use updated regexes from upstream (#19)

via https://github.com/openai/tiktoken/pull/258/files

src/openai_public.rs

@@ -26,6 +26,11 @@ const IM_SEP: &str = "<|im_sep|>";
 #[derive(Clone, Debug, Copy)]
 pub struct EncodingFactory {}
 impl EncodingFactory {
+  // The pattern in the original GPT-2 release is:
+  // r"'s|'t|'re|'ve|'m|'ll|'d| ?[\p{L}]+| ?[\p{N}]+| ?[^\s\p{L}\p{N}]+|\s+(?!\S)|\s+"""
+  // This is equivalent, but executes faster:
+  const LEGACY_SPLITTER_REGEX: &str = r"'(?:[sdmt]|ll|ve|re)| ?\p{L}++| ?\p{N}++| ?[^\s\p{L}\p{N}]++|\s++$|\s+(?!\S)|\s";
+
   pub fn gpt2() -> Result<Encoding, EncodingFactoryError> {
     // todo!
     // vocab_bpe_file: sha256 = 1ce1664773c50f3e0cc8842619a93edc4624525b728b188a9e0be33b7726adc5
@@ -45,7 +50,7 @@ impl EncodingFactory {
     special_tokens.shrink_to_fit();
     Encoding::new(
       "r50k_base",
-      r"'s|'t|'re|'ve|'m|'ll|'d| ?\p{L}+| ?\p{N}+| ?[^\s\p{L}\p{N}]+|\s+(?!\S)|\s+",
+      EncodingFactory::LEGACY_SPLITTER_REGEX,
       mergeable_ranks,
       special_tokens,
       Some(50257),
@@ -64,7 +69,7 @@ impl EncodingFactory {
     special_tokens.shrink_to_fit();
     Encoding::new(
       "p50k_base",
-      r"'s|'t|'re|'ve|'m|'ll|'d| ?\p{L}+| ?\p{N}+| ?[^\s\p{L}\p{N}]+|\s+(?!\S)|\s+",
+      EncodingFactory::LEGACY_SPLITTER_REGEX,
       mergeable_ranks,
       special_tokens,
       Some(50281),
@@ -107,9 +112,12 @@ impl EncodingFactory {
     .map_err(|_| EncodingFactoryError::FailedToLoadEncoding)?;
     let mut special_tokens: HashMap<String, Rank> = special_tokens.iter().cloned().collect();
     special_tokens.shrink_to_fit();
+    // use faster version from tiktoken upstream https://github.com/openai/tiktoken/pull/258/files#r1487668172
+    // const PATTERN: &str = r"(?i:'s|'t|'re|'ve|'m|'ll|'d)|[^\r\n\p{L}\p{N}]?\p{L}+|\p{N}{1,3}| ?[^\s\p{L}\p{N}]+[\r\n]*|\s*[\r\n]+|\s+(?!\S)|\s+";
+    const PATTERN: &str = r"'(?i:[sdmt]|ll|ve|re)|[^\r\n\p{L}\p{N}]?+\p{L}++|\p{N}{1,3}+| ?[^\s\p{L}\p{N}]++[\r\n]*+|\s++$|\s*[\r\n]|\s+(?!\S)|\s";
     Encoding::new(
             "cl100k_base",
-            r"(?i:'s|'t|'re|'ve|'m|'ll|'d)|[^\r\n\p{L}\p{N}]?\p{L}+|\p{N}{1,3}| ?[^\s\p{L}\p{N}]+[\r\n]*|\s*[\r\n]+|\s+(?!\S)|\s+",
+            PATTERN,
             mergeable_ranks,
             special_tokens,
             None,