Crate wasm_encoder

A WebAssembly encoder.

The main builder is the Module. You can build a section with a section-specific builder, like TypeSection or ImportSection, and then add it to the module with Module::section. When you are finished building the module, call either Module::as_slice or Module::finish to get the encoded bytes. The former gives a shared reference to the underlying bytes as a slice, while the latter gives you ownership of them as a vector.

Example

If we wanted to build this module:

(module
  (type (func (param i32 i32) (result i32)))
  (func (type 0)
    local.get 0
    local.get 1
    i32.add)
  (export "f" (func 0)))

then we would do this:

use wasm_encoder::{
    CodeSection, Export, ExportSection, Function, FunctionSection, Instruction,
    Module, TypeSection, ValType,
};

let mut module = Module::new();

// Encode the type section.
let mut types = TypeSection::new();
let params = vec![ValType::I32, ValType::I32];
let results = vec![ValType::I32];
types.function(params, results);
module.section(&types);

// Encode the function section.
let mut functions = FunctionSection::new();
let type_index = 0;
functions.function(type_index);
module.section(&functions);

// Encode the export section.
let mut exports = ExportSection::new();
exports.export("f", Export::Function(0));
module.section(&exports);

// Encode the code section.
let mut codes = CodeSection::new();
let locals = vec![];
let mut f = Function::new(locals);
f.instruction(Instruction::LocalGet(0));
f.instruction(Instruction::LocalGet(1));
f.instruction(Instruction::I32Add);
f.instruction(Instruction::End);
codes.function(&f);
module.section(&codes);

// Extract the encoded Wasm bytes for this module.
let wasm_bytes = module.finish();

// We generated a valid Wasm module!
assert!(wasmparser::validate(&wasm_bytes).is_ok());

Modules

encoders

Low-level encoders.

Structs

AliasSection	An encoder for the alias section.
CodeSection	An encoder for the code section.
CustomSection	A custom section holding arbitrary data.
DataCountSection	An encoder for the data count section.
DataSection	An encoder for the data section.
DataSegment	A segment in the data section.
ElementSection	An encoder for the element section.
ElementSegment	An element segment in the element section.
ExportSection	An encoder for the export section.
Function	An encoder for a function body within the code section.
FunctionSection	An encoder for the function section.
GlobalSection	An encoder for the global section.
GlobalType	A global's type.
ImportSection	An encoder for the import section.
InstanceSection	An encoder for the instance section.
Limits	Limits for a table or memory.
MemArg	The immediate for a memory instruction.
MemorySection	An encoder for the memory section.
MemoryType	A memory's type.
Module	A Wasm module that is being encoded.
ModuleSection	An encoder for the module section.
RawSection	A section made up of uninterpreted, raw bytes.
StartSection	An encoder for the start section.
TableSection	An encoder for the table section.
TableType	A table's type.
TypeSection	An encoder for the type section.

Enums

BlockType	The type for a block/if/loop.
DataSegmentMode	A data segment's mode.
Element	An element in a segment in the element section.
ElementMode	An element segment's mode.
Elements	A sequence of elements in a segment in the element section.
EntityType	The type of an entity.
Export	A WebAssembly export.
Instruction	WebAssembly instructions.
ItemKind	Kinds of WebAssembly items
SectionId	Known section IDs.
ValType	The type of a value.

Traits

Section

A WebAssembly section.