I'm trying to do below:
fn get_replaced(parser: Parser, string_generators: Vec<Function>, initial_capacity: usize) -> Result<JsString, JsValue> {
// do something
}
#[wasm_bindgen]
pub fn markdown_img_url_editor(markdown_text: &str, converter: &Function, before_collect_callback: JsValue) -> Promise {
// do something
if before_collect_callback.is_null() || before_collect_callback.is_undefined() {
// do something
} else {
match before_collect_callback.dyn_into::<Function>() {
Ok(callback) => {
match callback.call0(&JsValue::NULL) {
Ok(maybe_promise) => {
if let Ok(p) = maybe_promise.dyn_into::<Promise>() {
// return p.then(&Closure::wrap(Box::new(move |_| get_replaced_wrap(parser, string_generators, markdown_text.len() + 128))));
let future = JsFuture::from(p).compat().then(|_| future::ready(get_replaced(parser, string_generators, markdown_text.len() + 128)));
let ff = future.compat();
return future_to_promise(ff);
At first, I want to call js_sys::Promise#then. However, there is no way to return something from the closure passed to js_sys::Promise#then.
So, I'm trying to convert js_sys::Promise to wasm_bindgen_futures::JsFuture, call futures::future::TryFutureExt#and_then and convert wasm_bindgen_futures::JsFuture to js_sys::Promise using future_to_promise.
Now, I get compile error shown below:
$cargo build
Compiling markdown_img_url_editor_rust v0.1.0 (C:\msys64\home\yumetodo\markdown_img_url_editor\markdown_img_url_editor_rust)
warning: unused import: `futures::future::Future`
--> src\lib.rs:6:5
|
6 | use futures::future::Future;
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= note: #[warn(unused_imports)] on by default
error[E0271]: type mismatch resolving `<futures_util::future::then::Then<futures_util::compat::compat01as03::Compat01As03<wasm_bindgen_futures::legacy_shared::JsFuture>, futures_util::future::ready::Ready<std::result::Result<js_sys::JsString, wasm_bindgen::JsValue>>, [closure@src\lib.rs:116:74: 116:159 parser:_, string_generators:_, markdown_text:_]> as core::future::future::Future>::Output == std::result::Result<wasm_bindgen::JsValue, _>`
--> src\lib.rs:118:36
|
118 | return future_to_promise(ff);
| ^^^^^^^^^^^^^^^^^ expected struct `js_sys::JsString`, found struct `wasm_bindgen::JsValue`
|
= note: expected type `std::result::Result<js_sys::JsString, wasm_bindgen::JsValue>`
found type `std::result::Result<wasm_bindgen::JsValue, _>`
= note: required because of the requirements on the impl of `futures_core::future::TryFuture` for `futures_util::future::then::Then<futures_util::compat::compat01as03::Compat01As03<wasm_bindgen_futures::legacy_shared::JsFuture>, futures_util::future::ready::Ready<std::result::Result<js_sys::JsString, wasm_bindgen::JsValue>>, [closure@src\lib.rs:116:74: 116:159 parser:_, string_generators:_, markdown_text:_]>`
= note: required by `wasm_bindgen_futures::legacy::future_to_promise`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0271`.
error: Could not compile `markdown_img_url_editor_rust`.
found type
std::result::Result<wasm_bindgen::JsValue, _>
I cannot understand the reason these error was occered. get_replaced returns Result<JsString, JsValue>. Why error meesage says that found type std::result::Result<wasm_bindgen::JsValue, _>????
Please tell me how to resolve this error or anthoer solution.
Cargo.toml
[package]
name = "markdown_img_url_editor_rust"
version = "0.1.0"
authors = ["yumetodo <[email protected]>"]
edition = "2018"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
pulldown-cmark = "0.5.3"
pulldown-cmark-to-cmark = "1.2.2"
wasm-bindgen = "0.2.50"
# wasm-bindgen-futures = "0.3.27"
wasm-bindgen-futures = { version="0.3.27", features=["futures_0_3"] }
js-sys = "0.3.27"
futures-preview = { version="0.3.0-alpha", features=["compat"] }
# futures-preview="0.3.0-alpha"
[lib]
crate-type = ["cdylib"]
full source code is below:
https://github.com/yumetodo/markdown_img_url_editor/tree/refaactor/by_rust/markdown_img_url_editor_rust
My build env is below:
$rustup --version
rustup 1.18.3 (435397f48 2019-05-22)
$cargo --version
cargo 1.37.0 (9edd08916 2019-08-02)
$rustc --version
rustc 1.37.0 (eae3437df 2019-08-13)
OS: Windows 10 1809, Ubuntu 18.04
Finally, I gave up to fight and decide to refactor API. future_to_promise request static lifetime &str and pulldown_cmark only accept &'a str is a critical problem.
ref: https://qiitadon.com/web/statuses/102710559203790261(written in Japanese)
To refactor API, I made a bold assumption that the parser will produce the same result for the same input. So, I can decide not to hold parser.
As a result, I make such API
#[wasm_bindgen]
pub struct MarkdownImgUrlEditor {
markdown_text: String,
string_generators: Vec<Function>,
initial_capacity: usize,
}
#[wasm_bindgen]
impl MarkdownImgUrlEditor {
#[wasm_bindgen(constructor)]
pub fn new(text: String, converter: &Function) -> Result<MarkdownImgUrlEditor, JsValue> {
}
pub fn replace(&mut self) -> Result<String, JsValue> {
}
}
the process that before_collect_callback do will be executed between calling new and replace.
https://github.com/yumetodo/markdown_img_url_editor/pull/13
BTW, I noticed that pulldown_cmark is broken. I cannot get image alt.
So, I created an issue.