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Move the macro support code into its own crate (#529)

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konstin
2018-07-29 17:59:46 +02:00
committed by Alex Crichton
parent 0f50f39079
commit 0bd21b7bd2
7 changed files with 282 additions and 21 deletions
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22
crates/macro-support/Cargo.toml Normal file
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[package]
name = "wasm-bindgen-macro-support"
version = "0.2.15"
authors = ["The wasm-bindgen Developers"]
license = "MIT/Apache-2.0"
repository = "https://github.com/rustwasm/wasm-bindgen/tree/master/crates/macro-support"
homepage = "https://rustwasm.github.io/wasm-bindgen/"
documentation = "https://docs.rs/wasm-bindgen"
description = """
The part of the implementation of the `#[wasm_bindgen]` attribute that is not in the shared backend crate
"""
[features]
spans = ["proc-macro2/nightly", "wasm-bindgen-backend/spans"]
extra-traits = ["syn/extra-traits"]
[dependencies]
syn = { version = '0.14', features = ['full'] }
quote = '0.6'
proc-macro2 = "0.4.9"
wasm-bindgen-backend = { path = "../backend", version = "=0.2.15" }
wasm-bindgen-shared = { path = "../shared", version = "=0.2.15" }

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crates/macro-support/LICENSE-APACHE Normal file
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crates/macro-support/LICENSE-MIT Normal file
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Copyright (c) 2014 Alex Crichton
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//! This crate contains the part of the implementation of the `#[wasm_bindgen]` optsibute that is
//! not in the shared backend crate.
#![doc(html_root_url = "https://docs.rs/wasm-bindgen-macro-support/0.2")]
extern crate proc_macro2;
extern crate quote;
#[macro_use]
extern crate syn;
extern crate wasm_bindgen_backend as backend;
extern crate wasm_bindgen_shared as shared;
pub use parser::BindgenAttrs;
use parser::MacroParse;
use quote::ToTokens;
mod parser;
/// Takes the parsed input from a `#[wasm_bindgen]` macro and returns the generated bindings
pub fn expand(item: syn::Item, opts: parser::BindgenAttrs) -> proc_macro2::TokenStream {
let mut tokens = proc_macro2::TokenStream::new();
let mut program = backend::ast::Program::default();
item.macro_parse(&mut program, (Some(opts), &mut tokens));
program.to_tokens(&mut tokens);
tokens
}

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use backend::ast;
use backend::util::{ident_ty, ShortHash};
use proc_macro2::{Ident, Span, TokenStream, TokenTree};
use quote::ToTokens;
use shared;
use syn;
/// Parsed attributes from a `#[wasm_bindgen(..)]`.
#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
#[derive(Default)]
pub struct BindgenAttrs {
/// List of parsed attributes
pub attrs: Vec<BindgenAttr>,
}
impl BindgenAttrs {
/// Find and parse the wasm_bindgen attributes.
