pip_services3_expressions.tokenizers.ITokenizer module

class pip_services3_expressions.tokenizers.ITokenizer.ITokenizer

Bases: abc.ABC

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 chr(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.

comment_state: pip_services3_expressions.tokenizers.ICommentState.ICommentState

decode_strings: bool

has_next_token() → bool 

Checks if there is the next token exist.

Returns: True if scanner has the next token.

merge_whitespaces: bool

next_token() → pip_services3_expressions.tokenizers.Token.Token 

Gets the next token from the scanner.

Returns: Next token of null if there are no more tokens left.

number_state: pip_services3_expressions.tokenizers.INumberState.INumberState

quote_state: pip_services3_expressions.tokenizers.IQuoteState.IQuoteState

scanner: pip_services3_expressions.io.IScanner.IScanner

skip_comments: bool

skip_eof: bool

skip_unknown: bool

skip_whitespaces: bool

symbol_state: pip_services3_expressions.tokenizers.ISymbolState.ISymbolState

tokenize_buffer(buffer: str) → List[pip_services3_expressions.tokenizers.Token.Token]

Tokenizes a string buffer into a list of tokens structures.

Parameters: buffer – A string buffer to be tokenized.
Returns: A list of token structures.

tokenize_buffer_to_strings(buffer: str) → List[str]

Tokenizes a string buffer into a list of strings.

Parameters: buffer – A string buffer to be tokenized.
Returns: A list of token strings.

tokenize_stream(scanner: pip_services3_expressions.io.IScanner.IScanner) → List[pip_services3_expressions.tokenizers.Token.Token]

Tokenizes a textual stream into a list of token structures.

Parameters: scanner – A textual stream to be tokenized.
Returns: A list of token structures.

tokenize_stream_to_string(scanner: pip_services3_expressions.io.IScanner.IScanner) → List[str]

Tokenizes a textual stream into a list of strings.

Parameters: scanner – A textual stream to be tokenized.
Returns: A list of token strings.

unify_numbers: bool

whitespace_state: pip_services3_expressions.tokenizers.IWhitespaceState.IWhitespaceState

word_state: pip_services3_expressions.tokenizers.IWordState.IWordState