[ Character I/O | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]

# 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 ECLiPSe 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.

### Modes and Determinism

- read_token(-, -) is det

### Modules

This predicate is sensitive to its module context (tool predicate, see @/2).

### 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

       See read_token/3 for examples.

## See Also

get_chtab / 2, set_chtab / 2, read_token / 3