ferroni 1.8.1

// regint.rs - Port of regint.h
// Internal types, OpCode, Operation, BitSet, MemStatus, regex_t.

use std::collections::HashMap;

use crate::oniguruma::*;
use crate::regenc::OnigEncoding;

// === Feature Flags (C #define USE_*) ===
pub const USE_CALL: bool = true;
pub const USE_CALLOUT: bool = true;
pub const USE_BACKREF_WITH_LEVEL: bool = true;
pub const USE_CAPTURE_HISTORY: bool = true;

// === Config Constants ===
pub const DEFAULT_PARSE_DEPTH_LIMIT: u32 = 4096;
pub const INIT_MATCH_STACK_SIZE: usize = 160;
pub const DEFAULT_MATCH_STACK_LIMIT_SIZE: u32 = 0;
/// Rust-only (ADR-008): the backtrack stack never grows past this many
/// entries unless a larger `match_stack_limit` is set. C lets it grow without
/// bound when the limit is 0, so one hostile line can exhaust memory. This
/// is a separate cap and not a default for `match_stack_limit`: a non-zero
/// limit turns off other optimizations that a plain search is allowed.
pub const HARD_MATCH_STACK_CAP: usize = 10_000_000;
pub const DEFAULT_RETRY_LIMIT_IN_MATCH: u64 = 10_000_000;
pub const DEFAULT_RETRY_LIMIT_IN_SEARCH: u64 = 0;
pub const DEFAULT_TIME_LIMIT_MSEC: u64 = 0;
pub const DEFAULT_SUBEXP_CALL_LIMIT_IN_SEARCH: u64 = 0;
pub const DEFAULT_SUBEXP_CALL_MAX_NEST_LEVEL: i32 = 20;

// === Internal Constants ===
pub const CHAR_MAP_SIZE: usize = 256;
pub const INFINITE_LEN: OnigLen = ONIG_INFINITE_DISTANCE;
pub const STEP_BACK_MAX_CHAR_LEN: i32 = 65535;
pub const LOOK_BEHIND_MAX_CHAR_LEN: i32 = STEP_BACK_MAX_CHAR_LEN;
pub const INFINITE_REPEAT: i32 = -1;

#[inline]
pub fn is_infinite_repeat(n: i32) -> bool {
    n == INFINITE_REPEAT
}

// === Bytecode Types ===
pub type RelAddrType = i32;
pub type AbsAddrType = i32;
pub type LengthType = i32;
pub type RelPositionType = i32;
pub type RepeatNumType = i32;
pub type MemNumType = i32;
pub type ModeType = i32;

// === MemStatus (bit status for captures) ===
pub type MemStatusType = u32;

pub const MEM_STATUS_BITS_NUM: usize = 32;

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mem_status_clear(stats: &mut MemStatusType) {
    *stats = 0;
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mem_status_on_all(stats: &mut MemStatusType) {
    *stats = !0u32;
}

#[inline]
pub fn mem_status_at(stats: MemStatusType, n: usize) -> bool {
    if n < MEM_STATUS_BITS_NUM {
        (stats & (1u32 << n)) != 0
    } else {
        (stats & 1) != 0
    }
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mem_status_at0(stats: MemStatusType, n: usize) -> bool {
    if n > 0 && n < MEM_STATUS_BITS_NUM {
        (stats & (1u32 << n)) != 0
    } else {
        (stats & 1) != 0
    }
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mem_status_is_all_on(stats: MemStatusType) -> bool {
    (stats & 1) != 0
}

#[inline]
pub fn mem_status_on(stats: &mut MemStatusType, n: usize) {
    if n < MEM_STATUS_BITS_NUM {
        if n != 0 {
            *stats |= 1u32 << n;
        }
    } else {
        *stats |= 1;
    }
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mem_status_on_simple(stats: &mut MemStatusType, n: usize) {
    if n < MEM_STATUS_BITS_NUM {
        *stats |= 1u32 << n;
    }
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mem_status_limit_at(stats: MemStatusType, n: usize) -> bool {
    if n < MEM_STATUS_BITS_NUM {
        (stats & (1u32 << n)) != 0
    } else {
        false
    }
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mem_status_limit_on(stats: &mut MemStatusType, n: usize) {
    if n < MEM_STATUS_BITS_NUM && n != 0 {
        *stats |= 1u32 << n;
    }
}

