Fix conditionals to use [[ and (( rather than [

This fixes a small issue in src/widgets.zsh which makes it so if you
alias [ to g[ (as is done in prezto if the gnu-utility module is loaded)
autosuggestions would fail.

The documentation for GNU test mentions that -o and -a should be avoided
if possible because it's not very clear. Also, with zsh and [[ -o
actually tests if an option is set, which makes this option even more
confusing.

src/async.zsh

@@ -63,7 +63,7 @@ _zsh_autosuggest_async_pty_create() {
 	typeset -h REPLY
 
 	# If we won't get a fd back from zpty, try to guess it
-	if [ $_ZSH_AUTOSUGGEST_ZPTY_RETURNS_FD -eq 0 ]; then
+	if (( ! $_ZSH_AUTOSUGGEST_ZPTY_RETURNS_FD )); then
 		integer -l zptyfd
 		exec {zptyfd}>&1  # Open a new file descriptor (above 10).
 		exec {zptyfd}>&-  # Close it so it's free to be used by zpty.

src/bind.zsh

@@ -88,13 +88,13 @@ _zsh_autosuggest_bind_widgets() {
 
 	# Find every widget we might want to bind and bind it appropriately
 	for widget in ${${(f)"$(builtin zle -la)"}:#${(j:|:)~ignore_widgets}}; do
-		if [ ${ZSH_AUTOSUGGEST_CLEAR_WIDGETS[(r)$widget]} ]; then
+		if [[ ${ZSH_AUTOSUGGEST_CLEAR_WIDGETS[(r)$widget]} ]]; then
 			_zsh_autosuggest_bind_widget $widget clear
-		elif [ ${ZSH_AUTOSUGGEST_ACCEPT_WIDGETS[(r)$widget]} ]; then
+		elif [[ ${ZSH_AUTOSUGGEST_ACCEPT_WIDGETS[(r)$widget]} ]]; then
 			_zsh_autosuggest_bind_widget $widget accept
-		elif [ ${ZSH_AUTOSUGGEST_EXECUTE_WIDGETS[(r)$widget]} ]; then
+		elif [[ ${ZSH_AUTOSUGGEST_EXECUTE_WIDGETS[(r)$widget]} ]]; then
 			_zsh_autosuggest_bind_widget $widget execute
-		elif [ ${ZSH_AUTOSUGGEST_PARTIAL_ACCEPT_WIDGETS[(r)$widget]} ]; then
+		elif [[ ${ZSH_AUTOSUGGEST_PARTIAL_ACCEPT_WIDGETS[(r)$widget]} ]]; then
 			_zsh_autosuggest_bind_widget $widget partial_accept
 		else
 			# Assume any unspecified widget might modify the buffer
@@ -106,13 +106,13 @@ _zsh_autosuggest_bind_widgets() {
 # Given the name of an original widget and args, invoke it, if it exists
 _zsh_autosuggest_invoke_original_widget() {
 	# Do nothing unless called with at least one arg
-	[ $# -gt 0 ] || return
+	(( $# )) || return
 
 	local original_widget_name="$1"
 
 	shift
 
-	if [ $widgets[$original_widget_name] ]; then
+	if [[ -n $widgets[$original_widget_name] ]]; then
 		zle $original_widget_name -- $@
 	fi
 }

src/highlight.zsh

@@ -7,7 +7,7 @@
 _zsh_autosuggest_highlight_reset() {
 	typeset -g _ZSH_AUTOSUGGEST_LAST_HIGHLIGHT
 
-	if [ -n "$_ZSH_AUTOSUGGEST_LAST_HIGHLIGHT" ]; then
+	if [[ -n "$_ZSH_AUTOSUGGEST_LAST_HIGHLIGHT" ]]; then
 		region_highlight=("${(@)region_highlight:#$_ZSH_AUTOSUGGEST_LAST_HIGHLIGHT}")
 		unset _ZSH_AUTOSUGGEST_LAST_HIGHLIGHT
 	fi
@@ -17,7 +17,7 @@ _zsh_autosuggest_highlight_reset() {
 _zsh_autosuggest_highlight_apply() {
 	typeset -g _ZSH_AUTOSUGGEST_LAST_HIGHLIGHT
 
-	if [ $#POSTDISPLAY -gt 0 ]; then
+	if (( $#POSTDISPLAY )); then
 		_ZSH_AUTOSUGGEST_LAST_HIGHLIGHT="$#BUFFER $(($#BUFFER + $#POSTDISPLAY)) $ZSH_AUTOSUGGEST_HIGHLIGHT_STYLE"
 		region_highlight+=("$_ZSH_AUTOSUGGEST_LAST_HIGHLIGHT")
 	else

src/start.zsh

@@ -15,7 +15,7 @@ _zsh_autosuggest_start() {
 	# to the widget list variables to take effect on the next precmd.
 	add-zsh-hook precmd _zsh_autosuggest_bind_widgets
 
