Finished extracting backspace

src/Editor/Iterators/index.js

@@ -1,7 +1,7 @@
 import * as emojiTrie from "emoji-trie"
 import * as UTF8 from "lib/encoding/UTF8"
 
-// Right-to-left (RTL) iterator; returns a substring.
+// Right-to-left iterator; returns a substring.
 export const RTL = {
 	rune(str) {
 		// return emojiTrie.atEnd(str)?.emoji || UTF8.atEnd(str)
@@ -70,7 +70,7 @@ export const RTL = {
 	},
 }
 
-// Left-to-right (LTR) iterator; returns a substring.
+// Left-to-right iterator; returns a substring.
 export const LTR = {
 	rune(str) {
 		// return emojiTrie.atStart(str)?.emoji || UTF8.atStart(str)

src/Editor/backspace/backspace.js

@@ -7,34 +7,32 @@ import must from "lib/must"
 // Returns the next right-to-left cursor for a boundary.
 function nextRTLCursor(elements, { ...rtl }, boundary) {
 	const y = must(elements.findIndex(each => each.key === rtl.key))
-	const substr = Spans.textContent(elements[y].props.children).slice(0, rtl.offset)
+	const textContent = Spans.textContent(elements[y].props.children)
 	if (!rtl.offset && y) {
 		Object.assign(rtl, {
 			key: elements[y - 1].key,
 			offset: Spans.textContent(elements[y - 1].props.children).length,
 		})
 		return rtl
 	}
-	// const runes = Iterators.RTL[boundary](substr) // DEBUG
-	// rtl.offset -= runes.length                    // DEBUG
-	rtl.offset -= Iterators.RTL[boundary](substr).length
+	const substr = Iterators.RTL[boundary](textContent.slice(0, rtl.offset))
+	rtl.offset -= substr.length
 	return rtl
 }
 
 // Returns the next left-to-right cursor for a boundary.
 function nextLTRCursor(elements, { ...ltr }, boundary) {
 	const y = must(elements.findIndex(each => each.key === ltr.key))
-	const substr = Spans.textContent(elements[y].props.children).slice(ltr.offset)
-	if (ltr.offset === substr.length && y + 1 < elements.length) {
+	const textContent = Spans.textContent(elements[y].props.children)
+	if (ltr.offset === textContent.length && y + 1 < elements.length) {
 		Object.assign(ltr, {
 			key: elements[y + 1].key,
-			offset: Spans.textContent(elements[y + 1].props.children).length,
+			offset: 0,
 		})
 		return ltr
 	}
-	// const runes = Iterators.LTR[boundary](substr) // DEBUG
-	// ltr.offset += runes.length                    // DEBUG
-	ltr.offset += Iterators.LTR[boundary](substr).length
+	const substr = Iterators.LTR[boundary](textContent.slice(ltr.offset))
+	ltr.offset += substr.length
 	return ltr
 }
 

src/Editor/backspace/dropCursors.js

@@ -3,37 +3,14 @@ import * as Spans from "../Spans"
 import JSONClone from "lib/JSONClone"
 import must from "lib/must"
 
