Module openj9.dtfj

Package com.ibm.dtfj.javacore.parser.framework.scanner

Class LookAheadBuffer

java.lang.Object

com.ibm.dtfj.javacore.parser.framework.scanner.LookAheadBuffer

All Implemented Interfaces:

ILookAheadBuffer

public class LookAheadBuffer
extends Object
implements ILookAheadBuffer

Constructor Summary

Constructors

Constructor	Description
LookAheadBuffer(int size, IScanner scanner)

Method Summary

Modifier and Type	Method	Description
boolean	allConsumed()
void	consume()	Consumes the first element in the buffer
void	init()
int	length()
IParserToken	lookAhead(int depth)	Looks ahead by a depth amount.
boolean	match(String tokenType)	Matches a given type to the token type found at the first element of the buffer.
int	maxDepth()
void	setLookAheadDepth(int depth)	Depth of the lookahead can be changed after creation.

Methods declared in class java.lang.Object

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

Constructor Details

LookAheadBuffer

public LookAheadBuffer(int size,
 IScanner scanner)

Method Details

match

public boolean match(String tokenType)

Description copied from interface: ILookAheadBuffer

Matches a given type to the token type found at the first element of the buffer.

Specified by:

match in interface ILookAheadBuffer

Parameters:

tokenType -

Returns:

true if match is successful

consume

public void consume()
             throws IOException,
ScannerException

Consumes the first element in the buffer

Specified by:

consume in interface ILookAheadBuffer

Throws:

ScannerException

IOException

allConsumed

public boolean allConsumed()

Specified by:

allConsumed in interface ILookAheadBuffer

Returns:

true if all tokens from both the input stream and the lookahead buffer have been consumed

lookAhead

public IParserToken lookAhead(int depth)
                       throws IOException,
ScannerException,
IndexOutOfBoundsException

Description copied from interface: ILookAheadBuffer

Looks ahead by a depth amount. The lowest depth to look ahead is 1. Note that in some cases, a lookahead may be attempted on an earlier error condition that lead to an empty buffer (e.g., an exception was thrown during a fill process, and although more tokens may remain in the input source, the lookahead value may itself be null. Consequently, the lookahead buffer refills first before attempting the lookahead.

Specified by:

lookAhead in interface ILookAheadBuffer

Parameters:

depth - to lookahead

Returns:

token at specified lookahead depth or IndexOutOfBoundsException.

Throws:

ScannerException

IOException

IndexOutOfBoundsException - if depth is outside the depth range of the buffer. Minimum depth is always 1.

See Also:

• ILookAheadBuffer.lookAhead(int)

init

public void init()
          throws IOException,
ScannerException

Specified by:

init in interface ILookAheadBuffer

Throws:

ScannerException

IOException

setLookAheadDepth

public void setLookAheadDepth(int depth)
                       throws IOException,
ScannerException

Description copied from interface: ILookAheadBuffer

Depth of the lookahead can be changed after creation.
If the new depth is less that the current depth, no new tokens will be read until the outstanding tokens (current depth - new depth) are first consumed.
If the new depth is greater than the current depth, the lookahead will read new tokens to fill the delta.

Specified by:

setLookAheadDepth in interface ILookAheadBuffer

Parameters:

depth - to change

Throws:

ScannerException

IOException

See Also:

• ILookAheadBuffer.setLookAheadDepth(int)

length

public int length()

Specified by:

length in interface ILookAheadBuffer

maxDepth

public int maxDepth()

Specified by:

maxDepth in interface ILookAheadBuffer