Slightly improve performance of builders

Builders would keep a `serde_json::Map<String, Value>`, which would
require re-creating owned strings for the same parameter multiple times
in some cases, depending on builder defaults and keying strategies.

This commit uses a `std::collections::HashMap<&'static str, Value>`
internally, and moves over values to a `serde_json::Map<String, Value>`
when it comes time to sending them to the appropriate `http` module
function.

This saves the number of heap-allocated string creations on most
builders, with specific performance increase on `builder::CreateMessage`
and `builder::CreateEmbed` & co.

1 files changed, 11 insertions, 15 deletions

diff --git a/src/builder/edit_guild.rs b/src/builder/edit_guild.rs
index 0719305..45969fe 100644
--- a/src/builder/edit_guild.rs
+++ b/src/builder/edit_guild.rs
@@ -1,5 +1,6 @@
 use internal::prelude::*;
 use model::{ChannelId, Region, UserId, VerificationLevel};
+use std::collections::HashMap;
 
 /// A builder to optionally edit certain fields of a [`Guild`]. This is meant
 /// for usage with [`Guild::edit`].
@@ -11,7 +12,7 @@ use model::{ChannelId, Region, UserId, VerificationLevel};
 /// [`Guild`]: ../model/struct.Guild.html
 /// [Manage Guild]: ../model/permissions/constant.MANAGE_GUILD.html
 #[derive(Clone, Debug, Default)]
-pub struct EditGuild(pub Map<String, Value>);
+pub struct EditGuild(pub HashMap<&'static str, Value>);
 
 impl EditGuild {
     /// Set the "AFK voice channel" that users are to move to if they have been
@@ -24,7 +25,7 @@ impl EditGuild {
     /// [`afk_timeout`]: #method.afk_timeout
     pub fn afk_channel<C: Into<ChannelId>>(mut self, channel: Option<C>) -> Self {
         self.0.insert(
-            "afk_channel_id".to_string(),
+            "afk_channel_id",
             match channel {
                 Some(channel) => Value::Number(Number::from(channel.into().0)),
                 None => Value::Null,
@@ -40,7 +41,7 @@ impl EditGuild {
     /// [`afk_channel`]: #method.afk_channel
     pub fn afk_timeout(mut self, timeout: u64) -> Self {
         self.0.insert(
-            "afk_timeout".to_string(),
+            "afk_timeout",
             Value::Number(Number::from(timeout)),
         );
 
@@ -78,7 +79,7 @@ impl EditGuild {
     /// [`utils::read_image`]: ../utils/fn.read_image.html
     pub fn icon(mut self, icon: Option<&str>) -> Self {
         self.0.insert(
-            "icon".to_string(),
+            "icon",
             icon.map_or_else(|| Value::Null, |x| Value::String(x.to_string())),
         );
 
@@ -89,8 +90,7 @@ impl EditGuild {
     ///
     /// **Note**: Must be between (and including) 2-100 chracters.
     pub fn name(mut self, name: &str) -> Self {
-        self.0
-            .insert("name".to_string(), Value::String(name.to_string()));
+        self.0.insert("name", Value::String(name.to_string()));
 
         self
     }
@@ -99,10 +99,8 @@ impl EditGuild {
     ///
     /// **Note**: The current user must be the owner of the guild.
     pub fn owner<U: Into<UserId>>(mut self, user_id: U) -> Self {
-        self.0.insert(
-            "owner_id".to_string(),
-            Value::Number(Number::from(user_id.into().0)),
-        );
+        let id = Value::Number(Number::from(user_id.into().0));
+        self.0.insert("owner_id", id);
 
         self
     }
@@ -134,8 +132,7 @@ impl EditGuild {
     ///
     /// [`Region::UsWest`]: ../model/enum.Region.html#variant.UsWest
     pub fn region(mut self, region: Region) -> Self {
-        self.0
-            .insert("region".to_string(), Value::String(region.name().to_string()));
+        self.0.insert("region", Value::String(region.name().to_string()));
 
         self
     }
@@ -149,8 +146,7 @@ impl EditGuild {
     /// [`features`]: ../model/struct.LiveGuild.html#structfield.features
     pub fn splash(mut self, splash: Option<&str>) -> Self {
         let splash = splash.map_or(Value::Null, |x| Value::String(x.to_string()));
-
-        self.0.insert("splash".to_string(), splash);
+        self.0.insert("splash", splash);
 
         self
     }
@@ -189,7 +185,7 @@ impl EditGuild {
         where V: Into<VerificationLevel> {
         let num = Value::Number(Number::from(verification_level.into().num()));
 
-        self.0.insert("verification_level".to_string(), num);
+        self.0.insert("verification_level", num);
 
         self
     }