Add ability to specify precision for decimal string conversion

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "typst-plugin-bigrational"
-version = "0.1.0"
+version = "0.1.1"
 edition = "2021"
 
 [lib]

rational.typ

@@ -111,13 +111,17 @@
   }
 }
 
-#let to-decimal-str(x) = {
+#let to-decimal-str(x, precision: 8) = {
   let (numer, denom) = rational(x)
-  str(p.to_decimal_string(bytes(numer), bytes(denom)))
+  str(p.to_decimal_string(bytes(numer), bytes(denom), int.to-bytes(precision)))
 }
 
-#let to-float(x) = {
-  float(to-decimal-str(x))
+#let to-float(x, precision: 8) = {
+  float(to-decimal-str(x, precision: precision))
+}
+
+#let to-decimal(x, precision: 8) = {
+  decimal(to-decimal-str(x, precision: precision))
 }
 
 #let abs-diff(a, b) = {
@@ -142,4 +146,4 @@
   let ordering-bytes = p.cmp(bytes(a-numer), bytes(a-denom), bytes(b-numer), bytes(b-denom))
 
   int.from-bytes(ordering-bytes)
-}
+}

src/lib.rs

@@ -198,12 +198,18 @@ fn repr(numer: &[u8], denom: &[u8]) -> Result<Vec<u8>, Box<dyn Error>> {
 }
 
 #[wasm_func]
-fn to_decimal_string(numer: &[u8], denom: &[u8]) -> Result<Vec<u8>, Box<dyn Error>> {
+fn to_decimal_string(
+    numer: &[u8],
+    denom: &[u8],
+    precision: &[u8],
+) -> Result<Vec<u8>, Box<dyn Error>> {
     let numer: BigInt = str::from_utf8(numer)?.parse()?;
     let denom: BigInt = str::from_utf8(denom)?.parse()?;
     let value = BigDecimal::new(numer, denom);
 
-    Ok(value.to_string().into_bytes())
+    let precision = usize::try_from(i64::from_le_bytes(precision.try_into()?))?;
+
+    Ok(format!("{value:#.precision$}").into_bytes())
 }
 
 #[wasm_func]