1use crate::{
2 encode_section, ComponentExportKind, ComponentSection, ComponentSectionId, ComponentValType,
3 Encode,
4};
5
6/// Represents the possible type bounds for type references.
7#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
8pub enum TypeBounds {
9 /// The type is bounded by equality to the type index specified.
10 Eq(u32),
11 /// This type is a fresh resource type,
12 SubResource,
13}
14
15impl Encode for TypeBounds {
16 fn encode(&self, sink: &mut Vec<u8>) {
17 match self {
18 Self::Eq(i: &u32) => {
19 sink.push(0x00);
20 i.encode(sink);
21 }
22 Self::SubResource => sink.push(0x01),
23 }
24 }
25}
26
27/// Represents a reference to a type.
28#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
29pub enum ComponentTypeRef {
30 /// The reference is to a core module type.
31 ///
32 /// The index is expected to be core type index to a core module type.
33 Module(u32),
34 /// The reference is to a function type.
35 ///
36 /// The index is expected to be a type index to a function type.
37 Func(u32),
38 /// The reference is to a value type.
39 Value(ComponentValType),
40 /// The reference is to a bounded type.
41 Type(TypeBounds),
42 /// The reference is to an instance type.
43 ///
44 /// The index is expected to be a type index to an instance type.
45 Instance(u32),
46 /// The reference is to a component type.
47 ///
48 /// The index is expected to be a type index to a component type.
49 Component(u32),
50}
51
52impl ComponentTypeRef {
53 /// Gets the export kind of the reference.
54 pub fn kind(&self) -> ComponentExportKind {
55 match self {
56 Self::Module(_) => ComponentExportKind::Module,
57 Self::Func(_) => ComponentExportKind::Func,
58 Self::Value(_) => ComponentExportKind::Value,
59 Self::Type(..) => ComponentExportKind::Type,
60 Self::Instance(_) => ComponentExportKind::Instance,
61 Self::Component(_) => ComponentExportKind::Component,
62 }
63 }
64}
65
66impl Encode for ComponentTypeRef {
67 fn encode(&self, sink: &mut Vec<u8>) {
68 self.kind().encode(sink);
69
70 match self {
71 Self::Module(idx: &u32) | Self::Func(idx: &u32) | Self::Instance(idx: &u32) | Self::Component(idx: &u32) => {
72 idx.encode(sink);
73 }
74 Self::Value(ty: &ComponentValType) => ty.encode(sink),
75 Self::Type(bounds: &TypeBounds) => bounds.encode(sink),
76 }
77 }
78}
79
80/// An encoder for the import section of WebAssembly components.
81///
82/// # Example
83///
84/// ```rust
85/// use wasm_encoder::{Component, ComponentTypeSection, PrimitiveValType, ComponentImportSection, ComponentTypeRef};
86///
87/// let mut types = ComponentTypeSection::new();
88///
89/// // Define a function type of `[string, string] -> string`.
90/// types
91/// .function()
92/// .params(
93/// [
94/// ("a", PrimitiveValType::String),
95/// ("b", PrimitiveValType::String)
96/// ]
97/// )
98/// .result(PrimitiveValType::String);
99///
100/// // This imports a function named `f` with the type defined above
101/// let mut imports = ComponentImportSection::new();
102/// imports.import("f", ComponentTypeRef::Func(0));
103///
104/// let mut component = Component::new();
105/// component.section(&types);
106/// component.section(&imports);
107///
108/// let bytes = component.finish();
109/// ```
110#[derive(Clone, Debug, Default)]
111pub struct ComponentImportSection {
112 bytes: Vec<u8>,
113 num_added: u32,
114}
115
116impl ComponentImportSection {
117 /// Create a new component import section encoder.
118 pub fn new() -> Self {
119 Self::default()
120 }
121
122 /// The number of imports in the section.
123 pub fn len(&self) -> u32 {
124 self.num_added
125 }
126
127 /// Determines if the section is empty.
128 pub fn is_empty(&self) -> bool {
129 self.num_added == 0
130 }
131
132 /// Define an import in the component import section.
133 pub fn import(&mut self, name: &str, ty: ComponentTypeRef) -> &mut Self {
134 encode_component_import_name(&mut self.bytes, name);
135 ty.encode(&mut self.bytes);
136 self.num_added += 1;
137 self
138 }
139}
140
141impl Encode for ComponentImportSection {
142 fn encode(&self, sink: &mut Vec<u8>) {
143 encode_section(sink, self.num_added, &self.bytes);
144 }
145}
146
147impl ComponentSection for ComponentImportSection {
148 fn id(&self) -> u8 {
149 ComponentSectionId::Import.into()
150 }
151}
152
153/// Prior to WebAssembly/component-model#263 import and export names were
154/// discriminated with a leading byte indicating what kind of import they are.
155/// After that PR though names are always prefixed with a 0x00 byte.
156///
157/// On 2023-10-28 in bytecodealliance/wasm-tools#1262 was landed to start
158/// transitioning to "always lead with 0x00". That updated the validator/parser
159/// to accept either 0x00 or 0x01 but the encoder wasn't updated at the time.
160///
161/// On 2024-09-03 in bytecodealliance/wasm-tools#TODO this encoder was updated
162/// to always emit 0x00 as a leading byte.
163///
164/// This function corresponds with the `importname'` production in the
165/// specification.
166pub(crate) fn encode_component_import_name(bytes: &mut Vec<u8>, name: &str) {
167 bytes.push(0x00);
168 name.encode(sink:bytes);
169}
170