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::func::format_json::serialize_json;
use crate::lang::adapter::Adapter;
use crate::lang::args::eval_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;

pub(crate) fn assert(
    adapter: &impl Adapter,
    machine: &mut Machine<'_>,
    stdin: Option<&Value>,
    node: Node,
) -> Result<Value, Error> {
    assert_func_arity(adapter, machine, stdin, &node, &Arity::minmax(1, 2))?;

    let mut values = eval_args(adapter, machine, stdin, node)?;
    let key = values.swap_remove(0).unwrap_or_default();
    let value = values.pop().flatten();

    match value {
        Some(v) => assert_nonempty_value(adapter, machine, key, &v),
        None => assert_machine_key(adapter, machine, key),
    }
}

fn assert_nonempty_value(
    adapter: &impl Adapter,
    machine: &mut Machine<'_>,
    key: Value,
    value: &Value,
) -> Result<Value, Error> {
    match value.is_empty() {
        true => Err(assert_error(adapter, machine, key, None)),
        false => Ok(Value::default()),
    }
}

fn assert_machine_key(
    adapter: &impl Adapter,
    machine: &mut Machine<'_>,
    key: Value,
) -> Result<Value, Error> {
    match key.as_bytes().is_some_and(|k| machine.map.contains_key(k)) {
        false => Err(assert_error(adapter, machine, key, None)),
        true => Ok(Value::default()),
    }
}

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

fn assert_message(
    adapter: &impl Adapter,
    machine: &mut Machine<'_>,
    key: Value,
    value: Option<Value>,
) -> String {
    match value {
        None => format!("assert failed: {}", key.into_string_lossy()),
        Some(v) => format!(
            "assert failed: {}: {}",
            key.into_string_lossy(),
            serialize_json(adapter, machine, v)
                .unwrap_or_default()
                .into_string_lossy()
        ),
    }
}