mirror of
https://github.com/fluencelabs/wasm-bindgen
synced 2025-04-28 15:12:16 +00:00
42053ddd4e
Currently closure shims are communicated to JS at runtime, although at runtime the same constant value is always passed to JS! More pressing, however, work in #1002 requires knowledge of closure descriptor indices at `wasm-bindgen` time which is not currently known. Since the closure descriptor shims and such are already constant values, this commit moves the descriptor function indices into the *descriptor* for a closure/function pointer. This way we can learn about these values at `wasm-bindgen` time instead of only knowing them at runtime. This should have no semantic change on users of `wasm-bindgen`, although some closure invocations may be slightly speedier because there's less arguments being transferred over the boundary. Overall though this will help #1002 as the closure shims that the Rust compiler generates may not be the exact ones we hand out to JS, but rather wrappers around them which do `anyref` business things.
691 lines
24 KiB
Rust
691 lines
24 KiB
Rust
use failure::Error;
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use super::{Context, ImportTarget, Js2Rust};
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use descriptor::{Descriptor, Function};
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/// Helper struct for manufacturing a shim in JS used to translate Rust types to
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/// JS, then invoking an imported JS function.
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pub struct Rust2Js<'a, 'b: 'a> {
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pub cx: &'a mut Context<'b>,
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/// Arguments of the JS shim that we're generating, aka the variables passed
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/// from Rust which are only numbers.
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shim_arguments: Vec<String>,
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/// Arguments which are forwarded to the imported JS function
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js_arguments: Vec<String>,
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/// Conversions that happen before we invoke the wasm function, such as
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/// converting a string to a ptr/length pair.
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prelude: String,
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/// "Destructors" or cleanup that must happen after the wasm function
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/// finishes. This is scheduled in a `finally` block.
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finally: String,
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/// Next global index to write to when passing arguments via the single
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/// global stack.
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global_idx: usize,
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/// Index of the next argument for unique name generation purposes.
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arg_idx: usize,
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/// Expression used to generate the return value. The string "JS" in this
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/// expression is replaced with the actual JS invocation eventually.
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ret_expr: String,
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/// Whether or not we're catching JS exceptions
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catch: bool,
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/// Whether or not the last argument is a slice representing variadic arguments.
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variadic: bool,
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}
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impl<'a, 'b> Rust2Js<'a, 'b> {
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pub fn new(cx: &'a mut Context<'b>) -> Rust2Js<'a, 'b> {
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Rust2Js {
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cx,
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shim_arguments: Vec::new(),
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js_arguments: Vec::new(),
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prelude: String::new(),
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finally: String::new(),
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global_idx: 0,
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arg_idx: 0,
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ret_expr: String::new(),
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catch: false,
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variadic: false,
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}
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}
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pub fn catch(&mut self, catch: bool) -> &mut Self {
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if catch {
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self.cx.expose_uint32_memory();
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self.cx.expose_add_heap_object();
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}
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self.catch = catch;
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self
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}
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pub fn variadic(&mut self, variadic: bool) -> &mut Self {
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if variadic {
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self.cx.expose_uint32_memory();
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self.cx.expose_add_heap_object();
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}
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self.variadic = variadic;
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self
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}
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/// Generates all bindings necessary for the signature in `Function`,
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/// creating necessary argument conversions and return value processing.
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pub fn process(&mut self, function: &Function) -> Result<&mut Self, Error> {
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for arg in function.arguments.iter() {
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self.argument(arg)?;
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}
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self.ret(&function.ret)?;
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Ok(self)
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}
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/// Get a generated name for an argument.
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fn shim_argument(&mut self) -> String {
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let s = format!("arg{}", self.arg_idx);
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self.arg_idx += 1;
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self.shim_arguments.push(s.clone());
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s
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}
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fn argument(&mut self, arg: &Descriptor) -> Result<(), Error> {
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let abi = self.shim_argument();
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let (arg, optional) = match arg {
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Descriptor::Option(t) => (&**t, true),
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_ => (arg, false),
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};
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if let Some(ty) = arg.vector_kind() {
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let abi2 = self.shim_argument();
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let f = self.cx.expose_get_vector_from_wasm(ty);
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self.prelude(&format!(
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"let v{0} = {prefix}{func}({0}, {1});",
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abi,
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abi2,
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func = f,
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prefix = if optional {
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format!("{} == 0 ? undefined : ", abi)
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} else {
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String::new()
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},
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));
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if !arg.is_by_ref() && !arg.is_clamped_by_ref() {
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self.prelude(&format!(
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"\
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{start}
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v{0} = v{0}.slice();
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wasm.__wbindgen_free({0}, {1} * {size});
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{end}\
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",
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abi,
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abi2,
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size = ty.size(),
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start = if optional {
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format!("if ({} !== 0) {{", abi)
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} else {
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String::new()
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},
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end = if optional { "}" } else { "" },
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));
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self.cx.require_internal_export("__wbindgen_free")?;
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}
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self.js_arguments.push(format!("v{}", abi));
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return Ok(());
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}
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// No need to special case `optional` here because `takeObject` will
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// naturally work.
