Read a list of segment records directly from a file (#22)

* Read a list of segment records directly from a file

* add text_signature

src/parameter/mod.rs

@@ -287,7 +287,7 @@ where
 
         // Read segment records
         let segment_records: Vec<SegmentRecord<Self::Pure, Self::IdealGas>> =
-            serde_json::from_reader(BufReader::new(File::open(file_segments)?))?;
+            SegmentRecord::from_json(file_segments)?;
 
         // Read binary records
         let binary_records = file_binary

src/parameter/segment.rs

@@ -1,5 +1,10 @@
+use super::ParameterError;
+use serde::de::DeserializeOwned;
 use serde::{Deserialize, Serialize};
+use std::fs::File;
 use std::hash::{Hash, Hasher};
+use std::io::BufReader;
+use std::path::Path;
 
 /// Parameters describing an individual segment of a molecule.
 #[derive(Serialize, Deserialize, Debug, Clone)]
@@ -25,6 +30,15 @@ impl<M, I> SegmentRecord<M, I> {
             ideal_gas_record,
         }
     }
+
+    /// Read a list of `SegmentRecord`s from a JSON file.
+    pub fn from_json<P: AsRef<Path>>(file: P) -> Result<Vec<Self>, ParameterError>
+    where
+        I: DeserializeOwned,
+        M: DeserializeOwned,
+    {
+        Ok(serde_json::from_reader(BufReader::new(File::open(file)?))?)
+    }
 }
 
 impl<M, I> Hash for SegmentRecord<M, I> {

src/python/parameter.rs

@@ -482,6 +482,25 @@ macro_rules! impl_segment_record {
                 )))
             }
 
+            /// Read a list of `SegmentRecord`s from a JSON file.
+            ///
+            /// Parameters
+            /// ----------
+            /// path : str
+            ///     Path to file containing the segment records.
+            ///
+            /// Returns
+            /// -------
+            /// SegmentRecord
+            #[staticmethod]
+            #[pyo3(text_signature = "(path)")]
+            fn from_json(path: &str) -> Result<Vec<Self>, ParameterError> {
+                Ok(SegmentRecord::from_json(path)?
+                    .into_iter()
+                    .map(|s| Self(s))
+                    .collect())
+            }
+
             #[getter]
             fn get_identifier(&self) -> String {
                 self.0.identifier.clone()