1use crate::{encode_section, Encode, Section, SectionId};
2use alloc::vec::Vec;
3
4/// An encoder for the function section of WebAssembly modules.
5///
6/// # Example
7///
8/// ```
9/// use wasm_encoder::{Module, FunctionSection, ValType};
10///
11/// let mut functions = FunctionSection::new();
12/// let type_index = 0;
13/// functions.function(type_index);
14///
15/// let mut module = Module::new();
16/// module.section(&functions);
17///
18/// // Note: this will generate an invalid module because we didn't generate a
19/// // code section containing the function body. See the documentation for
20/// // `CodeSection` for details.
21///
22/// let bytes = module.finish();
23/// ```
24#[derive(Clone, Debug, Default)]
25pub struct FunctionSection {
26 bytes: Vec<u8>,
27 num_added: u32,
28}
29
30impl FunctionSection {
31 /// Construct a new module function section encoder.
32 pub fn new() -> Self {
33 Self::default()
34 }
35
36 /// The number of functions in the section.
37 pub fn len(&self) -> u32 {
38 self.num_added
39 }
40
41 /// Determines if the section is empty.
42 pub fn is_empty(&self) -> bool {
43 self.num_added == 0
44 }
45
46 /// Define a function in a module's function section.
47 pub fn function(&mut self, type_index: u32) -> &mut Self {
48 type_index.encode(&mut self.bytes);
49 self.num_added += 1;
50 self
51 }
52}
53
54impl Encode for FunctionSection {
55 fn encode(&self, sink: &mut Vec<u8>) {
56 encode_section(sink, self.num_added, &self.bytes);
57 }
58}
59
60impl Section for FunctionSection {
61 fn id(&self) -> u8 {
62 SectionId::Function.into()
63 }
64}
65