//! [balena] **tem**plating **en**gine
//!
//! A crate that provides facilities to:
//!
//! * parse an expression
//! * evaluate an expression
//! * evaluate an expression as a boolean (logical expressions)
//! * register custom functions and filters
//!
//! [Expression language documentation].
//!
//! # Versioning
//!
//! This crate is being actively developed and it does NOT follow [Semantic Versioning] yet.
//! It will follow semantic versioning when it reaches version 1.0.
//!
//! MINOR version changes denotes incompatible API changes and PATCH version changes denotes
//! both new functionality in a backwards-compatible manner and backwards-compatible bug fixes.
//!
//! # Examples
//!
//! ## Helpers
//!
//! ### JSON evaluation
//!
//! ```rust
//! use balena_temen::{evaluate, Value};
//! use serde_json::json;
//!
//! let data = json!({
//!     "wifi": {
//!         "ssid": "Balena Ltd",
//!         "id": {
//!             "$$eval": "super.ssid | slugify"
//!         }
//!     }
//! });
//! let evaluated = json!({
//!     "wifi": {
//!         "ssid": "Balena Ltd",
//!         "id": "balena-ltd"
//!     }
//! });
//! assert_eq!(evaluate(data).unwrap(), evaluated);
//! ```
//!
//! ### JSON with custom evaluation keyword
//!
//! ```rust
//! use balena_temen::{Context, Engine, EngineBuilder, evaluate_with_engine, Value};
//! use serde_json::json;
//!
//! let data = json!({
//!     "evalMePlease": "3 + 5 * 2"
//! });
//! let evaluated = json!(13);
//!
//! let mut ctx = Context::default();
//! let engine: Engine = EngineBuilder::default()
//!     .eval_keyword("evalMePlease")
//!     .into();
//!
//! assert_eq!(evaluate_with_engine(data, &engine, &mut ctx).unwrap(), evaluated);
//! ```
//!
//! ## Intermediate
//!
//! ### Single expression evaluation
//!
//! ```rust
//! use balena_temen::{
//!     ast::Identifier,
//!     Engine, Context, Value
//! };
//! use serde_json::json;
//!
//! let engine = Engine::default();       // Default functions, filters
//! let mut ctx = Context::default();     // Default context
//! let position = Identifier::default(); // Evaluate from the root
//! let data = Value::Null;
//!
//! assert_eq!(
//!     engine.eval("2 + 3", &position, &data, &mut ctx).unwrap(),
//!     json!(5)
//! );
//!
//! assert_eq!(
//!     engine.eval("`Balena templating engine!` | slugify", &position, &data, &mut ctx).unwrap(),
//!     json!("balena-templating-engine")
//! );
//! ```
//!
//! ### Single logical expression evaluation
//!
//! ```rust
//! use balena_temen::{
//!     ast::Identifier,
//!     Engine, Context, Value
//! };
//! use serde_json::json;
//!
//! let engine = Engine::default();       // Default functions, filters
//! let mut ctx = Context::default();     // Default context
//! let position = Identifier::default(); // Evaluate from the root
//! let data = Value::Null;
//!
//! assert_eq!(
//!     engine.eval_as_bool("1 == 1", &position, &data, &mut ctx).unwrap(),
//!     json!(true)
//! );
//!
//! assert_eq!(
//!     engine.eval_as_bool("2 > 4", &position, &data, &mut ctx).unwrap(),
//!     json!(false)
//! );
//!
//! assert_eq!(
//!     engine.eval_as_bool("1 > 4 or 3 > 2", &position, &data, &mut ctx).unwrap(),
//!     json!(true)
//! );
//! ```
//!
//! ## Advanced
//!
//! ### Custom functions and filters
//!
//! Visit [`EngineBuilder::function`] and [`EngineBuilder::filter`] methods
//! documentation for examples.
//!
//! ### Expression parsing
//!
//! ```rust
//! use balena_temen::ast::*;
//!
//! // Parse expression automatically
//! let parsed: Expression = "1 + 2 == 3".parse().unwrap();
//!
//! // Construct expression manually
//! let lhs = Expression::new(
//!     ExpressionValue::Math(
//!         MathExpression::new(
//!             Expression::new(ExpressionValue::Integer(1)),
//!             Expression::new(ExpressionValue::Integer(2)),
//!             MathOperator::Addition
//!         )
//!     )
//! );
//! let rhs = Expression::new(
//!     ExpressionValue::Integer(3)
//! );
//! let full_expression = Expression::new(
//!     ExpressionValue::Logical(
//!         LogicalExpression::new(
//!             lhs, rhs, LogicalOperator::Equal
//!         )
//!     )
//! );
//!
//! // Compare and check that the expression was parsed correctly
//! assert_eq!(parsed, full_expression);
//! ```
//!
//! Visit [ast] module documentation for more info.
//!
//! ### Identifier parsing
//!
//! ```rust
//! use balena_temen::ast::*;
//!
//! let s = "wifi.networks[0].ssid";
//!
//! // Parse it
//! let parsed: Identifier = s.parse().unwrap();
//!
//! // Create manually
//! let manual = Identifier::default()
//!     .name("wifi")
//!     .name("networks")
//!     .index(0)
//!     .name("ssid");
//!
//! assert_eq!(parsed, manual);
//! ```
//!
//! [balena]: https://www.balena.io
//! [ast]: ast/index.html
//! [`EngineBuilder::function`]: struct.EngineBuilder.html#method.function
//! [`EngineBuilder::filter`]: struct.EngineBuilder.html#method.filter
//! [Semantic Versioning]: https://semver.org/
//! [Expression language documentation]: https://github.com/balena-io-modules/balena-temen/blob/master/docs/expression.md
#![allow(clippy::possible_missing_comma)]

pub use serde_json::Value;

pub use crate::{
    builtin::{
        filter::FilterFn,
        function::FunctionFn,
    },
    context::Context,
    engine::{
        builder::EngineBuilder,
        Engine,
        helper::{
            evaluate,
            evaluate_with_engine
        }
    }
};

#[allow(deprecated)]
pub use crate::engine::helper::{eval, eval_with_engine};

pub(crate) mod builtin;

pub mod ast;
mod context;
mod engine;
pub mod error;
mod parser;
mod utils;