/* Regex AST and flags, matched directly by the backtracking engine. */

use alloc::{boxed::Box, string::String, vec::Vec};

/* Inline flag state threaded into the matcher. */

#[derive(Clone, Copy, Default)]

pub struct Flags {

pub ignorecase: bool, // (?i)

pub dotall: bool, // (?s), dot also matches newline

pub multiline: bool, // (?m), anchors match at line boundaries

}

/* One entry inside a bracket set. Predefined classes stay symbolic. */

#[derive(Clone)]

pub enum ClassItem {

Ch(char),

Range(char, char),

Digit,

NotDigit,

Word,

NotWord,

Space,

NotSpace,

}

#[derive(Clone)]

pub enum Node {

Empty,

Char(char),

AnyChar, // the dot

Class { items: Vec<ClassItem>, negated: bool },

Start, // caret anchor

End, // dollar anchor

WordBoundary, // backslash b

NotWordBoundary, // backslash B

Group { index: usize, name: Option<String>, node: Box<Node> },

NonCap(Box<Node>),

Concat(Vec<Node>),

Alt(Vec<Node>),

Repeat { node: Box<Node>, min: usize, max: Option<usize>, greedy: bool },

Backref(usize),

Look { node: Box<Node>, behind: bool, negative: bool },

}

/* Compiled pattern, the tree plus capture metadata and flags. */

pub struct Program {

pub root: Node,

pub group_count: usize,

pub names: Vec<(String, usize)>, // maps a group name to its index

pub flags: Flags,

}

#[derive(Debug)]

pub struct ParseError {

pub msg: &'static str,

pub pos: usize, // codepoint offset into the pattern

}