-	if [ -n "${ZSH_AUTOSUGGEST_USE_ASYNC+x}" ]; then
+	if [[ -n "${ZSH_AUTOSUGGEST_USE_ASYNC+x}" ]]; then
 		_zsh_autosuggest_async_start
 	fi
 }

src/widgets.zsh

@@ -13,14 +13,14 @@ _zsh_autosuggest_disable() {
 _zsh_autosuggest_enable() {
 	unset _ZSH_AUTOSUGGEST_DISABLED
 
-	if [ $#BUFFER -gt 0 ]; then
+	if (( $#BUFFER )); then
 		_zsh_autosuggest_fetch
 	fi
 }
 
 # Toggle suggestions (enable/disable)
 _zsh_autosuggest_toggle() {
-	if [ -n "${_ZSH_AUTOSUGGEST_DISABLED+x}" ]; then
+	if [[ -n "${_ZSH_AUTOSUGGEST_DISABLED+x}" ]]; then
 		_zsh_autosuggest_enable
 	else
 		_zsh_autosuggest_disable
@@ -59,30 +59,30 @@ _zsh_autosuggest_modify() {
 	fi
 
 	# Optimize if manually typing in the suggestion
-	if [ $#BUFFER -gt $#orig_buffer ]; then
+	if [[ $#BUFFER > $#orig_buffer ]]; then
 		local added=${BUFFER#$orig_buffer}
 
 		# If the string added matches the beginning of the postdisplay
-		if [ "$added" = "${orig_postdisplay:0:$#added}" ]; then
+		if [[ "$added" = "${orig_postdisplay:0:$#added}" ]]; then
 			POSTDISPLAY="${orig_postdisplay:$#added}"
 			return $retval
 		fi
 	fi
 
 	# Don't fetch a new suggestion if the buffer hasn't changed
-	if [ "$BUFFER" = "$orig_buffer" ]; then
+	if [[ "$BUFFER" = "$orig_buffer" ]]; then
 		POSTDISPLAY="$orig_postdisplay"
 		return $retval
 	fi
 
 	# Bail out if suggestions are disabled
-	if [ -n "${_ZSH_AUTOSUGGEST_DISABLED+x}" ]; then
+	if [[ -n "${_ZSH_AUTOSUGGEST_DISABLED+x}" ]]; then
 		return $?
 	fi
 
 	# Get a new suggestion if the buffer is not empty after modification
-	if [ $#BUFFER -gt 0 ]; then
-		if [ -z "$ZSH_AUTOSUGGEST_BUFFER_MAX_SIZE" -o $#BUFFER -le "$ZSH_AUTOSUGGEST_BUFFER_MAX_SIZE" ]; then
+	if [[ $#BUFFER > 0 ]]; then
+		if [[ -z "$ZSH_AUTOSUGGEST_BUFFER_MAX_SIZE" ]] || (( "$#BUFFER" <= "$ZSH_AUTOSUGGEST_BUFFER_MAX_SIZE" )); then
 			_zsh_autosuggest_fetch
 		fi
 	fi
@@ -105,7 +105,7 @@ _zsh_autosuggest_fetch() {
 _zsh_autosuggest_suggest() {
 	local suggestion="$1"
 
-	if [ -n "$suggestion" ] && [ $#BUFFER -gt 0 ]; then
+	if [[ -n "$suggestion" ]] && (( $#BUFFER )); then
 		POSTDISPLAY="${suggestion#$BUFFER}"
 	else
 		unset POSTDISPLAY
@@ -118,12 +118,12 @@ _zsh_autosuggest_accept() {
 
 	# When vicmd keymap is active, the cursor can't move all the way
 	# to the end of the buffer
-	if [ "$KEYMAP" = "vicmd" ]; then
+	if [[ "$KEYMAP" = "vicmd" ]]; then
 		max_cursor_pos=$((max_cursor_pos - 1))
 	fi
 
 	# Only accept if the cursor is at the end of the buffer
-	if [ $CURSOR -eq $max_cursor_pos ]; then
+	if [[ $CURSOR = $max_cursor_pos ]]; then
 		# Add the suggestion to the buffer
 		BUFFER="$BUFFER$POSTDISPLAY"
 
@@ -165,7 +165,7 @@ _zsh_autosuggest_partial_accept() {
 	retval=$?
 
 	# If we've moved past the end of the original buffer
-	if [ $CURSOR -gt $#original_buffer ]; then
+	if (( $CURSOR > $#original_buffer )); then
 		# Set POSTDISPLAY to text right of the cursor
 		POSTDISPLAY="$RBUFFER"