fn find(attrs: &mut Vec<syn::Attribute>) -> BindgenAttrs {
let pos = attrs
.iter()
.enumerate()
.find(|&(_, ref m)| m.path.segments[0].ident == "wasm_bindgen")
.map(|a| a.0);
let pos = match pos {
Some(i) => i,
None => return BindgenAttrs::default(),
};
let mut tts = attrs.remove(pos).tts.into_iter();
let tt = match tts.next() {
Some(TokenTree::Group(d)) => d.stream(),
Some(_) => panic!("malformed #[wasm_bindgen] attribute"),
None => return BindgenAttrs::default(),
};
if tts.next().is_some() {
panic!("malformed #[wasm_bindgen] attribute");
}
syn::parse(tt.into()).expect("malformed #[wasm_bindgen] attribute")
}
/// Get the first module attribute
fn module(&self) -> Option<&str> {
self.attrs
.iter()
.filter_map(|a| match a {
BindgenAttr::Module(s) => Some(&s[..]),
_ => None,
})
.next()
}
/// Get the first version attribute
fn version(&self) -> Option<&str> {
self.attrs
.iter()
.filter_map(|a| match a {
BindgenAttr::Version(s) => Some(&s[..]),
_ => None,
})
.next()
}
/// Whether the catch attribute is present
fn catch(&self) -> bool {
self.attrs.iter().any(|a| match a {
BindgenAttr::Catch => true,
_ => false,
})
}
/// Whether the constructor attribute is present
fn constructor(&self) -> bool {
self.attrs.iter().any(|a| match a {
BindgenAttr::Constructor => true,
_ => false,
})
}
/// Get the first static_method_of attribute
fn static_method_of(&self) -> Option<&Ident> {
self.attrs
.iter()
.filter_map(|a| match a {
BindgenAttr::StaticMethodOf(c) => Some(c),
_ => None,
})
.next()
}
/// Whether the method attributes is present
fn method(&self) -> bool {
self.attrs.iter().any(|a| match a {
BindgenAttr::Method => true,
_ => false,
})
}
/// Get the first js_namespace attribute
fn js_namespace(&self) -> Option<&Ident> {
self.attrs
.iter()
.filter_map(|a| match a {
BindgenAttr::JsNamespace(s) => Some(s),
_ => None,
})
.next()
}
/// Get the first getter attribute
fn getter(&self) -> Option<Option<Ident>> {
self.attrs
.iter()
.filter_map(|a| match a {
BindgenAttr::Getter(g) => Some(g.clone()),
_ => None,
})
.next()
}
/// Get the first setter attribute
fn setter(&self) -> Option<Option<Ident>> {
self.attrs
.iter()
.filter_map(|a| match a {
BindgenAttr::Setter(s) => Some(s.clone()),
_ => None,
})
.next()
}
/// Whether the structural attributes is present
fn structural(&self) -> bool {
self.attrs.iter().any(|a| match *a {
BindgenAttr::Structural => true,
_ => false,
})
}
/// Whether the readonly attributes is present
fn readonly(&self) -> bool {
self.attrs.iter().any(|a| match *a {
BindgenAttr::Readonly => true,
_ => false,
})
}
/// Get the first js_name attribute
fn js_name(&self) -> Option<&Ident> {
self.attrs
.iter()
.filter_map(|a| match a {
BindgenAttr::JsName(s) => Some(s),
_ => None,
})
.next()
}
/// Get the first js_name attribute
fn js_class(&self) -> Option<&str> {
self.attrs
.iter()
.filter_map(|a| match a {
BindgenAttr::JsClass(s) => Some(&s[..]),
_ => None,
})
.next()
}
}
impl syn::synom::Synom for BindgenAttrs {
named!(parse -> Self, alt!(
do_parse!(
opts: call!(
syn::punctuated::Punctuated::<_, syn::token::Comma>::parse_terminated
) >>
(BindgenAttrs {
attrs: opts.into_iter().collect(),
})
) => { |s| s }
|
epsilon!() => { |_| BindgenAttrs { attrs: Vec::new() } }
));
}
/// The possible attributes in the `#[wasm_bindgen]`.
