Prevent multiple prompt resets in one execution cycle (#368)

* Update zsh-async to 1.6.0 for buffer status indicator

* Prevent multiple prompt resets in one execution cycle

The prompt ends up in a weird state when `zle reset-prompt` is called
multiple times during one execution cycle. This can happen when multiple
async tasks finish at nearly the same time. What happened here is that
`async_process_results` called `prompt_pure_async_callback` multiple
times during it's execution. In turn, `prompt_pure_async_callback` did
multiple calls to `zle reset-prompt`. My theory is that ZLE ends up in a
weird state that is reset after all the current code has completed
executing.

This behavior is observable when the prompt "moves upwards" and erases
previous lines in the terminal.

Fixes #356.

async.zsh

@@ -3,7 +3,7 @@
 #
 # zsh-async
 #
-# version: 1.5.2
+# version: 1.6.0
 # author: Mathias Fredriksson
 # url: https://github.com/mafredri/zsh-async
 #
@@ -202,6 +202,7 @@ _async_worker() {
 # 	$3 = resulting stdout from execution
 # 	$4 = execution time, floating point e.g. 2.05 seconds
 # 	$5 = resulting stderr from execution
+#	$6 = has next result in buffer (0 = buffer empty, 1 = yes)
 #
 async_process_results() {
 	setopt localoptions unset noshwordsplit noksharrays noposixidentifiers noposixstrings
@@ -234,7 +235,13 @@ async_process_results() {
 			# Remove the extracted items from the buffer.
 			ASYNC_PROCESS_BUFFER[$worker]=${ASYNC_PROCESS_BUFFER[$worker][$pos+1,$len]}
 
+			len=${#ASYNC_PROCESS_BUFFER[$worker]}
+			if (( len > 1 )); then
+				pos=${ASYNC_PROCESS_BUFFER[$worker][(i)$null]}  # Get index of NULL-character (delimiter).
+			fi
+
 			if (( $#items == 5 )); then
+				items+=($(( len != 0 )))
 				$callback "${(@)items}"  # Send all parsed items to the callback.
 			else
 				# In case of corrupt data, invoke callback with *async* as job
@@ -243,11 +250,6 @@ async_process_results() {
 			fi
 
 			(( num_processed++ ))
-
-			len=${#ASYNC_PROCESS_BUFFER[$worker]}
-			if (( len > 1 )); then
-				pos=${ASYNC_PROCESS_BUFFER[$worker][(i)$null]}  # Get index of NULL-character (delimiter).
-			fi
 		done
 	done
 

pure.zsh

@@ -340,7 +340,8 @@ prompt_pure_check_git_arrows() {
 
 prompt_pure_async_callback() {
 	setopt localoptions noshwordsplit
-	local job=$1 code=$2 output=$3 exec_time=$4
+	local job=$1 code=$2 output=$3 exec_time=$4 next_pending=$6
+	local do_render=0
 
 	case $job in
 		prompt_pure_async_vcs_info)
@@ -371,7 +372,7 @@ prompt_pure_async_callback() {
 			prompt_pure_vcs_info[branch]=$info[branch]
 			prompt_pure_vcs_info[top]=$info[top]
 
-			prompt_pure_preprompt_render
+			do_render=1
 			;;
 		prompt_pure_async_git_aliases)
 			if [[ -n $output ]]; then
@@ -387,7 +388,7 @@ prompt_pure_async_callback() {
 				typeset -g prompt_pure_git_dirty="*"
 			fi
 
-			[[ $prev_dirty != $prompt_pure_git_dirty ]] && prompt_pure_preprompt_render
+			[[ $prev_dirty != $prompt_pure_git_dirty ]] && do_render=1
 
 			# When prompt_pure_git_last_dirty_check_timestamp is set, the git info is displayed in a different color.
 			# To distinguish between a "fresh" and a "cached" result, the preprompt is rendered before setting this
@@ -402,19 +403,27 @@ prompt_pure_async_callback() {
 				prompt_pure_check_git_arrows ${(ps:\t:)output}
 				if [[ $prompt_pure_git_arrows != $REPLY ]]; then
 					typeset -g prompt_pure_git_arrows=$REPLY
-					prompt_pure_preprompt_render
+					do_render=1
 				fi
 			elif (( code != 99 )); then
 				# Unless the exit code is 99, prompt_pure_async_git_arrows
 				# failed with a non-zero exit status, meaning there is no
 				# upstream configured.
 				if [[ -n $prompt_pure_git_arrows ]]; then
 					unset prompt_pure_git_arrows
-					prompt_pure_preprompt_render
+					do_render=1
 				fi
 			fi
 			;;
 	esac
+
+	if (( next_pending )); then
+		(( do_render )) && typeset -g prompt_pure_async_render_requested=1
+		return
+	fi
+
+	[[ ${prompt_pure_async_render_requested:-$do_render} = 1 ]] && prompt_pure_preprompt_render
+	unset prompt_pure_async_render_requested
 }
 
 prompt_pure_setup() {