built-in method

phrase/3

Description

phrase(GrammarRuleBody, Input, Rest)
phrase(::GrammarRuleBody, Input, Rest)
phrase(Object::GrammarRuleBody, Input, Rest)

True when the GrammarRuleBody grammar rule body can be applied to the Input-Rest difference list of tokens. In the most common case, GrammarRuleBody is a non-terminal defined by a grammar rule. This built-in method is declared private and thus cannot be used as a message to an object. When using a backend Prolog compiler supporting a module system, calls in the format phrase(Module:GrammarRuleBody, Input, Rest) may also be used.

This method is opaque to cuts in the first argument. When the first argument is sufficiently instantiated at compile-time, the method call is compiled in order to eliminate the implicit overheads of converting the grammar rule body into a goal and meta-calling it. For performance reasons, the second and third arguments are only type-checked at compile time.

Meta-predicate template

phrase(2, *, *)

Modes and number of proofs

phrase(+callable, ?list, ?list) - zero_or_more

Errors

GrammarRuleBody is a variable:

instantiation_error

GrammarRuleBody is neither a variable nor a callable term:

type_error(callable, GrammarRuleBody)

Examples

To parse a list of tokens using a local non-terminal:

phrase(NonTerminal, Input, Rest)

To parse a list of tokens using a non-terminal within the scope of self:

phrase(::NonTerminal, Input, Rest)

To parse a list of tokens using a public non-terminal of an explicit object:

phrase(Object::NonTerminal, Input, Rest)

See also

call//1-N, phrase/2, phrase/3