From 51ac49c66e310d387036f9d8685d448df1b551a3 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sat, 18 Jul 2020 12:58:46 +0100
Subject: [PATCH] wip for test

---
 src/bin/slotmap-slot-idx-test.rs |  2 ++
 src/slotmap-slot-idx.rs          | 23 +++++++++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 src/bin/slotmap-slot-idx-test.rs

diff --git a/src/bin/slotmap-slot-idx-test.rs b/src/bin/slotmap-slot-idx-test.rs
new file mode 100644
index 00000000..f4455867
--- /dev/null
+++ b/src/bin/slotmap-slot-idx-test.rs
@@ -0,0 +1,2 @@
+fn main () {
+}
diff --git a/src/slotmap-slot-idx.rs b/src/slotmap-slot-idx.rs
index 9560393c..c764dab5 100644
--- a/src/slotmap-slot-idx.rs
+++ b/src/slotmap-slot-idx.rs
@@ -3,12 +3,30 @@ use serde::ser::{self,*};
 use thiserror::Error;
 use std::line;
 
+pub trait KeyData {
+  fn get_idx_version(self) -> (u32, u32);
+}
+
+impl KeyData for slotmap::KeyData {
+  fn get_idx_version(self) -> (u32, u32) {
+    keydata_extract(self).unwrap()
+  }
+}
+
+pub fn keydata_extract(key : slotmap::KeyData) -> Result<(u32, u32), Error> {
+  let mut m : MainExtractor = std::default::Default::default();
+  key.serialize(&mut m)?;
+  Ok(( m.idx    .ok_or(error(line!()))?,
+       m.version.ok_or(error(line!()))? ))
+}
+
 #[derive(Error,Debug)]
-enum Error {
+pub enum Error {
   WasCustomSerialize,
   Unexpected(std::num::NonZeroU32),
 }
 
+#[derive(Default)]
 struct MainExtractor {
   idx: Option<u32>,
   version: Option<u32>,
@@ -20,7 +38,8 @@ type R<Return> = Result<Return,Error>;
 type ROk = R<()>;
 
 
-fn unexpected<T>(line: u32) -> R<T> { Err(Error::Unexpected(std::convert::TryFrom::try_from(line).unwrap())) }
+fn error(line: u32) -> Error { Error::Unexpected(std::convert::TryFrom::try_from(line).unwrap()) }
+fn unexpected<T>(line: u32) -> R<T> { Err(error(line)) }
 
 type Imp = Impossible<(),Error>;
 
-- 
2.30.2