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prolog_codewalk.pl -- Prolog code walker |
This module walks over the loaded program, searching for callable predicates. It started as part of library(prolog_autoload) and has been turned into a separate module to facilitate operations that require the same reachability analysis, such as finding references to a predicate, finding unreachable code, etc.
For example, the following determins the call graph of the loaded
program. By using source(true)
, The exact location of the call in the
source file is passed into _Where.
:- dynamic calls/2. assert_call_graph :- retractall(calls(_, _)), prolog_walk_code([ trace_reference(_), on_trace(assert_edge), source(false) ]), predicate_property(calls(_,_), number_of_clauses(N)), format('Got ~D edges~n', [N]). assert_edge(Callee, Caller, _Where) :- calls(Caller, Callee), !. assert_edge(Callee, Caller, _Where) :- assertz(calls(Caller, Callee)).
Options processed:
ignore
or
error
(default is ignore
).source(false)
and then process only interesting
clauses with source information.user
and library
.true
(default), analysis is
only restarted if the inferred meta-predicate contains a
callable argument. If all
, it will be restarted until no
more new meta-predicates can be found.false
(default true
), do not analyse the arguments
of meta predicates. Standard Prolog control structures are
always analysed.trace_reference
.
Called as call(Cond, Callee, Context)
, where Context is a
dict containing the following keys:
File:Line
representing the location of the declaration.trace_reference
is found, call
call(OnEdge, Callee, Caller, Location)
, where Location is a
dict containing a subset of the keys clause
, file
,
character_count
, line_count
and line_position
. If
full position information is available all keys are present.
If the clause layout is unknown the only the clause
, file
and line_count
are available and the line is the start line
of the clause. For a dynamic clause, only the clause
is
present. If the position is associated to a directive,
the clause
is missing. If nothing is known the Location
is an empty dict.on_edge
, but location is not translated and is one
of these:
clause_term_position(+ClauseRef, +TermPos)
clause(+ClauseRef)
file_term_position(+Path, +TermPos)
file(+File, +Line, -1, _)
Caller is the qualified head of the calling clause or the atom '<initialization>'.
false
(default true
), to not try to obtain detailed
source information for printed messages.true
(default false
), report derived meta-predicates
and iterations.
@compat OnTrace was called using Caller-Location in older versions.
same_term
, ==
, =@=
or subsumes_term
module_class(+list(Classes))