pipa-lang 1.0.0-alpha.1

A tiny template language
Documentation 
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// SPDX-FileCopyrightText: Copyright 2026 olav@occy.org
// SPDX-License-Identifier: MPL-2.0

use crate::lang::adapter::Adapter;
use crate::lang::args::eval_string_args;
use crate::lang::arity::Arity;
use crate::lang::arity::assert_func_arity;
use crate::lang::error::Error;
use crate::lang::error::ErrorKind;
use crate::lang::machine::Machine;
use crate::lang::node::Node;
use crate::value::Value;
use regex::Regex;
use std::sync::LazyLock;

pub(crate) fn pattern(
    adapter: &impl Adapter,
    machine: &mut Machine<'_>,
    stdin: Option<&Value>,
    node: Node,
) -> Result<Value, Error> {
    assert_func_arity(adapter, machine, stdin, &node, &Arity::new(2))?;

    let mut values = eval_string_args(adapter, machine, stdin, node)?.unwrap_or_default();
    let value = values.pop().unwrap_or_default();
    let pattern = values.pop().unwrap_or_default();

    Ok(compile(adapter, machine, pattern)?.is_match(&value).into())
}

fn compile(
    adapter: &impl Adapter,
    machine: &mut Machine<'_>,
    pattern: String,
) -> Result<Regex, Error> {
    static CACHE: LazyLock<papaya::HashMap<String, Regex, ahash::RandomState>> =
        LazyLock::new(Default::default);

    if let Some(regex) = CACHE.pin().get(&pattern) {
        return Ok(regex.clone());
    }

    if pattern.is_empty() {
        return Err(func_error(
            adapter,
            machine,
            String::from("empty regexp pattern"),
        ));
    }

    let Ok(regex) = Regex::new(&pattern) else {
        return Err(func_error(
            adapter,
            machine,
            format!("bad regexp pattern: {pattern}"),
        ));
    };

    CACHE.pin().insert(pattern, regex.clone());
    Ok(regex)
}

fn func_error(adapter: &impl Adapter, machine: &mut Machine<'_>, message: String) -> Error {
    Error {
        kind: ErrorKind::Func,
        source: adapter.template_source().map(String::from),
        span: machine.span,
        message,
    }
}