// === BitSet (256 bits for ASCII character classes) ===
pub const BITS_PER_BYTE: usize = 8;
pub const SINGLE_BYTE_SIZE: usize = 1 << BITS_PER_BYTE;
pub const BITS_IN_ROOM: usize = 32;
pub const BITSET_REAL_SIZE: usize = SINGLE_BYTE_SIZE / BITS_IN_ROOM;
pub type Bits = u32;
pub type BitSet = [Bits; BITSET_REAL_SIZE];

pub const SIZE_BITSET: usize = std::mem::size_of::<BitSet>();

#[inline]
pub fn bitset_clear(bs: &mut BitSet) {
    for slot in bs.iter_mut() {
        *slot = 0;
    }
}

#[inline]
pub fn bs_room(pos: usize) -> usize {
    pos >> 5
}

#[inline]
pub fn bs_bit(pos: usize) -> u32 {
    1u32 << (pos & 0x1f)
}

#[inline]
pub fn bitset_at(bs: &BitSet, pos: usize) -> bool {
    (bs[bs_room(pos)] & bs_bit(pos)) != 0
}

/// The positions of the set bits of `bs`, ascending. Visits whole words, so
/// sparse sets cost their population rather than 256 bit tests.
#[inline]
pub fn bitset_members(bs: &BitSet) -> impl Iterator<Item = usize> + '_ {
    bs.iter().enumerate().flat_map(|(room, &word)| {
        let mut bits = word;
        std::iter::from_fn(move || {
            (bits != 0).then(|| {
                let pos = room * BITS_IN_ROOM + bits.trailing_zeros() as usize;
                bits &= bits - 1;
                pos
            })
        })
    })
}

#[inline]
pub fn bitset_set_bit(bs: &mut BitSet, pos: usize) {
    bs[bs_room(pos)] |= bs_bit(pos);
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn bitset_clear_bit(bs: &mut BitSet, pos: usize) {
    bs[bs_room(pos)] &= !bs_bit(pos);
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn bitset_invert_bit(bs: &mut BitSet, pos: usize) {
    bs[bs_room(pos)] ^= bs_bit(pos);
}

// === Anchor Flags ===
pub const ANCR_PREC_READ: i32 = 1 << 0;
pub const ANCR_PREC_READ_NOT: i32 = 1 << 1;
pub const ANCR_LOOK_BEHIND: i32 = 1 << 2;
pub const ANCR_LOOK_BEHIND_NOT: i32 = 1 << 3;
pub const ANCR_BEGIN_BUF: i32 = 1 << 4;
pub const ANCR_BEGIN_LINE: i32 = 1 << 5;
pub const ANCR_BEGIN_POSITION: i32 = 1 << 6;
pub const ANCR_END_BUF: i32 = 1 << 7;
pub const ANCR_SEMI_END_BUF: i32 = 1 << 8;
pub const ANCR_END_LINE: i32 = 1 << 9;
pub const ANCR_WORD_BOUNDARY: i32 = 1 << 10;
pub const ANCR_NO_WORD_BOUNDARY: i32 = 1 << 11;
pub const ANCR_WORD_BEGIN: i32 = 1 << 12;
pub const ANCR_WORD_END: i32 = 1 << 13;
pub const ANCR_ANYCHAR_INF: i32 = 1 << 14;
pub const ANCR_ANYCHAR_INF_ML: i32 = 1 << 15;
pub const ANCR_TEXT_SEGMENT_BOUNDARY: i32 = 1 << 16;
pub const ANCR_NO_TEXT_SEGMENT_BOUNDARY: i32 = 1 << 17;
pub const ANCR_ANYCHAR_INF_MASK: i32 = ANCR_ANYCHAR_INF | ANCR_ANYCHAR_INF_ML;

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn anchor_has_body(anchor_type: i32) -> bool {
    anchor_type < ANCR_BEGIN_BUF
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn is_word_anchor_type(anchor_type: i32) -> bool {
    anchor_type == ANCR_WORD_BOUNDARY
        || anchor_type == ANCR_NO_WORD_BOUNDARY
        || anchor_type == ANCR_WORD_BEGIN
        || anchor_type == ANCR_WORD_END
}

