xref: /freebsd/usr.sbin/bsdconfig/share/struct.subr (revision d0b2dbfa0ecf2bbc9709efc5e20baf8e4b44bbbf)

if [ ! "$_STRUCT_SUBR" ]; then _STRUCT_SUBR=1
#
# Copyright (c) 2012-2013 Devin Teske
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
#
############################################################ INCLUDES

BSDCFG_SHARE="/usr/share/bsdconfig"
. $BSDCFG_SHARE/common.subr || exit 1

############################################################ FUNCTIONS

# f_struct_define $type $member_name1 ...
#
# Define a new `structure' type $type made up of the properties $member_name1
# $member_name2 and so-on. Properties are not typed and can hold any type of
# data (including names of other structs).
#
# Before creating instances of a struct (using f_struct_new $type $name) you
# should use this function to define $type.
#
# Both $type and member names should consist only of alpha-numeric letters or
# the underscore.
#
f_struct_define()
{
	local type="$1"
	[ "$type" ] || return $FAILURE
	shift
	setvar "_struct_typedef_$type" "$*"
}

# f_struct_new $type $name
#
# Create a new `structure' named $name of type $type.  There are two ways to
# access properties of a struct, but they are not equal (each method has its
# own unique benefits, discussed below).
#
# The primary method of accessing (both setting and getting) properties of any
# struct is through the f_struct() function below.
#
# The secondary method of accessing data is by using $name as a function.
#
# Both access methods are cross-platform compatible with any version of sh(1).
# Below is an example of the primary access method:
#
# 	f_struct_new MY_STRUCT_TYPE my_struct
# 	f_struct my_struct set abc 123
# 	f_struct my_struct get abc # prints 123 to stdout
# 	f_struct my_struct get abc abc # sets local variable $abc to 123
#
# Alternatively, the secondary access method (details below):
#
# 	f_struct_new MY_STRUCT_TYPE my_struct
# 	my_struct set abc 123
# 	my_struct get abc # prints 123 to stdout
# 	my_struct get abc abc # sets local variable $abc to 123
#
# The secondary form should only be used if/when:
# 	+ You are certain that the structure already exists
# 	+ You want a syntax error if/when the struct does not exist
#
# The primary benefit to the secondary form is syntax cleanliness and read-
# ability. If you are unsure if a given struct exists (which would cause a
# syntax error when using this form), you can use the primary access method to
# first test for the existence of the struct. For example:
#
# 	if f_struct my_struct; then
# 		my_struct get abc # only executed if my_struct exists
# 	fi
#
# For more information, see the f_struct() function.
#
f_struct_new()
{
	local type="$1" name="$2"
	f_dprintf "f_struct_new: type=[%s] name=[%s]" "$type" "$name"
	[ "$name" ] || return $FAILURE
	setvar "_struct_type_$name" "$type" || return $FAILURE
	# OK to use bare $name at this point
	eval $name\(\){ f_struct $name \"\$@\"\; }
}

# f_struct $name
# f_struct $name get $property [$var_to_set]
# f_struct $name set $property $new_value
# f_struct $name unset $property
#
# Access routine for getting, setting, unsetting, and testing properties of
# `structures'.
#
# If only given $name, returns success if struct $name has been created (using
# the f_struct_new() function above).
#
# For getting properties of a struct (versus setting) there are two methods of
# access. If $var_to_set is missing or NULL, the value of the property is
# printed to standard output for capturing in a sub-shell (which is less-
# recommended because of performance degredation; for example, when called in a
# loop). Returns success unless the property is unset.
#
# For setting properties of a struct, sets the value of $property to $new_value
# and returns success.
#
# For unsetting, the underlying environment variable associated with the given
# $property is unset.
#
f_struct()
{
	local __name="$1" __action="$2" __property="$3"
	case $# in
	0) return $FAILURE ;;
	1) f_have "$__name" ;;
	*) case "$__action" in
	   get) local __var_to_set="$4"
	        f_getvar "_struct_value_${__name}_$__property" "$__var_to_set"
	        ;;
	   set) local new_value="$4"
	        setvar "_struct_value_${__name}_$__property" "$new_value" ;;
	   unset) unset "_struct_value_${__name}_$__property" ;;
	   esac
	esac
	# Return the status of the last command above
}

# f_struct_free $name
#
# Unset the collection of environment variables and accessor-function
# associated with struct $name.
#
f_struct_free()
{
	local name="$1" type member members
	f_getvar "_struct_type_$name" type
	f_dprintf "f_struct_free: name=[%s] type=[%s]" "$name" "$type"
	[ "$name" ] || return $FAILURE
	f_getvar "_struct_typedef_$type" members
	for member in $members; do
		f_struct "$name" unset $member
	done
	unset -f "$name"
	unset "_struct_type_$name"
}

# f_struct_copy $from_name $to_name
#
# Copy the properties of one struct to another. If struct $to_name does not
# exist, it is created. If struct $from_name does not exist, nothing is done
# and struct $to_name remains unmodified.
#
# Returns success unless struct $to_name did not exist and f_struct_new() was
# unable to create it.
#
f_struct_copy()
{
	local from_name="$1" to_name="$2" type
	f_dprintf "f_struct_copy: from_name=[%s] to_name=[%s]" \
	          "$from_name" "$to_name"
	f_getvar "_struct_type_$from_name" type
	f_struct "$to_name" ||
		f_struct_new "$type" "$to_name" || return $FAILURE
	f_struct "$from_name" || return $SUCCESS
	f_dprintf "f_struct_copy: copying properties from %s to %s" \
	          "$from_name" "$to_name"
	local property properties from_value n=0 k=0
	f_getvar "_struct_typedef_$type" properties
	for property in $properties; do
		k=$(( $k + 1 ))
		if f_struct "$from_name" get $property from_value; then
			f_struct "$to_name" set $property "$from_value"
			n=$(( $n + 1 ))
		else
			f_struct "$to_name" unset $property
		fi
	done
	f_dprintf "f_struct_copy: copied %u of %u properties from %s to %s" \
	          "$n" "$k" "$from_name" "$to_name"
}

############################################################ MAIN

f_dprintf "%s: Successfully loaded." struct.subr

fi # ! $_STRUCT_SUBR