1 files changed, 67 insertions, 0 deletions
diff --git a/2.27.1/src/float.rs b/2.27.1/src/float.rs
new file mode 100644
index 0000000..78ca622
--- /dev/null
+++ b/2.27.1/src/float.rs
@@ -0,0 +1,67 @@
+use std::f64;
+
+#[derive(Debug)]
+pub enum ProtobufFloatParseError {
+    EmptyString,
+    CannotParseFloat,
+}
+
+pub type ProtobufFloatParseResult<T> = Result<T, ProtobufFloatParseError>;
+
+pub const PROTOBUF_NAN: &str = "nan";
+pub const PROTOBUF_INF: &str = "inf";
+
+/// Format float as in protobuf `.proto` files
+pub fn format_protobuf_float(f: f64) -> String {
+    if f.is_nan() {
+        PROTOBUF_NAN.to_owned()
+    } else if f.is_infinite() {
+        if f > 0.0 {
+            format!("{}", PROTOBUF_INF)
+        } else {
+            format!("-{}", PROTOBUF_INF)
+        }
+    } else {
+        let i = f as i64;
+        if i as f64 == f {
+            // Older rust versions did print float without `.0` suffix
+            format!("{:?}.0", i)
+        } else {
+            // TODO: make sure doesn't lose precision
+            format!("{:?}", f)
+        }
+    }
+}
+
+/// Parse float from `.proto` format
+pub fn parse_protobuf_float(s: &str) -> ProtobufFloatParseResult<f64> {
+    if s.is_empty() {
+        return Err(ProtobufFloatParseError::EmptyString);
+    }
+    if s == PROTOBUF_NAN {
+        return Ok(f64::NAN);
+    }
+    if s == PROTOBUF_INF || s == format!("+{}", PROTOBUF_INF) {
+        return Ok(f64::INFINITY);
+    }
+    if s == format!("-{}", PROTOBUF_INF) {
+        return Ok(f64::NEG_INFINITY);
+    }
+    match s.parse() {
+        Ok(f) => Ok(f),
+        Err(_) => Err(ProtobufFloatParseError::CannotParseFloat),
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_format_protobuf_float() {
+        assert_eq!("10.0", format_protobuf_float(10.0));
+        assert_eq!("-10.0", format_protobuf_float(-10.0));
+        assert_eq!("10.5", format_protobuf_float(10.5));
+        assert_eq!("-10.5", format_protobuf_float(-10.5));
+    }
+}