prepare ContainerIterator for sharing code with ObjectIterator

2 files changed, 163 insertions, 92 deletions

diff --git a/container_iterator.go b/container_iterator.go
index 71c17be..8c04be6 100644
--- a/container_iterator.go
+++ b/container_iterator.go
@@ -19,13 +19,21 @@
 package schwift
 
 import (
-	"encoding/json"
 	"fmt"
-	"strconv"
-	"strings"
 	"time"
 )
 
+//ContainerInfo is a result type returned by ContainerIterator for detailed
+//container listings. The metadata in this type is a subset of Container.Headers(),
+//but since it is returned as part of the detailed container listing, it can be
+//obtained without making additional HEAD requests on the container(s).
+type ContainerInfo struct {
+	Container    *Container
+	ObjectCount  uint64
+	BytesUsed    uint64
+	LastModified time.Time
+}
+
 //ContainerIterator iterates over the accounts in a container. It is typically
 //constructed with the Account.Containers() method. For example:
 //
@@ -61,55 +69,14 @@ type ContainerIterator struct {
 	//Options may contain additional query parameters for the GET request.
 	Options *RequestOptions
 
-	marker string
-	eof    bool
+	base *iteratorBase
 }
 
-//ContainerInfo is a result type returned by ContainerIterator for detailed
-//container listings. The metadata in this type is a subset of Container.Headers(),
-//but since it is returned as part of the detailed container listing, it can be
-//obtained without making additional HEAD requests on the container(s).
-type ContainerInfo struct {
-	Container    *Container
-	ObjectCount  uint64
-	BytesUsed    uint64
-	LastModified time.Time
-}
-
-func (i ContainerIterator) request(limit int, detailed bool) Request {
-	r := Request{
-		Method:  "GET",
-		Headers: headersToHTTP(i.Headers),
-		Options: cloneRequestOptions(i.Options),
+func (i *ContainerIterator) getBase() *iteratorBase {
+	if i.base == nil {
+		i.base = &iteratorBase{i: i}
 	}
-
-	if i.Prefix != "" {
-		r.Options.Values.Set("prefix", i.Prefix)
-	}
-
-	if i.marker == "" {
-		r.Options.Values.Del("marker")
-	} else {
-		r.Options.Values.Set("marker", i.marker)
-	}
-
-	if limit < 0 {
-		r.Options.Values.Del("limit")
-	} else {
-		r.Options.Values.Set("limit", strconv.FormatUint(uint64(limit), 10))
-	}
-
-	if detailed {
-		r.Headers.Set("Accept", "application/json")
-		r.Options.Values.Set("format", "json")
-		r.ExpectStatusCodes = []int{200}
-	} else {
-		r.Headers.Set("Accept", "text/plain")
-		r.Options.Values.Set("format", "plain")
-		r.ExpectStatusCodes = []int{200, 204}
-	}
-
-	return r
+	return i.base
 }
 
 //NextPage queries Swift for the next page of container names. If limit is
@@ -122,47 +89,21 @@ func (i ContainerIterator) request(limit int, detailed bool) Request {
 //This method offers maximal flexibility, but most users will prefer the
 //simpler interfaces offered by Collect() and Foreach().
 func (i *ContainerIterator) NextPage(limit int) ([]*Container, error) {
-	if i.eof {
-		return nil, nil
-	}
-	resp, err := i.request(limit, false).Do(i.Account.client)
-	if err != nil {
-		return nil, err
-	}
-
-	buf, err := collectResponseBody(resp)
+	names, err := i.getBase().nextPage(limit)
 	if err != nil {
 		return nil, err
 	}
-	bufStr := strings.TrimSuffix(string(buf), "\n")
-	var result []*Container
-	if bufStr != "" {
-		names := strings.Split(bufStr, "\n")
-		result = make([]*Container, len(names))
-		for idx, name := range names {
-			result[idx] = i.Account.Container(name)
-		}
-	}
 
-	if len(result) == 0 {
-		i.eof = true
-		i.marker = ""
-	} else {
-		i.eof = false
-		i.marker = result[len(result)-1].Name()
+	result := make([]*Container, len(names))
+	for idx, name := range names {
+		result[idx] = i.Account.Container(name)
 	}
 	return result, nil
 }
 