#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
pub enum BindgenAttr {
Catch,
Constructor,
Method,
StaticMethodOf(Ident),
JsNamespace(Ident),
Module(String),
Version(String),
Getter(Option<Ident>),
Setter(Option<Ident>),
Structural,
Readonly,
JsName(Ident),
JsClass(String),
}
impl syn::synom::Synom for BindgenAttr {
named!(parse -> Self, alt!(
call!(term, "catch") => { |_| BindgenAttr::Catch }
|
call!(term, "constructor") => { |_| BindgenAttr::Constructor }
|
call!(term, "method") => { |_| BindgenAttr::Method }
|
do_parse!(
call!(term, "static_method_of") >>
punct!(=) >>
cls: call!(term2ident) >>
(cls)
)=> { BindgenAttr::StaticMethodOf }
|
do_parse!(
call!(term, "getter") >>
val: option!(do_parse!(
punct!(=) >>
s: call!(term2ident) >>
(s)
)) >>
(val)
)=> { BindgenAttr::Getter }
|
do_parse!(
call!(term, "setter") >>
val: option!(do_parse!(
punct!(=) >>
s: call!(term2ident) >>
(s)
)) >>
(val)
)=> { BindgenAttr::Setter }
|
call!(term, "structural") => { |_| BindgenAttr::Structural }
|
call!(term, "readonly") => { |_| BindgenAttr::Readonly }
|
do_parse!(
call!(term, "js_namespace") >>
punct!(=) >>
ns: call!(term2ident) >>
(ns)
)=> { BindgenAttr::JsNamespace }
|
do_parse!(
call!(term, "module") >>
punct!(=) >>
s: syn!(syn::LitStr) >>
(s.value())
)=> { BindgenAttr::Module }
|
do_parse!(
call!(term, "version") >>
punct!(=) >>
s: syn!(syn::LitStr) >>
(s.value())
)=> { BindgenAttr::Version }
|
do_parse!(
call!(term, "js_name") >>
punct!(=) >>
ns: call!(term2ident) >>
(ns)
)=> { BindgenAttr::JsName }
|
do_parse!(
call!(term, "js_class") >>
punct!(=) >>
s: syn!(syn::LitStr) >>
(s.value())
)=> { BindgenAttr::JsClass }
));
}
/// Consumes a `Ident` with the given name
fn term<'a>(cursor: syn::buffer::Cursor<'a>, name: &str) -> syn::synom::PResult<'a, ()> {
if let Some((ident, next)) = cursor.ident() {
if ident == name {
return Ok(((), next));
}
}
syn::parse_error()
}
/// Consumes a `Ident` and returns it.
fn term2ident<'a>(cursor: syn::buffer::Cursor<'a>) -> syn::synom::PResult<'a, Ident> {
match cursor.ident() {
Some(pair) => Ok(pair),
None => syn::parse_error(),
}
}
/// Conversion trait with context.
///
/// Used to convert syn tokens into an AST, that we can then use to generate glue code. The context
/// (`Ctx`) is used to pass in the attributes from the `#[wasm_bindgen]`, if needed.
trait ConvertToAst<Ctx> {
/// What we are converting to.
type Target;
/// Convert into our target.
///
/// Since this is used in a procedural macro, use panic to fail.
fn convert(self, context: Ctx) -> Self::Target;
}
impl<'a> ConvertToAst<()> for &'a mut syn::ItemStruct {
type Target = ast::Struct;
fn convert(self, (): ()) -> Self::Target {
if self.generics.params.len() > 0 {
panic!(
"structs with #[wasm_bindgen] cannot have lifetime or \
type parameters currently"
);
}
let mut fields = Vec::new();
if let syn::Fields::Named(names) = &mut self.fields {
for field in names.named.iter_mut() {
match field.vis {
syn::Visibility::Public(..) => {}
_ => continue,
}
let name = match &field.ident {
Some(n) => n,
None => continue,
};
let ident = self.ident.to_string();
let name_str = name.to_string();
let getter = shared::struct_field_get(&ident, &name_str);
let setter = shared::struct_field_set(&ident, &name_str);
let opts = BindgenAttrs::find(&mut field.attrs);
let comments = extract_doc_comments(&field.attrs);
fields.push(ast::StructField {
name: name.clone(),
struct_name: self.ident.clone(),
readonly: opts.readonly(),
ty: field.ty.clone(),
getter: Ident::new(&getter, Span::call_site()),
setter: Ident::new(&setter, Span::call_site()),
comments,
});
}
}
let comments: Vec<String> = extract_doc_comments(&self.attrs);
ast::Struct {
name: self.ident.clone(),
fields,
comments,
}
}
}
impl ConvertToAst<BindgenAttrs> for syn::ForeignItemFn {
type Target = ast::ImportKind;
fn convert(self, opts: BindgenAttrs) -> Self::Target {
let js_name = opts.js_name().unwrap_or(&self.ident).clone();
let wasm = function_from_decl(&js_name, self.decl, self.attrs, self.vis, false).0;
let catch = opts.catch();
let js_ret = if catch {
// TODO: this assumes a whole bunch:
//
// * The outer type is actually a `Result`
// * The error type is a `JsValue`
// * The actual type is the first type parameter
//
// should probably fix this one day...
