use go 1.12

Signed-off-by: hongming <talonwan@yunify.com>

vendor/github.com/mholt/caddy/caddyhttp/push/link_parser.go

@@ -0,0 +1,77 @@
+// Copyright 2015 Light Code Labs, LLC
+//
+// 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"
+)
+
+const (
+	commaSeparator     = ","
+	semicolonSeparator = ";"
+	equalSeparator     = "="
+)
+
+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,</resource2>; as=style
+// Link: </resource>;</resource2>
+func parseLinkHeader(header string) []linkResource {
+	resources := []linkResource{}
+
+	if header == "" {
+		return resources
+	}
+
+	for _, link := range strings.Split(header, commaSeparator) {
+		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:]), semicolonSeparator) {
+			parts := strings.SplitN(strings.TrimSpace(param), equalSeparator, 2)
+			key := strings.TrimSpace(parts[0])
+
+			if key == "" {
+				continue
+			}
+
+			if len(parts) == 1 {
+				l.params[key] = key
+			}
+
+			if len(parts) == 2 {
+				l.params[key] = strings.TrimSpace(parts[1])
+			}
+		}
+
+		resources = append(resources, l)
+	}
+
+	return resources
+}