prolog_clause:clause

clause_info(+ClauseRef, -File, -TermPos, -VarOffsets) is semidet

clause_info(+ClauseRef, -File, -TermPos, -VarOffsets, +Options) is semidet

Fetches source information for the given clause. File is the file from which the clause was loaded. TermPos describes the source layout in a format compatible to the subterm_positions option of read_term/2. VarOffsets provides access to the variable allocation in a stack-frame. See make_varnames/5 for details.

Note that positions are character positions, i.e., not bytes. Line endings count as a single character, regardless of whether the actual ending is \n or =|\r\n|_.

Defined options are:

variable_names(-Names): Unify Names with the variable names list (Name=Var) as returned by read_term/3. This argument is intended for reporting source locations and refactoring based on analysis of the compiled code.
head(-Head)
body(-Body): Get the head and body as terms. This is similar to clause/3, but a seperate call would break the variable identity.