org.rigwit.forth

Class ForthStringReader

java.lang.Object

org.rigwit.forth.ForthReader

org.rigwit.forth.ForthStringReader

public class ForthStringReader
extends ForthReader

Reads input directly from the Forth data space. It is used by EVALUATE.

Field Summary

Fields inherited from class org.rigwit.forth.ForthReader

bufferSize, description, lineNumber, position

Constructor Summary

Constructors

Constructor and Description
ForthStringReader(VM vm, int offset, int length) Construct a reader to read a string directly form the Forth data space, starting at offset and lasting for length characters.

Method Summary

Methods

Modifier and Type	Method and Description
protected int	charAt(int off) Return the character at the given offset into the buffer or -1 if the character is unavailable.
void	close() Close the input stream.
int	getBase() Return the location of the first character in the input stream.
int	read() Reads a single character.
boolean	refill() Attempt to fill the input buffer from the input source, and return true if successful.
ForthReader	restoreInput(VM vm) Restore the current input environment from the system stack.
void	saveInput(VM vm) Save the current input parameters on the system stack.

Methods inherited from class org.rigwit.forth.ForthReader

backup, getDescription, getLineNumber, getPosition, isEmpty, ready, setLineNumber, setPosition, size

Methods inherited from class java.lang.Object

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

Constructor Detail

ForthStringReader

public ForthStringReader(VM vm,
                 int offset,
                 int length)

Construct a reader to read a string directly form the Forth data space, starting at offset and lasting for length characters.

Parameters:

vm - the virtual machine where the string is stored.

offset - the start of the string

length - the length of the string, in characters

Method Detail

read

public int read()
         throws java.io.IOException

Description copied from class: ForthReader

Reads a single character.

Specified by:

read in class ForthReader

Returns:

The character read, as an integer in the range 0x00-0xffff, or -1 if the end of the stream has been reached.

Throws:

java.io.IOException - when there is a problem reading the input stream.

close

public void close()
           throws java.io.IOException

Description copied from class: ForthReader

Close the input stream.

Specified by:

close in class ForthReader

Throws:

java.io.IOException

charAt

protected int charAt(int off)

Description copied from class: ForthReader

Return the character at the given offset into the buffer or -1 if the character is unavailable. A character may be unavailable if the offset is outwith the buffer, or if the input stream is out of characters.

Specified by:

charAt in class ForthReader

Parameters:

off - the offset from the start of the buffer to obtain a character.

Returns:

The character at the given offset or -1 if the character is not available.

getBase

public int getBase()

Description copied from class: ForthReader

Return the location of the first character in the input stream. This will normally be zero, but some readers may overload this to return a non-zero value.

Overrides:

getBase in class ForthReader

Returns:

the location of the first character of the string.

saveInput

public void saveInput(VM vm)

Description copied from class: ForthReader

Save the current input parameters on the system stack. Called by the save-input function. Place all of the parameters on the data stack followed by the number of parameters.

Specified by:

saveInput in class ForthReader

Parameters:

vm - the virtual machine to use when saving the current input environment.

restoreInput

public ForthReader restoreInput(VM vm)

Description copied from class: ForthReader

Restore the current input environment from the system stack. Called by the restore-input function. This is the counter part to the saveInput() method. The top of the stack holds the number of parameters saved.

Specified by:

restoreInput in class ForthReader

Parameters:

vm - the virtual machine to recover input parameters form.

Returns:

the ForthReader to use for further input or null if the input environment could not be recovered.

refill

public boolean refill()

Description copied from class: ForthReader

Attempt to fill the input buffer from the input source, and return true if successful.

If successful, make the result the input buffer, set position to zero, set bufferSize to the number of bytes read, and return true. Receipt of a line containing no characters is considered successful. If there is no input available return false.

This method is called by the Forth function refill.

Specified by:

refill in class ForthReader

Returns:

true if a line was successfully read into the buffer.