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if arg.is_anyref() {
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self.cx.expose_take_object();
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self.js_arguments.push(format!("takeObject({})", abi));
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return Ok(());
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} else if arg.is_ref_anyref() {
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self.cx.expose_get_object();
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self.js_arguments.push(format!("getObject({})", abi));
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return Ok(());
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}
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if optional {
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if arg.is_wasm_native() {
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let value = self.shim_argument();
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self.js_arguments.push(format!(
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"{present} === 0 ? undefined : {value}",
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value = value,
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present = abi,
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));
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return Ok(());
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}
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if arg.is_abi_as_u32() {
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self.js_arguments
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.push(format!("{0} === 0xFFFFFF ? undefined : {0}", abi));
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return Ok(());
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}
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if let Some(signed) = arg.get_64() {
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let f = if signed {
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self.cx.expose_int64_cvt_shim()
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} else {
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self.cx.expose_uint64_cvt_shim()
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};
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self.shim_argument();
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let low = self.shim_argument();
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let high = self.shim_argument();
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let name = format!("n{}", abi);
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self.prelude(&format!(
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"
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u32CvtShim[0] = {present} === 0 ? 0 : {low};
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u32CvtShim[1] = {present} === 0 ? 0 : {high};
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const {name} = {present} === 0 ? undefined : {f}[0];
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",
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present = abi,
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low = low,
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high = high,
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f = f,
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name = name,
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));
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self.js_arguments.push(name);
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return Ok(());
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}
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match *arg {
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Descriptor::Boolean => {
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self.js_arguments
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.push(format!("{0} === 0xFFFFFF ? undefined : {0} !== 0", abi));
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return Ok(());
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}
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Descriptor::Char => {
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let value = self.shim_argument();
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self.js_arguments.push(format!(
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"{present} === 0 ? undefined : String.fromCodePoint({value})",
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value = value,
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present = abi,
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));
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return Ok(());
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}
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_ => bail!(
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"unsupported optional argument type for calling JS function from Rust: {:?}",
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arg
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),
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};
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}
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if let Some(signed) = arg.get_64() {
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let f = if signed {
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self.cx.expose_int64_cvt_shim()
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} else {
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self.cx.expose_uint64_cvt_shim()
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};
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let high = self.shim_argument();
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let name = format!("n{}", abi);
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self.prelude(&format!(
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"\
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u32CvtShim[0] = {low};
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u32CvtShim[1] = {high};
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const {name} = {f}[0];
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",
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low = abi,
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high = high,
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f = f,
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name = name,
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));
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self.js_arguments.push(name);
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return Ok(());
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}
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if let Some(class) = arg.rust_struct() {
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if arg.is_by_ref() {
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bail!("cannot invoke JS functions with custom ref types yet")
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}
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self.cx.require_class_wrap(class);
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let assign = format!("let c{0} = {1}.__wrap({0});", abi, class);
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self.prelude(&assign);
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self.js_arguments.push(format!("c{}", abi));
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return Ok(());
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}
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if let Some((f, mutable)) = arg.stack_closure() {
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let arg2 = self.shim_argument();
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let (js, _ts, _js_doc) = {
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let mut builder = Js2Rust::new("", self.cx);
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if mutable {
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builder
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.prelude("let a = this.a;\n")
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.prelude("this.a = 0;\n")
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.rust_argument("a")
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.finally("this.a = a;\n");
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} else {
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builder.rust_argument("this.a");
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}
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builder
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.rust_argument("this.b")
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.process(f)?