extract_first_ty_param(wasm.ret.as_ref())
.expect("can't `catch` without returning a Result")
} else {
wasm.ret.clone()
};
let mut operation_kind = ast::OperationKind::Regular;
if let Some(g) = opts.getter() {
operation_kind = ast::OperationKind::Getter(g);
}
if let Some(s) = opts.setter() {
operation_kind = ast::OperationKind::Setter(s);
}
let kind = if opts.method() {
let class = wasm
.arguments
.get(0)
.expect("methods must have at least one argument");
let class = match class.ty {
syn::Type::Reference(syn::TypeReference {
mutability: None,
ref elem,
..
}) => &**elem,
_ => panic!("first argument of method must be a shared reference"),
};
let class_name = match *class {
syn::Type::Path(syn::TypePath {
qself: None,
ref path,
}) => path,
_ => panic!("first argument of method must be a path"),
};
let class_name = extract_path_ident(class_name)
.expect("first argument of method must be a bare type");
let class_name = opts
.js_class()
.map(Into::into)
.unwrap_or_else(|| class_name.to_string());
let kind = ast::MethodKind::Operation(ast::Operation {
is_static: false,
kind: operation_kind,
});
ast::ImportFunctionKind::Method {
class: class_name,
ty: class.clone(),
kind,
}
} else if let Some(cls) = opts.static_method_of() {
let class = cls.to_string();
let ty = ident_ty(cls.clone());
let kind = ast::MethodKind::Operation(ast::Operation {
is_static: true,
kind: operation_kind,
});
ast::ImportFunctionKind::Method { class, ty, kind }
} else if opts.constructor() {
let class = match wasm.ret {
Some(ref ty) => ty,
_ => panic!("constructor returns must be bare types"),
};
let class_name = match *class {
syn::Type::Path(syn::TypePath {
qself: None,
ref path,
}) => path,
_ => panic!("first argument of method must be a path"),
};
let class_name = extract_path_ident(class_name)
.expect("first argument of method must be a bare type");
ast::ImportFunctionKind::Method {
class: class_name.to_string(),
ty: class.clone(),
kind: ast::MethodKind::Constructor,
}
} else {
ast::ImportFunctionKind::Normal
};
let shim = {
let ns = match kind {
ast::ImportFunctionKind::Normal => (0, "n"),
ast::ImportFunctionKind::Method { ref class, .. } => (1, &class[..]),
};
let data = (ns, &self.ident);
format!("__wbg_{}_{}", js_name, ShortHash(data))
};
ast::ImportKind::Function(ast::ImportFunction {
function: wasm,
kind,
js_ret,
catch,
structural: opts.structural(),
rust_name: self.ident.clone(),
shim: Ident::new(&shim, Span::call_site()),
})
}
}
impl ConvertToAst<()> for syn::ForeignItemType {
type Target = ast::ImportKind;
fn convert(self, (): ()) -> Self::Target {
ast::ImportKind::Type(ast::ImportType {
vis: self.vis,
name: self.ident,
attrs: self.attrs,
})
}
}
impl ConvertToAst<BindgenAttrs> for syn::ForeignItemStatic {
type Target = ast::ImportKind;
fn convert(self, opts: BindgenAttrs) -> Self::Target {
if self.mutability.is_some() {
panic!("cannot import mutable globals yet")
}
let js_name = opts.js_name().unwrap_or(&self.ident);
let shim = format!("__wbg_static_accessor_{}_{}", js_name, self.ident);
ast::ImportKind::Static(ast::ImportStatic {
ty: *self.ty,
vis: self.vis,
rust_name: self.ident.clone(),
js_name: js_name.clone(),
shim: Ident::new(&shim, Span::call_site()),
})
}
}
impl ConvertToAst<BindgenAttrs> for syn::ItemFn {
type Target = ast::Function;
fn convert(self, attrs: BindgenAttrs) -> Self::Target {
match self.vis {
syn::Visibility::Public(_) => {}
_ => panic!("can only bindgen public functions"),
}
if self.constness.is_some() {
panic!("can only bindgen non-const functions");
}
if self.unsafety.is_some() {
panic!("can only bindgen safe functions");
}
let name = attrs.js_name().unwrap_or(&self.ident);
function_from_decl(name, self.decl, self.attrs, self.vis, false).0
}
}
/// Construct a function (and gets the self type if appropriate) for our AST from a syn function.
