1 files changed, 48 insertions, 0 deletions
diff --git a/vanilla/node_modules/bidi-js/src/mirroring.js b/vanilla/node_modules/bidi-js/src/mirroring.js
new file mode 100644
index 0000000..c214b04
--- /dev/null
+++ b/vanilla/node_modules/bidi-js/src/mirroring.js
@@ -0,0 +1,48 @@
+import data from './data/bidiMirroring.data.js'
+import { parseCharacterMap } from './util/parseCharacterMap.js'
+
+let mirrorMap
+
+function parse () {
+  if (!mirrorMap) {
+    //const start = performance.now()
+    const { map, reverseMap } = parseCharacterMap(data, true)
+    // Combine both maps into one
+    reverseMap.forEach((value, key) => {
+      map.set(key, value)
+    })
+    mirrorMap = map
+    //console.log(`mirrored chars parsed in ${performance.now() - start}ms`)
+  }
+}
+
+export function getMirroredCharacter (char) {
+  parse()
+  return mirrorMap.get(char) || null
+}
+
+/**
+ * Given a string and its resolved embedding levels, build a map of indices to replacement chars
+ * for any characters in right-to-left segments that have defined mirrored characters.
+ * @param string
+ * @param embeddingLevels
+ * @param [start]
+ * @param [end]
+ * @return {Map<number, string>}
+ */
+export function getMirroredCharactersMap(string, embeddingLevels, 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 map = new Map()
+  for (let i = start; i <= end; i++) {
+    if (embeddingLevels[i] & 1) { //only odd (rtl) levels
+      const mirror = getMirroredCharacter(string[i])
+      if (mirror !== null) {
+        map.set(i, mirror)
+      }
+    }
+  }
+  return map
+}