.\" gd_entry_list.3.  The gd_entry_list man page.
.\"
.\" Copyright (C) 2012 D. V. Wiebe
.\"
.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.\"
.\" This file is part of the GetData project.
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.\" under the terms of the GNU Free Documentation License, Version 1.2 or
.\" any later version published by the Free Software Foundation; with no
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.TH gd_entry_list 3 "28 June 2012" "Version 0.8.0" "GETDATA"
.SH NAME
gd_entry_list, gd_field_list, gd_field_list_by_type gd_mfield_list, gd_mfield_list_by_type,
gd_mvector_list, gd_vector_list \(em list field entries in a dirfile
.SH SYNOPSIS
.B #include <getdata.h>
.HP
.nh
.ad l
.BI "const char **gd_entry_list(DIRFILE *" dirfile ", const char *" parent ,
.BI "unsigned int " type ", unsigned int " flags );
.HP
.BI "const char **gd_field_list(DIRFILE *" dirfile );
.HP
.BI "const char **gd_field_list_by_type(DIRFILE *" dirfile ", gd_entype_t " type );
.HP
.BI "const char **gd_mfield_list(DIRFILE *" dirfile ", const char *" parent );
.HP
.BI "const char **gd_mfield_list_by_type(DIRFILE *" dirfile ,
.BI "const char *" parent ", gd_entype_t " type );
.HP
.BI "const char **gd_mvector_list(DIRFILE *" dirfile ", const char *" parent );
.HP
.BI "const char **gd_vector_list(DIRFILE *" dirfile );
.hy
.ad n
.SH DESCRIPTION
The
.BR gd_entry_list ()
function queries a dirfile(5) database specified by
.I dirfile
and returns a list of names of field entries satisfying the supplied criteria.
If
.I parent
is non-NULL, metafields under the field specified by
.I parent
are considered; otherwise, top-level fields are considered, and metafields
ignored.

The
.I type
argument should be one of the following symbols indicating an explicit entry
type to list:
.IP
.nh
.ad l
.BR GD_BIT_ENTRY ", " GD_CARRAY_ENTRY ", " GD_CONST_ENTRY ", " GD_DIVIDE_ENTRY ,
.BR GD_INDEX_ENTRY ", " GD_LINCOM_ENTRY ", " GD_LINTERP_ENTRY ,
.BR GD_MPLEX_ENTRY ", " GD_MULTIPLY_ENTRY ", " GD_PHASE_ENTRY ,
.BR GD_POLYNOM_ENTRY ", " GD_RAW_ENTRY ", " GD_RECIP_ENTRY ,
.BR GD_SBIT_ENTRY ", " GD_STRING_ENTRY ", " GD_WINDOW_ENTRY .
.ad n
.hy
.PP
.RB ( GD_INDEX_ENTRY
is a special field type for the implicit
.I INDEX
field) or else one of the following special symbols:
.TP
.B GD_ALL_ENTRIES \fR(= 0)
List entries of all types.
.TP
.B GD_ALIAS_ENTRIES
List only aliases.  This is the only way to get a list including aliases which
do not point to valid field codes.
.TP
.B GD_SCALAR_ENTRIES
List only scalar field types
.RB ( CONST ", " CARRAY ", " STRING ).
.TP
.B GD_VECTOR_ENTRIES
List only vector field types (all field types except the scalar field types
listed above).
.PP
The
.I flags
argument should be zero or more of the following flags, bitwise or'd together:
.TP
.B GD_ENTRIES_HIDDEN
Include hidden entries (see
.BR gd_hidden (3))
in the list: normally hidden entries are skipped;
.TP
.B GD_ENTRIES_NOALIAS
Exclude aliases from the list: normally aliases are considered the same as
their target (that is: if a field satisfies the criteria, both its canonical
name and all its aliases will appear in the list).
.PP
The array returned will be de-allocated by a call to
.BR gd_close (3)
and should not be de-allocated by the caller.  The list returned should not be
assumed to be in any particular order.  The array is terminated by a NULL
pointer.  The number of elements in the array, excluding the terminating NULL,
can be obtained from an equivalent call to
.BR gd_nentries (3).

The caller may not modify any strings in the array, or the array itself.  Doing
so may cause database corruption.  The pointer returned is guaranteed to be
valid at least until
.BR gd_entry_list ()
is called again on the same DIRFILE object, or until the array is de-allocated
by a call to
.BR gd_close (3).
(Although the data may have become obsolete, if metadata have been modified in
the interrim.)
.SS Special Cases
The call
.RS
.BI gd_field_list( dirfile );
.RE
.PP
is equivalent to
.RS
.BI gd_entry_list( dirfile ", NULL, GD_ALL_ENTRIES, 0);
.RE
.PP
The call
.RS
.BI gd_field_list_by_type( dirfile ", " type );
.RE
.PP
is equivalent to
.RS
.BI gd_entry_list( dirfile ", NULL, " type ", 0);"
.RE
.PP
The call
.RS
.BI gd_mfield_list( dirfile ", " parent );
.RE
.PP
is equivalent to
.RS
.BI gd_entry_list( dirfile ", " parent ", GD_ALL_ENTRIES, 0);"
.RE
.PP
The call
.RS
.BI gd_mfield_list_by_type( dirfile ", " parent ", " type );
.RE
.PP
is equivalent to
.RS
.BI gd_entry_list( dirfile ", " parent ", " type ", 0);"
.RE
.PP
The call
.RS
.BI gd_mvector_list( dirfile ", " parent );
.RE
.PP
is equivalent to
.RS
.BI gd_entry_list( dirfile ", " parent ", GD_VECTOR_ENTRIES, 0);"
.RE
.PP
The call
.RS
.BI gd_vector_list( dirfile );
.RE
.PP
is equivalent to
.RS
.BI gd_entry_list( dirfile ", NULL, GD_VECTOR_ENTRIES, 0);"
.RE

.SH RETURN VALUE
Upon successful completion, these functions returns a pointer to an array of
strings containing the names of all the entries in the database satisfying the
supplied criteria.  On error, they return zero and sets
the dirfile error to a non-zero error value.  Possible error values are:
.TP 8
.B GD_E_BAD_CODE
The supplied parent field code was not found, or referred to a metafield itself.
.TP
.B GD_E_BAD_DIRFILE
The supplied dirfile was invalid.
.TP
.B GD_E_BAD_ENTRY
The
.I type
parameter supplied was not one of the symbols listed above.
.PP
The dirfile error may be retrieved by calling
.BR gd_error (3).
A descriptive error string for the last error encountered can be obtained from
a call to
.BR gd_error_string (3).
.SH SEE ALSO
.BR dirfile (5),
.BR gd_open (3),
.BR gd_error (3),
.BR gd_error_string (3),
.BR gd_hidden (3),
.BR gd_nentries (3)