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/*
Copyright 2017 Martin Buck

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the Software
is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall
be included all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

//! internal utility functions

use std::{
    collections::HashMap,
    hash::{Hash, Hasher},
};

/// Splits a line into a Vec of its words
pub fn to_words(line: &str) -> Vec<&str> {
    let split = line.trim().split(" ");
    split.collect::<Vec<&str>>()
}

/// Allows random adds anywhere on the Vec<Vec> by automatically resizing it with empty vectors
pub fn safe_append_at<T>(vec: &mut Vec<Vec<T>>, i: usize, val: T)
where
    T: Clone,
{
    if i >= vec.len() {
        vec.resize(i + 1, Vec::new());
    }

    vec[i].push(val);
}

/// Max of two f64 values
pub fn max_f64(a: f64, b: f64) -> f64 {
    if a > b {
        return a;
    }
    b
}

/// Max of three f64 values
pub fn max_f64_3(a: f64, b: f64, c: f64) -> f64 {
    max_f64(max_f64(a, b), c)
}

/// Generates the hash of an f64
pub fn hash_f64<H>(x: f64, state: &mut H)
where
    H: Hasher,
{
    let (m, e, s) = integer_decode(x);
    m.hash(state);
    e.hash(state);
    s.hash(state);
}

/// Returns the mantissa, exponent and sign as integers.
/// taken from https://github.com/rust-lang/rust/blob/5c674a11471ec0569f616854d715941757a48a0a/src/libcore/num/f64.rs#L203-L216
fn integer_decode(x: f64) -> (u64, i16, i8) {
    let bits: u64 = unsafe { std::mem::transmute(x) };
    let sign: i8 = if bits >> 63 == 0 { 1 } else { -1 };
    let mut exponent: i16 = ((bits >> 52) & 0x7ff) as i16;
    let mantissa = if exponent == 0 {
        (bits & 0xfffffffffffff) << 1
    } else {
        (bits & 0xfffffffffffff) | 0x10000000000000
    };
    // Exponent bias + mantissa shift
    exponent -= 1023 + 52;
    (mantissa, exponent, sign)
}

/// Returns a container with duplicates removed and indices representing the original order
pub fn pack_dupes_indexed<'a, I, T>(idata: I) -> (Vec<T>, Vec<usize>)
where
    I: Iterator<Item = &'a T>,
    T: 'a + Eq + Hash + Clone,
{
    let mut map = HashMap::new();
    let mut packed_data = Vec::new();
    let mut ids = Vec::new();
    for x in idata {
        let id = map.entry(x).or_insert_with(|| {
            let value = packed_data.len();
            packed_data.push(x.clone());
            value
        });
        ids.push(*id);
    }

    (packed_data, ids)
}