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

/*
 * Copyright 2018 The Starlark in Rust Authors.
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

use crate::typing::Ty;
use crate::values::starlark_type_id::StarlarkTypeId;
use crate::values::structs::value::FrozenStruct;
use crate::values::structs::value::Struct;
use crate::values::type_repr::StarlarkTypeRepr;
use crate::values::FrozenStringValue;
use crate::values::FrozenValue;
use crate::values::StringValue;
use crate::values::UnpackValue;
use crate::values::Value;

/// Reference to a struct allocated on the heap.
///
/// Struct implementation (for example, memory layout) may change,
/// this type provides implementation agnostics API to it.
#[derive(Debug)]
pub struct StructRef<'v>(&'v Struct<'v>);

impl<'v> StructRef<'v> {
    /// Downcast a value to a struct reference.
    pub fn from_value(value: Value<'v>) -> Option<StructRef<'v>> {
        Struct::from_value(value).map(StructRef)
    }

    #[inline]
    pub(crate) fn is_instance(value: Value<'v>) -> bool {
        debug_assert!(StarlarkTypeId::of::<Struct>() == StarlarkTypeId::of::<FrozenStruct>());
        value.starlark_type_id() == StarlarkTypeId::of::<Struct>()
    }

    /// Iterate over struct fields.
    pub fn iter(&self) -> impl ExactSizeIterator<Item = (StringValue<'v>, Value<'v>)> + '_ {
        self.0.iter()
    }
}

impl<'v> StarlarkTypeRepr for StructRef<'v> {
    fn starlark_type_repr() -> Ty {
        FrozenStruct::starlark_type_repr()
    }
}

impl<'v> UnpackValue<'v> for StructRef<'v> {
    fn unpack_value(value: Value<'v>) -> Option<Self> {
        StructRef::from_value(value)
    }
}

/// Reference to the frozen struct.
#[derive(Debug)]
pub struct FrozenStructRef<'f>(&'f FrozenStruct);

impl<'f> FrozenStructRef<'f> {
    /// Iterate over struct fields.
    pub fn iter(&self) -> impl ExactSizeIterator<Item = (FrozenStringValue, FrozenValue)> + 'f {
        self.0.iter_frozen()
    }

    /// Downcast a value to a struct reference.
    pub fn from_value(value: FrozenValue) -> Option<FrozenStructRef<'f>> {
        value
            .downcast_frozen_ref::<FrozenStruct>()
            .map(|f| FrozenStructRef(f.as_ref()))
    }
}