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
use super::*;
/// An encoder for the table section.
///
/// # Example
///
/// ```
/// use wasm_encoder::{Module, TableSection, TableType, ValType};
///
/// let mut tables = TableSection::new();
/// tables.table(TableType {
/// element_type: ValType::FuncRef,
/// minimum: 128,
/// maximum: None,
/// });
///
/// let mut module = Module::new();
/// module.section(&tables);
///
/// let wasm_bytes = module.finish();
/// ```
#[derive(Clone, Default, Debug)]
pub struct TableSection {
bytes: Vec<u8>,
num_added: u32,
}
impl TableSection {
/// Construct a new table section encoder.
pub fn new() -> Self {
Self::default()
}
/// How many tables have been defined inside this section so far?
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 a table.
pub fn table(&mut self, table_type: TableType) -> &mut Self {
table_type.encode(&mut self.bytes);
self.num_added += 1;
self
}
}
impl Section for TableSection {
fn id(&self) -> u8 {
SectionId::Table.into()
}
fn encode<S>(&self, sink: &mut S)
where
S: Extend<u8>,
{
let num_added = encoders::u32(self.num_added);
let n = num_added.len();
sink.extend(
encoders::u32(u32::try_from(n + self.bytes.len()).unwrap())
.chain(num_added)
.chain(self.bytes.iter().copied()),
);
}
}
/// A table's type.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct TableType {
/// The table's element type.
pub element_type: ValType,
/// Minimum size, in elements, of this table
pub minimum: u32,
/// Maximum size, in elements, of this table
pub maximum: Option<u32>,
}
impl TableType {
pub(crate) fn encode(&self, bytes: &mut Vec<u8>) {
bytes.push(self.element_type.into());
let mut flags = 0;
if self.maximum.is_some() {
flags |= 0b001;
}
bytes.push(flags);
bytes.extend(encoders::u32(self.minimum));
if let Some(max) = self.maximum {
bytes.extend(encoders::u32(max));
}
}
}