Add capacity-related methods/property to HTTPManagerRequest.HTTPHeaders

Fixes #66.

README.md

@@ -416,8 +416,10 @@ work by you shall be dual licensed as above, without any additional terms or con
 * Fix the Obj-C `-setValue:forHeaderField:` and `-setValue:forDefaultHeaderField:` methods to take a nullable value ([#67][]).
 * Add `HTTPManagerRetryBehavior.init(any:)` to combine multiple retry behaviors together ([#69][]).
 * Declare support for Swift 4.2 in the podspec.
+* Add `HTTPManagerRequest.HTTPHeaders` methods `init(minimumCapacity:`) and `reserveCapacity(_:)` and property `capacity` ([#66][]).
 
 [#65]: https://github.com/postmates/PMHTTP/issues/65 "Obj-C convenience functions for requests with data"
+[#66]: https://github.com/postmates/PMHTTP/issues/66 "Add HTTPManagerRequest.HTTPHeaders.init(minimumCapacity:) and .reserveCapacity(_:)"
 [#67]: https://github.com/postmates/PMHTTP/issues/67 "Obj-C -[HTTPManagerRequest setValue:forHeaderField:] should take nullable value"
 [#69]: https://github.com/postmates/PMHTTP/issues/69 "HTTPManagerRetryBehavior should support composition"
 

Sources/HTTPManagerRequest.swift

@@ -357,6 +357,10 @@ extension HTTPManagerRequest {
             }
         }
 
+        public init(minimumCapacity: Int) {
+            dictionary = Dictionary(minimumCapacity: minimumCapacity)
+        }
+
         public var description: String {
             return String(describing: dictionary)
         }
@@ -394,6 +398,10 @@ extension HTTPManagerRequest {
             return dictionary.isEmpty
         }
 
+        public var capacity: Int {
+            return dictionary.capacity
+        }
+
         public var startIndex: Index {
             return dictionary.startIndex
         }
@@ -416,6 +424,10 @@ extension HTTPManagerRequest {
             }
         }
 
+        public mutating func reserveCapacity(_ minimumCapacity: Int) {
+            dictionary.reserveCapacity(minimumCapacity)
+        }
+
         public func index(forKey key: String) -> Index? {
             return dictionary.index(forKey: key)
         }