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//! Compile-time comparison, parsing, and const equivalents of std methods. //! //! # Features //! //! This crate provides: //! //! - Compile-time parsing through the [`Parser`] type, and [`parse_any`] macro. //! //! - Functions for comparing many standard library types, //! with the [`const_eq`]/[`const_eq_for`]/[`const_cmp`]/[`const_cmp_for`] macros //! for more conveniently calling them, powered by the [`polymorphism`] module. //! //! - Const fn equivalents of other standard library functions and methods. //! //! //! # Examples //! //! ### Parsing an enum //! //! This example demonstrates how you can parse a simple enum from an environment variable, //! at compile-time. //! //! ```rust //! use konst::eq_str; //! use konst::{unwrap_opt_or, unwrap_ctx}; //! //! #[derive(Debug, PartialEq)] //! enum Direction { //! Forward, //! Backward, //! Left, //! Right, //! } //! //! impl Direction { //! const fn try_parse(input: &str) -> Result<Self, ParseDirectionError> { //! // As of Rust 1.51.0, string patterns don't work in const contexts //! match () { //! _ if eq_str(input, "forward") => Ok(Direction::Forward), //! _ if eq_str(input, "backward") => Ok(Direction::Backward), //! _ if eq_str(input, "left") => Ok(Direction::Left), //! _ if eq_str(input, "right") => Ok(Direction::Right), //! _ => Err(ParseDirectionError), //! } //! } //! } //! //! const CHOICE: &str = unwrap_opt_or!(option_env!("chosen-direction"), "forward"); //! //! const DIRECTION: Direction = unwrap_ctx!(Direction::try_parse(CHOICE)); //! //! fn main() { //! match DIRECTION { //! Direction::Forward => assert_eq!(CHOICE, "forward"), //! Direction::Backward => assert_eq!(CHOICE, "backward"), //! Direction::Left => assert_eq!(CHOICE, "left"), //! Direction::Right => assert_eq!(CHOICE, "right"), //! } //! } //! # #[derive(Debug, PartialEq)] //! # pub struct ParseDirectionError; //! # //! # use std::fmt::{self, Display}; //! # //! # impl Display for ParseDirectionError { //! # fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { //! # f.write_str("Failed to parse a Direction") //! # } //! # } //! # //! # impl ParseDirectionError { //! # const fn panic(&self) -> ! { //! # [/*failed to parse a Direction*/][0] //! # } //! # } //! # //! # //! //! ``` //! //! ### Parsing a struct //! //! This example demonstrates how you can use [`Parser`] to parse a struct at compile-time. //! #![cfg_attr(feature = "parsing", doc = "```rust")] #![cfg_attr(not(feature = "parsing"), doc = "```ignore")] //! use konst::{ //! parsing::{Parser, ParseValueResult}, //! for_range, parse_any, try_rebind, unwrap_ctx, //! }; //! //! const PARSED: Struct = { //! // You can also parse strings from environment variables, or from an `include_str!(....)` //! let input = "\ //! 1000, //! circle, //! red, blue, green, blue, //! "; //! //! unwrap_ctx!(parse_struct(Parser::from_str(input))).0 //! }; //! //! fn main(){ //! assert_eq!( //! PARSED, //! Struct{ //! amount: 1000, //! repeating: Shape::Circle, //! colors: [Color::Red, Color::Blue, Color::Green, Color::Blue], //! } //! ); //! } //! //! #[derive(Debug, Clone, PartialEq, Eq)] //! pub struct Struct { //! pub amount: usize, //! pub repeating: Shape, //! pub colors: [Color; 4], //! } //! //! #[derive(Debug, Clone, PartialEq, Eq)] //! pub enum Shape { //! Circle, //! Square, //! Line, //! } //! //! #[derive(Debug, Copy, Clone, PartialEq, Eq)] //! pub enum Color { //! Red, //! Blue, //! Green, //! } //! //! pub const fn parse_struct(mut parser: Parser<'_>) -> ParseValueResult<'_, Struct> { //! try_rebind!{(let amount, parser) = parser.trim_start().parse_usize()} //! try_rebind!{parser = parser.strip_prefix(",")} //! //! try_rebind!{(let repeating, parser) = parse_shape(parser.trim_start())} //! try_rebind!{parser = parser.strip_prefix(",")} //! //! try_rebind!{(let colors, parser) = parse_colors(parser.trim_start())} //! //! Ok((Struct{amount, repeating, colors}, parser)) //! } //! //! pub const fn parse_shape(mut parser: Parser<'_>) -> ParseValueResult<'_, Shape> { //! let shape = parse_any!