// === OpCode Enum ===
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(u8)]
pub enum OpCode {
    Finish = 0,
    End = 1,
    Str1 = 2,
    Str2 = 3,
    Str3 = 4,
    Str4 = 5,
    Str5 = 6,
    StrN = 7,
    StrMb2n1 = 8,
    StrMb2n2 = 9,
    StrMb2n3 = 10,
    StrMb2n = 11,
    StrMb3n = 12,
    StrMbn = 13,
    CClass = 14,
    CClassMb = 15,
    CClassMix = 16,
    CClassNot = 17,
    CClassMbNot = 18,
    CClassMixNot = 19,
    AnyChar = 20,
    AnyCharMl = 21,
    AnyCharStar = 22,
    AnyCharMlStar = 23,
    AnyCharStarPeekNext = 24,
    AnyCharMlStarPeekNext = 25,
    Word = 26,
    WordAscii = 27,
    NoWord = 28,
    NoWordAscii = 29,
    WordBoundary = 30,
    NoWordBoundary = 31,
    WordBegin = 32,
    WordEnd = 33,
    TextSegmentBoundary = 34,
    BeginBuf = 35,
    EndBuf = 36,
    BeginLine = 37,
    EndLine = 38,
    SemiEndBuf = 39,
    CheckPosition = 40,
    BackRef1 = 41,
    BackRef2 = 42,
    BackRefN = 43,
    BackRefNIc = 44,
    BackRefMulti = 45,
    BackRefMultiIc = 46,
    BackRefWithLevel = 47,
    BackRefWithLevelIc = 48,
    BackRefCheck = 49,
    BackRefCheckWithLevel = 50,
    MemStart = 51,
    MemStartPush = 52,
    MemEndPush = 53,
    MemEndPushRec = 54,
    MemEnd = 55,
    MemEndRec = 56,
    Fail = 57,
    Jump = 58,
    Push = 59,
    PushSuper = 60,
    Pop = 61,
    PopToMark = 62,
    PushOrJumpExact1 = 63,
    PushIfPeekNext = 64,
    Repeat = 65,
    RepeatNg = 66,
    RepeatInc = 67,
    RepeatIncNg = 68,
    EmptyCheckStart = 69,
    EmptyCheckEnd = 70,
    EmptyCheckEndMemst = 71,
    EmptyCheckEndMemstPush = 72,
    Move = 73,
    StepBackStart = 74,
    StepBackNext = 75,
    CutToMark = 76,
    Mark = 77,
    SaveVal = 78,
    UpdateVar = 79,
    Call = 80,
    Return = 81,
    CalloutContents = 82,
    CalloutName = 83,
    CClassStar = 84,
    CClassMixStar = 85,
    CClassMbStar = 86,
    WordStar = 87,
    WordAsciiStar = 88,
    CClassStarPeekNext = 89,
    WordAsciiStarPeekNext = 90,
    AltLiterals = 91,
    CClassNotStar = 92,
    CClassMbNotStar = 93,
    CClassMixNotStar = 94,
    /// Rust-only (ADR-008): a fixed-length look-behind whose body is the
    /// single character or string instruction that follows it.
    LookBehindOp = 95,
    /// Rust-only (ADR-008): `PushOrJumpExact1` with a byte set. Pushes the
    /// alternative only when the current byte can start the main path.
    PushOrJumpByteSet = 96,
    /// A bounded run of identical ASCII character classes.
    CClassRun = 97,
    /// Rust-only (ADR-008): positive ASCII class star with no exit choices.
    /// Emitted only by the explicitly enabled decimal rewrite pass.
    CClassPossessiveStar = 98,
    /// Rust-only (ADR-008): decimal prefix reserving the final digit for its tail.
    DecimalTailPrefix = 99,
}

// === SaveType ===
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(i32)]
pub enum SaveType {
    Keep = 0,
    S = 1,
    RightRange = 2,
}

// === UpdateVarType ===
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(i32)]
pub enum UpdateVarType {
    KeepFromStackLast = 0,
    SFromStack = 1,
    RightRangeFromStack = 2,
    RightRangeFromSStack = 3,
    RightRangeToS = 4,
    RightRangeInit = 5,
}

// === CheckPositionType ===
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(i32)]
pub enum CheckPositionType {
    SearchStart = 0,
    CurrentRightRange = 1,
}

// === TextSegmentBoundaryType ===
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(i32)]
pub enum TextSegmentBoundaryType {
    ExtendedGraphemeCluster = 0,
    Word = 1,
}

// === Stack Pop Level ===
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(i32)]
pub enum StackPopLevel {
    Free = 0,
    MemStart = 1,
    All = 2,
}

