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

use std::any::Any;

use tracing::Level;

use crate::{Primitive, Shape, Tensor};

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Broadcast {
    pub shape: Vec<usize>,
}
impl Broadcast {
    pub fn new(shape: impl Shape) -> Self {
        Self {
            shape: shape.shape().to_vec(),
        }
    }

    pub fn shape(&self) -> &[usize] {
        &self.shape
    }
}

impl Primitive for Broadcast {
    fn clone_boxed(&self) -> Box<dyn Primitive> {
        Box::new(self.clone())
    }

    fn dot_label(&self) -> String {
        format!("Broadcast({:?})", self.shape)
    }

    fn as_any(&self) -> &dyn Any {
        self
    }

    #[tracing::instrument(ret(level = Level::TRACE))]
    fn jvp(&self, output: &Tensor, primals: &[Tensor], tangents: &[Tensor]) -> Tensor {
        let tangent_x = &tangents[0];
        tangent_x.broadcast_to(self.shape())
    }

    #[tracing::instrument(ret(level = Level::TRACE))]
    fn vjp(&self, _output: &Tensor, primals: &[Tensor], cotangent: &Tensor) -> Vec<Tensor> {
        let x = &primals[0];
        let shape = x.shape().to_vec();
        let diff = cotangent.ndim() - shape.ndim();
        let mut dims = Vec::new();
        for i in 0..cotangent.ndim() {
            if i < diff || shape[i - diff] != cotangent.shape_at(i) {
                dims.push(i);
            }
        }
        let cotangent_x = cotangent.sum((dims, true)).reshape(&shape);
        vec![cotangent_x]
    }
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Reshape {
    pub shape: Vec<usize>,
}
impl Reshape {
    pub fn new(shape: impl Shape) -> Self {
        Self {
            shape: shape.shape().to_vec(),
        }
    }

    pub fn shape(&self) -> &[usize] {
        &self.shape
    }
}

impl Primitive for Reshape {
    fn clone_boxed(&self) -> Box<dyn Primitive> {
        Box::new(self.clone())
    }

    fn as_any(&self) -> &dyn Any {
        self
    }

    fn dot_label(&self) -> String {
        format!("Reshape({:?})", self.shape)
    }

    #[tracing::instrument(ret(level = Level::TRACE))]
    fn jvp(&self, output: &Tensor, _primals: &[Tensor], tangents: &[Tensor]) -> Tensor {
        let tangent_x = &tangents[0];
        tangent_x.reshape(self.shape())
    }

    #[tracing::instrument(ret(level = Level::TRACE))]
    fn vjp(&self, _output: &Tensor, primals: &[Tensor], cotangent: &Tensor) -> Vec<Tensor> {
        let x = &primals[0];
        let cotangent_x = cotangent.reshape(x);
        vec![cotangent_x]
    }
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Transpose {
    pub dims: Vec<usize>,
}

impl Transpose {
    pub fn new(dims: impl Into<Vec<usize>>) -> Self {
        Self { dims: dims.into() }
    }

    pub fn dims(&self) -> &[usize] {
        &self.dims
    }
}

impl Primitive for Transpose {
    fn clone_boxed(&self) -> Box<dyn Primitive> {
        Box::new(self.clone())
    }

    fn as_any(&self) -> &dyn Any {
        self
    }

    fn dot_label(&self) -> String {
        format!("Transpose({:?})", self.dims())
    }

    #[tracing::instrument(ret(level = Level::TRACE))]
    fn jvp(&self, _output: &Tensor, _primals: &[Tensor], tangents: &[Tensor]) -> Tensor {
        let tangent_x = &tangents[0];
        tangent_x.transpose(self.dims())
    }

    #[tracing::instrument(ret(level = Level::TRACE))]
    fn vjp(&self, _output: &Tensor, _primals: &[Tensor], cotangent: &Tensor) -> Vec<Tensor> {
        let mut dims = vec![0; self.dims.len()];
        for i in 0..dims.len() {
            dims[self.dims[i]] = i;
        }
        let cotangent_x = cotangent.transpose(dims);
        vec![cotangent_x]
    }
}