xref: /freebsd/usr.sbin/bsdconfig/share/struct.subr (revision 193d9e768ba63fcfb187cfd17f461f7d41345048)
1if [ ! "$_STRUCT_SUBR" ]; then _STRUCT_SUBR=1
2#
3# Copyright (c) 2012-2013 Devin Teske
4# All rights reserved.
5#
6# Redistribution and use in source and binary forms, with or without
7# modification, are permitted provided that the following conditions
8# are met:
9# 1. Redistributions of source code must retain the above copyright
10#    notice, this list of conditions and the following disclaimer.
11# 2. Redistributions in binary form must reproduce the above copyright
12#    notice, this list of conditions and the following disclaimer in the
13#    documentation and/or other materials provided with the distribution.
14#
15# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25# SUCH DAMAGE.
26#
27# $FreeBSD$
28#
29############################################################ INCLUDES
30
31BSDCFG_SHARE="/usr/share/bsdconfig"
32. $BSDCFG_SHARE/common.subr || exit 1
33
34############################################################ FUNCTIONS
35
36# f_struct_define $type $member_name1 ...
37#
38# Define a new `structure' type $type made up of the properties $member_name1
39# $member_name2 and so-on. Properties are not typed and can hold any type of
40# data (including names of other structs).
41#
42# Before creating instances of a struct (using f_struct_new $type $name) you
43# should use this function to define $type.
44#
45# Both $type and member names should consist only of alpha-numeric letters or
46# the underscore.
47#
48f_struct_define()
49{
50	local type="$1"
51	[ "$type" ] || return $FAILURE
52	shift
53	setvar "_struct_typedef_$type" "$*"
54}
55
56# f_struct_new $type $name
57#
58# Create a new `structure' named $name of type $type.  There are two ways to
59# access properties of a struct, but they are not equal (each method has its
60# own unique benefits, discussed below).
61#
62# The primary method of accessing (both setting and getting) properties of any
63# struct is through the f_struct() function below.
64#
65# The secondary method of accessing data is by using $name as a function.
66#
67# Both access methods are cross-platform compatible with any version of sh(1).
68# Below is an example of the primary access method:
69#
70# 	f_struct_new MY_STRUCT_TYPE my_struct
71# 	f_struct my_struct set abc 123
72# 	f_struct my_struct get abc # prints 123 to stdout
73# 	f_struct my_struct get abc abc # sets local variable $abc to 123
74#
75# Alternatively, the secondary access method (details below):
76#
77# 	f_struct_new MY_STRUCT_TYPE my_struct
78# 	my_struct set abc 123
79# 	my_struct get abc # prints 123 to stdout
80# 	my_struct get abc abc # sets local variable $abc to 123
81#
82# The secondary form should only be used if/when:
83# 	+ You are certain that the structure already exists
84# 	+ You want a syntax error if/when the struct does not exist
85#
86# The primary benefit to the secondary form is syntax cleanliness and read-
87# ability. If you are unsure if a given struct exists (which would cause a
88# syntax error when using this form), you can use the primary access method to
89# first test for the existence of the struct. For example:
90#
91# 	if f_struct my_struct; then
92# 		my_struct get abc # only executed if my_struct exists
93# 	fi
94#
95# For more information, see the f_struct() function.
96#
97f_struct_new()
98{
99	local type="$1" name="$2"
100	f_dprintf "f_struct_new: type=[%s] name=[%s]" "$type" "$name"
101	[ "$name" ] || return $FAILURE
102	setvar "_struct_type_$name" "$type" || return $FAILURE
103	# OK to use bare $name at this point
104	eval $name\(\){ f_struct $name \"\$@\"\; }
105}
106
107# f_struct $name
108# f_struct $name get $property [$var_to_set]
109# f_struct $name set $property $new_value
110# f_struct $name unset $property
111#
112# Access routine for getting, setting, unsetting, and testing properties of
113# `structures'.
114#
115# If only given $name, returns success if struct $name has been created (using
116# the f_struct_new() function above).
117#
118# For getting properties of a struct (versus setting) there are two methods of
119# access. If $var_to_set is missing or NULL, the value of the property is
120# printed to standard output for capturing in a sub-shell (which is less-
121# recommended because of performance degredation; for example, when called in a
122# loop). Returns success unless the property is unset.
123#
124# For setting properties of a struct, sets the value of $property to $new_value
125# and returns success.
126#
127# For unsetting, the underlying environment variable associated with the given
128# $property is unset.
129#
130f_struct()
131{
132	local __name="$1" __action="$2" __property="$3"
133	case $# in
134	0) return $FAILURE ;;
135	1) f_have "$__name" ;;
136	*) case "$__action" in
137	   get) local __var_to_set="$4"
138	        f_getvar "_struct_value_${__name}_$__property" "$__var_to_set"
139	        ;;
140	   set) local new_value="$4"
141	        setvar "_struct_value_${__name}_$__property" "$new_value" ;;
142	   unset) unset "_struct_value_${__name}_$__property" ;;
143	   esac
144	esac
145	# Return the status of the last command above
146}
147
148# f_struct_free $name
149#
150# Unset the collection of environment variables and accessor-function
151# associated with struct $name.
152#
153f_struct_free()
154{
155	local name="$1" type member members
156	f_getvar "_struct_type_$name" type
157	f_dprintf "f_struct_free: name=[%s] type=[%s]" "$name" "$type"
158	[ "$name" ] || return $FAILURE
159	f_getvar "_struct_typedef_$type" members
160	for member in $members; do
161		f_struct "$name" unset $member
162	done
163	unset -f "$name"
164	unset "_struct_type_$name"
165}
166
167# f_struct_copy $from_name $to_name
168#
169# Copy the properties of one struct to another. If struct $to_name does not
170# exist, it is created. If struct $from_name does not exist, nothing is done
171# and struct $to_name remains unmodified.
172#
173# Returns success unless struct $to_name did not exist and f_struct_new() was
174# unable to create it.
175#
176f_struct_copy()
177{
178	local from_name="$1" to_name="$2" type
179	f_dprintf "f_struct_copy: from_name=[%s] to_name=[%s]" \
180	          "$from_name" "$to_name"
181	f_getvar "_struct_type_$from_name" type
182	f_struct "$to_name" ||
183		f_struct_new "$type" "$to_name" || return $FAILURE
184	f_struct "$from_name" || return $SUCCESS
185	f_dprintf "f_struct_copy: copying properties from %s to %s" \
186	          "$from_name" "$to_name"
187	local property properties from_value n=0 k=0
188	f_getvar "_struct_typedef_$type" properties
189	for property in $properties; do
190		k=$(( $k + 1 ))
191		if f_struct "$from_name" get $property from_value; then
192			f_struct "$to_name" set $property "$from_value"
193			n=$(( $n + 1 ))
194		else
195			f_struct "$to_name" unset $property
196		fi
197	done
198	f_dprintf "f_struct_copy: copied %u of %u properties from %s to %s" \
199	          "$n" "$k" "$from_name" "$to_name"
200}
201
202############################################################ MAIN
203
204f_dprintf "%s: Successfully loaded." struct.subr
205
206fi # ! $_STRUCT_SUBR
207