hermes-tokenizer 1.8.85

//! Fast scalar pretokenizer for the DeepSeek V3/V3.1/V4 scheme — a
//! `Sequence` of three `Split` (Isolated) pre-tokenizers applied in order:
//!
//! 1. `\p{N}{1,3}` — number runs, three chars at a time
//! 2. `[\u{4E00}-\u{9FA5}\u{3040}-\u{30FF}]+` — CJK ideograph / kana runs
//! 3. the main regex:
//!    `[ascii punct][A-Za-z]+|[^\r\n\p{L}\p{P}\p{S}]?[\p{L}\p{M}]+| ?[\p{P}\p{S}]+[\r\n]*|\s*[\r\n]+|\s+(?!\S)|\s+`
//!
//! Sequence `Split`s re-split every piece produced by the previous stage,
//! and spans a regex does not match survive as their own pieces (the digit
//! pieces from stage 1, or the control-character gaps stage 3 skips).
//!
//! A single left-to-right pass reproduces the hierarchy by treating number
//! chars and CJK-range chars as hard piece boundaries for the main regex:
//! no match may cross one, and the `(?!\S)` lookahead succeeds at a
//! boundary exactly as it does at end of input (so a whitespace run ending
//! at a digit stays whole). Within a CJK piece the main regex still runs —
//! the ranges contain a few non-letters (U+309B/U+309C voicing marks are
//! `\p{S}`, U+30A0/U+30FB are `\p{P}`, U+3040 etc. are unassigned) — with
//! the piece edges as the region bounds. Each scan therefore carries a
//! `cjk_region` flag: a char belongs to the current region iff
//! `is_deepseek_cjk(cp) == cjk_region`.

use super::{
    decode_cp, is_ascii_ws, is_digit, is_letter, scan_newlines, scan_numbers_max3,
    swar_scan_letters,
};
use crate::pretokenize::Pretoken;
use crate::pretokenize::unicode::{DsCharClass, ds_class_of, is_deepseek_cjk};

pub struct FastDeepSeekV3Pretokenizer<'a> {
    bytes: &'a [u8],
    pos: usize,
}

impl<'a> FastDeepSeekV3Pretokenizer<'a> {
    #[inline]
    pub fn new(bytes: &'a [u8]) -> Self {
        Self { bytes, pos: 0 }
    }

    /// Resume iteration at a byte offset previously returned by [`Self::pos`].
    #[inline]
    pub fn with_pos(bytes: &'a [u8], pos: usize) -> Self {
        Self { bytes, pos }
    }

    /// Current position as a byte offset into the input.
    #[inline]
    pub fn pos(&self) -> usize {
        self.pos
    }
}

impl<'a> Iterator for FastDeepSeekV3Pretokenizer<'a> {
    type Item = Pretoken<'a>;

    #[inline]
    fn next(&mut self) -> Option<Pretoken<'a>> {
        if self.pos >= self.bytes.len() {
            return None;
        }
        let start = self.pos;
        self.pos = advance_pos(self.bytes, start);
        Some(Pretoken(&self.bytes[start..self.pos]))
    }
}

// SAFETY: delegates to `fill_spans_keyed_with_buf`, which writes exactly
// the first `n` entries from live in-bounds spans of `self.bytes`.
unsafe impl<'a> crate::pretokenize::PretokenSpans<'a> for FastDeepSeekV3Pretokenizer<'a> {
    /// Chunked pull with the cursor in a local across the whole chunk (the
    /// per-`next` store-load of `self.pos` costs real time in the encode
    /// loop's register-starved surroundings).
    #[inline(never)]
    fn fill_spans_keyed(
        &mut self,
        batch: &mut crate::pretokenize::SpanBatch<'a>,
        prefetch: &impl Fn(u64),
    ) -> usize {
        let (bytes, len) = (self.bytes, self.bytes.len());
        let mut pos = self.pos;
        let n = crate::pretokenize::fill_spans_keyed_with_buf(
            bytes,
            || {
                if pos >= len {
                    return None;
                }
                let start = pos;
                // advance_pos returns an in-bounds end > start.
                pos = advance_pos(bytes, start);
                Some((start, pos))
            },
            batch,
            prefetch,
        );
        self.pos = pos;
        n
    }
}

/// If the char at `pos` is `\p{L}` or `\p{M}` within the region, return the
/// offset just past it.
#[inline(always)]
fn lm_end_at(bytes: &[u8], pos: usize, cjk_region: bool) -> Option<usize> {
    let &b = bytes.get(pos)?;
    if b < 0x80 {
        if !cjk_region && is_letter(b) {
            return Some(pos + 1);
        }
        return None;
    }
    let (cp, l) = unsafe { decode_cp(bytes, pos) };
    if is_deepseek_cjk(cp) != cjk_region {
        return None;
    }
    match ds_class_of(cp) {
        DsCharClass::Letter | DsCharClass::Mark => Some(pos + l),
        _ => None,
    }
}

