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# Copyright 2024 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
# shellcheck shell=sh disable=3043
# This file contains functions considered experimental in nature. Any functions
# defined here may eventually be promoted to the core library or to a distinct
# module. They may also be dropped without warning, either because they were
# not considered as being sufficiently within the scope of gentoo-functions as
# a project or because they were deemed to be insufficiently useful. As such, it
# serves as a staging ground for new ideas. Note that GENFUN_API_LEVEL must
# never be incremented on account of any changes made to this module.
warn "sourcing the experimental module from gentoo-functions; no stability guarantee is provided"
#
# Expects three parameters, all of which must be integers, and determines
# whether the first is numerically greater than or equal to the second, and
# numerically lower than or equal to the third.
#
int_between()
{
if [ "$#" -lt 3 ]; then
warn "int_between: too few arguments (got $#, expected 3)"
false
elif ! is_int "$2" || ! is_int "$3"; then
_warn_for_args int_between "$@"
false
else
is_int "$1" && [ "$1" -ge "$2" ] && [ "$1" -le "$3" ]
fi
}
#
# Returns 0 provided that two conditions hold. Firstly, that the standard input
# is connected to a tty. Secondly, that the standard output has not been closed.
# This technique is loosely based on the IO::Interactive::Tiny module from CPAN.
#
is_interactive()
{
test -t 0 && { true 3>&1; } 2>/dev/null
}
#
# Continuously reads lines from the standard input, prepending each with a
# timestamp before printing to the standard output. Timestamps shall be in the
# format of "%FT%T%z", per strftime(3). Output buffering shall not be employed.
#
prepend_ts()
{
if hash gawk 2>/dev/null; then
prepend_ts()
{
gawk '{ print strftime("%FT%T%z"), $0; fflush(); }'
}
elif hash ts 2>/dev/null; then
prepend_ts()
{
ts '%FT%T%z'
}
elif bash -c '(( BASH_VERSINFO >= 4 ))' 2>/dev/null; then
prepend_ts()
{
bash -c 'while read -r; do printf "%(%FT%T%z)T %s\n" -1 "${REPLY}"; done'
}
else
warn "prepend_ts: this function requires that either bash, gawk or moreutils be installed"
return 1
fi
prepend_ts
}
#
# Expects three parameters and determines whether the first is lexicographically
# greater than or equal to the second, and lexicographically lower than or equal
# to the third. The effective system collation shall affect the results, given
# the involvement of the sort(1) utility.
#
str_between()
{
local i
if [ "$#" -ne 3 ]; then
warn "str_between: wrong number of arguments (got $#, expected 3)"
false
else
set -- "$2" "$1" "$3"
i=0
printf '%s\n' "$@" |
sort |
while IFS= read -r line; do
eval "[ \"\${line}\" = \"\$$(( i += 1 ))\" ]" || ! break
done
fi
}
#
# Takes the first parameter as a string (s), the second parameter as a numerical
# position (m) and, optionally, the third parameter as a numerical length (n).
# It shall then print a <newline> terminated substring of s that is at most, n
# characters in length and which begins at position m, numbering from 1. If n is
# omitted, or if n specifies more characters than are left in the string, the
# length of the substring shall be limited by the length of s. The function
# shall return 0 provided that none of the parameters are invalid.
#
substr()
{
local i str
if [ "$#" -lt 2 ]; then
warn "substr: too few arguments (got $#, expected at least 2)"
return 1
elif ! is_int "$2"; then
_warn_for_args substr "$2"
return 1
elif [ "$#" -ge 3 ]; then
if ! is_int "$3"; then
_warn_for_args substr "$3"
return 1
elif [ "$3" -lt 0 ]; then
set -- "$1" "$2" 0
fi
fi
str=$1
i=0
while [ "$(( i += 1 ))" -lt "$2" ]; do
str=${str#?}
done
i=0
while [ "${#str}" -gt "${3-${#str}}" ]; do
str=${str%?}
done
if [ "${#str}" -gt 0 ]; then
printf '%s\n' "${str}"
fi
}
#
# Takes the first parameter as either a relative pathname or an integer
# referring to a number of iterations. To be recognised as a pathname, the first
# four characters must form the special prefix, ".../". It recurses upwards from
# the current directory until either the relative pathname is found to exist,
# the specified number of iterations has occurred, or the root directory is
# encountered. In the event that the root directory is reached without either of
# the first two conditions being satisfied, the return value shall be 1.
# Otherwise, the value of PWD shall be printed to the standard output.
#
up()
{
local i
i=0
while [ "${PWD}" != / ]; do
chdir ../
case $1 in
.../*)
test -e "${1#.../}"
;;
*)
test "$(( i += 1 ))" -eq "$1"
esac \
&& pwd && return
done
}
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