xP: abort autocomplete when no longer applicable

xP/public/xP.js

@@ -421,16 +421,28 @@ let BufferContainer = {
 }
 
 let Input = {
+	counter: 0,
+	stamp: textarea => {
+		return [Input.counter,
+			textarea.selectionStart, textarea.selectionEnd, textarea.value]
+	},
+
 	complete: textarea => {
 		if (textarea.selectionStart !== textarea.selectionEnd)
 			return false
 
+		// Cancel any previous autocomplete, and ensure applicability.
+		Input.counter++
+		let state = Input.stamp(textarea)
 		rpc.send({
 			command: 'BufferComplete',
 			bufferName: bufferCurrent,
 			text: textarea.value,
 			position: textarea.selectionEnd,
 		}).then(resp => {
+			if (!Input.stamp(textarea).every((v, k) => v === state[k]))
+				return
+
 			// TODO: Somehow display remaining options, or cycle through.
 			if (resp.completions.length)
 				textarea.setRangeText(resp.completions[0],
@@ -456,8 +468,6 @@ let Input = {
 		// TODO: And perhaps on other actions, too.
 		rpc.send({command: 'Active'})
 
-		// TODO: Cancel any current autocomplete.
-
 		let textarea = event.currentTarget
 		let handled = false
 		switch (event.keyCode) {