/// `[\p{L}\p{M}]+` from `pos`, bounded by the region.
#[inline(always)]
fn scan_lm_from(bytes: &[u8], pos: usize, cjk_region: bool) -> usize {
    let len = bytes.len();
    let mut p = pos;
    loop {
        if !cjk_region {
            p = swar_scan_letters(bytes, p);
        }
        if p >= len || unsafe { *bytes.get_unchecked(p) } < 0x80 {
            return p; // ASCII non-letter (or any ASCII inside a CJK region)
        }
        let (cp, l) = unsafe { decode_cp(bytes, p) };
        if is_deepseek_cjk(cp) != cjk_region {
            return p;
        }
        match ds_class_of(cp) {
            DsCharClass::Letter | DsCharClass::Mark => p += l,
            _ => return p,
        }
    }
}

/// `[\p{P}\p{S}]+` from `pos`, bounded by the region.
#[inline(always)]
fn scan_ps_from(bytes: &[u8], pos: usize, cjk_region: bool) -> usize {
    let len = bytes.len();
    let mut p = pos;
    loop {
        if !cjk_region {
            while p < len {
                let b = unsafe { *bytes.get_unchecked(p) };
                if b >= 0x80 {
                    break;
                }
                if !b.is_ascii_punctuation() {
                    return p;
                }
                p += 1;
            }
        }
        if p >= len || unsafe { *bytes.get_unchecked(p) } < 0x80 {
            return p;
        }
        let (cp, l) = unsafe { decode_cp(bytes, p) };
        if is_deepseek_cjk(cp) != cjk_region || ds_class_of(cp) != DsCharClass::PunctSym {
            return p;
        }
        p += l;
    }
}

/// Whitespace-led token starting at `start`: `\s*[\r\n]+` | `\s+(?!\S)` |
/// `\s+`, in that priority, with the lookahead succeeding at a piece
/// boundary (number/CJK char) as well as at end of input. Main region only.
#[inline(always)]
fn ws_token_end(bytes: &[u8], start: usize) -> usize {
    let len = bytes.len();
    let mut p = start;
    let mut last_nl_end = 0usize; // 0 = run contains no \r\n
    let mut last_char_start = start;
    let mut at_boundary = false;
    while p < len {
        let b = unsafe { *bytes.get_unchecked(p) };
        if b == b'\r' || b == b'\n' {
            last_char_start = p;
            p += 1;
            last_nl_end = p;
        } else if is_ascii_ws(b) {
            last_char_start = p;
            p += 1;
        } else if b < 0x80 {
            at_boundary = is_digit(b);
            break;
        } else {
            let (cp, l) = unsafe { decode_cp(bytes, p) };
            if ds_class_of(cp) == DsCharClass::Whitespace {
                last_char_start = p;
                p += l;
            } else {
                at_boundary = ds_class_of(cp) == DsCharClass::Number || is_deepseek_cjk(cp);
                break;
            }
        }
    }
    if last_nl_end != 0 {
        return last_nl_end; // `\s*[\r\n]+`: through the last newline, even at EOS
    }
    if p >= len || at_boundary {
        return p; // `\s+(?!\S)`: lookahead succeeds at EOS / piece boundary
    }
    if last_char_start > start {
        return last_char_start; // `\s+(?!\S)`: all but the last ws char
    }
    p // `\s+`: single whitespace char before content
}

/// Unmatched-gap piece: chars the main regex cannot match (`Other` class not
/// prefixing a letter/mark run), emitted as one piece like HF's Isolated
/// split leaves them. `first_len` is the byte length of the char at `pos`,
/// which the caller already established starts a gap.
#[inline(always)]
fn scan_gap_from(bytes: &[u8], pos: usize, first_len: usize, cjk_region: bool) -> usize {
    let len = bytes.len();
    let mut p = pos + first_len;
    while p < len {
        let b = unsafe { *bytes.get_unchecked(p) };
        let (cp, l) = if b < 0x80 {
            (b as u32, 1)
        } else {
            unsafe { decode_cp(bytes, p) }
        };
        if is_deepseek_cjk(cp) != cjk_region || ds_class_of(cp) != DsCharClass::Other {
            return p;
        }
        // This char starts a `[^\r\n\p{L}\p{P}\p{S}]?[\p{L}\p{M}]+` match,
        // so the gap ends before it.
        if lm_end_at(bytes, p + l, cjk_region).is_some() {
            return p;
        }
        p += l;
    }
    p
}

/// One main-regex token starting at `pos` in the main (non-CJK) region.
/// The char at `pos` is not a number char and not CJK.
#[inline(always)]
fn advance_main(bytes: &[u8], pos: usize) -> usize {
    let b0 = unsafe { *bytes.get_unchecked(pos) };

    // Hot path 1: ASCII letter — `[\p{L}\p{M}]+` with empty prefix
    if is_letter(b0) {
        return scan_lm_from(bytes, pos + 1, false);
    }

