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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
| commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
| tree | 173a775858bd501c378080a10dca74132f05bc50 /vendor/instant/README.md | |
| parent | Initial commit. (diff) | |
| download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip | |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/instant/README.md')
| -rw-r--r-- | vendor/instant/README.md | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/vendor/instant/README.md b/vendor/instant/README.md new file mode 100644 index 000000000..0e35ad656 --- /dev/null +++ b/vendor/instant/README.md @@ -0,0 +1,143 @@ +# Instant
+
+If you call `std::time::Instant::now()` on a WASM platform, it will panic. This crate provides a partial
+replacement for `std::time::Instant` that works on WASM too. This defines the type `instant::Instant` which is:
+
+* A struct emulating the behavior of **std::time::Instant** if you are targeting `wasm32-unknown-unknown` or `wasm32-unknown-asmjs`
+**and** you enabled either the `stdweb` or the `wasm-bindgen` feature. This emulation is based on the javascript `performance.now()` function.
+* A type alias for `std::time::Instant` otherwise.
+
+
+
+Note that even if the **stdweb** or **wasm-bindgen** feature is enabled, this crate will continue to rely on `std::time::Instant`
+as long as you are not targeting wasm32. This allows for portable code that will work on both native and WASM platforms.
+
+This crate also exports the function `instant::now()` which returns a representation of the current time as an `f64`, expressed in milliseconds, in a platform-agnostic way. `instant::now()` will either:
+
+* Call `performance.now()` when compiling for a WASM platform with the features **stdweb** or **wasm-bindgen** enabled, or using a custom javascript function.
+* Return the time elapsed since the *Unix Epoch* on *native*, *non-WASM* platforms.
+
+*Note*: The old feature, `now`, has been deprecated. `instant::now()` is always exported and the `now` feature flag no longer has any effect. It remains listed in `Cargo.toml` to avoid introducing breaking changes and may be removed in future versions.
+
+## Examples
+### Using `instant` for a native platform.
+_Cargo.toml_:
+```toml
+[dependencies]
+instant = "0.1"
+```
+
+_main.rs_:
+```rust
+fn main() {
+ // Will be the same as `std::time::Instant`.
+ let now = instant::Instant::now();
+}
+```
+
+-----
+
+### Using `instant` for a WASM platform.
+This example shows the use of the `stdweb` feature. It would be similar with `wasm-bindgen`.
+
+_Cargo.toml_:
+```toml
+[dependencies]
+instant = { version = "0.1", features = [ "stdweb" ] }
+```
+
+_main.rs_:
+```rust
+fn main() {
+ // Will emulate `std::time::Instant` based on `performance.now()`.
+ let now = instant::Instant::now();
+}
+```
+
+-----
+
+### Using `instant` for a WASM platform where `performance.now()` is not available.
+This example shows the use of the `inaccurate` feature.
+
+_Cargo.toml_:
+```toml
+[dependencies]
+instant = { version = "0.1", features = [ "wasm-bindgen", "inaccurate" ] }
+```
+
+_main.rs_:
+```rust
+fn main() {
+ // Will emulate `std::time::Instant` based on `Date.now()`.
+ let now = instant::Instant::now();
+}
+```
+
+
+-----
+
+### Using `instant` for any platform enabling a feature transitively.
+_Cargo.toml_:
+```toml
+[features]
+stdweb = [ "instant/stdweb" ]
+wasm-bindgen = [ "instant/wasm-bindgen" ]
+
+[dependencies]
+instant = "0.1"
+```
+
+_lib.rs_:
+```rust
+fn my_function() {
+ // Will select the proper implementation depending on the
+ // feature selected by the user.
+ let now = instant::Instant::now();
+}
+```
+
+-----
+
+### Using `instant::now()`
+_Cargo.toml_:
+```toml
+[features]
+stdweb = [ "instant/stdweb" ]
+wasm-bindgen = [ "instant/wasm-bindgen" ]
+
+[dependencies]
+instant = "0.1"
+```
+
+_lib.rs_:
+```rust
+fn my_function() {
+ // Will select the proper implementation depending on the
+ // feature selected by the user.
+ let now_instant = instant::Instant::now();
+ let now_milliseconds = instant::now(); // In milliseconds.
+}
+```
+
+### Using the feature `now` without `stdweb` or `wasm-bindgen`.
+_Cargo.toml_:
+```toml
+[dependencies]
+instant = "0.1"
+```
+
+_lib.rs_:
+```rust
+fn my_function() {
+ // Will use the 'now' javascript implementation.
+ let now_instant = instant::Instant::now();
+ let now_milliseconds = instant::now(); // In milliseconds.
+}
+```
+
+_javascript WASM bindings file_:
+```js
+function now() {
+ return Date.now() / 1000.0;
+}
+```
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