normal generic code written by normal people

to de-deplicate some bits

src/data/displacement.rs

@@ -1,4 +1,5 @@
 use super::vector::Vector;
+use crate::data::try_read_enum;
 use crate::error::InvalidNeighbourError;
 use binrw::{BinRead, BinResult, ReadOptions};
 use bitflags::bitflags;
@@ -137,15 +138,12 @@ impl BinRead for NeighbourSpan {
         options: &ReadOptions,
         args: Self::Args,
     ) -> BinResult<Self> {
-        let start = reader.stream_position().unwrap();
-        let raw = u8::read_options(reader, options, args)?;
-
-        NeighbourSpan::try_from(raw)
-            .map_err(|_| InvalidNeighbourError::InvalidNeighbourSpan(raw))
-            .map_err(|e| binrw::Error::Custom {
-                pos: start,
-                err: Box::new(e),
-            })
+        try_read_enum(
+            reader,
+            options,
+            args,
+            InvalidNeighbourError::InvalidNeighbourSpan,
+        )
     }
 }
 
@@ -166,15 +164,12 @@ impl BinRead for NeighbourOrientation {
         options: &ReadOptions,
         args: Self::Args,
     ) -> BinResult<Self> {
-        let start = reader.stream_position().unwrap();
-        let raw = u8::read_options(reader, options, args)?;
-
-        NeighbourOrientation::try_from(raw)
-            .map_err(|_| InvalidNeighbourError::InvalidNeighbourOrientation(raw))
-            .map_err(|e| binrw::Error::Custom {
-                pos: start,
-                err: Box::new(e),
-            })
+        try_read_enum(
+            reader,
+            options,
+            args,
+            InvalidNeighbourError::InvalidNeighbourOrientation,
+        )
     }
 }
 

src/data/mod.rs

@@ -10,14 +10,16 @@ pub use self::vector::*;
 use crate::bspfile::LumpType;
 use crate::{BspResult, StringError};
 use arrayvec::ArrayString;
+use binrw::error::CustomError;
 use binrw::{BinRead, BinResult, ReadOptions};
 use bitflags::bitflags;
 use bv::BitVec;
+use num_enum::TryFromPrimitive;
 use std::borrow::Cow;
 use std::cmp::min;
 use std::fmt;
 use std::fmt::{Debug, Display, Formatter};
-use std::io::{Cursor, Read};
+use std::io::{Cursor, Read, Seek};
 use std::mem::{align_of, size_of};
 use std::ops::Index;
 use std::sync::Mutex;
@@ -470,3 +472,27 @@ impl Packfile {
         Ok(Some(buff))
     }
 }
+
+fn try_read_enum<T, R, E, F>(
+    reader: &mut R,
+    options: &ReadOptions,
+    args: <<T as TryFromPrimitive>::Primitive as BinRead>::Args,
+    err_map: F,
+) -> BinResult<T>
+where
+    R: Read + Seek,
+    T: TryFromPrimitive,
+    T::Primitive: BinRead,
+    F: FnOnce(T::Primitive) -> E,
+    E: CustomError + 'static,
+{
+    let start = reader.stream_position().unwrap();
+    let raw = <T::Primitive>::read_options(reader, options, args)?;
+
+    T::try_from_primitive(raw)
+        .map_err(|e| err_map(e.number))
+        .map_err(|e| binrw::Error::Custom {
+            pos: start,
+            err: Box::new(e),
+        })
+}