-// // Returns the span and character offsets for an array of
-// // spans at an offset.
-// function computeSpanOffsets(spans, offset) {
-// 	const offsets = {
-// 		span: 0,
-//  		char: 0,
-// 	}
-//
-// 	let x = 0
-// 	for (; x < spans.length; x++) {
-// 		const children = spans[x].props.children
-// 		if (offset - children.length <= 0) {
-// 			Object.assign(offsets, {
-// 				span: x,
-// 				char: offset,
-// 			})
-// 			return offsets
-// 		}
-// 		offset -= children.length
-// 	}
-// 	return null
-// }
-
 // Returns the span and character offsets for an array of
 // spans at an offset.
-function computeSpanOffsets(spans, offset) {
+function Span_offsets(spans, offset) { // TODO
 	let x = 0
 	for (; x < spans.length; x++) {
 		const children = spans[x].props.children
 		if (offset - children.length <= 0) {
-			return { span: x, char: offset }
+			return [x, offset]
 		}
 		offset -= children.length
 	}
@@ -43,16 +20,16 @@ function computeSpanOffsets(spans, offset) {
 // Drops a number of characters from an array of spans at an
 // offset. Returns the number of characters dropped.
 function dropChars(spans, offset, nchars) {
-	const offsets = must(computeSpanOffsets(spans, offset))
-	if (nchars > offsets.char) {
-		nchars = offsets.char
+	const offsets = must(Span_offsets(spans, offset))
+	if (nchars > offsets[1]) {
+		nchars = offsets[1]
 	}
-	spans[offsets.span].props.children = (
-		spans[offsets.span].props.children.slice(0, offsets.char - nchars) +
-		spans[offsets.span].props.children.slice(offsets.char)
+	spans[offsets[0]].props.children = (
+		spans[offsets[0]].props.children.slice(0, offsets[1] - nchars) +
+		spans[offsets[0]].props.children.slice(offsets[1])
 	)
-	if (!spans[offsets.span].props.children) {
-		spans.splice(offsets.span, 1)
+	if (!spans[offsets[0]].props.children) {
+		spans.splice(offsets[0], 1)
 	}
 	Spans.defer(spans)
 	return nchars
@@ -61,11 +38,16 @@ function dropChars(spans, offset, nchars) {
 // Counts the number of characters between the offsets of a
 // set of cursors.
 function nchars(cursors) {
-	const nchars = 0
+	let nchars = 0
 	if (cursors[0].key === cursors[1].key) {
-		return cursors[1].offset - cursors[0].offset
+		// Hello, [world]!
+		nchars = cursors[1].offset - cursors[0].offset
+	} else {
+		//  Hello, world!
+		// [Hello, world]!
+		nchars = cursors[1].offset
 	}
-	return cursors[1].offset
+	return nchars
 }
 
 // Drops the characters between a set of cursors.

src/Editor/useEditor.js

@@ -1,6 +1,6 @@
 import * as Cursors from "./Cursors"
 import * as Elements from "./Elements"
-import backspaceHandler from "./backspace"
+import backspace from "./backspace"
 import must from "lib/must"
 import newHashID from "lib/newHashID"
 import React from "react"
@@ -106,32 +106,27 @@ const methods = state => ({
 	// },
 
 	backspaceRTLRune() {
-		const { elements, cursors } = state
-		const collapsed = backspaceHandler(elements, cursors, "rtl", "rune")
+		const collapsed = backspace(state.elements, state.cursors, "rtl", "rune")
 		this.select(collapsed)
 		this.render()
 	},
 	backspaceRTLWord() {
-		const { elements, cursors } = state
-		const collapsed = backspaceHandler(elements, cursors, "rtl", "word")
+		const collapsed = backspace(state.elements, state.cursors, "rtl", "word")
 		this.select(collapsed)
 		this.render()
 	},
 	backspaceRTLLine() {
-		const { elements, cursors } = state
-		const collapsed = backspaceHandler(elements, cursors, "rtl", "line")
+		const collapsed = backspace(state.elements, state.cursors, "rtl", "line")
 		this.select(collapsed)
 		this.render()
 	},
 	backspaceLTRRune() {
-		const { elements, cursors } = state
-		const collapsed = backspaceHandler(elements, cursors, "ltr", "rune")
+		const collapsed = backspace(state.elements, state.cursors, "ltr", "rune")
 		this.select(collapsed)
 		this.render()
 	},
 	backspaceLTRWord() {
-		const { elements, cursors } = state
-		const collapsed = backspaceHandler(elements, cursors, "ltr", "word")
+		const collapsed = backspace(state.elements, state.cursors, "ltr", "word")
 		this.select(collapsed)
 		this.render()
 	},