    // Hot path 2: space prefix
    if b0 == b' ' {
        let Some(&b1) = bytes.get(pos + 1) else {
            return pos + 1; // trailing lone space (`\s+(?!\S)` at EOS)
        };
        if is_letter(b1) {
            return scan_lm_from(bytes, pos + 2, false); // " word"
        }
        if b1 < 0x80 {
            if is_digit(b1) {
                return pos + 1; // ws run whole before a digit piece
            }
            if b1.is_ascii_punctuation() {
                // ` ?[\p{P}\p{S}]+[\r\n]*`
                let p = scan_ps_from(bytes, pos + 2, false);
                return scan_newlines(bytes, p);
            }
            if is_ascii_ws(b1) {
                return ws_token_end(bytes, pos);
            }
            return pos + 1; // `\s+`: single space before an ASCII control
        }
        let (cp, l) = unsafe { decode_cp(bytes, pos + 1) };
        if is_deepseek_cjk(cp) {
            return pos + 1; // ws run whole before a CJK piece
        }
        let p1 = pos + 1 + l;
        match ds_class_of(cp) {
            DsCharClass::Letter | DsCharClass::Mark => scan_lm_from(bytes, p1, false),
            DsCharClass::Number => pos + 1,
            DsCharClass::Whitespace => ws_token_end(bytes, pos),
            DsCharClass::PunctSym => {
                let p = scan_ps_from(bytes, p1, false);
                scan_newlines(bytes, p)
            }
            DsCharClass::Other => pos + 1, // `\s+`: single space before a control
        }
    } else if b0 < 0x80 {
        if b0 == b'\r' || b0 == b'\n' {
            return ws_token_end(bytes, pos); // \r\n are excluded from prefixes
        }
        if is_ascii_ws(b0) {
            // \t \x0b \x0c may prefix a letter/mark run
            if let Some(e) = lm_end_at(bytes, pos + 1, false) {
                return scan_lm_from(bytes, e, false);
            }
            return ws_token_end(bytes, pos);
        }
        if b0.is_ascii_punctuation() {
            // `[ascii punct][A-Za-z]+` — ASCII letters only
            if let Some(&b1) = bytes.get(pos + 1)
                && is_letter(b1)
            {
                return swar_scan_letters(bytes, pos + 1);
            }
            let p = scan_ps_from(bytes, pos + 1, false);
            return scan_newlines(bytes, p);
        }
        // ASCII control: may prefix a letter/mark run, else starts a gap
        if let Some(e) = lm_end_at(bytes, pos + 1, false) {
            return scan_lm_from(bytes, e, false);
        }
        scan_gap_from(bytes, pos, 1, false)
    } else {
        let (cp, l) = unsafe { decode_cp(bytes, pos) };
        let p0 = pos + l;
        match ds_class_of(cp) {
            DsCharClass::Letter | DsCharClass::Mark => scan_lm_from(bytes, p0, false),
            DsCharClass::Whitespace => {
                // Non-\r\n whitespace may prefix a letter/mark run
                if let Some(e) = lm_end_at(bytes, p0, false) {
                    return scan_lm_from(bytes, e, false);
                }
                ws_token_end(bytes, pos)
            }
            DsCharClass::PunctSym => {
                let p = scan_ps_from(bytes, p0, false);
                scan_newlines(bytes, p)
            }
            // `Other` (controls/format/unassigned); `Number` is unreachable
            // (the caller dispatched it to the digit rule).
            DsCharClass::Number | DsCharClass::Other => {
                if let Some(e) = lm_end_at(bytes, p0, false) {
                    return scan_lm_from(bytes, e, false);
                }
                scan_gap_from(bytes, pos, l, false)
            }
        }
    }
}

/// One main-regex token starting at `pos` inside a CJK piece. The char at
/// `pos` is in the CJK ranges. No whitespace, newlines, or ASCII exist in
/// the region, so only the letter/mark, punct/symbol, and gap rules apply.
#[inline(always)]
fn advance_cjk(bytes: &[u8], pos: usize) -> usize {
    let (cp, l) = unsafe { decode_cp(bytes, pos) };
    let p0 = pos + l;
    match ds_class_of(cp) {
        DsCharClass::Letter | DsCharClass::Mark => scan_lm_from(bytes, p0, true),
        DsCharClass::PunctSym => scan_ps_from(bytes, p0, true),
        _ => {
            // Unassigned (e.g. U+3040): may prefix a letter/mark run
            if let Some(e) = lm_end_at(bytes, p0, true) {
                return scan_lm_from(bytes, e, true);
            }
            scan_gap_from(bytes, pos, l, true)
        }
    }
}

/// Advance past one token starting at `pos`. Returns the new position.
/// `pos` must be < `bytes.len()`.
#[inline(always)]
fn advance_pos(bytes: &[u8], pos: usize) -> usize {
    let b0 = unsafe { *bytes.get_unchecked(pos) };
    if b0 < 0x80 {
        if is_digit(b0) {
            return scan_numbers_max3(bytes, pos + 1, 1); // `\p{N}{1,3}`
        }
        return advance_main(bytes, pos);
    }
    let (cp, l) = unsafe { decode_cp(bytes, pos) };
    if is_deepseek_cjk(cp) {
        return advance_cjk(bytes, pos);
    }
    if ds_class_of(cp) == DsCharClass::Number {
        return scan_numbers_max3(bytes, pos + l, 1);
    }
    advance_main(bytes, pos)
}