| Title: Tokenizer
Description: None
Copyright (c) 1999 Steven J. Metsker.
Copyright (c) 2001 The Open For Business Project - www.ofbiz.org
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A tokenizer divides a string into tokens. This class is
highly customizable with regard to exactly how this division
occurs, but it also has defaults that are suitable for many
languages. This class assumes that the character values read
from the string lie in the range 0-255. For example, the
Unicode value of a capital A is 65, so
System.out.println((char)65); prints out a
capital A.
The behavior of a tokenizer depends on its character state
table. This table is an array of 256 TokenizerState
states. The state table decides which state to
enter upon reading a character from the input
string.
For example, by default, upon reading an 'A', a tokenizer
will enter a "word" state. This means the tokenizer will
ask a WordState object to consume the 'A',
along with the characters after the 'A' that form a word.
The state's responsibility is to consume characters and
return a complete token.
The default table sets a SymbolState for every character
from 0 to 255, and then overrides this with:
From To State
0 ' ' whitespaceState
'a' 'z' wordState
'A' 'Z' wordState
160 255 wordState
'0' '9' numberState
'-' '-' numberState
'.' '.' numberState
'"' '"' quoteState
'\'' '\'' quoteState
'/' '/' slashState
In addition to allowing modification of the state table,
this class makes each of the states above available. Some
of these states are customizable. For example, wordState
allows customization of what characters can be part of a
word, after the first character.
author:
Steven J. Metsker
version:
1.0 |