// === Optimize Type ===
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum OptimizeType {
    None,
    Str,
    StrFast,
    StrFastStepForward,
    Map,
}

// === CClass Flags ===
pub const FLAG_NCCLASS_NOT: u32 = 1 << 0;
pub const FLAG_NCCLASS_SHARE: u32 = 1 << 1;

// === Operation (Bytecode Instruction) ===
//
// In C this is a struct with opcode + union. In Rust we use struct + enum payload.
// The opcode field is stored separately for direct access (needed for dispatch).
pub struct Operation {
    pub opcode: OpCode,
    pub payload: OperationPayload,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum CClassAsciiFastKind {
    None,
    Eq(u8),
    EqFoldLower(u8),
}

pub enum OperationPayload {
    None,
    /// Captures around the repeated decimal/optional-underscore body, outer first.
    DecimalTailPrefix {
        captures: Vec<MemNumType>,
    },
    Exact {
        s: [u8; 16],
    },
    ExactN {
        s: Vec<u8>,
        n: LengthType,
    },
    ExactLenN {
        s: Vec<u8>,
        n: LengthType,
        len: LengthType,
    },
    CClass {
        bsp: Box<BitSet>,
        ascii_fast: CClassAsciiFastKind,
    },
    CClassRun {
        bsp: Box<BitSet>,
        len: u8,
    },
    CClassMb {
        mb: Vec<u32>,
    },
    CClassMix {
        mb: Vec<u32>,
        bsp: Box<BitSet>,
    },
    AnyCharStarPeekNext {
        c: u8,
    },
    CClassStarPeekNext {
        bsp: Box<BitSet>,
        c: u8,
    },
    WordAsciiStarPeekNext {
        c: u8,
    },
    WordBoundary {
        mode: ModeType,
    },
    TextSegmentBoundary {
        boundary_type: TextSegmentBoundaryType,
        not: bool,
    },
    CheckPosition {
        check_type: CheckPositionType,
    },
    BackRefN {
        n1: MemNumType,
    },
    BackRefGeneral {
        num: i32,
        ns: Vec<MemNumType>,
        nest_level: i32,
    },
    MemoryStart {
        num: MemNumType,
    },
    MemoryEnd {
        num: MemNumType,
    },
    Jump {
        addr: RelAddrType,
    },
    Push {
        addr: RelAddrType,
    },
    PushOrJumpExact1 {
        addr: RelAddrType,
        c: u8,
        /// Rust-only (ADR-008): on a guarded `Push`, the backtracks its jump
        /// counts for the push it skips (see `guard_skipped_retries`).
        /// Upstream's own instruction counts none.
        skipped_retries: u32,
    },
    PushIfPeekNext {
        addr: RelAddrType,
        c: u8,
    },
    PopToMark {
        id: MemNumType,
    },
    Repeat {
        id: MemNumType,
        addr: RelAddrType,
    },
    RepeatInc {
        id: MemNumType,
    },
    EmptyCheckStart {
        mem: MemNumType,
    },
    EmptyCheckEnd {
        mem: MemNumType,
        empty_status_mem: MemStatusType,
    },
    Move {
        n: RelPositionType,
    },
    StepBackStart {
        initial: LengthType,
        remaining: LengthType,
        addr: RelAddrType,
    },
    CutToMark {
        id: MemNumType,
        restore_pos: bool,
    },
    Mark {
        id: MemNumType,
        save_pos: bool,
    },
    SaveVal {
        save_type: SaveType,
        id: MemNumType,
    },
    UpdateVar {
        var_type: UpdateVarType,
        id: MemNumType,
        clear: bool,
    },
    Call {
        addr: AbsAddrType,
    },
    Return,
    CalloutContents {
        num: MemNumType,
    },
    CalloutName {
        num: MemNumType,
        id: MemNumType,
    },
    AltLiterals {
        trie_idx: u32,
    },
    LookBehindOp {
        /// Characters to step back, as `StepBackStart`.
        char_len: u32,
        /// `(?<!...)` rather than `(?<=...)`.
        not: bool,
    },
    PushOrJumpByteSet {
        addr: RelAddrType,
        /// The bytes the main path can consume first.
        bsp: Box<BitSet>,
        /// The backtracks the jump counts for the push it skips (see
        /// `guard_skipped_retries`).
        skipped_retries: u32,
    },
}

