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// Copyright 2015 Matthew Holt and The Caddy Authors
//
// 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 push
import (
"strings"
)
// linkResource contains the results of a parsed Link header.
type linkResource struct {
uri string
params map[string]string
}
// parseLinkHeader is responsible for parsing Link header
// and returning list of found resources.
//
// Accepted formats are:
//
// Link: <resource>; as=script
// Link: <resource>; as=script,<resource>; as=style
// Link: <resource>;<resource2>
//
// where <resource> begins with a forward slash (/).
func parseLinkHeader(header string) []linkResource {
resources := []linkResource{}
if header == "" {
return resources
}
for _, link := range strings.Split(header, comma) {
l := linkResource{params: make(map[string]string)}
li, ri := strings.Index(link, "<"), strings.Index(link, ">")
if li == -1 || ri == -1 {
continue
}
l.uri = strings.TrimSpace(link[li+1 : ri])
for _, param := range strings.Split(strings.TrimSpace(link[ri+1:]), semicolon) {
before, after, isCut := strings.Cut(strings.TrimSpace(param), equal)
key := strings.TrimSpace(before)
if key == "" {
continue
}
if isCut {
l.params[key] = strings.TrimSpace(after)
} else {
l.params[key] = key
}
}
resources = append(resources, l)
}
return resources
}
const (
comma = ","
semicolon = ";"
equal = "="
)
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