use dedicated Metadata type instead of http.Header

1 files changed, 72 insertions, 0 deletions

diff --git a/metadata.go b/metadata.go
new file mode 100644
index 0000000..3e01c02
--- /dev/null
+++ b/metadata.go
@@ -0,0 +1,72 @@
+/******************************************************************************
+*
+*  Copyright 2018 Stefan Majewsky <majewsky@gmx.net>
+*
+*  Licensed under the Apache License, Version 2.0 (the "License");
+*  you may not use this file except in compliance with the License.
+*  You may obtain a copy of the License at
+*
+*      http://www.apache.org/licenses/LICENSE-2.0
+*
+*  Unless required by applicable law or agreed to in writing, software
+*  distributed under the License is distributed on an "AS IS" BASIS,
+*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+*  See the License for the specific language governing permissions and
+*  limitations under the License.
+*
+******************************************************************************/
+
+package schwift
+
+import "net/textproto"
+
+//Metadata works like http.Header, but does not allow multiple values per key.
+type Metadata map[string]string
+
+//NewMetadata constructs a Metadata instance from a list of key-value pairs
+//with compact syntax. It is recommended over a map literal since it correctly
+//formats keys with textproto.CanonicalMIMEHeaderKey(). For example:
+//
+//    m = NewMetadata(
+//        "color", "blue",
+//        "size", "large",
+//    )
+//
+//    //...is equivalent to...
+//
+//    m = make(Metadata)
+//    m.Set("color", "blue")
+//    m.Set("size", "large")
+//
+//NewMetadata panics if it is called with an odd number of arguments.
+func NewMetadata(args ...string) Metadata {
+	if len(args)%2 == 1 {
+		panic("NewMetadata called with an odd number of arguments")
+	}
+	m := make(Metadata)
+	for idx := 0; idx < len(args); idx += 2 {
+		m.Set(args[idx], args[idx+1])
+	}
+	return m
+}
+
+//Del works just like http.Header.Del().
+func (m Metadata) Del(key string) {
+	k := textproto.CanonicalMIMEHeaderKey(key)
+	delete(m, k)
+}
+
+//Get works just like http.Header.Get().
+func (m Metadata) Get(key string) string {
+	if m == nil {
+		return ""
+	}
+	k := textproto.CanonicalMIMEHeaderKey(key)
+	return m[k]
+}
+
+//Set works just like http.Header.Set().
+func (m Metadata) Set(key, value string) {
+	k := textproto.CanonicalMIMEHeaderKey(key)
+	m[k] = value
+}