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SP_read_from_string()
#include <sicstus/sicstus.h> int SP_read_from_string(SP_term_ref t, const char *string, SP_term_ref values[])
Assigns to tt
the result of reading a term from the its
textual representation string
. Variables that occur in the
term are bound to the corresponding term in val
.
The SP_term_ref to assign.
The string to read from.
The SP_term_refs to bind variables to.
The vector is terminated by 0
(zero).
values
may be NULL
, which is treated as an empty
vector.
Nonzero on success, and 0 otherwise.
The variables in the term are ordered according to their first
occurrence during a depth first traversal in increasing argument
order. That is, the same order as used by
terms:term_variables_bag/2
(see lib-terms). Variables that
do not have a corresponding entry in vals
are ignored. Entries
in vals
that do not correspond to a variable in the term are
ignored.
The string should be encoded using the SICStus Prolog internal encoding.
This example creates the term foo(X,42,42,X)
(without error
checking):
SP_term_ref x = SP_new_term_ref(); SP_term_ref y = SP_new_term_ref(); SP_term_ref term = SP_new_term_ref(); SP_term_ref vals[] = {x,y,x,0}; // zero-terminated SP_put_variable(x); SP_put_integer(y,42); SP_read_from_string(term, "foo(A,B,B,C).", vals); #if 0 A corresponds to vals[0] (x), B to vals[1] (y), C to vals[2] (x). A and C therefore both are bound to the variable referred to by x. B is bound to the term referred to by y (42). So term refers to a term foo(X,42,42,X). #endif
See Reading a goal from a string, for an example of using
SP_read_from_string()
to call an arbitrary goal.