monq.jfa

Class EmptyCharSource

java.lang.Object

monq.jfa.EmptyCharSource

All Implemented Interfaces:

CharSource

Direct Known Subclasses:

ByteCharSource, CharSequenceCharSource, DfaRun, ReaderCharSource

public class EmptyCharSource
extends java.lang.Object
implements CharSource

represents a minimal implementation of the CharSource interface mainly providing the ability to push characters back into the stream for later reading. Objects of this class don't deliver any data except it was pushed into them before. Subclasses exist which read from input sources.

Extend this class and override the read() methods to create a character source which is not empty up front. The implementation of the read() function should look like this:

   public int read() throws java.io.IOException {
     int ch = super.readOne();
     if( ch>=0 ) return ch;
     <em>code to deliver new data</em>
   }

Hint: Use objects of this class with DfaRun.setIn() from within an FaAction to force early EOF and stop the DfaRun.

Author:

© 2004 Harald Kirsch

Constructor Summary

Constructors

Constructor and Description
EmptyCharSource()
EmptyCharSource(int initialDepth)

Method Summary

Modifier and Type	Method and Description
int	pop(java.lang.StringBuilder out)
int	pop(java.lang.StringBuilder out, int count)
void	pushBack(java.lang.StringBuilder buf, int start) moves the tail of buf starting with character index startAt back onto the character source while deleting them from the given StringBuilder.
int	read() returns a single character or -1 to indicate end of file.

Methods inherited from class java.lang.Object

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

Constructor Detail

EmptyCharSource

public EmptyCharSource()

EmptyCharSource

public EmptyCharSource(int initialDepth)

Method Detail

pushBack

public void pushBack(java.lang.StringBuilder buf,
                     int start)

Description copied from interface: CharSource

moves the tail of buf starting with character index startAt back onto the character source while deleting them from the given StringBuilder. The data is pushed from back to front such that a sequence of read/pushBack/read will read two times the same string.

Specified by:

pushBack in interface CharSource

pop

public int pop(java.lang.StringBuilder out)

pop

public int pop(java.lang.StringBuilder out,
               int count)

read

public int read()
         throws java.io.IOException

Description copied from interface: CharSource

returns a single character or -1 to indicate end of file.

Specified by:

read in interface CharSource

Throws:

java.io.IOException