fn function_from_decl(
name: &Ident,
mut decl: Box<syn::FnDecl>,
attrs: Vec<syn::Attribute>,
vis: syn::Visibility,
allow_self: bool,
) -> (ast::Function, Option<ast::MethodSelf>) {
if decl.variadic.is_some() {
panic!("can't bindgen variadic functions")
}
if decl.generics.params.len() > 0 {
panic!("can't bindgen functions with lifetime or type parameters")
}
assert_no_lifetimes(&mut decl);
let syn::FnDecl { inputs, output, .. } = { *decl };
let mut method_self = None;
let arguments = inputs
.into_iter()
.filter_map(|arg| match arg {
syn::FnArg::Captured(c) => Some(c),
syn::FnArg::SelfValue(_) => {
assert!(method_self.is_none());
method_self = Some(ast::MethodSelf::ByValue);
None
}
syn::FnArg::SelfRef(ref a) if allow_self => {
assert!(method_self.is_none());
if a.mutability.is_some() {
method_self = Some(ast::MethodSelf::RefMutable);
} else {
method_self = Some(ast::MethodSelf::RefShared);
}
None
}
_ => panic!("arguments cannot be `self` or ignored"),
})
.collect::<Vec<_>>();
let ret = match output {
syn::ReturnType::Default => None,
syn::ReturnType::Type(_, ty) => Some(*ty),
};
(
ast::Function {
name: name.clone(),
arguments,
ret,
rust_vis: vis,
rust_attrs: attrs,
},
method_self,
)
}
pub(crate) trait MacroParse<Ctx> {
/// Parse the contents of an object into our AST, with a context if necessary.
///
/// The context is used to have access to the attributes on `#[wasm_bindgen]`, and to allow
/// writing to the output `TokenStream`.
fn macro_parse(self, program: &mut ast::Program, context: Ctx);
}
impl<'a> MacroParse<(Option<BindgenAttrs>, &'a mut TokenStream)> for syn::Item {
fn macro_parse(
self,
program: &mut ast::Program,
(opts, tokens): (Option<BindgenAttrs>, &'a mut TokenStream),
) {
match self {
syn::Item::Fn(mut f) => {
let no_mangle = f
.attrs
.iter()
.enumerate()
.filter_map(|(i, m)| m.interpret_meta().map(|m| (i, m)))
.find(|&(_, ref m)| m.name() == "no_mangle");
match no_mangle {
Some((i, _)) => {
f.attrs.remove(i);
}
_ => {}
}
let comments = extract_doc_comments(&f.attrs);
f.to_tokens(tokens);
program.exports.push(ast::Export {
class: None,
method_self: None,
constructor: None,
comments,
rust_name: f.ident.clone(),
function: f.convert(opts.unwrap_or_default()),
});
}
syn::Item::Struct(mut s) => {
program.structs.push((&mut s).convert(()));
s.to_tokens(tokens);
}
syn::Item::Impl(mut i) => {
(&mut i).macro_parse(program, ());
i.to_tokens(tokens);
}
syn::Item::ForeignMod(mut f) => {
let opts = opts.unwrap_or_else(|| BindgenAttrs::find(&mut f.attrs));
f.macro_parse(program, opts);
}
syn::Item::Enum(e) => {
e.to_tokens(tokens);
e.macro_parse(program, ());
}
_ => panic!(
"#[wasm_bindgen] can only be applied to a function, \
struct, enum, impl, or extern block"
),
}
}
}
impl<'a> MacroParse<()> for &'a mut syn::ItemImpl {
fn macro_parse(self, program: &mut ast::Program, (): ()) {
if self.defaultness.is_some() {
panic!("default impls are not supported");
}
if self.unsafety.is_some() {
panic!("unsafe impls are not supported");
}
if self.trait_.is_some() {
panic!("trait impls are not supported");
}
if self.generics.params.len() > 0 {
panic!("generic impls aren't supported");
}
let name = match *self.self_ty {
syn::Type::Path(syn::TypePath {
qself: None,
ref path,
}) => match extract_path_ident(path) {
Some(ident) => ident,
None => panic!("unsupported self type in impl"),
},
_ => panic!("unsupported self type in impl"),
};
for item in self.items.iter_mut() {
(&name, item).macro_parse(program, ())
}
}
}
impl<'a, 'b> MacroParse<()> for (&'a Ident, &'b mut syn::ImplItem) {
