Revert "reorg internal state"

This reverts commit 5b3c150.

Author: cometkim

README.md

@@ -215,7 +215,7 @@ Since [Hermes doesn't support the `Intl.Segmenter` API](https://github.com/faceb
 
 | Name                         | Unicode® | ESM? |   Size    | Size (min) | Size (min+gzip) | Size (min+br) | Size (min+zstd) |
 |------------------------------|----------|------|----------:|-----------:|----------------:|--------------:|----------------:|
-| `unicode-segmenter/grapheme` |   16.0.0 |   ✔️ |    10,725 |      6,650 |           3,364 |         2,732 |           3,485 |
+| `unicode-segmenter/grapheme` |   16.0.0 |   ✔️ |    10,708 |      6,659 |           3,363 |         2,739 |           3,490 |
 | `graphemer`                  |   15.0.0 |   ✖️ ️|   410,435 |     95,104 |          15,752 |        10,660 |          15,911 |
 | `grapheme-splitter`          |   10.0.0 |   ✖️ |   122,254 |     23,682 |           7,852 |         4,802 |           6,753 |
 | `@formatjs/intl-segmenter`*  |   15.0.0 |   ✖️ |   603,510 |    369,673 |          72,273 |        49,530 |          68,027 |
@@ -231,7 +231,7 @@ Since [Hermes doesn't support the `Intl.Segmenter` API](https://github.com/faceb
 
 | Name                         | Bytecode size | Bytecode size (gzip)* |
 |------------------------------|--------------:|----------------------:|
-| `unicode-segmenter/grapheme` |        20,229 |                11,393 |
+| `unicode-segmenter/grapheme` |        20,259 |                11,417 |
 | `graphemer`                  |       134,089 |                31,766 |
 | `grapheme-splitter`          |        63,946 |                19,162 |
 

src/grapheme.js

@@ -45,47 +45,47 @@ const BMP_MAX = 0xFFFF;
  * @return {GraphemeSegmenter} iterator for grapheme cluster segments
  */
 export function* graphemeSegments(input) {
+  let cp = input.codePointAt(0);
+
+  // do nothing on empty string
+  if (cp == null) return;
+
+  /** Current cursor position. */
+  let cursor = cp <= BMP_MAX ? 1 : 2;
+
   /** Total length of the input string. */
   let len = input.length;
 
-  // do nothing on empty string
-  if (len === 0) return;
+  /** Category of codepoint immediately preceding cursor */
+  let catBefore = cat(cp);
 
-  let cp = /** @type {number}*/ (input.codePointAt(0));
+  /** @type {GraphemeCategoryNum} Category of codepoint immediately preceding cursor. */
+  let catAfter = 0;
 
-  /** Memoize the beginning code point of the segment. */
-  let _hd = cp;
+  /** The number of RIS codepoints preceding `cursor`. */
+  let risCount = 0;
 
   /**
    * Emoji state for GB11: tracks if we've seen Extended_Pictographic followed by Extend* ZWJ
    * Only relevant when catBefore === ZWJ && catAfter === Extended_Pictographic
    */
   let emoji = false;
 
-  /** The number of RI codepoints preceding `cursor`. */
-  let riCount = 0;
-
   /** InCB=Consonant - segment started with Indic consonant */
   let consonant = false;
 
   /** InCB=Linker - seen a linker after consonant */
   let linker = false;
 
-  /** Category of codepoint immediately preceding cursor */
-  let catBefore = cat(cp);
+  let index = 0;
 
-  /** Memoize the beginning category of the segment */
+  /** Beginning category of a segment */
   let _catBegin = catBefore;
 
-  /** @type {GraphemeCategoryNum} Category of codepoint immediately preceding cursor. */
-  let catAfter = 0;
-
-  let index = 0;
-  let cursor = 0;
+  /** Memoize the beginning code point of the segment. */
+  let _hd = cp;
 
   while (cursor < len) {
-    cursor += cp <= BMP_MAX ? 1 : 2;
-
     cp = /** @type {number} */ (input.codePointAt(cursor));
     catAfter = cat(cp);
 
@@ -117,8 +117,8 @@ export function* graphemeSegments(input) {
     }
     // GB12, GB13: RI × RI (odd count means no break)
     else if (catBefore === 10 && catAfter === 10) {
-      // riCount is count BEFORE current RI, so odd means this is 2nd, 4th, etc.
-      boundary = riCount++ % 2 === 1;
+      // risCount is count BEFORE current RI, so odd means this is 2nd, 4th, etc.
+      boundary = risCount++ % 2 === 1;
     }
     // GB6: L × (L | V | LV | LVT)
     else if (catBefore === 5) {
@@ -150,7 +150,7 @@ export function* graphemeSegments(input) {
 
       // Reset segment state
       emoji = false;
-      riCount = 0;
+      risCount = 0;
       index = cursor;
       _catBegin = catAfter;
       _hd = cp;
@@ -181,6 +181,7 @@ export function* graphemeSegments(input) {
       }
     }
 
+    cursor += cp <= BMP_MAX ? 1 : 2;
     catBefore = catAfter;
   }