lib/preexec: the last remnants of the $OSTYPE have been swept away

- Use a POSIX-compliant/portable extended regular expression to match on word-boundaries, rather than guessing which regex library `bash` was linked against. See https://stackoverflow.com/a/12696899/555333 for explanation and code suggestion.

lib/preexec.bash

@@ -37,26 +37,20 @@ function __check_preexec_conflict() {
 	_bash-it-array-contains-element "${f}" "${preexec_functions[@]}"
 }
 
-function safe_append_prompt_command {
-	local prompt_re f
-	__bp_trim_whitespace f "${1?}"
+function safe_append_prompt_command() {
+	local prompt_re prompt_er f
 
-	if [ "${bash_preexec_imported:-${__bp_imported:-missing}}" == "defined" ]; then
+	if [[ "${bash_preexec_imported:-${__bp_imported:-missing}}" == "defined" ]]; then
 		# We are using bash-preexec
+		__bp_trim_whitespace f "${1?}"
 		if ! __check_precmd_conflict "${f}"; then
 			precmd_functions+=("${f}")
 		fi
 	else
-		# Set OS dependent exact match regular expression
-		if [[ ${OSTYPE} == darwin* ]]; then
-			# macOS
-			prompt_re="[[:<:]]${1}[[:>:]]"
-		else
-			# Linux, FreeBSD, etc.
-			prompt_re="\<${1}\>"
-		fi
-
-		if [[ ${PROMPT_COMMAND} =~ ${prompt_re} ]]; then
+		# Match on word-boundaries
+		prompt_re='(^|[^[:alnum:]_])'
+		prompt_er='([^[:alnum:]_]|$)'
+		if [[ ${PROMPT_COMMAND} =~ ${prompt_re}"${1}"${prompt_er} ]]; then
 			return
 		elif [[ -z ${PROMPT_COMMAND} ]]; then
 			PROMPT_COMMAND="${1}"
@@ -66,12 +60,12 @@ function safe_append_prompt_command {
 	fi
 }
 
-function safe_append_preexec {
+function safe_append_preexec() {
 	local prompt_re f
-	__bp_trim_whitespace f "${1?}"
 
-	if [ "${bash_preexec_imported:-${__bp_imported:-missing}}" == "defined" ]; then
+	if [[ "${bash_preexec_imported:-${__bp_imported:-missing}}" == "defined" ]]; then
 		# We are using bash-preexec
+		__bp_trim_whitespace f "${1?}"
 		if ! __check_preexec_conflict "${f}"; then
 			preexec_functions+=("${f}")
 		fi