fn macro_parse(self, program: &mut ast::Program, (): ()) {
let (class, item) = self;
replace_self(class, item);
let method = match item {
syn::ImplItem::Const(_) => panic!("const definitions aren't supported"),
syn::ImplItem::Type(_) => panic!("type definitions in impls aren't supported"),
syn::ImplItem::Method(ref mut m) => m,
syn::ImplItem::Macro(_) => panic!("macros in impls aren't supported"),
syn::ImplItem::Verbatim(_) => panic!("unparsed impl item?"),
};
match method.vis {
syn::Visibility::Public(_) => {}
_ => return,
}
if method.defaultness.is_some() {
panic!("default methods are not supported");
}
if method.sig.constness.is_some() {
panic!("can only bindgen non-const functions");
}
if method.sig.unsafety.is_some() {
panic!("can only bindgen safe functions");
}
let opts = BindgenAttrs::find(&mut method.attrs);
let comments = extract_doc_comments(&method.attrs);
let is_constructor = opts.constructor();
let constructor = if is_constructor {
Some(method.sig.ident.to_string())
} else {
None
};
let (function, method_self) = function_from_decl(
opts.js_name().unwrap_or(&method.sig.ident),
Box::new(method.sig.decl.clone()),
method.attrs.clone(),
method.vis.clone(),
true,
);
program.exports.push(ast::Export {
class: Some(class.clone()),
method_self,
constructor,
function,
comments,
rust_name: method.sig.ident.clone(),
});
}
}
impl MacroParse<()> for syn::ItemEnum {
fn macro_parse(self, program: &mut ast::Program, (): ()) {
match self.vis {
syn::Visibility::Public(_) => {}
_ => panic!("only public enums are allowed"),
}
let variants = self
.variants
.iter()
.enumerate()
.map(|(i, v)| {
match v.fields {
syn::Fields::Unit => (),
_ => panic!("Only C-Style enums allowed"),
}
let value = match v.discriminant {
Some((
_,
syn::Expr::Lit(syn::ExprLit {
attrs: _,
lit: syn::Lit::Int(ref int_lit),
}),
)) => {
if int_lit.value() > <u32>::max_value() as u64 {
panic!("Enums can only support numbers that can be represented as u32");
}
int_lit.value() as u32
}
None => i as u32,
_ => panic!("Enums may only have number literal values"),
};
ast::Variant {
name: v.ident.clone(),
value,
}
})
.collect();
let comments = extract_doc_comments(&self.attrs);
program.enums.push(ast::Enum {
name: self.ident,
variants,
comments,
});
}
}
impl MacroParse<BindgenAttrs> for syn::ItemForeignMod {
fn macro_parse(self, program: &mut ast::Program, opts: BindgenAttrs) {
match self.abi.name {
Some(ref l) if l.value() == "C" => {}
None => {}
_ => panic!("only foreign mods with the `C` ABI are allowed"),
}
for mut item in self.items.into_iter() {
let item_opts = {
let attrs = match item {
syn::ForeignItem::Fn(ref mut f) => &mut f.attrs,
syn::ForeignItem::Type(ref mut t) => &mut t.attrs,
syn::ForeignItem::Static(ref mut s) => &mut s.attrs,
_ => panic!("only foreign functions/types allowed for now"),
};
BindgenAttrs::find(attrs)
};
let module = item_opts.module().or(opts.module()).map(|s| s.to_string());
let version = item_opts
.version()
.or(opts.version())
.map(|s| s.to_string());
let js_namespace = item_opts.js_namespace().or(opts.js_namespace()).cloned();
let mut kind = match item {
syn::ForeignItem::Fn(f) => f.convert(item_opts),
syn::ForeignItem::Type(t) => t.convert(()),
syn::ForeignItem::Static(s) => s.convert(item_opts),
_ => panic!("only foreign functions/types allowed for now"),
};
program.imports.push(ast::Import {
module,
version,
js_namespace,
kind,
});
}
}
}
/// Get the first type parameter of a generic type, errors on incorrect input.
