refactor: Still trying to reorganize edit mode to be more robust

node_modules/bidi-js/src/reordering.js

@@ -0,0 +1,99 @@
+import { getBidiCharType, TRAILING_TYPES } from './charTypes.js'
+import { getMirroredCharacter } from './mirroring.js'
+
+/**
+ * Given a start and end denoting a single line within a string, and a set of precalculated
+ * bidi embedding levels, produce a list of segments whose ordering should be flipped, in sequence.
+ * @param {string} string - the full input string
+ * @param {GetEmbeddingLevelsResult} embeddingLevelsResult - the result object from getEmbeddingLevels
+ * @param {number} [start] - first character in a subset of the full string
+ * @param {number} [end] - last character in a subset of the full string
+ * @return {number[][]} - the list of start/end segments that should be flipped, in order.
+ */
+export function getReorderSegments(string, embeddingLevelsResult, start, end) {
+  let strLen = string.length
+  start = Math.max(0, start == null ? 0 : +start)
+  end = Math.min(strLen - 1, end == null ? strLen - 1 : +end)
+
+  const segments = []
+  embeddingLevelsResult.paragraphs.forEach(paragraph => {
+    const lineStart = Math.max(start, paragraph.start)
+    const lineEnd = Math.min(end, paragraph.end)
+    if (lineStart < lineEnd) {
+      // Local slice for mutation
+      const lineLevels = embeddingLevelsResult.levels.slice(lineStart, lineEnd + 1)
+
+      // 3.4 L1.4: Reset any sequence of whitespace characters and/or isolate formatting characters at the
+      // end of the line to the paragraph level.
+      for (let i = lineEnd; i >= lineStart && (getBidiCharType(string[i]) & TRAILING_TYPES); i--) {
+        lineLevels[i] = paragraph.level
+      }
+
+      // L2. From the highest level found in the text to the lowest odd level on each line, including intermediate levels
+      // not actually present in the text, reverse any contiguous sequence of characters that are at that level or higher.
+      let maxLevel = paragraph.level
+      let minOddLevel = Infinity
+      for (let i = 0; i < lineLevels.length; i++) {
+        const level = lineLevels[i]
+        if (level > maxLevel) maxLevel = level
+        if (level < minOddLevel) minOddLevel = level | 1
+      }
+      for (let lvl = maxLevel; lvl >= minOddLevel; lvl--) {
+        for (let i = 0; i < lineLevels.length; i++) {
+          if (lineLevels[i] >= lvl) {
+            const segStart = i
+            while (i + 1 < lineLevels.length && lineLevels[i + 1] >= lvl) {
+              i++
+            }
+            if (i > segStart) {
+              segments.push([segStart + lineStart, i + lineStart])
+            }
+          }
+        }
+      }
+    }
+  })
+  return segments
+}
+
+/**
+ * @param {string} string
+ * @param {GetEmbeddingLevelsResult} embedLevelsResult
+ * @param {number} [start]
+ * @param {number} [end]
+ * @return {string} the new string with bidi segments reordered
+ */
+export function getReorderedString(string, embedLevelsResult, start, end) {
+  const indices = getReorderedIndices(string, embedLevelsResult, start, end)
+  const chars = [...string]
+  indices.forEach((charIndex, i) => {
+    chars[i] = (
+      (embedLevelsResult.levels[charIndex] & 1) ? getMirroredCharacter(string[charIndex]) : null
+    ) || string[charIndex]
+  })
+  return chars.join('')
+}
+
+/**
+ * @param {string} string
+ * @param {GetEmbeddingLevelsResult} embedLevelsResult
+ * @param {number} [start]
+ * @param {number} [end]
+ * @return {number[]} an array with character indices in their new bidi order
+ */
+export function getReorderedIndices(string, embedLevelsResult, start, end) {
+  const segments = getReorderSegments(string, embedLevelsResult, start, end)
+  // Fill an array with indices
+  const indices = []
+  for (let i = 0; i < string.length; i++) {
+    indices[i] = i
+  }
+  // Reverse each segment in order
+  segments.forEach(([start, end]) => {
+    const slice = indices.slice(start, end + 1)
+    for (let i = slice.length; i--;) {
+      indices[end - i] = slice[i]
+    }
+  })
+  return indices
+}