Struct CodeBuilder

pub struct CodeBuilder<'a> { /* private fields */ }

Builder-style structure used to create a Module or pre-compile a module to a serialized list of bytes.

This structure can be used for more advanced configuration when compiling a WebAssembly module. Most configuration can use simpler constructors such as:

• Module::new
• Module::from_file
• Module::from_binary

Note that a CodeBuilder always involves compiling WebAssembly bytes to machine code. To deserialize a list of bytes use Module::deserialize instead.

A CodeBuilder requires a source of WebAssembly bytes to be configured before calling compile_module_serialized or compile_module. This can be provided with either the wasm or wasm_file method. Note that only a single source of bytes can be provided.

WebAssembly Text Format

This builder supports the WebAssembly Text Format (*.wat files). WebAssembly text files are automatically converted to a WebAssembly binary and then the binary is compiled. This requires the wat feature of the wasmtime crate to be enabled, and the feature is enabled by default.

If the text format is not desired then the CodeBuilder::wat method can be used to disable this conversion.

Implementations

impl<'a> CodeBuilder<'a>

pub fn new(engine: &'a Engine) -> CodeBuilder<'a>

Creates a new builder which will insert modules into the specified Engine.

pub fn wasm( &mut self, wasm_bytes: &'a [u8], wasm_path: Option<&'a Path>, ) -> Result<&mut Self>

Configures the WebAssembly binary or text that is being compiled.

The wasm_bytes parameter is either a binary WebAssembly file or a WebAssembly module in its text format. This will be stored within the CodeBuilder for processing later when compilation is finalized.

The optional wasm_path parameter is the path to the wasm_bytes on disk, if any. This may be used for diagnostics and other debugging-related purposes, but this method will not read the path specified.

Errors

If wasm bytes have already been configured via a call to this method or CodeBuilder::wasm_file then an error will be returned.

pub fn wat(&mut self, enable: bool) -> Result<&mut Self>

Configures whether the WebAssembly text format is supported in this builder.

This support is enabled by default if the wat crate feature is also enabled.

Errors

If this feature is explicitly enabled here via this method and the wat crate feature is disabled then an error will be returned.

pub fn wasm_file(&mut self, file: &'a Path) -> Result<&mut Self>

Reads the file specified for the WebAssembly bytes that are going to be compiled.

This method will read file from the filesystem and interpret it either as a WebAssembly binary or as a WebAssembly text file. The contents are inspected to do this, the file extension is not consulted.

Errors

If wasm bytes have already been configured via a call to this method or CodeBuilder::wasm then an error will be returned.

If file can’t be read or an error happens reading it then that will also be returned.

pub fn compile_module_serialized(&self) -> Result<Vec<u8>>

Finishes this compilation and produces a serialized list of bytes.

This method requires that either CodeBuilder::wasm or CodeBuilder::wasm_file was invoked prior to indicate what is being compiled.

This method will block the current thread until compilation has finished, and when done the serialized artifact will be returned.

Note that this method will never cache compilations, even if the cache feature is enabled.

Errors

This can fail if the input wasm module was not valid or if another compilation-related error is encountered.

pub fn compile_component_serialized(&self) -> Result<Vec<u8>>

Available on crate feature component-model only.

Same as CodeBuilder::compile_module_serialized except that it compiles a serialized Component instead of a module.

impl<'a> CodeBuilder<'a>

pub fn compile_module(&self) -> Result<Module>

Available on crate feature runtime only.

Same as CodeBuilder::compile_module_serialized except that a Module is produced instead.

Note that this method will cache compilations if the cache feature is enabled and turned on in Config.

pub fn compile_component(&self) -> Result<Component>

Available on crate features runtime and component-model only.

Same as CodeBuilder::compile_module except that it compiles a Component instead of a module.