Make OIDs Equatable and Hashable

SwiftGit2/OID.swift

@@ -35,6 +35,11 @@ public struct OID {
 		pointer.dealloc(1)
 	}
 	
+	/// Create an instance from a libgit2 `git_oid`.
+	public init(oid: git_oid) {
+		self.oid = oid
+	}
+	
 	// MARK: - Properties
 	
 	public let oid: git_oid
@@ -50,3 +55,15 @@ extension OID: Printable {
 		return String(bytesNoCopy: string, length: length, encoding: NSASCIIStringEncoding, freeWhenDone: true)!
 	}
 }
+
+extension OID: Hashable {
+	public var hashValue: Int {
+		return Int(self.oid.id.0) ^ Int(self.oid.id.1) ^ Int(self.oid.id.2)
+	}
+}
+
+public func == (lhs: OID, rhs: OID) -> Bool {
+	var left = lhs.oid
+	var right = rhs.oid
+	return git_oid_cmp(&left, &right) == 0
+}

SwiftGit2Tests/OIDSpec.swift

@@ -38,5 +38,29 @@ class OIDSpec: QuickSpec {
 				expect(oid.description).to(equal(SHA))
 			}
 		}
+		
+		describe("==") {
+			it("should be equal when identical") {
+				let SHA = "1234567890123456789012345678901234567890"
+				let oid1 = OID(string: SHA)!
+				let oid2 = OID(string: SHA)!
+				expect(oid1).to(equal(oid2))
+			}
+			
+			it("should be not equal when different") {
+				let oid1 = OID(string: "1234567890123456789012345678901234567890")!
+				let oid2 = OID(string: "0000000000000000000000000000000000000000")!
+				expect(oid1).notTo(equal(oid2))
+			}
+		}
+		
+		describe("hashValue") {
+			it("should be equal when OIDs are equal") {
+				let SHA = "1234567890123456789012345678901234567890"
+				let oid1 = OID(string: SHA)!
+				let oid2 = OID(string: SHA)!
+				expect(oid1.hashValue).to(equal(oid2.hashValue))
+			}
+		}
 	}
 }