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.finish("function", "this.f")
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};
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self.cx.function_table_needed = true;
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self.global_idx();
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self.prelude(&format!(
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"\
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let cb{0} = {js};\n\
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cb{0}.f = wasm.__wbg_function_table.get({idx});\n\
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cb{0}.a = {0};\n\
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cb{0}.b = {1};\n\
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",
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abi,
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arg2,
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js = js,
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idx = f.shim_idx,
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));
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self.finally(&format!("cb{0}.a = cb{0}.b = 0;", abi));
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self.js_arguments.push(format!("cb{0}.bind(cb{0})", abi));
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return Ok(());
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}
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let invoc_arg = match *arg {
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ref d if d.is_number() => abi,
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Descriptor::Boolean => format!("{} !== 0", abi),
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Descriptor::Char => format!("String.fromCodePoint({})", abi),
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_ => bail!(
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"unsupported argument type for calling JS function from Rust: {:?}",
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arg
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),
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};
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self.js_arguments.push(invoc_arg);
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Ok(())
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}
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fn ret(&mut self, ty: &Descriptor) -> Result<(), Error> {
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if let Descriptor::Unit = ty {
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self.ret_expr = "JS;".to_string();
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return Ok(());
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}
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let (ty, optional) = match ty {
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Descriptor::Option(t) => (&**t, true),
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_ => (ty, false),
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};
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if ty.is_by_ref() {
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bail!("cannot return a reference from JS to Rust")
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}
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if let Some(ty) = ty.vector_kind() {
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let f = self.cx.pass_to_wasm_function(ty)?;
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self.cx.expose_uint32_memory();
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self.shim_arguments.insert(0, "ret".to_string());
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let mut prelude = String::new();
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let expr = if optional {
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prelude.push_str("const val = JS;");
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self.cx.expose_is_like_none();
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format!("isLikeNone(val) ? [0, 0] : {}(val)", f)
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} else {
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format!("{}(JS)", f)
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};
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self.ret_expr = format!(
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"\
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{}
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const retptr = {};
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const retlen = WASM_VECTOR_LEN;
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const mem = getUint32Memory();
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mem[ret / 4] = retptr;
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mem[ret / 4 + 1] = retlen;
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",
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prelude, expr
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);
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return Ok(());
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}
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if ty.is_anyref() {
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self.cx.expose_add_heap_object();
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if optional {
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self.cx.expose_is_like_none();
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self.ret_expr = "
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const val = JS;
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return isLikeNone(val) ? 0 : addHeapObject(val);
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"
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.to_string();
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} else {
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self.ret_expr = "return addHeapObject(JS);".to_string()
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}
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return Ok(());
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}
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if optional {
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if ty.is_wasm_native() {
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self.cx.expose_is_like_none();
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self.cx.expose_uint32_memory();
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match ty {
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Descriptor::I32 => self.cx.expose_int32_memory(),
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Descriptor::U32 => (),
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Descriptor::F32 => self.cx.expose_f32_memory(),
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Descriptor::F64 => self.cx.expose_f64_memory(),
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_ => (),
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};
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self.shim_arguments.insert(0, "ret".to_string());
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self.ret_expr = format!(
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"
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const val = JS;
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getUint32Memory()[ret / 4] = !isLikeNone(val);
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{mem}[ret / {size} + 1] = isLikeNone(val) ? 0 : val;
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",
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size = match ty {
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Descriptor::I32 => 4,
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Descriptor::U32 => 4,
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Descriptor::F32 => 4,
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Descriptor::F64 => 8,
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_ => unreachable!(),
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},
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mem = match ty {
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Descriptor::I32 => "getInt32Memory()",
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Descriptor::U32 => "getUint32Memory()",
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Descriptor::F32 => "getFloat32Memory()",
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Descriptor::F64 => "getFloat64Memory()",
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_ => unreachable!(),
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}
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);
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return Ok(());
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}
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if ty.is_abi_as_u32() {
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self.cx.expose_is_like_none();
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self.ret_expr = "
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const val = JS;
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return isLikeNone(val) ? 0xFFFFFF : val;
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"
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.to_string();
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return Ok(());
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}
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if let Some(signed) = ty.get_64() {
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self.cx.expose_is_like_none();
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self.cx.expose_uint32_memory();
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let f = if signed {
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self.cx.expose_int64_memory();
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"getInt64Memory"
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} else {
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self.cx.expose_uint64_memory();
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"getUint64Memory"
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};
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self.shim_arguments.insert(0, "ret".to_string());
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self.ret_expr = format!(
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"
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const val = JS;
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getUint32Memory()[ret / 4] = !isLikeNone(val);
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{}()[ret / 8 + 1] = isLikeNone(val) ? BigInt(0) : val;
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",
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f
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);
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return Ok(());
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}
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match *ty {
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Descriptor::Boolean => {
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self.cx.expose_is_like_none();
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self.ret_expr = "
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const val = JS;
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return isLikeNone(val) ? 0xFFFFFF : val ? 1 : 0;
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"
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.to_string();
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return Ok(());
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}
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Descriptor::Char => {
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self.cx.expose_is_like_none();
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self.cx.expose_uint32_memory();
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self.shim_arguments.insert(0, "ret".to_string());
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self.ret_expr = "
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const val = JS;
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getUint32Memory()[ret / 4] = !isLikeNone(val);
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getUint32Memory()[ret / 4 + 1] = isLikeNone(val) ? 0 : val.codePointAt(0);
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"
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.to_string();
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return Ok(());
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}
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_ => bail!(
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"unsupported optional return type for calling JS function from Rust: {:?}",
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ty
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),
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};
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}
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if ty.is_number() {
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self.ret_expr = "return JS;".to_string();
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return Ok(());
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}
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if let Some(signed) = ty.get_64() {
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let f = if signed {
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self.cx.expose_int64_memory();
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"getInt64Memory"
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} else {
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self.cx.expose_uint64_memory();
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"getUint64Memory"
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};
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self.shim_arguments.insert(0, "ret".to_string());
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self.ret_expr = format!(
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"\
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const val = JS;\n\
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{}()[ret / 8] = val;\n\
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",
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f
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);
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return Ok(());
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}
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if let Some(class) = ty.rust_struct() {
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if ty.is_by_ref() {
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bail!("cannot invoke JS functions returning custom ref types yet")
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}
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// Insert an assertion to the type of the returned value as
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// otherwise this will cause memory unsafety on the Rust side of
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// things.
