL_TABSIZE

public static final int DFL_TABSIZE

Default tab width.

See Also:

Constant Field Values

m_in

protected java.io.Reader m_in

Input stream.

m_out

protected DiagnosticOutputI m_out

Diagnostic output stream.

m_ungetc

protected int m_ungetc

Pushed-back (unread) character.

m_colNo

protected int m_colNo

Column position (of the last character read).

m_tabSz

protected int m_tabSz

Tab (HT) column width.

m_tabSp

protected int m_tabSp

Pending tab (HT) character replacement.

Constructor Detail

CharInputStreamDfl

public CharInputStreamDfl()

Default constructor.

Since:

1.1, 2001-05-18

CharInputStreamDfl

public CharInputStreamDfl(java.io.Reader in)

Constructor.

Parameters:

in - The input stream from which to read characters.

Since:

1.1, 2001-05-18

CharInputStreamDfl

public CharInputStreamDfl(java.io.Reader in,
                          DiagnosticOutputI out)

Constructor.

Parameters:

in - The input stream from which to read characters.

out - The diagnostic output stream to write to.

Since:

1.1, 2001-05-18

Method Detail

setOutput

public void setOutput(DiagnosticOutputI out)

Establish the output stream to which diagnostic messages (warning and error messages) are written during parsing.

Specified by:

setOutput in interface DiagnosticWriterI

Parameters:

out - The diagnostic output stream.

Since:

1.1, 2001-05-18

setInput

public void setInput(java.io.Reader in)

Establish the input stream from which to read characters.

Specified by:

setInput in interface CharInputStreamI

Parameters:

in - The input stream from which to read characters.

Since:

1.1, 2001-05-18

close

public void close()

Close the input stream.

Specified by:

close in interface CharInputStreamI

Since:

1.1, 2001-05-18

readChar

public int readChar()
             throws java.io.IOException

Read the next character from the input stream.

This character stream handles various combinations of newline termination characters (LF, CR, and CR/LF pairs), returning a single newline character ('\n') for any given combination.

This stream also handles formfeed (FF) and null (NUL) characters, replacing them with spaces (SP).

Tab (HT) characters are replaced by one or more space (SP) characters, so that the character following the tab is aligned on a tab-sized column. Tab character replacement can be disabled by specifying a tab size of zero (see setTabSize(int)).

Specified by:

readChar in interface CharInputStreamI

Returns:

The next character code read from the input stream, or -1 if there are no more characters to read (i.e., the end of the input stream was reached).

Throws:

java.io.IOException - Thrown if an I/O (read) error occurs.

Since:

1.1, 2001-05-18

setTabSize

public void setTabSize(int n)

Establish the tab (HT) column width.

Setting a tab width of zero disables the replacing of tab (HT) characters with spaces, i.e., tab characters are read as is. The default tab width is 8.

Parameters:

n - The tab column width.

Since:

1.1, 2001-06-02

finalize

protected void finalize()

Finalization. Closes the underlying output stream, if any.

Overrides:

finalize in class java.lang.Object

Since:

1.1, 2001-05-18