Add lightweight wasm support to rust-decimal

.github/workflows/main.yml

@@ -124,12 +124,19 @@ jobs:
         name:
           - stable
           - beta
+          - stable / wasm
+          - beta / wasm
         include:
-          # This allows us to define targets in the future (e.g. wasm32-unknown-unknown)
           - name: stable
             rust: stable
           - name: beta
             rust: beta
+          - name: stable / wasm
+            rust: stable
+            target: wasm32-unknown-unknown
+          - name: beta / wasm
+            rust: beta
+            target: wasm32-unknown-unknown
     steps:
       - uses: actions/checkout@v4
 
@@ -187,12 +194,19 @@ jobs:
         name:
           - stable
           - beta
+          - stable / wasm
+          - beta / wasm
         include:
-          # This allows us to define targets in the future (e.g. wasm32-unknown-unknown)
           - name: stable
             rust: stable
           - name: beta
             rust: beta
+          - name: stable / wasm
+            rust: stable
+            target: wasm32-unknown-unknown
+          - name: beta / wasm
+            rust: beta
+            target: wasm32-unknown-unknown
     steps:
       - uses: actions/checkout@v4
 

Cargo.toml

@@ -1,12 +1,12 @@
 [package]
 authors = ["Paul Mason <[email protected]>"]
 build = "build.rs"
-categories = ["science","mathematics","data-structures"]
+categories = ["science", "mathematics", "data-structures"]
 description = "Decimal number implementation written in pure Rust suitable for financial and fixed-precision calculations."
 documentation = "https://docs.rs/rust_decimal/"
 edition = "2021"
-exclude = [ "tests/generated/*" ]
-keywords = ["decimal","financial","fixed","precision","number"]
+exclude = ["tests/generated/*"]
+keywords = ["decimal", "financial", "fixed", "precision", "number"]
 license = "MIT"
 name = "rust_decimal"
 readme = "./README.md"
@@ -17,6 +17,7 @@ version = "1.35.0"
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+targets = ["x86_64-unknown-linux-gnu", "wasm32-unknown-unknown"]
 
 [dependencies]
 arbitrary = { default-features = false, optional = true, version = "1.0" }
@@ -37,19 +38,27 @@ serde = { default-features = false, optional = true, version = "1.0" }
 serde_json = { default-features = false, optional = true, version = "1.0" }
 tokio-postgres = { default-features = false, optional = true, version = "0.7" }
 
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+wasm-bindgen = { default-features = false, version = "0.2" }
+
 [dev-dependencies]
-bincode = { default-features = false, version = "1.0" }
-bytes = { default-features = false, version = "1.0" }
 criterion = { default-features = false, version = "0.5" }
 csv = "1"
-futures = { default-features = false, version = "0.3" }
-rand = { default-features = false, features = ["getrandom"], version = "0.8" }
 rust_decimal_macros = { default-features = false, version = "1.33" }
 serde = { default-features = false, features = ["derive"], version = "1.0" }
 serde_json = "1.0"
-tokio = { default-features = false, features = ["macros", "rt-multi-thread", "test-util"], version = "1.0" }
 version-sync = { default-features = false, features = ["html_root_url_updated", "markdown_deps_updated"], version = "0.9" }
+
+[target.'cfg(target_arch = "wasm32")'.dev-dependencies]
+wasm-bindgen = { default-features = false, version = "0.2" }
+
+[target.'cfg(not(target_arch = "wasm32"))'.dev-dependencies]
+bincode = { default-features = false, version = "1.0" }
+bytes = { default-features = false, version = "1.0" }
+futures = { default-features = false, version = "0.3" }
+rand = { default-features = false, features = ["getrandom"], version = "0.8" }
 postgres = { default-features = false, version = "0.19" }
+tokio = { default-features = false, features = ["macros", "rt-multi-thread", "test-util"], version = "1.0" }
 tokio-postgres = { default-features = false, version = "0.7" }
 
 [features]
@@ -77,15 +86,15 @@ rkyv = ["dep:rkyv"]
 rkyv-safe = ["rkyv/validation"]
 rocket-traits = ["dep:rocket"]
 rust-fuzz = ["dep:arbitrary"]
-serde = ["dep:serde"]
+serde = ["dep:serde", "wasm-bindgen/serde"]
 serde-arbitrary-precision = ["serde-with-arbitrary-precision"]
 serde-bincode = ["serde-str"] # Backwards compatability
 serde-float = ["serde-with-float"]
 serde-str = ["serde-with-str"]
 serde-with-arbitrary-precision = ["serde", "serde_json/arbitrary_precision", "serde_json/std"]
 serde-with-float = ["serde"]
 serde-with-str = ["serde"]
-std = ["arrayvec/std", "borsh?/std", "bytes?/std", "rand?/std", "rkyv?/std", "serde?/std", "serde_json?/std"]
+std = ["arrayvec/std", "wasm-bindgen/std", "borsh?/std", "bytes?/std", "rand?/std", "rkyv?/std", "serde?/std", "serde_json?/std"]
 tokio-pg = ["db-tokio-postgres"] # Backwards compatability
 
 [[bench]]

README.md

@@ -104,6 +104,7 @@ assert_eq!(total, dec!(27.26));
 * [rocket-traits](#rocket-traits)
 * [rust-fuzz](#rust-fuzz)
 * [std](#std)
+* [wasm](#wasm)
 
 **Database**
 
@@ -331,6 +332,12 @@ Please see the `examples` directory for more information regarding `serde_json`
 Enable `std` library support. This is enabled by default, however in the future will be opt in. For now, to support `no_std`
 libraries, this crate can be compiled with `--no-default-features`.
 