// === Callout constants ===
pub const CALLOUT_IN_PROGRESS: i32 = OnigCalloutIn::Progress as i32;
pub const CALLOUT_IN_RETRACTION: i32 = OnigCalloutIn::Retraction as i32;
pub const CALLOUT_IN_BOTH: i32 = CALLOUT_IN_PROGRESS | CALLOUT_IN_RETRACTION;

/// Builtin callout IDs (hard-coded instead of global name registry)
pub const CALLOUT_BUILTIN_FAIL: i32 = 0;
pub const CALLOUT_BUILTIN_MAX: i32 = 1;
pub const CALLOUT_BUILTIN_COUNT: i32 = 2;
pub const CALLOUT_BUILTIN_CMP: i32 = 3;
pub const CALLOUT_BUILTIN_SKIP: i32 = 4;

/// Result codes for callout functions
pub const ONIG_CALLOUT_FAIL: i32 = 1;
pub const ONIG_CALLOUT_SUCCESS: i32 = 0;

// === Callout argument ===
#[derive(Clone, Debug)]
pub enum CalloutArg {
    Long(i64),
    Char(u8),
    Tag(Vec<u8>),
    Str(Vec<u8>),
}

// === CalloutListEntry ===
pub struct CalloutListEntry {
    pub of: i32,         // 0=contents, 1=name
    pub callout_in: i32, // CALLOUT_IN_PROGRESS / RETRACTION / BOTH
    pub builtin_id: i32, // CALLOUT_BUILTIN_MAX etc., -1 for contents
    pub tag: Option<Vec<u8>>,
    pub tag_start: usize, // byte offset of tag start in pattern
    pub tag_end: usize,   // byte offset of tag end in pattern
    pub args: Vec<CalloutArg>,
    pub content_end: Option<Vec<u8>>, // Content end bytes for content callouts
}

// === RepeatRange ===
#[derive(Clone, Debug)]
pub struct RepeatRange {
    pub lower: i32,
    pub upper: i32,
    pub u_offset: i32,
}

// === RegexExt (Callout Extension) ===
pub struct RegexExt {
    pub pattern: Vec<u8>,
    pub tag_table: Option<HashMap<Vec<u8>, i32>>,
    pub callout_num: i32,
    pub callout_list: Vec<CalloutListEntry>,
}

// === regex_t (re_pattern_buffer) ===
pub struct RegexType {
    /// Rust-only: findings of the compile-time backtracking check.
    pub(crate) backtrack_warnings: Vec<crate::backtrack_lint::BacktrackWarning>,
    /// Rust-only: reports from the explicitly enabled AST rewrite pass.
    pub(crate) backtrack_rewrites: Vec<crate::backtrack_rewrite::BacktrackingRewrite>,
    // bytecode
    pub(crate) ops: Vec<Operation>,
    pub(crate) string_pool: Vec<u8>,

    // capture info
    pub(crate) num_mem: i32,
    pub(crate) num_repeat: i32,
    pub(crate) num_empty_check: i32,
    pub(crate) num_call: i32,
    pub(crate) capture_history: MemStatusType,
    pub(crate) push_mem_start: MemStatusType,
    pub(crate) push_mem_end: MemStatusType,
    pub(crate) stack_pop_level: StackPopLevel,
    pub(crate) repeat_range: Vec<RepeatRange>,

    // metadata
    pub(crate) enc: OnigEncoding,
    pub(crate) options: OnigOptionType,
    /// Owned syntax configuration captured at compile time. Keeping a clone
    /// avoids tying a compiled regex to the lifetime of its caller's syntax.
    pub(crate) syntax: OnigSyntaxType,
    pub(crate) case_fold_flag: OnigCaseFoldType,
    pub(crate) name_table: Option<crate::regparse_types::NameTable>,

    // optimization
    pub(crate) optimize: OptimizeType,
    pub(crate) threshold_len: i32,
    pub(crate) anchor: i32,
    pub(crate) anc_dist_min: OnigLen,
    pub(crate) anc_dist_max: OnigLen,
    pub(crate) sub_anchor: i32,
    pub(crate) exact: Vec<u8>,
    /// Reuse the forward literal search plan across haystacks (ADR-008).
    pub(crate) exact_finder: Option<Box<memchr::memmem::Finder<'static>>>,
    pub(crate) map: [u8; CHAR_MAP_SIZE],
    pub(crate) map_offset: i32,
    pub(crate) map_bytes: [u8; 3],
    pub(crate) map_byte_count: u8,
    /// Rust-only (ADR-008): the ASCII part of `map` as byte ranges, for a
    /// map search that checks eight ASCII bytes at a time.
    pub(crate) map_ascii_ranges: MapAsciiRanges,
    pub(crate) dist_min: OnigLen,
    pub(crate) dist_max: OnigLen,
    /// True when capture registers are needed for matching semantics even if
    /// the caller does not request a region (e.g. backrefs, recursive mem ops).
    pub(crate) needs_capture_tracking: bool,

