Use enum instead of BTreeMap to select xchan.

Since it only makes sence to fetch an xchan by one of the methods 
(address, hash or guid) we don't need a data type that can hold more 
than one value.

Had to implement my own serializer for it, since serde_urlencoded don't 
know how to serialize enums by default.

1 files changed, 26 insertions, 7 deletions

diff --git a/src/xchan.rs b/src/xchan.rs
index 88b3cb1..d81758a 100644
--- a/src/xchan.rs
+++ b/src/xchan.rs
@@ -16,37 +16,56 @@
 
 use client::{self, Client};
 use error::Error;
-use std::collections::BTreeMap;
+use serde::{Serialize, Serializer};
+
+enum XChanSelector<'a> {
+    Address(&'a str),
+    Hash(&'a str),
+    GUID(&'a str),
+}
+
+impl<'a> Serialize for XChanSelector<'a> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        match *self {
+            XChanSelector::Address(addr) => [("address", addr)].serialize(serializer),
+            XChanSelector::Hash(hash) => [("hash", hash)].serialize(serializer),
+            XChanSelector::GUID(guid) => [("guid", guid)].serialize(serializer),
+        }
+    }
+}
 
 pub struct XChanFetcher<'a> {
     client: &'a Client,
-    data: BTreeMap<&'a str, &'a str>,
+    data: Option<XChanSelector<'a>>,
 }
 
 impl<'a> XChanFetcher<'a> {
     pub fn new(client: &'a Client) -> XChanFetcher<'a> {
         XChanFetcher {
             client,
-            data: BTreeMap::new(),
+            data: None,
         }
     }
 
     pub fn by_address(&mut self, addr: &'a str) -> &mut XChanFetcher<'a> {
-        self.data.insert("address", addr);
+        self.data = Some(XChanSelector::Address(addr));
         self
     }
 
     pub fn by_hash(&mut self, hash: &'a str) -> &mut XChanFetcher<'a> {
-        self.data.insert("hash", hash);
+        self.data = Some(XChanSelector::Hash(hash));
         self
     }
 
     pub fn by_guid(&mut self, guid: &'a str) -> &mut XChanFetcher<'a> {
-        self.data.insert("guid", guid);
+        self.data = Some(XChanSelector::GUID(guid));
         self
     }
 
     pub fn fetch(&self) -> Result<String, Error> {
-        self.client.fetch_stream(client::ZOTAPI_XCHAN_PATH, &self.data)
+        self.client.fetch_stream(client::ZOTAPI_XCHAN_PATH, &self.data.as_ref().unwrap())
     }
 }