+### `wasm`
+
+Enable [`wasm-bindgen`](https://github.com/rustwasm/wasm-bindgen) support which makes `Decimal` compatible with the
+`wasm_bindgen` attribute macro and exposes `fromNumber()` and `toNumber()` methods to convert between `Decimal` and
+the primitive `number` type across boundaries.
+
 ## Building
 
 Please refer to the [Build document](BUILD.md) for more information on building and testing Rust Decimal.

src/decimal.rs

@@ -27,6 +27,8 @@ use num_traits::float::FloatCore;
 use num_traits::{FromPrimitive, Num, One, Signed, ToPrimitive, Zero};
 #[cfg(feature = "rkyv")]
 use rkyv::{Archive, Deserialize, Serialize};
+#[cfg(target_arch = "wasm32")]
+use wasm_bindgen::prelude::wasm_bindgen;
 
 /// The smallest value that can be represented by this decimal type.
 const MIN: Decimal = Decimal {
@@ -121,6 +123,7 @@ pub struct UnpackedDecimal {
     archive_attr(derive(Clone, Copy, Debug))
 )]
 #[cfg_attr(feature = "rkyv-safe", archive(check_bytes))]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen)]
 pub struct Decimal {
     // Bits 0-15: unused
     // Bits 16-23: Contains "e", a value between 0-28 that indicates the scale

src/lib.rs

@@ -18,13 +18,19 @@ mod arithmetic_impls;
 mod fuzz;
 #[cfg(feature = "maths")]
 mod maths;
-#[cfg(any(feature = "db-diesel1-mysql", feature = "db-diesel2-mysql"))]
+#[cfg(all(
+    any(feature = "db-diesel1-mysql", feature = "db-diesel2-mysql"),
+    not(target_arch = "wasm32")
+))]
 mod mysql;
-#[cfg(any(
-    feature = "db-tokio-postgres",
-    feature = "db-postgres",
-    feature = "db-diesel1-postgres",
-    feature = "db-diesel2-postgres",
+#[cfg(all(
+    any(
+        feature = "db-tokio-postgres",
+        feature = "db-postgres",
+        feature = "db-diesel1-postgres",
+        feature = "db-diesel2-postgres",
+    ),
+    not(target_arch = "wasm32")
 ))]
 mod postgres;
 #[cfg(feature = "proptest")]
@@ -52,6 +58,8 @@ mod serde;
     )
 ))]
 pub mod serde;
+#[cfg(target_arch = "wasm32")]
+pub mod wasm;
 
 pub use decimal::{Decimal, RoundingStrategy};
 pub use error::Error;
@@ -72,11 +80,11 @@ pub mod prelude {
     // pub use rust_decimal_macros::dec;
 }
 
-#[cfg(all(feature = "diesel1", not(feature = "diesel2")))]
+#[cfg(all(feature = "diesel1", not(feature = "diesel2"), not(target_arch = "wasm32")))]
 #[macro_use]
 extern crate diesel1 as diesel;
 
-#[cfg(feature = "diesel2")]
+#[cfg(all(feature = "diesel2", not(target_arch = "wasm32")))]
 extern crate diesel2 as diesel;
 
 /// Shortcut for `core::result::Result<T, rust_decimal::Error>`. Useful to distinguish

src/wasm.rs

@@ -0,0 +1,26 @@
+use num_traits::{FromPrimitive, ToPrimitive};
+use wasm_bindgen::prelude::*;
+
+use crate::Decimal;
+
+#[wasm_bindgen]
+impl Decimal {
+    /// Returns a new `Decimal` object instance by converting a primitive number.
+    #[wasm_bindgen(js_name = fromNumber)]
+    #[must_use]
+    pub fn from_number(value: f64) -> Option<Decimal> {
+        Decimal::from_f64(value)
+    }
+
+    /// Returns the value of this `Decimal` converted to a primitive number.
+    ///
+    /// # Caution
+    /// At the time of writing this implementation the conversion from `Decimal` to `f64` cannot
+    /// fail. To prevent undefined behavior in case the underlying implementation changes `f64::NAN`
+    /// is returned as a stable fallback value.
+    #[wasm_bindgen(js_name = toNumber)]
+    #[must_use]
+    pub fn to_number(&self) -> f64 {
+        self.to_f64().unwrap_or(f64::NAN)
+    }
+}