    /// True when the pattern uses `\K`, so the match start can move away from
    /// the position its attempt began at. The region is then the only place
    /// that carries the whole match: `[attempt position, attempt position +
    /// match length]` no longer describes it.
    pub(crate) keep_moves_match_start: bool,

    /// First-byte prefilter map for regset dispatch.
    /// Unlike `map` (which may be repurposed as BMH skip table when optimize=StrFast),
    /// this always contains the character membership map for possible first bytes.
    /// Only valid when `has_first_byte_map` is true.
    pub(crate) first_byte_map: [u8; CHAR_MAP_SIZE],
    pub(crate) has_first_byte_map: bool,
    /// Rust-only RegSet routing hint: the optimizer (C's) has an unbounded
    /// distance, but the extra class and type maps would give one within a
    /// bounded distance of the match start. Such an entry is dispatched by
    /// its start bytes, with C's optimizer still deciding which positions it
    /// attempts; `first_byte_map` holds those maps' start bytes where they
    /// sit at the match start.
    pub(crate) start_dispatch: bool,

    // subroutine call support
    pub(crate) called_addrs: Vec<i32>, // group_num -> called entry address
    pub(crate) unset_call_addrs: Vec<(usize, i32)>, // (op_index, group_num) for patching

    // extension (callouts)
    pub(crate) extp: Option<RegexExt>,

    // literal alternation tries (for AltLiterals opcode)
    pub(crate) literal_tries: Vec<crate::literal_trie::LiteralTrie>,

    /// Rust-only (ADR-008): some guarded push carries
    /// `GUARD_RETRIES_BY_CHECKS`.
    pub(crate) check_dependent_guards: bool,

    // Aho-Corasick automaton for pure literal alternation fast path.
    // `ac_alt_has_capture` is true when the alternation is wrapped in a single
    // capture group, so the fast path must also populate region[1].
    pub(crate) ac_alt: Option<aho_corasick::AhoCorasick>,
    pub(crate) ac_alt_has_capture: bool,

    /// Rust-only (ADR-008): skips for a leading class run
    /// (`crate::leading_run`).
    pub(crate) leading_run: Option<Box<crate::leading_run::LeadingRun>>,
    /// Rust-only (ADR-008): bytecode start bytes for positions C's optimizer
    /// does not narrow down (`crate::leading_run`).
    pub(crate) search_start_map: Option<Box<crate::leading_run::SearchStartMap>>,
    /// Rust-only (ADR-008): where attempts can pass the leading checks
    /// (`crate::leading_run::SearchJump`).
    pub(crate) search_jump: Option<Box<crate::leading_run::SearchJump>>,
    /// Rust-only (ADR-008): literals one of which every match contains,
    /// for RegSet fallback searches (`crate::required_literals`).
    pub(crate) required_literals: Option<Box<crate::required_literals::RequiredLiterals>>,
}

/// The ASCII bytes of an optimizer map as at most [`MapAsciiRanges::MAX`]
/// inclusive ranges. Rust-only (ADR-008): `map_search` tests eight ASCII
/// bytes at a time against them (`first_member`), instead of one table
/// lookup and one character step per byte.
#[derive(Clone, Copy, Debug, Default)]
pub(crate) struct MapAsciiRanges {
    ranges: [(u8, u8); MapAsciiRanges::MAX],
    /// Zero when the map's ASCII part needs more ranges than fit.
    count: u8,
}

impl MapAsciiRanges {
    pub(crate) const MAX: usize = 6;

    /// The ranges of `map` below 0x80, or none if they do not fit.
    pub(crate) fn of(map: &[u8; CHAR_MAP_SIZE]) -> Self {
        let mut out = Self::default();
        let mut at = 0;
        while at < 0x80 {
            if map[at] == 0 {
                at += 1;
                continue;
            }
            let lo = at;
            while at < 0x80 && map[at] != 0 {
                at += 1;
            }
            if out.count as usize == Self::MAX {
                return Self::default();
            }
            out.ranges[out.count as usize] = (lo as u8, (at - 1) as u8);
            out.count += 1;
        }
        out
    }

