redesign the header API

I'm quite satisfied with this right now (though this doesn't say
anything about how I feel about it tomorrow), but it's ugly that some
guts (headers.Base) are exposed in the public API.

1 files changed, 120 insertions, 0 deletions

diff --git a/headers/uint64.go b/headers/uint64.go
new file mode 100644
index 0000000..6e8668b
--- /dev/null
+++ b/headers/uint64.go
@@ -0,0 +1,120 @@
+/******************************************************************************
+*
+*  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 headers
+
+import (
+	"strconv"
+)
+
+//Uint64 is a helper type that provides type-safe access to a Swift header
+//whose value is an unsigned integer. It cannot be directly constructed, but
+//some subtypes of schwift.Headers have fields of this type. For example:
+//
+//    var hdr AccountHeaders
+//    //the following two statements are equivalent:
+//    hdr.Set("X-Account-Meta-Quota-Bytes", "1048576")
+//    hdr.QuotaBytes.Set(1 << 20)
+//    //because hdr.QuotaBytes is a headers.Uint64 instance
+type Uint64 struct {
+	Base
+}
+
+//Exists checks whether there is a value for this header.
+func (f Uint64) Exists() bool {
+	return f.H.Get(f.K) != ""
+}
+
+//Get returns the value for this header, or 0 if there is no value (or if it is
+//not a valid uint64).
+func (f Uint64) Get() uint64 {
+	v, err := strconv.ParseUint(f.H.Get(f.K), 10, 64)
+	if err != nil {
+		return 0
+	}
+	return v
+}
+
+//Set writes a new value for this header into the corresponding schwift.Headers
+//instance.
+func (f Uint64) Set(value uint64) {
+	f.H.Set(f.K, strconv.FormatUint(value, 10))
+}
+
+//Del removes this key from the original schwift.Headers instance, so that the
+//key will remain unchanged on the server during Update().
+func (f Uint64) Del() {
+	f.H.Del(f.K)
+}
+
+//Clear sets this key to an empty string in the original schwift.Headers
+//instance, so that the key will be removed on the server during Update().
+func (f Uint64) Clear() {
+	f.H.Clear(f.K)
+}
+
+//Validate is only used internally, but needs to be exported to cross package
+//boundaries.
+func (f Uint64) Validate() error {
+	val := f.H.Get(f.K)
+	if val == "" {
+		return nil
+	}
+	_, err := strconv.ParseUint(val, 10, 64)
+	if err == nil {
+		return nil
+	}
+	return MalformedHeaderError{f.K, err}
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+//Uint64Readonly is a readonly variant of Uint64. It is used for fields that
+//cannot be set by the client.
+type Uint64Readonly struct {
+	Base
+}
+
+//Exists checks whether there is a value for this header.
+func (f Uint64Readonly) Exists() bool {
+	return f.H.Get(f.K) != ""
+}
+
+//Get returns the value for this header, or 0 if there is no value (or if it is
+//not a valid uint64).
+func (f Uint64Readonly) Get() uint64 {
+	v, err := strconv.ParseUint(f.H.Get(f.K), 10, 64)
+	if err != nil {
+		return 0
+	}
+	return v
+}
+
+//Validate is only used internally, but needs to be exported to cross package
+//boundaries.
+func (f Uint64Readonly) Validate() error {
+	val := f.H.Get(f.K)
+	if val == "" {
+		return nil
+	}
+	_, err := strconv.ParseUint(val, 10, 64)
+	if err == nil {
+		return nil
+	}
+	return MalformedHeaderError{f.K, err}
+}