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

comment_state

Token state to process comments.

comment_state: ICommentState

decode_strings

Decodes quoted strings.

decode_strings: bool

merge_whitespaces

Merges whitespaces.

merge_whitespaces: bool

number_state

Token state to process numbers.

number_state: INumberState

quote_state

Token state to process quoted strings.

quote_state: IQuoteState

scanner

Stream scanner to tokenize.

scanner: IScanner

skip_comments

Skips comments.

skip_comments: bool

skip_eof

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

skip_eof: bool

skip_unknown

Skips unknown characters.

skip_unknown: bool

skip_whitespaces

Skips whitespaces.

skip_whitespaces: bool

symbol_state

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

symbol_state: ISymbolState

unify_numbers

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

unify_numbers: bool

whitespace_state

Token state to process white space delimiters.

whitespace_state: IWhitespaceState

word_state

Token state to process words or indentifiers.

word_state: IWordState

Instance methods

has_next_token

Checks if there is a next token.

has_next_token(): bool

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

next_token

Gets the next token from the scanner.

next_token(): Token

• returns: Token - next token or None if there are no more tokens left.

tokenize_buffer

Tokenizes a string buffer into a list of tokens structures.

tokenize_buffer(buffer: str): List[Token]

• buffer: str - string buffer to be tokenized.
• returns: List[Token] - list of token structures.

tokenize_buffer_to_strings

Tokenizes a string buffer into a list of strings.

tokenize_buffer_to_strings(buffer: str): List[str]

• buffer: str - string buffer to be tokenized.
• returns: List[str] - list of token strings.

tokenize_stream

Tokenizes a text stream into a list of token structures.

tokenize_stream(scanner: IScanner): List[Token]

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

tokenize_stream_to_strings

Tokenizes a text stream into a list of strings.

tokenize_stream_to_strings(scanner: IScanner): List[str]

• scanner: IScanner - text stream to be tokenized.
• returns: List[str] - list of token strings.