fn extract_first_ty_param(ty: Option<&syn::Type>) -> Result<Option<syn::Type>, ()> {
let t = match ty {
Some(t) => t,
None => return Ok(None),
};
let path = match *t {
syn::Type::Path(syn::TypePath {
qself: None,
ref path,
}) => path,
_ => return Err(()),
};
let seg = path.segments.last().ok_or(())?.into_value();
let generics = match seg.arguments {
syn::PathArguments::AngleBracketed(ref t) => t,
_ => return Err(()),
};
let ty = match *generics.args.first().ok_or(())?.into_value() {
syn::GenericArgument::Type(ref t) => t,
_ => return Err(()),
};
match *ty {
syn::Type::Tuple(ref t) if t.elems.len() == 0 => return Ok(None),
_ => {}
}
Ok(Some(ty.clone()))
}
/// Replace `Self` with the given name in `item`.
fn replace_self(name: &Ident, item: &mut syn::ImplItem) {
struct Walk<'a>(&'a Ident);
impl<'a> syn::visit_mut::VisitMut for Walk<'a> {
fn visit_ident_mut(&mut self, i: &mut Ident) {
if i == "Self" {
*i = self.0.clone();
}
}
}
syn::visit_mut::VisitMut::visit_impl_item_mut(&mut Walk(name), item);
}
/// Extract the documentation comments from a Vec of attributes
fn extract_doc_comments(attrs: &[syn::Attribute]) -> Vec<String> {
attrs
.iter()
.filter_map(|a| {
// if the path segments include an ident of "doc" we know this
// this is a doc comment
if a.path.segments.iter().any(|s| s.ident.to_string() == "doc") {
Some(
// We want to filter out any Puncts so just grab the Literals
a.tts.clone().into_iter().filter_map(|t| match t {
TokenTree::Literal(lit) => {
// this will always return the quoted string, we deal with
// that in the cli when we read in the comments
Some(lit.to_string())
},
_ => None,
})
)
} else {
None
}
})
//Fold up the [[String]] iter we created into Vec<String>
.fold(vec![], |mut acc, a| {acc.extend(a); acc})
}
/// Check there are no lifetimes on the function.
fn assert_no_lifetimes(decl: &mut syn::FnDecl) {
struct Walk;
impl<'ast> syn::visit_mut::VisitMut for Walk {
fn visit_lifetime_mut(&mut self, _i: &mut syn::Lifetime) {
panic!(
"it is currently not sound to use lifetimes in function \
signatures"
);
}
}
syn::visit_mut::VisitMut::visit_fn_decl_mut(&mut Walk, decl);
}
/// If the path is a single ident, return it.
fn extract_path_ident(path: &syn::Path) -> Option<Ident> {
if path.leading_colon.is_some() {
return None;
}
if path.segments.len() != 1 {
return None;
}
match path.segments.first().unwrap().value().arguments {
syn::PathArguments::None => {}
_ => return None,
}
path.segments.first().map(|v| v.value().ident.clone())
}