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self.ret_expr = format!(
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"\
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const val = JS;
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if (!(val instanceof {0})) {{
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throw new Error('expected value of type {0}');
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}}
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const ret = val.ptr;
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val.ptr = 0;
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return ret;\
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",
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class
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);
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return Ok(());
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}
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self.ret_expr = match *ty {
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Descriptor::Boolean => "return JS;".to_string(),
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Descriptor::Char => "return JS.codePointAt(0);".to_string(),
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_ => bail!(
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"unsupported return type for calling JS function from Rust: {:?}",
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ty
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),
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};
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Ok(())
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}
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|
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/// Returns whether this shim won't actually do anything when called other
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/// than forward the invocation somewhere else.
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///
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/// This is used as an optimization to wire up imports directly where
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/// possible and avoid a shim in some circumstances.
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pub fn is_noop(&self) -> bool {
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let Rust2Js {
|
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// fields which may affect whether we do nontrivial work
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catch,
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finally,
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js_arguments,
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prelude,
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ret_expr,
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variadic,
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shim_arguments,
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|
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// all other fields, listed explicitly here so if one is added we'll
|
|
// trigger a nonexhaustive error.
|
|
arg_idx: _,
|
|
cx: _,
|
|
global_idx: _,
|
|
} = self;
|
|
|
|
!catch &&
|
|
!variadic &&
|
|
prelude.is_empty() &&
|
|
finally.is_empty() &&
|
|
// make sure our faux return expression is "simple" by not
|
|
// performing any sort of transformation on the return value
|
|
(ret_expr == "JS;" || ret_expr == "return JS;") &&
|
|
// similarly we want to make sure that all the arguments are simply
|
|
// forwarded from the shim we would generate to the import,
|
|
// requiring no transformations
|
|
js_arguments == shim_arguments
|
|
}
|
|
|
|
pub fn finish(&self, invoc: &ImportTarget) -> Result<String, Error> {
|
|
let mut ret = String::new();
|
|
ret.push_str("function(");
|
|
ret.push_str(&self.shim_arguments.join(", "));
|
|
if self.catch {
|
|
if self.shim_arguments.len() > 0 {
|
|
ret.push_str(", ")
|
|
}
|
|
ret.push_str("exnptr");
|
|
}
|
|
ret.push_str(") {\n");
|
|
ret.push_str(&self.prelude);
|
|
|
|
let handle_variadic = |invoc: &str, js_arguments: &[String]| {
|
|
let ret = if self.variadic {
|
|
let (last_arg, args) = match js_arguments.split_last() {
|
|
Some(pair) => pair,
|
|
None => bail!("a function with no arguments cannot be variadic"),
|
|
};
|
|
if args.len() > 0 {
|
|
self.ret_expr.replace(
|
|
"JS",
|
|
&format!("{}({}, ...{})", invoc, args.join(", "), last_arg),
|
|
)
|
|
} else {
|
|
self.ret_expr
|
|
.replace("JS", &format!("{}(...{})", invoc, last_arg))
|
|
}
|
|
} else {
|
|
self.ret_expr
|
|
.replace("JS", &format!("{}({})", invoc, js_arguments.join(", ")))
|
|
};
|
|
Ok(ret)
|
|
};
|
|
|
|
let fixed = |desc: &str, class: &Option<String>, amt: usize| {
|
|
if self.variadic {
|
|
bail!("{} cannot be variadic", desc);
|
|
}
|
|
match (class, self.js_arguments.len()) {
|
|
(None, n) if n == amt + 1 => {
|
|
Ok((self.js_arguments[0].clone(), &self.js_arguments[1..]))
