Description

The ITokenizer interface defines the main elements of a tokenizer.

Important points

• 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 String.fromCharCode(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.

Fields

commentState

A token state to process comments.

abstract commentState: ICommentState?

decodeStrings

Decodes quoted strings.

abstract decodeStrings: bool

mergeWhitespaces

Merges whitespaces.

abstract mergeWhitespaces: bool

numberState

A token state to process numbers.

abstract numberState: INumberState?

quoteState

Token state to process quoted strings.

abstract quoteState: IQuoteState?

scanner

Stream scanner to tokenize.

abstract scanner: IScanner?

skipComments

Skips comments.

abstract skipComments: bool

skipEof

Skips End-Of-File token at the end of stream.

abstract skipEof: bool

skipUnknown

Skip unknown characters.

abstract skipUnknown: bool

skipWhitespaces

Skips whitespaces.

abstract skipWhitespaces: bool

symbolState

Token state to process symbols (single like “=” or muti-character like “<>")

abstract symbolState: ISymbolState?

unifyNumbers

Unifies numbers: “Integers” and “Floats” makes just “Numbers”.

abstract unifyNumbers: bool

whitespaceState

Token state to process white space delimiters.

abstract whitespaceState: IWhitespaceState?

wordState

Token state to process words or indentifiers.

abstract wordState: IWordState?

Instance methods

hasNextToken

Checks if there is a next token.

bool hasNextToken()

• returns: bool - true if scanner has a next token.

nextToken

Gets the next token from the scanner.

Token? nextToken()

• returns: Token? - next token or null if there are no more tokens left.

tokenizeBuffer

Tokenizes a string buffer into a list of tokens structures.

List<Token> tokenizeBuffer(String buffer)

• buffer: String - string buffer to be tokenized.
• returns: List<Token> - list of token structures.

tokenizeBufferToStrings

Tokenizes a string buffer into a list of strings.

List<String?> tokenizeBufferToStrings(String buffer)

• buffer: String - string buffer to be tokenized.
• returns: List<String?> - list of token strings.

tokenizeStream

Tokenizes a text stream into a list of token structures.

List<Token> tokenizeStream(IScanner scanner)

• scanner: IScanner - text stream to be tokenized.
• returns: List<Token> - list of token structures.

tokenizeStreamToStrings

Tokenizes a text stream into a list of strings.

List<String?> tokenizeStreamToStrings(IScanner scanner)

• scanner: IScanner - text stream to be tokenized.
• returns: List<String?> - list of token strings.