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README.md

@@ -1,2 +1,23 @@
-# bash-trap-stack
-command stack for bash traps
+# Bash Trap Stack
+## Purpose
+The traps.sh shell script allows you to create a stack of commands to execute for trap.
+## Commands
+* traps_start - registers the exit trap
+* traps_push $@ - pushes $@ as one entry to the stack
+* traps_pop - pops one entry from the stack and execute
+* traps_drop - pops one entry from the stack and do nothing
+* traps_isEmpty - returns 0 if empty, returns 1 if not empty
+* traps_stop - unregisters the exit trap if there is nothing on the stack
+* traps_cancel - unregisters the exit trap and remove all entries from the stack
+* traps_exit - unregisters the exit map and pops all entries from the stack
+* traps_diag - print the stack on pipe 1
+## User Variables
+* TRAPS_DEBUG=0 - provides more verbose output on pipe 2
+* TRAPS_SIGNAL=EXIT - controls the trap signal
+## Typical Sequence
+* traps_start
+* traps_push echo "test"
+* traps_pop
+* traps_stop
+## Notes
+You can use *set -eE* along with *TRAPS_SIGNAL=ERR* before you start the trap stack to get the function and line number that triggered the trap.

test.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+
+# SPDX-License-Identifier: MIT
+# Copyright (C) 2022 Da Xue
+
+. traps.sh
+
+TRAPS_DEBUG=1
+
+function traps_test {
+	traps_start
+	traps_push "echo" "traps 1" "test 1" "drop"
+	traps_push "echo" "traps 2" "test 2" "pop"
+	traps_push "echo" "traps 3" "test 3" "drop"
+	traps_push "echo" "traps 2" "test 2" "pop"
+	traps_diag
+	echo 
+	traps_isEmpty && echo "Empty" || echo "Not Empty"
+	echo 
+	traps_drop
+	traps_diag
+	echo
+	traps_pop
+	traps_diag
+	echo
+	traps_drop
+	traps_diag
+	echo
+	traps_pop
+	traps_diag
+	echo
+	traps_stop
+	echo
+	traps_start
+	traps_cancel
+	echo
+	traps_pop && echo "FAILED" || true
+	traps_diag
+	echo
+	traps_cancel && echo "FAILED" || true
+	traps_diag
+	echo
+	set -eE
+	TRAPS_SIGNAL=ERR
+	traps_start
+	traps_push echo "test"
+	false
+}
+
+if [ "${BASH_SOURCE[0]##*/}" = "${0##*/}" ]; then
+	traps_test
+fi

traps.sh

@@ -0,0 +1,149 @@
+#!/bin/bash
+
+# SPDX-License-Identifier: MIT
+# Copyright (C) 2022 Da Xue
+
+TRAPS_DEBUG=0
+TRAPS_SIGNAL=EXIT
+
+declare -a TRAPS_PARAMS
+declare -a TRAPS_LENGTHS
+TRAPS_LENGTH=
+
+function traps_start {
+	if [ -z "$TRAPS_LENGTH" ]; then
+		TRAPS_LENGTH=0
+		if [ "$TRAPS_SIGNAL" = "ERR" ]; then
+			trap 'traps_exit "$FUNCNAME" "$LINENO"' $TRAPS_SIGNAL
+		else
+			trap traps_exit $TRAPS_SIGNAL
+		fi
+	else
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: duplicate call" >&2
+		fi
+		return 1
+	fi
+}
+
+function traps_isEmpty {
+	if [ -z "$TRAPS_LENGTH" ]; then
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: traps not started" >&2
+		fi
+		return 2
+	fi
+	if [ $TRAPS_LENGTH -gt 0 ]; then
+		return 1
+	fi
+	return 0
+}
+
+function traps_push {
+	if [ -z "$TRAPS_LENGTH" ]; then
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: traps not started" >&2
+		fi
+		return 1
+	fi
+	TRAPS_PARAMS+=("$@")
+	TRAPS_LENGTHS+=($#)
+	((TRAPS_LENGTH=TRAPS_LENGTH+1))
+}
+
+function traps_pop {
+	if [ -z "$TRAPS_LENGTH" ]; then
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: traps not started" >&2
+		fi
+		return 1
+	elif [ $TRAPS_LENGTH -gt 0 ]; then
+		local trap_length=${TRAPS_LENGTHS[@]: -1}
+		local trap_cmd=(${TRAPS_PARAMS[@]: -$trap_length})
+		local traps_params_end=$((${#TRAPS_PARAMS[@]}-trap_length))
+		TRAPS_PARAMS=("${TRAPS_PARAMS[@]:0:$traps_params_end}")
+		TRAPS_LENGTH=$((TRAPS_LENGTH-1))
+		TRAPS_LENGTHS=(${TRAPS_LENGTHS[@]:0:$TRAPS_LENGTH})
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: ${trap_cmd[@]}" >&2
+		fi
+		"${trap_cmd[@]}"
+	else
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: traps empty" >&2
+		fi
+		return 1
+	fi
+}
+
+function traps_drop {
+	if [ -z "$TRAPS_LENGTH" ]; then
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: traps not started" >&2
+		fi
+		return 1
+	elif [ $TRAPS_LENGTH -gt 0 ]; then
+		local trap_length=${TRAPS_LENGTHS[@]: -1}
+		local traps_params_end=$((${#TRAPS_PARAMS[@]}-trap_length))
+		TRAPS_PARAMS=("${TRAPS_PARAMS[@]:0:$traps_params_end}")
+		TRAPS_LENGTH=$((TRAPS_LENGTH-1))
+		TRAPS_LENGTHS=(${TRAPS_LENGTHS[@]:0:$TRAPS_LENGTH})
+	else
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: traps empty" >&2
+		fi
+		return 1
+	fi
+}
+
+
+function traps_stop {
+	if [ "$TRAPS_LENGTH" = "0" ]; then
+		TRAPS_LENGTH=
+		trap - $TRAPS_SIGNAL
+	else
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: registered traps" >&2
+			traps_diag >&2
+		fi
+		return 1
+	fi
+}
+
+function traps_cancel {
+	if [ -z "$TRAPS_LENGTH" ]; then
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: traps not started" >&2
+		fi
+		return 1
+	fi
+	TRAPS_PARAMS=()
+	TRAPS_LENGTHS=()
+	TRAPS_LENGTH=
+	trap - $TRAPS_SIGNAL
+}
+
+function traps_exit {
+	if [ "$TRAPS_DEBUG" -eq 1 ]; then
+		if [ "$TRAPS_SIGNAL" = "ERR" ]; then
+			echo "$FUNCNAME: $TRAPS_SIGNAL IN $1 LINE $2" >&2
+		fi
+	fi
+	trap - $TRAPS_SIGNAL
+	if [ -z "$TRAPS_LENGTH" ]; then
+		if [ "$TRAPS_DEBUG" -eq 1 ]; then
+			echo "$FUNCNAME: traps not initiated" >&2
+		fi
+		return 1
+	fi
+	while [ "$TRAPS_LENGTH" -gt 0 ]; do
+		traps_pop
+	done
+	return 1
+}
+
+function traps_diag {
+	echo "$FUNCNAME params: ${TRAPS_PARAMS[@]}"
+	echo "$FUNCNAME lengths: ${TRAPS_LENGTHS[@]}"
+	echo "$FUNCNAME length: $TRAPS_LENGTH"
+}