    /// Whether `first_member` applies: the map has an ASCII member.
    #[inline]
    pub(crate) fn usable(&self) -> bool {
        self.count != 0
    }

    /// For eight ASCII bytes (little-endian, every high bit clear), the
    /// index of the first byte inside a range. Adding `0x80 - lo` sets a
    /// byte's high bit exactly when the byte is at least `lo`, and adding
    /// `0x7F - hi` when it is above `hi`; no sum carries into the next byte.
    #[inline]
    pub(crate) fn first_member(&self, chunk: u64) -> Option<usize> {
        const ONES: u64 = 0x0101_0101_0101_0101;
        const HIGH: u64 = 0x8080_8080_8080_8080;
        debug_assert_eq!(chunk & HIGH, 0, "ASCII bytes only");
        let mut hits = 0;
        for &(lo, hi) in &self.ranges[..self.count as usize] {
            let at_least_lo = chunk + ONES * (0x80 - lo as u64);
            let above_hi = chunk + ONES * (0x7F - hi as u64);
            hits |= at_least_lo & !above_hi;
        }
        let hits = hits & HIGH;
        (hits != 0).then(|| hits.trailing_zeros() as usize / 8)
    }
}

/// Set in a guard's `skipped_retries` when the backtracks it skips depend on
/// position checks on its main path (anchors, word boundaries, fused
/// look-behinds); the other bits then hold the largest count. Such a guard
/// jumps only where an upper bound of the count is good enough (see
/// `guard_may_jump` in `regexec.rs`), and pushes like the unguarded
/// instruction otherwise.
pub(crate) const GUARD_RETRIES_BY_CHECKS: u32 = 1 << 31;

// === Optimization data structures ===
pub const OPT_EXACT_MAXLEN: usize = 24;

#[derive(Clone, Copy, Default)]
pub struct MinMaxLen {
    pub min: OnigLen,
    pub max: OnigLen,
}

impl MinMaxLen {
    pub fn new() -> Self {
        MinMaxLen { min: 0, max: 0 }
    }

    pub fn clear(&mut self) {
        self.min = 0;
        self.max = 0;
    }

    pub fn set(&mut self, min: OnigLen, max: OnigLen) {
        self.min = min;
        self.max = max;
    }

    pub fn add(&mut self, other: &MinMaxLen) {
        self.min = crate::regcomp::distance_add(self.min, other.min);
        self.max = crate::regcomp::distance_add(self.max, other.max);
    }

    pub fn alt_merge(&mut self, other: &MinMaxLen) {
        if self.min > other.min {
            self.min = other.min;
        }
        if self.max < other.max {
            self.max = other.max;
        }
    }

    pub fn is_equal(&self, other: &MinMaxLen) -> bool {
        self.min == other.min && self.max == other.max
    }
}

#[derive(Clone, Copy, Default)]
pub struct OptAnc {
    pub left: i32,
    pub right: i32,
}

impl OptAnc {
    pub fn new() -> Self {
        OptAnc { left: 0, right: 0 }
    }

    pub fn clear(&mut self) {
        self.left = 0;
        self.right = 0;
    }
}

#[derive(Clone, Copy, Default)]
pub struct OptStr {
    pub mm: MinMaxLen,
    pub anc: OptAnc,
    pub reach_end: i32,
    pub len: usize,
    pub s: [u8; OPT_EXACT_MAXLEN],
}

impl OptStr {
    pub fn new() -> Self {
        OptStr {
            mm: MinMaxLen::new(),
            anc: OptAnc::new(),
            reach_end: 0,
            len: 0,
            s: [0u8; OPT_EXACT_MAXLEN],
        }
    }

    pub fn clear(&mut self) {
        self.mm.clear();
        self.anc.clear();
        self.reach_end = 0;
        self.len = 0;
        self.s[0] = 0;
    }

    pub fn is_full(&self) -> bool {
        self.len >= OPT_EXACT_MAXLEN
    }
}

#[derive(Clone, Copy)]
pub struct OptMap {
    pub mm: MinMaxLen,
    pub anc: OptAnc,
    pub value: i32,
    pub map: [u8; CHAR_MAP_SIZE],
}

impl OptMap {
    pub fn new() -> Self {
        OptMap {
            mm: MinMaxLen::new(),
            anc: OptAnc::new(),
            value: 0,
            map: [0u8; CHAR_MAP_SIZE],
        }
    }

    pub fn clear(&mut self) {
        self.mm.clear();
        self.anc.clear();
        self.value = 0;
        self.map = [0u8; CHAR_MAP_SIZE];
    }
}

impl Default for OptMap {
    fn default() -> Self {
        Self {
            mm: MinMaxLen::default(),
            anc: OptAnc::default(),
            value: 0,
            map: [0u8; CHAR_MAP_SIZE],
        }
    }
}