{parser, strip_prefix; //! "circle" => Shape::Circle, //! "square" => Shape::Square, //! "line" => Shape::Line, //! _ => return Err(parser.into_other_error()) //! }; //! Ok((shape, parser)) //! } //! //! pub const fn parse_colors(mut parser: Parser<'_>) -> ParseValueResult<'_, [Color; 4]> { //! let mut colors = [Color::Red; 4]; //! //! for_range!{i in 0..4 => //! try_rebind!{(colors[i], parser) = parse_color(parser.trim_start())} //! try_rebind!{parser = parser.strip_prefix(",")} //! } //! //! Ok((colors, parser)) //! } //! //! pub const fn parse_color(mut parser: Parser<'_>) -> ParseValueResult<'_, Color> { //! let color = parse_any!{parser, strip_prefix; //! "red" => Color::Red, //! "blue" => Color::Blue, //! "green" => Color::Green, //! _ => return Err(parser.into_other_error()) //! }; //! Ok((color, parser)) //! } //! //! //! //! ``` //! //! # Cargo features //! //! These are the features of these crates: //! //! - `"cmp"`(enabled by default): //! Enables all comparison functions and macros, //! the string equality and ordering comparison functions don't require this feature. //! //! - `"parser"`(enabled by default): //! Enables the [`parsing`] module, for parsing from `&str` and `&[u8]`. //! //! - `"constant_time_slice"`(disabled by default):<br> //! Improves the performance of slice functions that split slices, //! from taking linear time to taking constant time, //! this requires using some nightly Rust features. //! <br>Note that only functions which mention this feature in their documentation are affected. //! //! - `"const_generics"` (disabled by default): //! Changes impls for arrays to use const generics instead of only supporting small arrays. //! This feature requires Rust 1.51.0. //! //! # No-std support //! //! `konst` is `#![no_std]`, it can be used anywhere Rust can be used. //! //! # Minimum Supported Rust Version //! //! `konst` requires Rust 1.46.0, because it uses looping an branching in const contexts. //! //! Features that require newer versions of Rust, or the nightly compiler, //! need to be explicitly enabled with cargo features. //! //! //! //! [`const_eq`]: ./macro.const_eq.html //! [`const_eq_for`]: ./macro.const_eq_for.html //! [`const_cmp`]: ./macro.const_cmp.html //! [`const_cmp_for`]: ./macro.const_cmp_for.html //! [`polymorphism`]: ./polymorphism/index.html //! [`parsing`]: ./parsing/index.html //! [`Parser`]: ./parsing/struct.Parser.html //! [`parse_any`]: macro.parse_any.html //! #![cfg_attr( feature = "constant_time_slice", feature(const_slice_from_raw_parts, const_fn_union, const_ptr_offset) )] #![cfg_attr(feature = "docsrs", feature(doc_cfg))] #![no_std] #[macro_use] mod macros; #[doc(hidden)] pub mod __for_cmp_impls; // pub mod other; #[cfg(feature = "cmp")] #[cfg_attr(feature = "docsrs", doc(cfg(feature = "cmp")))] pub mod polymorphism; pub mod primitive; pub mod range; pub mod nonzero; pub mod other; #[cfg(feature = "parsing")] #[cfg_attr(feature = "docsrs", doc(cfg(feature = "parsing")))] pub mod parsing; mod utils; #[cfg(feature = "parsing")] #[cfg_attr(feature = "docsrs", doc(cfg(feature = "parsing")))] pub use crate::parsing::Parser; #[cfg(feature = "parsing")] #[doc(hidden)] pub use konst_proc_macros::{__priv_bstr_end, __priv_bstr_start}; pub mod slice; pub mod string; pub use crate::string::{cmp_str, eq_str}; #[cfg(feature = "cmp")] #[cfg_attr(feature = "docsrs", doc(cfg(feature = "cmp")))] pub use crate::string::{cmp_option_str, eq_option_str}; #[doc(hidden)] pub mod __ { pub use core::{ cmp::Ordering::{self, Equal, Greater, Less}, compile_error, matches, ops::Range, option::Option::{self, None, Some}, result::Result::{self, Err, Ok}, }; pub mod v { pub use core::{ option::Option::Some, result::Result::{Err, Ok}, }; } pub use crate::__for_cmp_impls::U8Ordering; #[cfg(feature = "cmp")] #[cfg_attr(feature = "docsrs", doc(cfg(feature = "cmp")))] pub use crate::polymorphism::{ CmpWrapper, ConstCmpMarker, IsAConstCmpMarker, IsNotStdKind, IsStdKind, }; }