webwork.expr

Class Token

java.lang.Object

webwork.expr.Token

All Implemented Interfaces:

Serializable

public class Token
extends Object
implements Serializable

Describes the input token stream.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
int	beginColumn The column number of the first character of this Token.
int	beginLine The line number of the first character of this Token.
int	endColumn The column number of the last character of this Token.
int	endLine The line number of the last character of this Token.
String	image The string image of the token.
int	kind An integer that describes the kind of this token.
Token	next A reference to the next regular (non-special) token from the input stream.
Token	specialToken This field is used to access special tokens that occur prior to this token, but after the immediately preceding regular (non-special) token.

Constructor Summary

Constructors

Constructor and Description
Token() No-argument constructor
Token(int kind) Constructs a new token for the specified Image.
Token(int kind, String image) Constructs a new token for the specified Image and Kind.

Method Summary

Methods

Modifier and Type	Method and Description
Object	getValue() An optional attribute value of the Token.
static Token	newToken(int ofKind)
static Token	newToken(int ofKind, String image) Returns a new Token object, by default.
String	toString() Returns the image.

Methods inherited from class java.lang.Object

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

Field Detail

kind

public int kind

An integer that describes the kind of this token. This numbering system is determined by JavaCCParser, and a table of these numbers is stored in the file ...Constants.java.

beginLine

public int beginLine

The line number of the first character of this Token.

beginColumn

public int beginColumn

The column number of the first character of this Token.

endLine

public int endLine

The line number of the last character of this Token.

endColumn

public int endColumn

The column number of the last character of this Token.

image

public String image

The string image of the token.

next

public Token next

A reference to the next regular (non-special) token from the input stream. If this is the last token from the input stream, or if the token manager has not read tokens beyond this one, this field is set to null. This is true only if this token is also a regular token. Otherwise, see below for a description of the contents of this field.

specialToken

public Token specialToken

This field is used to access special tokens that occur prior to this token, but after the immediately preceding regular (non-special) token. If there are no such special tokens, this field is set to null. When there are more than one such special token, this field refers to the last of these special tokens, which in turn refers to the next previous special token through its specialToken field, and so on until the first special token (whose specialToken field is null). The next fields of special tokens refer to other special tokens that immediately follow it (without an intervening regular token). If there is no such token, this field is null.

Constructor Detail

Token

public Token()

No-argument constructor

Token

public Token(int kind)

Constructs a new token for the specified Image.

Token

public Token(int kind,
     String image)

Constructs a new token for the specified Image and Kind.

Method Detail

getValue

public Object getValue()

An optional attribute value of the Token. Tokens which are not used as syntactic sugar will often contain meaningful values that will be used later on by the compiler or interpreter. This attribute value is often different from the image. Any subclass of Token that actually wants to return a non-null value can override this method as appropriate.

toString

public String toString()

Returns the image.

Overrides:

toString in class Object

newToken

public static Token newToken(int ofKind,
             String image)

Returns a new Token object, by default. However, if you want, you can create and return subclass objects based on the value of ofKind. Simply add the cases to the switch for all those special cases. For example, if you have a subclass of Token called IDToken that you want to create if ofKind is ID, simply add something like : case MyParserConstants.ID : return new IDToken(ofKind, image); to the following switch statement. Then you can cast matchedToken variable to the appropriate type and use sit in your lexical actions.

newToken

public static Token newToken(int ofKind)