A.40 library(prolog_xref): Prolog cross-referencer data collection
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Availability::- use_module(library(prolog_xref)).(can be autoloaded)
Source[nondet]xref_called(?Source, ?Called, ?By)
[nondet]xref_called(?Source, ?Called, ?By, ?Cond)
[nondet]xref_called(?Source, ?Called, ?By, ?Cond, ?Line)
True when By is called from Called in Source. Note that xref_called/3 and xref_called/4 use distinct/2 to return only distinct Called-By pairs. The xref_called/5 version may return duplicate Called-By if Called is called from multiple clauses in By, but at most one call per clause.
By is a head term or one of the reserved terms '<directive>'(Line) or '<public>'(Line), indicating the call is from an (often initialization/1) directive or there is a public/1 directive that claims the predicate is called from in some untractable way.
Cond is the (accumulated) condition as defined by :- if(Cond) under which the calling code is compiled.
Line is the start line of the calling clause.