Add float filter

askama_shared/src/filters/mod.rs

@@ -22,12 +22,13 @@ use escaping::{self, MarkupDisplay};
 // Askama or should refer to a local `filters` module. It should contain all the
 // filters shipped with Askama, even the optional ones (since optional inclusion
 // in the const vector based on features seems impossible right now).
-pub const BUILT_IN_FILTERS: [&str; 20] = [
+pub const BUILT_IN_FILTERS: [&str; 21] = [
     "abs",
     "capitalize",
     "center",
     "e",
     "escape",
+    "float",
     "format",
     "indent",
     "int",
@@ -77,6 +78,14 @@ where
     escape(i)
 }
 
+/// Casts number to f32
+pub fn float<T>(number: T) -> Result<f32>
+where
+    T: NumCast,
+{
+    number.to_f32().ok_or(Fmt(fmt::Error))
+}
+
 /// Formats arguments according to the specified format
 ///
 /// The first argument to this filter must be a string literal (as in normal
@@ -259,6 +268,15 @@ mod tests {
     use super::*;
     use std::f32::INFINITY;
 
+    #[test]
+    fn test_float() {
+        assert_eq!(float(1).unwrap(), 1.0 as f32);
+        assert_eq!(float(1.9).unwrap(), 1.9 as f32);
+        assert_eq!(float(-1.9).unwrap(), -1.9 as f32);
+        assert_eq!(float(INFINITY as f64).unwrap(), INFINITY);
+        assert_eq!(float(-INFINITY as f64).unwrap(), -INFINITY);
+    }
+
     #[test]
     fn test_linebreaks() {
         assert_eq!(