wasmparser/readers/component/
aliases.rs

1use crate::{BinaryReader, ComponentExternalKind, ExternalKind, FromReader, Result};
2
3/// Represents the kind of an outer alias in a WebAssembly component.
4#[derive(Clone, Copy, Debug, Eq, PartialEq)]
5pub enum ComponentOuterAliasKind {
6    /// The alias is to a core module.
7    CoreModule,
8    /// The alias is to a core type.
9    CoreType,
10    /// The alias is to a component type.
11    Type,
12    /// The alias is to a component.
13    Component,
14}
15
16/// Represents an alias in a WebAssembly component.
17#[derive(Debug, Clone, Eq, PartialEq)]
18pub enum ComponentAlias<'a> {
19    /// The alias is to an export of a component instance.
20    InstanceExport {
21        /// The alias kind.
22        kind: ComponentExternalKind,
23        /// The instance index.
24        instance_index: u32,
25        /// The export name.
26        name: &'a str,
27    },
28    /// The alias is to an export of a module instance.
29    CoreInstanceExport {
30        /// The alias kind.
31        kind: ExternalKind,
32        /// The instance index.
33        instance_index: u32,
34        /// The export name.
35        name: &'a str,
36    },
37    /// The alias is to an outer item.
38    Outer {
39        /// The alias kind.
40        kind: ComponentOuterAliasKind,
41        /// The outward count, starting at zero for the current component.
42        count: u32,
43        /// The index of the item within the outer component.
44        index: u32,
45    },
46}
47
48/// Section reader for the component alias section
49pub type ComponentAliasSectionReader<'a> = crate::SectionLimited<'a, ComponentAlias<'a>>;
50
51impl<'a> FromReader<'a> for ComponentAlias<'a> {
52    fn from_reader(reader: &mut BinaryReader<'a>) -> Result<Self> {
53        // We don't know what type of alias it is yet, so just read the sort bytes
54        let offset = reader.original_position();
55        let byte1 = reader.read_u8()?;
56        let byte2 = if byte1 == 0x00 {
57            Some(reader.read_u8()?)
58        } else {
59            None
60        };
61
62        Ok(match reader.read_u8()? {
63            0x00 => ComponentAlias::InstanceExport {
64                kind: ComponentExternalKind::from_bytes(byte1, byte2, offset)?,
65                instance_index: reader.read_var_u32()?,
66                name: reader.read_string()?,
67            },
68            0x01 => ComponentAlias::CoreInstanceExport {
69                kind: BinaryReader::external_kind_from_byte(
70                    byte2.ok_or_else(|| {
71                        BinaryReader::invalid_leading_byte_error(
72                            byte1,
73                            "core instance export kind",
74                            offset,
75                        )
76                    })?,
77                    offset,
78                )?,
79                instance_index: reader.read_var_u32()?,
80                name: reader.read_string()?,
81            },
82            0x02 => ComponentAlias::Outer {
83                kind: component_outer_alias_kind_from_bytes(byte1, byte2, offset)?,
84                count: reader.read_var_u32()?,
85                index: reader.read_var_u32()?,
86            },
87            x => reader.invalid_leading_byte(x, "alias")?,
88        })
89    }
90}
91
92fn component_outer_alias_kind_from_bytes(
93    byte1: u8,
94    byte2: Option<u8>,
95    offset: usize,
96) -> Result<ComponentOuterAliasKind> {
97    Ok(match byte1 {
98        0x00 => match byte2.unwrap() {
99            0x10 => ComponentOuterAliasKind::CoreType,
100            0x11 => ComponentOuterAliasKind::CoreModule,
101            x => {
102                return Err(BinaryReader::invalid_leading_byte_error(
103                    x,
104                    "component outer alias kind",
105                    offset + 1,
106                ))
107            }
108        },
109        0x03 => ComponentOuterAliasKind::Type,
110        0x04 => ComponentOuterAliasKind::Component,
111        x => {
112            return Err(BinaryReader::invalid_leading_byte_error(
113                x,
114                "component outer alias kind",
115                offset,
116            ))
117        }
118    })
119}
wasmparser/readers/component/aliases.rs

wasmparser/readers/component/
aliases.rs
