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
152
153
154
155
156
157

use crate::{
    encode_section, Encode, GlobalType, MemoryType, Section, SectionId, TableType, TagType,
    CORE_FUNCTION_SORT, CORE_GLOBAL_SORT, CORE_MEMORY_SORT, CORE_TABLE_SORT, CORE_TAG_SORT,
};

/// The type of an entity.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum EntityType {
    /// A function type.
    ///
    /// The value is an index into the types section.
    Function(u32),
    /// A table type.
    Table(TableType),
    /// A memory type.
    Memory(MemoryType),
    /// A global type.
    Global(GlobalType),
    /// A tag type.
    ///
    /// This variant is used with the exception handling proposal.
    Tag(TagType),
}

impl Encode for EntityType {
    fn encode(&self, sink: &mut Vec<u8>) {
        match self {
            Self::Function(i) => {
                sink.push(CORE_FUNCTION_SORT);
                i.encode(sink);
            }
            Self::Table(t) => {
                sink.push(CORE_TABLE_SORT);
                t.encode(sink);
            }
            Self::Memory(t) => {
                sink.push(CORE_MEMORY_SORT);
                t.encode(sink);
            }
            Self::Global(t) => {
                sink.push(CORE_GLOBAL_SORT);
                t.encode(sink);
            }
            Self::Tag(t) => {
                sink.push(CORE_TAG_SORT);
                t.encode(sink);
            }
        }
    }
}

impl From<TableType> for EntityType {
    fn from(t: TableType) -> Self {
        Self::Table(t)
    }
}

impl From<MemoryType> for EntityType {
    fn from(t: MemoryType) -> Self {
        Self::Memory(t)
    }
}

impl From<GlobalType> for EntityType {
    fn from(t: GlobalType) -> Self {
        Self::Global(t)
    }
}

impl From<TagType> for EntityType {
    fn from(t: TagType) -> Self {
        Self::Tag(t)
    }
}

#[cfg(feature = "wasmparser")]
impl TryFrom<wasmparser::TypeRef> for EntityType {
    type Error = ();
    fn try_from(type_ref: wasmparser::TypeRef) -> Result<Self, Self::Error> {
        Ok(match type_ref {
            wasmparser::TypeRef::Func(i) => EntityType::Function(i),
            wasmparser::TypeRef::Table(t) => EntityType::Table(t.try_into()?),
            wasmparser::TypeRef::Memory(m) => EntityType::Memory(m.into()),
            wasmparser::TypeRef::Global(g) => EntityType::Global(g.try_into()?),
            wasmparser::TypeRef::Tag(t) => EntityType::Tag(t.into()),
        })
    }
}

/// An encoder for the import section of WebAssembly modules.
///
/// # Example
///
/// ```rust
/// use wasm_encoder::{MemoryType, Module, ImportSection};
///
/// let mut imports = ImportSection::new();
/// imports.import(
///     "env",
///     "memory",
///     MemoryType {
///         minimum: 1,
///         maximum: None,
///         memory64: false,
///         shared: false,
///         page_size_log2: None,
///     }
/// );
///
/// let mut module = Module::new();
/// module.section(&imports);
///
/// let bytes = module.finish();
/// ```
#[derive(Clone, Debug, Default)]
pub struct ImportSection {
    bytes: Vec<u8>,
    num_added: u32,
}

impl ImportSection {
    /// Create a new import section encoder.
    pub fn new() -> Self {
        Self::default()
    }

    /// The number of imports in the section.
    pub fn len(&self) -> u32 {
        self.num_added
    }

    /// Determines if the section is empty.
    pub fn is_empty(&self) -> bool {
        self.num_added == 0
    }

    /// Define an import in the import section.
    pub fn import(&mut self, module: &str, field: &str, ty: impl Into<EntityType>) -> &mut Self {
        module.encode(&mut self.bytes);
        field.encode(&mut self.bytes);
        ty.into().encode(&mut self.bytes);
        self.num_added += 1;
        self
    }
}

impl Encode for ImportSection {
    fn encode(&self, sink: &mut Vec<u8>) {
        encode_section(sink, self.num_added, &self.bytes);
    }
}

impl Section for ImportSection {
    fn id(&self) -> u8 {
        SectionId::Import.into()
    }
}