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.TH "INQUIRE PATHS TO ANCESTORS" 3P "29 February 1991"
.SH NAME
INQUIRE PATHS TO ANCESTORS \- inquire the ancestors of the specified structure
.IX "Structure Networks" "INQUIRE PATHS TO ANCESTORS"
.SH SYNOPSIS
.SS C Syntax
.ft B
.ta 1.40i 3i
.nf
void
pinq_paths_ances ( struct_id, order, depth, store, error_ind, paths )
Pint	struct_id;	\fIstructure identifier\fP
Ppath_order	order;	\fIpath order\fP
Pint	depth;	\fIpath depth\fP
Pstore	store;	\fIhandle to Store object\fP
Pint	*error_ind;	\fI\s-2OUT\s+2 error indicator\fP
Pelem_ref_list_list	**paths;	\fI\s-2OUT\s+2 structure path list\fP
.fi
.ft R
.SS Required PHIGS Operating States
(PHOP, *, *, *)
.SH DESCRIPTION
.SS Purpose
\s-2INQUIRE PATHS TO ANCESTORS\s+2 determines the path or paths
in the Central Structure Store that reference the specified structure.
It performs the same function in \s-2PEX-SI\s0 as \s-2INQUIRE PATHS TO ANCESTORS\s+2
does in standard \s-2PHIGS\s+2.
.SS C Input Parameters
Applications using the \s-2C\s+2 binding must create a buffer to be used by this
function as memory space for storing data associated with the device state.
This buffer is passed as the \fIstore\fP argument.  
.LP
The store buffer is a data area managed by \s-2PHIGS\s+2. While the application 
is responsible for creating the inital buffer through a call to \s-2\CREATE STORE\s+2, 
\s-2PHIGS\s+2 manages this area such that there is sufficient memory for the 
specific inquiry. The data record within the store buffer is accessed 
by the pointer pointed to by \fIpaths\fR.
.IP \fIstruct_id\fP
Identifier of the structure to be inquired for ancestors.
.IP \fIorder\fP
Order in which the path lists are to be returned.
This is an enumerated type defined in phigs.h to have the following values:
.sp
.ta .5i +\w'PORDER_BOTTOM_FIRST     'u
.nf
	PORDER_TOP_FIRST	\fItop first\fP
	PORDER_BOTTOM_FIRST	\fIbottom first\fP
.fi
.IP \fIdepth\fP
Depth (maximum number of references) of path lists to return.
.IP \fIstore\fP
The memory buffer \s-2PHIGS\s+2 is to use for storing the information
returned.  
This buffer must exist prior to calling this function (see
\s-2CREATE STORE (3P)\s+2).
.SS C Output Parameters
.IP \fIerror_ind\fP
A pointer to the location to store the error number of any error detected
by this function.
.IP \fIpaths\fP
A pointer to a pointer to a Pelem_ref_list_list structure which
contains a list of the specified structure's structure path lists.
Pelem_ref_list_list is defined in phigs.h as follows:
.sp
.ta .5i +\w'Pelem_ref_list     'u +\w'num_elem_ref_lists;     'u
.nf
typedef struct{
.sp .2
	Pint	num_elem_ref_lists;	/* number of execute reference lists */
	Pelem_ref_list	*ex_ref_list;	/* list of execute reference lists */
.sp .2
} Pelem_ref_list_list;
.fi
.sp
The \fInum_elem_ref_lists\fP component specifies the number of structure path lists,
or execute reference lists. The \fIex_ref_list\fP component is a pointer to 
a list, \fInum_elem_ref_lists\fP long, of Pelem_ref_list structures, 
containing the specified structure's execute reference lists.
Pelem_ref_list is defined in phigs.h as follows:
.sp
.ta .5i +\w'Pelem_ref     'u +\w'num_elem_refs;     'u
.nf
typedef struct{
.sp .2
	Pint	num_elem_refs;	/* number of execute references */
	Pelem_ref	*elem_refs;	/* list of execute references */
.sp .2
} Pelem_ref_list;
.fi
.sp
\fIelem_refs\fP is a pointer to a list \fInum_elem_refs\fP long of Pelem_ref
structures containing the structure identifier and element number of each
execute reference structure element in the execute reference list.
Pelem_ref is defined in phigs.h as follows:
.sp
.ta .5i +\w'Pint     'u +\w'elem_pos;     'u
.nf
typedef struct {
.sp .2
	Pint	struct_id;	/* structure identifier */
	Pint	elem_pos;	/* element number */
.sp .2
} Pelem_ref;
.fi
.SS Execution
When \s-2INQUIRE PATHS TO ANCESTORSS\s+2 is called,
\fIpaths\fP is
filled with list(s) identifying the \s-2EXECUTE STRUCTURE\s+2 structure
elements which refer to \fIstruct_id\fP,
in the order of traversal.
These \s-2EXECUTE STRUCTURE\s+2 structure elements are represented as
(structure identifier, element position) pairs, giving the parent structure
identifier and the position of the \s-2EXECUTE STRUCTURE\s+2 structure element.
Whenever \fIstruct_id\fP itself is included at the bottom
of a returned path of ancestors, it is represented by a
(structure identifier, element position) pair with an element position of 0.
\fIorder\fP and \fIdepth\fP are used to determine the portion
of each path returned.  The number of references returned in each path 
is specified by \fIdepth\fP; a \fIdepth\fP of 0 returns all the references in the path.
In case of truncation, \fIorder\fP determines whether the head
(\s-2PORDER_TOP_FIRST\s+2) or the tail (\s-2PORDER_BOTTOM_FIRST\s+2) portion of 
a path is returned.  If a path truncation results in two or more 
partial paths with the same set of element references, only one of 
the identical path portions is returned.
.LP
For example, specifying \s-2PORDER_TOP_FIRST\s+2 and a depth of 0 returns all
paths to \fIstruct_id\fP. Specifying \s-2PORDER_TOP_FIRST\s+2
and a depth of 1 returns the root of each structure network that
references \fIstruct_id\fP. Specifying \s-2PORDER_BOTTOM_FIRST\s+2 and a depth of
2 returns all the parents of \fIstruct_id\fP.
.SH ERRORS
.IP 002
Ignoring function, function requires state 
(\s-2PHOP\s+2, \s-2*\s+2, \s-2*\s+2, \s-2*\s+2)
.IP 201
Ignoring function, the specified structure does not exist
.IP 207
Ignoring function, the specified path depth is less than zero
.SH SEE ALSO
.nf
.IP
.ta 0.5i
.SM "EXECUTE STRUCTURE (3P)"
.SM "INQUIRE PATHS DESCENDENTS (3P)"
.SM "CREATE STORE (3P)"
.SM "DELETE STORE (3P)"
.fi