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Argument Term in a Formula

This module defines a class term_c. The objects of this class correspond to argument terms in input formulas. Argument terms can be constants (symbolic constants/atoms or integers), variables, and anonymous variables. Note that there are other classes for argument terms in facts (which can be only constants) (class farg_c), and for argument terms in rules (which need a distinction between the first/binding occurence of a variable and other/bound occurrences) (class rarg_c).

Construction:

The constructor for this class is overloaded corresponding to the different kinds of terms:

Constructor from Variable:
term_c(var_t var);
This method creates a new argument term that is a variable.
Constructor from Constant (Ground Term):
term_c(cnst_t cnst);
This method creates a new argument term that is a constant, i.e. a ground term. Currently constants are either symbolic constants (atoms) or integers, see cnst_c.
Constructor for Anonymous Variable:
term_c(void);
This method creates a new argument term that is an anonymous variable.

Object Methods:

is_var:
bool_t is_var(void) const;
This method returns BOOL_TRUE if this term is a (non-anonymous) variable. Otherwise it returns BOOL_FALSE.
is_anon:
bool_t is_anon(void) const;
This method returns BOOL_TRUE if this term is an anonymous variable. Otherwise it returns BOOL_FALSE.
is_atom:
bool_t is_cnst(void) const;
This method returns BOOL_TRUE if this term is a constant (i.e. ground). Otherwise it returns BOOL_FALSE.
get_var:
var_t get_var(void) const;
This method may only be called if this term is a variable. It then returns a pointer to the variable (an object of class var_c).
get_cnst:
cnst_t get_cnst(void) const;
This method may only be called if this term is a constant (ground). It then returns a pointer to the constant (an object of class cnst_c).
print:
void print(void) const;
This method prints the term.

Implementation:

Stefan Brass (sbrass@sis.pitt.edu), October 10, 2001.    [HTML 3.2 Checked]