From 01af45ab3f5aea7b421ee5fa1b6ab64c89918bf9 Mon Sep 17 00:00:00 2001
From: Richard Newman <rnewman@twinql.com>
Date: Mon, 17 Apr 2017 21:09:45 -0700
Subject: [PATCH] Pre: define Display for ValueType.

---
 core/src/lib.rs | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/core/src/lib.rs b/core/src/lib.rs
index a6390a8d..67b0aa63 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -17,6 +17,7 @@ extern crate edn;
 pub mod values;
 
 use std::collections::BTreeMap;
+use std::fmt;
 use std::rc::Rc;
 use self::ordered_float::OrderedFloat;
 use self::edn::NamespacedKeyword;
@@ -44,19 +45,33 @@ pub enum ValueType {
 }
 
 impl ValueType {
-    pub fn to_edn_value(&self) -> edn::Value {
+    pub fn to_edn_value(self) -> edn::Value {
         match self {
-            &ValueType::Ref => values::DB_TYPE_REF.clone(),
-            &ValueType::Boolean => values::DB_TYPE_BOOLEAN.clone(),
-            &ValueType::Instant => values::DB_TYPE_INSTANT.clone(),
-            &ValueType::Long => values::DB_TYPE_LONG.clone(),
-            &ValueType::Double => values::DB_TYPE_DOUBLE.clone(),
-            &ValueType::String => values::DB_TYPE_STRING.clone(),
-            &ValueType::Keyword => values::DB_TYPE_KEYWORD.clone(),
+            ValueType::Ref => values::DB_TYPE_REF.clone(),
+            ValueType::Boolean => values::DB_TYPE_BOOLEAN.clone(),
+            ValueType::Instant => values::DB_TYPE_INSTANT.clone(),
+            ValueType::Long => values::DB_TYPE_LONG.clone(),
+            ValueType::Double => values::DB_TYPE_DOUBLE.clone(),
+            ValueType::String => values::DB_TYPE_STRING.clone(),
+            ValueType::Keyword => values::DB_TYPE_KEYWORD.clone(),
         }
     }
 }
 
+impl fmt::Display for ValueType {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", match *self {
+            ValueType::Ref =>     "db.type/ref",
+            ValueType::Boolean => "db.type/boolean",
+            ValueType::Instant => "db.type/instant",
+            ValueType::Long =>    "db.type/long",
+            ValueType::Double =>  "db.type/double",
+            ValueType::String =>  "db.type/string",
+            ValueType::Keyword => "db.type/keyword",
+        })
+    }
+}
+
 /// Represents a Mentat value in a particular value set.
 // TODO: expand to include :db.type/{instant,url,uuid}.
 // TODO: BigInt?