|
|
}
|
|
(None, _) => bail!("setters must have {} arguments", amt + 1),
|
|
(Some(class), n) if n == amt => Ok((class.clone(), &self.js_arguments[..])),
|
|
(Some(_), _) => bail!("static setters must have {} arguments", amt),
|
|
}
|
|
};
|
|
|
|
let mut invoc = match invoc {
|
|
ImportTarget::Function(f) => handle_variadic(&f, &self.js_arguments)?,
|
|
ImportTarget::Constructor(c) => {
|
|
handle_variadic(&format!("new {}", c), &self.js_arguments)?
|
|
}
|
|
ImportTarget::Method(f) => handle_variadic(&format!("{}.call", f), &self.js_arguments)?,
|
|
ImportTarget::StructuralMethod(f) => {
|
|
let (receiver, args) = match self.js_arguments.split_first() {
|
|
Some(pair) => pair,
|
|
None => bail!("methods must have at least one argument"),
|
|
};
|
|
handle_variadic(&format!("{}.{}", receiver, f), args)?
|
|
}
|
|
ImportTarget::StructuralGetter(class, field) => {
|
|
let (receiver, _) = fixed("getter", class, 0)?;
|
|
let expr = format!("{}.{}", receiver, field);
|
|
self.ret_expr.replace("JS", &expr)
|
|
}
|
|
ImportTarget::StructuralSetter(class, field) => {
|
|
let (receiver, val) = fixed("setter", class, 1)?;
|
|
let expr = format!("{}.{} = {}", receiver, field, val[0]);
|
|
self.ret_expr.replace("JS", &expr)
|
|
}
|
|
ImportTarget::StructuralIndexingGetter(class) => {
|
|
let (receiver, field) = fixed("indexing getter", class, 1)?;
|
|
let expr = format!("{}[{}]", receiver, field[0]);
|
|
self.ret_expr.replace("JS", &expr)
|
|
}
|
|
ImportTarget::StructuralIndexingSetter(class) => {
|
|
let (receiver, field) = fixed("indexing setter", class, 2)?;
|
|
let expr = format!("{}[{}] = {}", receiver, field[0], field[1]);
|
|
self.ret_expr.replace("JS", &expr)
|
|
}
|
|
ImportTarget::StructuralIndexingDeleter(class) => {
|
|
let (receiver, field) = fixed("indexing deleter", class, 1)?;
|
|
let expr = format!("delete {}[{}]", receiver, field[0]);
|
|
self.ret_expr.replace("JS", &expr)
|
|
}
|
|
};
|
|
|
|
if self.catch {
|
|
let catch = "\
|
|
const view = getUint32Memory();\n\
|
|
view[exnptr / 4] = 1;\n\
|
|
view[exnptr / 4 + 1] = addHeapObject(e);\n\
|
|
";
|
|
|
|
invoc = format!(
|
|
"\
|
|
try {{\n\
|
|
{}
|
|
}} catch (e) {{\n\
|
|
{}
|
|
}}\
|
|
",
|
|
&invoc, catch
|
|
);
|
|
};
|
|
|
|
if self.finally.len() > 0 {
|
|
invoc = format!(
|
|
"\
|
|
try {{\n\
|
|
{}
|
|
}} finally {{\n\
|
|
{}
|
|
}}\
|
|
",
|
|
&invoc, &self.finally
|
|
);
|
|
}
|
|
ret.push_str(&invoc);
|
|
|
|
ret.push_str("\n}\n");
|
|
Ok(ret)
|
|
}
|
|
|
|
fn global_idx(&mut self) -> usize {
|
|
let ret = self.global_idx;
|
|
self.global_idx += 1;
|
|
ret
|
|
}
|
|
|
|
fn prelude(&mut self, s: &str) -> &mut Self {
|
|
for line in s.lines() {
|
|
self.prelude.push_str(line);
|
|
self.prelude.push_str("\n");
|
|
}
|
|
self
|
|
}
|
|
|
|
fn finally(&mut self, s: &str) -> &mut Self {
|
|
for line in s.lines() {
|
|
self.finally.push_str(line);
|
|
self.finally.push_str("\n");
|
|
}
|
|
self
|
|
}
|
|
}
|