 //NextPageDetailed is like NextPage, but includes basic metadata.
 func (i *ContainerIterator) NextPageDetailed(limit int) ([]ContainerInfo, error) {
-	if i.eof {
-		return nil, nil
-	}
-	resp, err := i.request(limit, true).Do(i.Account.client)
-	if err != nil {
-		return nil, err
-	}
+	b := i.getBase()
 
 	var document []struct {
 		BytesUsed       uint64 `json:"bytes"`
@@ -170,14 +111,14 @@ func (i *ContainerIterator) NextPageDetailed(limit int) ([]ContainerInfo, error)
 		LastModifiedStr string `json:"last_modified"`
 		Name            string `json:"name"`
 	}
-	err = json.NewDecoder(resp.Body).Decode(&document)
-	closeErr := resp.Body.Close()
-	if err == nil {
-		err = closeErr
-	}
+	err := b.nextPageDetailed(limit, &document)
 	if err != nil {
 		return nil, err
 	}
+	if len(document) == 0 {
+		b.setMarker("") //indicate EOF to iteratorBase
+		return nil, nil
+	}
 
 	result := make([]ContainerInfo, len(document))
 	for idx, data := range document {
@@ -191,13 +132,7 @@ func (i *ContainerIterator) NextPageDetailed(limit int) ([]ContainerInfo, error)
 		}
 	}
 
-	if len(result) == 0 {
-		i.eof = true
-		i.marker = ""
-	} else {
-		i.eof = false
-		i.marker = result[len(result)-1].Container.Name()
-	}
+	b.setMarker(result[len(result)-1].Container.Name())
 	return result, nil
 }
 
diff --git a/iterator.go b/iterator.go
new file mode 100644
index 0000000..af01bbe
--- /dev/null
+++ b/iterator.go
@@ -0,0 +1,136 @@
+/******************************************************************************
+*
+*  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 (
+	"encoding/json"
+	"strconv"
+	"strings"
+)
+
+//iteratorInterface allows iteratorBase to access public attributes of
+//ContainerIterator/ObjectIterator.
+type iteratorInterface interface {
+	getAccount() *Account
+	getContainerName() string
+	getPrefix() string
+	getHeaders() map[string]string
+	getOptions() *RequestOptions
+}
+
+func (i ContainerIterator) getAccount() *Account          { return i.Account }
+func (i ContainerIterator) getContainerName() string      { return "" }
+func (i ContainerIterator) getPrefix() string             { return i.Prefix }
+func (i ContainerIterator) getHeaders() map[string]string { return i.Headers }
+func (i ContainerIterator) getOptions() *RequestOptions   { return i.Options }
+
+//iteratorBase provides shared behavior for ContainerIterator and ObjectIterator.
+type iteratorBase struct {
+	i      iteratorInterface
+	marker string
+	eof    bool
+}
+
+func (b *iteratorBase) request(limit int, detailed bool) Request {
+	r := Request{
+		Method:        "GET",
+		ContainerName: b.i.getContainerName(),
+		Headers:       headersToHTTP(b.i.getHeaders()),
+		Options:       cloneRequestOptions(b.i.getOptions()),
+	}
+
+	if prefix := b.i.getPrefix(); prefix != "" {
+		r.Options.Values.Set("prefix", prefix)
+	}
+
+	if b.marker == "" {
+		r.Options.Values.Del("marker")
+	} else {
+		r.Options.Values.Set("marker", b.marker)
+	}
+
+	if limit < 0 {
+		r.Options.Values.Del("limit")
+	} else {
+		r.Options.Values.Set("limit", strconv.FormatUint(uint64(limit), 10))
+	}
+
+	if detailed {
+		r.Headers.Set("Accept", "application/json")
+		r.Options.Values.Set("format", "json")
+		r.ExpectStatusCodes = []int{200}
+	} else {
+		r.Headers.Set("Accept", "text/plain")
+		r.Options.Values.Set("format", "plain")
+		r.ExpectStatusCodes = []int{200, 204}
+	}
+
+	return r
+}
+
+func (b *iteratorBase) nextPage(limit int) ([]string, error) {
+	if b.eof {
+		return nil, nil
+	}
+	resp, err := b.request(limit, false).Do(b.i.getAccount().client)
+	if err != nil {
+		return nil, err
+	}
+
+	buf, err := collectResponseBody(resp)
+	if err != nil {
+		return nil, err
+	}
+	bufStr := strings.TrimSuffix(string(buf), "\n")
+	var result []string
+	if bufStr != "" {
+		result = strings.Split(bufStr, "\n")
+	}
+
+	if len(result) == 0 {
+		b.eof = true
+		b.marker = ""
+	} else {
+		b.eof = false
+		b.marker = result[len(result)-1]
+	}
+	return result, nil
+}
+
+func (b *iteratorBase) nextPageDetailed(limit int, data interface{}) error {
+	if b.eof {
+		return nil
+	}
+	resp, err := b.request(limit, true).Do(b.i.getAccount().client)
+	if err != nil {
+		return err
+	}
+
+	err = json.NewDecoder(resp.Body).Decode(&data)
+	closeErr := resp.Body.Close()
+	if err == nil {
+		err = closeErr
+	}
+	return err
+}
+
+func (b *iteratorBase) setMarker(marker string) {
+	b.marker = marker
+	b.eof = marker == ""
+}