// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT

// file at the top-level directory of this distribution and at

// http://rust-lang.org/COPYRIGHT.

//

// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or

// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license

// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your

// option. This file may not be copied, modified, or distributed

// except according to those terms.

//! Big Integer Types for Rust

//!

//! * A [`BigUint`] is unsigned and represented as a vector of digits.

//! * A [`BigInt`] is signed and is a combination of [`BigUint`] and [`Sign`].

//!

//! Common numerical operations are overloaded, so we can treat them

//! the same way we treat other numbers.

//!

//! ## Example

//!

//! ```rust

//! # fn main() {

//! use num_bigint::BigUint;

//! use num_traits::One;

//!

//! // Calculate large fibonacci numbers.

//! fn fib(n: usize) -> BigUint {

//!     let mut f0 = BigUint::ZERO;

//!     let mut f1 = BigUint::ONE;

//!     for _ in 0..n {

//!         let f2 = f0 + &f1;

//!         f0 = f1;

//!         f1 = f2;

//!     }

//!     f0

//! }

//!

//! // This is a very large number.

//! println!("fib(1000) = {}", fib(1000));

//! # }

//! ```

//!

//! It's easy to generate large random numbers:

//!

#![cfg_attr(feature = "rand_0_10", doc = "```")]

#![cfg_attr(not(feature = "rand_0_10"), doc = "```ignore")]

//! # use ::rand_0_10 as rand;

//! use rand::{SeedableRng, rngs::SmallRng};

//! use num_bigint::{BigInt, BigRng010};

//!

//! // This seed is just for demonstration, but in most cases

//! // you'll probably want a non-deterministic `rng`.

//! let mut rng = SmallRng::seed_from_u64(42);

//! let a = rng.random_bigint(1000);

//!

//! let low = BigInt::from(-10000);

//! let high = BigInt::from(10000);

//! let b = rng.random_bigint_range(&low, &high);

//!

//! // Probably an even larger number.

//! println!("{}", a * b);

#![doc = "```"]

//!

//! See the "Features" section for instructions for enabling random number generation.

//!

//! ## Features

//!

//! The `std` crate feature is enabled by default, which enables [`std::error::Error`]

//! implementations and some internal use of floating point approximations. This can be disabled by

//! depending on `num-bigint` with `default-features = false`. Either way, the `alloc` crate is

//! always required for heap allocation of the [`BigInt`]/[`BigUint`] digits.

//!

//! ### Random Generation

//!

//! `num-bigint` supports the generation of random big integers when either of the `rand_0_9` or

//! `rand_0_10` features are enabled. The [`BigRng09`] and [`BigRng010`] traits provide extension

//! methods for any `rand_core` RNG of their respective version, while the structs [`RandomBits`],

//! [`UniformBigInt`], and [`UniformBigUint`] fulfill further functionality for random

//! distributions in `rand::distr`.

//!

//! For example, using `rand v0.10` in your `Cargo.toml` may look like this:

//!

//! ```toml

//! rand = "0.10"

//! num-bigint = { version = "0.5", features = ["rand_0_10"] }

//! ```

//!

//! Note that you must use the same version of `rand` as the feature you enable in `num-bigint`.

//! It's also fine for multiple versions to be enabled at once -- the random-distribution structs

//! will be shared with trait implementations for each `rand` feature that is enabled, while the

//! `BigRng` traits are distinct.

//!

//! You can instead use `rand_core_0_9` or `rand_core_0_10` for a more restricted subset, with

//! *only* the `BigRng` traits.

//!

//! ### Arbitrary Big Integers

//!

//! `num-bigint` supports `arbitrary` and `quickcheck` features to implement

//! [`arbitrary::Arbitrary`] and [`quickcheck::Arbitrary`], respectively, for both [`BigInt`] and

//! [`BigUint`]. These are useful for fuzzing and other forms of randomized testing.

//!

//! ### Serialization

//!

//! The `serde` feature adds implementations of [`Serialize`][serde::Serialize] and

//! [`Deserialize`][serde::Deserialize] for both [`BigInt`] and [`BigUint`]. Their serialized data is

//! generated portably, regardless of platform differences like the internal digit size.

//!

//!

//! ## Compatibility

//!

//! The `num-bigint` crate is tested for rustc 1.60 and greater.

#![cfg_attr(docsrs, feature(doc_cfg))]

#![warn(rust_2018_idioms)]

#![no_std]

#[macro_use]

extern crate alloc;

#[cfg(feature = "std")]

extern crate std;

use core::fmt;

#[macro_use]

mod macros;

mod bigint;

mod bigrand;

mod biguint;

#[cfg(target_pointer_width = "32")]

type UsizePromotion = u32;

#[cfg(target_pointer_width = "64")]

type UsizePromotion = u64;

#[cfg(target_pointer_width = "32")]

type IsizePromotion = i32;

#[cfg(target_pointer_width = "64")]

type IsizePromotion = i64;

#[derive(Debug, Clone, PartialEq, Eq)]

pub struct ParseBigIntError {

    kind: BigIntErrorKind,

}

#[derive(Debug, Clone, PartialEq, Eq)]

enum BigIntErrorKind {

    Empty,

    InvalidDigit,

}

impl ParseBigIntError {

    fn __description(&self) -> &str {

        use crate::BigIntErrorKind::*;

        match self.kind {

            Empty => "cannot parse integer from empty string",

            InvalidDigit => "invalid digit found in string",

        }

    }

    fn empty() -> Self {

        ParseBigIntError {

            kind: BigIntErrorKind::Empty,

        }

    }

    fn invalid() -> Self {

        ParseBigIntError {

            kind: BigIntErrorKind::InvalidDigit,

        }

    }

}

impl fmt::Display for ParseBigIntError {

    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

        self.__description().fmt(f)

    }

}

#[cfg(feature = "std")]

#[cfg_attr(docsrs, doc(cfg(feature = "std")))]

impl std::error::Error for ParseBigIntError {

    fn description(&self) -> &str {

        self.__description()

    }

}

/// The error type returned when a checked conversion regarding big integer fails.

#[derive(Debug, Copy, Clone, PartialEq, Eq)]

pub struct TryFromBigIntError<T> {

    original: T,

}

impl<T> TryFromBigIntError<T> {

    fn new(original: T) -> Self {

        TryFromBigIntError { original }

    }

    fn __description(&self) -> &str {

        "out of range conversion regarding big integer attempted"

    }

    /// Extract the original value, if available. The value will be available

    /// if the type before conversion was either [`BigInt`] or [`BigUint`].

    pub fn into_original(self) -> T {

        self.original

    }

}

#[cfg(feature = "std")]

#[cfg_attr(docsrs, doc(cfg(feature = "std")))]

impl<T> std::error::Error for TryFromBigIntError<T>

where

    T: fmt::Debug,

{

    fn description(&self) -> &str {

        self.__description()

    }

}

impl<T> fmt::Display for TryFromBigIntError<T> {

    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

        self.__description().fmt(f)

    }

}

pub use crate::biguint::BigUint;

pub use crate::biguint::ToBigUint;

pub use crate::biguint::U32Digits;

pub use crate::biguint::U64Digits;

pub use crate::bigint::BigInt;

pub use crate::bigint::Sign;

pub use crate::bigint::ToBigInt;

#[cfg(feature = "rand_core_0_10")]

pub use crate::bigrand::BigRng010;

#[cfg(feature = "rand_core_0_9")]

pub use crate::bigrand::BigRng09;

#[cfg(any(feature = "rand_0_10", feature = "rand_0_9"))]

pub use crate::bigrand::{RandomBits, UniformBigInt, UniformBigUint};

mod big_digit;