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read_token(?Token, ?Class)

Succeeds if the next token from the current input stream is successfully read and unified with Token and its token class with Class.

?Token: Variable or constant.
?Class: Variable or atom.

Description

This predicate is an interface to the Sepia tokenizer. It can be used to read terms which are not ended by a fullstop or even to build whole new parsers. The next token from the input stream is read and unified with Token. The token class of this token is unified with Class.

read_token(Token, Class) is equivalent to read_token(input, Token, Class). See read_token/3 for details.

Fail Conditions

Fails if Token does not unify with the next token read from the input stream or its class with Class.

Resatisfiable

No.

Exceptions

(5) type error: Class does not unify with an atom.
(190) end of file reached: End of file was encountered before reading any character.
(198) reading past the file end: Trying to read even after the error 190 was raised.

Examples