tabulon 0.1.10

A high-performance, JIT-compiled expression evaluation engine using Cranelift
Documentation 
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use crate::ast::Ast;
use std::collections::HashSet;

pub(crate) fn collect_vars(ast: &Ast) -> Vec<String> {
    fn walk(node: &Ast, seen: &mut HashSet<String>, out: &mut Vec<String>) {
        match node {
            Ast::Num(_) => {}
            Ast::Var(name) => {
                if !seen.contains(name) {
                    seen.insert(name.clone());
                    out.push(name.clone());
                }
            }
            Ast::Neg(a) | Ast::Not(a) => walk(a, seen, out),
            Ast::Add(a, b)
            | Ast::Sub(a, b)
            | Ast::Mul(a, b)
            | Ast::Div(a, b)
            | Ast::Pow(a, b)
            | Ast::Eq(a, b)
            | Ast::Ne(a, b)
            | Ast::Lt(a, b)
            | Ast::Le(a, b)
            | Ast::Gt(a, b)
            | Ast::Ge(a, b)
            | Ast::And(a, b)
            | Ast::Or(a, b)
            | Ast::Min(a, b)
            | Ast::Max(a, b) => {
                walk(a, seen, out);
                walk(b, seen, out);
            }
            Ast::If(c, t, e) => {
                walk(c, seen, out);
                walk(t, seen, out);
                walk(e, seen, out);
            }
            Ast::Ifs(args) => {
                for a in args {
                    walk(a, seen, out);
                }
            }
            Ast::Call { args, .. } => {
                for a in args {
                    walk(a, seen, out);
                }
            }
        }
    }
    let mut seen = HashSet::new();
    let mut out = Vec::new();
    walk(ast, &mut seen, &mut out);
    out
}