/tutorial/backtracking/tiny_prolog/prolog_builtins.e

  1class PROLOG_BUILTINS
  2inherit PROLOG_COMMONS ABSTRACT_BACKTRACKING
  3creation
  4	make
  5feature
  6	make is 
  7		do
  8			init_builtins
  9		end
 10feature
 11	current_term: PROLOG_TERM
 12	current_compound: PROLOG_COMPOUND
 13	current_atom: PROLOG_ATOM
 14	current_functor: PROLOG_FUNCTOR
 15	current_proc: ROUTINE[like Current, TUPLE[]]
 16	current_data: LINKED_LIST[LINKED_LIST[PROLOG_TERM]]
 17feature
 18	evaluate_current_state is
 19		local
 20			atom: PROLOG_ATOM
 21			compound: PROLOG_COMPOUND
 22			functor: PROLOG_FUNCTOR
 23		do
 24			current_compound ?= current_term
 25			if current_compound /= Void then
 26				current_atom := current_compound.atom
 27				check current_atom /= Void end
 28			else
 29				current_atom ?= current_term
 30			end
 31			if current_atom = Void then
 32				-- TODO gerer les exeception de call
 33				partial_fail
 34			else
 35				current_functor.make(current_atom,current_term.arity)
 36				current_proc := builtins.reference_at(current_functor)
 37				if current_proc /= Void then
 38					current_proc.call([Current])
 39				else
 40					evaluate_from_database
 41				end
 42			end
 43		end
 44feature
 45	evaluate_from_database is
 46		do
 47			current_data := database.reference_at(current_functor)
 48			if current_data = Void then
 49				partial_fail
 50			else
 51				
 52			end
 53		end
 54feature {}
 55	init_builtins is
 56		do
 57			if builtins.is_empty then really_init_builtins end
 58		end
 59	really_init_builtins is
 60		do
 61			add_bi(once "fail",      0, agent {like Current}.bi_fail)
 62			add_bi(once "true",      0, agent {like Current}.bi_true)
 63			add_bi(once "atom",      1, agent {like Current}.bi_atom)
 64			add_bi(once "integer",   1, agent {like Current}.bi_integer)
 65			add_bi(once "float",     1, agent {like Current}.bi_float)
 66			add_bi(once "number",    1, agent {like Current}.bi_number)
 67			add_bi(once "atomic",    1, agent {like Current}.bi_atomic)
 68			add_bi(once "compound",  1, agent {like Current}.bi_compound)
 69			add_bi(once "callable",  1, agent {like Current}.bi_callable)
 70			add_bi(once "var",       1, agent {like Current}.bi_var)
 71			add_bi(once "nonvar",    1, agent {like Current}.bi_nonvar)
 72			add_bi(once "=",         2, agent {like Current}.bi_unify)
 73			add_bi(once "\=",        2, agent {like Current}.bi_not_unify)
 74		end
 75	add_bi(name: STRING; arity: INTEGER; proc: like current_proc) is
 76		local
 77			functor: PROLOG_FUNCTOR
 78		do
 79			builtins.add(proc,get_functor_by_name(name,arity))
 80		end
 81feature {}
 82	partial_switch(success: BOOLEAN) is
 83		do
 84			if success then
 85				partial_success
 86			else
 87				partial_fail
 88			end
 89		end
 90feature {}
 91	bi_fail is
 92		do
 93			partial_fail
 94		end
 95	bi_true is
 96		do
 97			partial_success
 98		end
 99feature {} -- type testing
100	bi_atom is
101		do
102			inspect current_compound.args.first.type
103			when type_atom then partial_success
104			else partial_fail
105			end
106		end
107	bi_integer is
108		do
109			inspect current_compound.args.first.type
110			when type_integer then partial_success
111			else partial_fail
112			end
113		end
114	bi_float is
115		do
116			inspect current_compound.args.first.type
117			when type_float then partial_success
118			else partial_fail
119			end
120		end
121	bi_number is
122		do
123			inspect current_compound.args.first.type
124			when type_integer, type_float then partial_success
125			else partial_fail
126			end
127		end
128	bi_atomic is
129		do
130			inspect current_compound.args.first.type
131			when type_atom, type_integer, type_float then partial_success
132			else partial_fail
133			end
134		end
135	bi_compound is
136		do
137			inspect current_compound.args.first.type
138			when type_compound then partial_success
139			else partial_fail
140			end
141		end
142	bi_callable is
143		do
144			inspect current_compound.args.first.type
145			when type_atom, type_compound then partial_success
146			else partial_fail
147			end
148		end
149	bi_var is
150		do
151			inspect current_compound.args.first.type
152			when type_var then partial_success
153			else partial_fail
154			end
155		end
156	bi_nonvar is
157		do
158			inspect current_compound.args.first.type
159			when type_var then partial_fail
160			else partial_success
161			end
162		end
163feature {} -- unification
164	bi_unify is
165		do
166			if unify(current_compound.args.item(0),current_compound.args.item(1)) then
167				partial_success
168			else
169				partial_fail
170			end
171		end
172	bi_not_unify is
173		do
174			if unify(current_compound.args.item(0),current_compound.args.item(1)) then
175				partial_fail
176			else
177				partial_success
178			end
179		end
180
181
182	bi_functor is
183		do
184		end
185	bi_call is
186		do
187		end
188end
189