#[derive(Clone)]
pub struct OptNode {
    pub len: MinMaxLen,
    pub anc: OptAnc,
    pub sb: OptStr,
    pub sm: OptStr,
    pub spr: OptStr,
    pub map: OptMap,
}

impl Default for OptNode {
    fn default() -> Self {
        Self::new()
    }
}

impl OptNode {
    pub fn new() -> Self {
        OptNode {
            len: MinMaxLen::new(),
            anc: OptAnc::new(),
            sb: OptStr::new(),
            sm: OptStr::new(),
            spr: OptStr::new(),
            map: OptMap::new(),
        }
    }

    pub fn clear(&mut self) {
        self.len.clear();
        self.anc.clear();
        self.sb.clear();
        self.sm.clear();
        self.spr.clear();
        self.map.clear();
    }
}

// === Option check macros as functions ===
#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_ignorecase(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_IGNORECASE)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_extend(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_EXTEND)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_multiline(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_MULTILINE)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_singleline(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_SINGLELINE)
}

#[inline]
pub fn opton_find_longest(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_FIND_LONGEST)
}

#[inline]
pub fn opton_find_not_empty(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_FIND_NOT_EMPTY)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_negate_singleline(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_NEGATE_SINGLELINE)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_dont_capture_group(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_DONT_CAPTURE_GROUP)
}

#[inline]
pub fn opton_capture_group(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_CAPTURE_GROUP)
}

#[inline]
pub fn opton_notbol(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_NOTBOL)
}

#[inline]
pub fn opton_noteol(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_NOTEOL)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_posix_region(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_POSIX_REGION)
}

#[inline]
pub fn opton_check_validity_of_string(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_CHECK_VALIDITY_OF_STRING)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_callback_each_match(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_CALLBACK_EACH_MATCH)
}

#[inline]
pub fn opton_not_begin_string(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_NOT_BEGIN_STRING)
}

#[inline]
pub fn opton_not_end_string(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_NOT_END_STRING)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn opton_not_begin_position(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_NOT_BEGIN_POSITION)
}

#[inline]
pub fn opton_match_whole_string(option: OnigOptionType) -> bool {
    option.contains(ONIG_OPTION_MATCH_WHOLE_STRING)
}

// === Syntax macros ===
#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mc_esc(syn: &OnigSyntaxType) -> OnigCodePoint {
    syn.meta_char_table.esc
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mc_anychar(syn: &OnigSyntaxType) -> OnigCodePoint {
    syn.meta_char_table.anychar
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mc_anytime(syn: &OnigSyntaxType) -> OnigCodePoint {
    syn.meta_char_table.anytime
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mc_zero_or_one_time(syn: &OnigSyntaxType) -> OnigCodePoint {
    syn.meta_char_table.zero_or_one_time
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mc_one_or_more_time(syn: &OnigSyntaxType) -> OnigCodePoint {
    syn.meta_char_table.one_or_more_time
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn mc_anychar_anytime(syn: &OnigSyntaxType) -> OnigCodePoint {
    syn.meta_char_table.anychar_anytime
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn is_mc_esc_code(code: OnigCodePoint, syn: &OnigSyntaxType) -> bool {
    code == mc_esc(syn) && !is_syntax_op2(syn, ONIG_SYN_OP2_INEFFECTIVE_ESCAPE)
}

// === Value helpers ===
#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn digitval(code: OnigCodePoint) -> u32 {
    code - b'0' as u32
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn odigitval(code: OnigCodePoint) -> u32 {
    digitval(code)
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn is_code_word_ascii(code: OnigCodePoint) -> bool {
    code < 128
}

#[inline]
#[cfg_attr(coverage_nightly, coverage(off))]
pub fn is_code_digit_ascii(code: OnigCodePoint) -> bool {
    code < 128 && (code >= b'0' as u32 && code <= b'9' as u32)
}