1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151

///!
///! Misc stuff used throughout the crate.
///!

use std::ptr;

///
/// A storage with a name attached.
///
/// Typically, `T` will be either a `PlainRawStorage` or a `KeyedRawStorage`.
///
pub struct NamedStorage<T: ?Sized> {
    /// The name of the storage. Also used as a key, must be unique.
    pub name: String,

    ///
    pub contents: Box<T>,
}

///
/// A subset of data to serialize.
///
pub enum Subset {
    /// Serialize all plain histograms.
    AllPlain,

    /// Serialize all keyed histograms.
    AllKeyed,
}

///
/// A subformat of Json to use for serialization.
///
pub enum SerializationFormat {
    ///
    /// Simple Json:
    /// - `Flag` are represented as a single boolean;
    /// - `KeyedFlag` are represented as an array;
    /// - `Linear` are represented as an array of numbers, one cell per bucket;
    /// - `KeyedLinear` are represented as an object, one field per histogram,
    ///    with name = key, value = array of numbers as for `Linear`;
    /// - ...
    ///
    SimpleJson,
}

///
/// A value that can be represented as a u32.
///
pub trait Flatten {
    fn as_u32(&self) -> u32;
}

impl Flatten for u32 {
    fn as_u32(&self) -> u32 {
        *self
    }
}

impl Flatten for () {
    fn as_u32(&self) -> u32 {
        0
    }
}

impl Flatten for bool {
    fn as_u32(&self) -> u32 {
        if *self {
            1
        } else {
            0
        }
    }
}

//
// Representation of buckets shared by both plain and keyed linear histograms.
//
pub struct LinearBuckets {
    min: u32,
    max: u32, // Invariant: max > min
    pub buckets: usize,
}

impl LinearBuckets {
    pub fn new(min: u32, max: u32, buckets: usize) -> LinearBuckets {
        assert!(min < max);
        assert!(buckets > 0);
        assert!(buckets < (max - min) as usize);
        LinearBuckets {
            min: min,
            max: max,
            buckets: buckets
        }
    }

    pub fn get_bucket(&self, value: u32) -> usize {
        if value <= self.min {
            0
        } else if value >= self.max {
            self.buckets - 1 as usize
        } else {
            let num = value as f32 - self.min as f32;
            let den = self.max as f32 - self.min as f32;
            let res = (num / den) * self.buckets as f32;
            res as usize
        }
    }
}

/// Partial reimplementation of `Vec::resize`, until this method has
/// reached the stable version of Rust.
pub fn vec_resize<T>(vec: &mut Vec<T>, min_len: usize, value: T)
    where T: Clone
{
    let len = vec.len();
    if min_len <= len {
        return;
    }
    let delta = min_len - len;
    vec.reserve(delta);
    unsafe {
        let mut ptr = vec.as_mut_ptr().offset(len as isize);
        // Write all elements except the last one
        for i in 1..delta {
            ptr::write(ptr, value.clone());
            ptr = ptr.offset(1);
            // Increment the length in every step in case clone() panics
            vec.set_len(len + i);
        }

        // We can write the last element directly without cloning needlessly
        ptr::write(ptr, value);
        vec.set_len(len + delta);
    }
}

pub fn vec_with_size<T>(size: usize, value: T) -> Vec<T>
    where T: Clone
{
    let mut vec = Vec::with_capacity(size);
    unsafe {
        // Resize. In future versions of Rust, we should
        // be able to use `vec.resize`.
        vec.set_len(size);
        for i in 0 .. size {
            vec[i] = value.clone();
        }
    }
    vec
}