xP: implement Readline's M-l, M-u, M-c

xP/public/xP.js

@@ -742,7 +742,7 @@ let Input = {
 		return true
 	},
 
-	backward: (b, textarea) => {
+	backward: textarea => {
 		if (textarea.selectionStart !== textarea.selectionEnd)
 			return false
 
@@ -756,7 +756,7 @@ let Input = {
 		return true
 	},
 
-	forward: (b, textarea) => {
+	forward: textarea => {
 		if (textarea.selectionStart !== textarea.selectionEnd)
 			return false
 
@@ -769,6 +769,42 @@ let Input = {
 		return true
 	},
 
+	modifyWord: (textarea, cb) => {
+		let start = textarea.selectionStart
+		let end = textarea.selectionEnd
+		if (start === end) {
+			let len = textarea.value.length
+			while (start < len && /\s/.test(textarea.value.charAt(start)))
+				start++;
+			end = start
+			while (end < len && !/\s/.test(textarea.value.charAt(end)))
+				end++;
+		}
+		if (start === end)
+			return false
+
+		const text = textarea.value, modified = cb(text.substring(start, end))
+		textarea.value = text.slice(0, start) + modified + text.slice(end)
+		end = start + modified.length
+		textarea.setSelectionRange(end, end)
+		return true
+	},
+
+	downcase: textarea => {
+		return Input.modifyWord(textarea, text => text.toLowerCase())
+	},
+
+	upcase: textarea => {
+		return Input.modifyWord(textarea, text => text.toUpperCase())
+	},
+
+	capitalize: textarea => {
+		return Input.modifyWord(textarea, text => {
+			const cps = Array.from(text.toLowerCase())
+			return cps[0].toUpperCase() + cps.slice(1).join('')
+		})
+	},
+
 	first: (b, textarea) => {
 		if (b.historyAt <= 0)
 			return false
@@ -823,8 +859,11 @@ let Input = {
 		if (hasShortcutModifiers(event)) {
 			handled = true
 			switch (event.key) {
-			case 'b': success = Input.backward(b, textarea); break
-			case 'f': success = Input.forward(b, textarea);  break
+			case 'b': success = Input.backward(textarea);    break
+			case 'f': success = Input.forward(textarea);     break
+			case 'l': success = Input.downcase(textarea);    break
+			case 'u': success = Input.upcase(textarea);      break
+			case 'c': success = Input.capitalize(textarea);  break
 			case '<': success = Input.first(b, textarea);    break
 			case '>': success = Input.last(b, textarea);     break
 			case 'p': success = Input.previous(b, textarea); break