Use vendored dependencies

vendor/github.com/tomnomnom/linkheader/main.go

@@ -0,0 +1,151 @@
+// Package linkheader provides functions for parsing HTTP Link headers
+package linkheader
+
+import (
+	"fmt"
+	"strings"
+)
+
+// A Link is a single URL and related parameters
+type Link struct {
+	URL    string
+	Rel    string
+	Params map[string]string
+}
+
+// HasParam returns if a Link has a particular parameter or not
+func (l Link) HasParam(key string) bool {
+	for p := range l.Params {
+		if p == key {
+			return true
+		}
+	}
+	return false
+}
+
+// Param returns the value of a parameter if it exists
+func (l Link) Param(key string) string {
+	for k, v := range l.Params {
+		if key == k {
+			return v
+		}
+	}
+	return ""
+}
+
+// String returns the string representation of a link
+func (l Link) String() string {
+
+	p := make([]string, 0, len(l.Params))
+	for k, v := range l.Params {
+		p = append(p, fmt.Sprintf("%s=\"%s\"", k, v))
+	}
+	if l.Rel != "" {
+		p = append(p, fmt.Sprintf("%s=\"%s\"", "rel", l.Rel))
+	}
+	return fmt.Sprintf("<%s>; %s", l.URL, strings.Join(p, "; "))
+}
+
+// Links is a slice of Link structs
+type Links []Link
+
+// FilterByRel filters a group of Links by the provided Rel attribute
+func (l Links) FilterByRel(r string) Links {
+	links := make(Links, 0)
+	for _, link := range l {
+		if link.Rel == r {
+			links = append(links, link)
+		}
+	}
+	return links
+}
+
+// String returns the string representation of multiple Links
+// for use in HTTP responses etc
+func (l Links) String() string {
+	if l == nil {
+		return fmt.Sprint(nil)
+	}
+
+	var strs []string
+	for _, link := range l {
+		strs = append(strs, link.String())
+	}
+	return strings.Join(strs, ", ")
+}
+
+// Parse parses a raw Link header in the form:
+//   <url>; rel="foo", <url>; rel="bar"; wat="dis"
+// returning a slice of Link structs
+func Parse(raw string) Links {
+	var links Links
+
+	// One chunk: <url>; rel="foo"
+	for _, chunk := range strings.Split(raw, ",") {
+
+		link := Link{URL: "", Rel: "", Params: make(map[string]string)}
+
+		// Figure out what each piece of the chunk is
+		for _, piece := range strings.Split(chunk, ";") {
+
+			piece = strings.Trim(piece, " ")
+			if piece == "" {
+				continue
+			}
+
+			// URL
+			if piece[0] == '<' && piece[len(piece)-1] == '>' {
+				link.URL = strings.Trim(piece, "<>")
+				continue
+			}
+
+			// Params
+			key, val := parseParam(piece)
+			if key == "" {
+				continue
+			}
+
+			// Special case for rel
+			if strings.ToLower(key) == "rel" {
+				link.Rel = val
+			} else {
+				link.Params[key] = val
+			}
+		}
+
+		if link.URL != "" {
+			links = append(links, link)
+		}
+	}
+
+	return links
+}
+
+// ParseMultiple is like Parse, but accepts a slice of headers
+// rather than just one header string
+func ParseMultiple(headers []string) Links {
+	links := make(Links, 0)
+	for _, header := range headers {
+		links = append(links, Parse(header)...)
+	}
+	return links
+}
+
+// parseParam takes a raw param in the form key="val" and
+// returns the key and value as seperate strings
+func parseParam(raw string) (key, val string) {
+
+	parts := strings.SplitN(raw, "=", 2)
+	if len(parts) == 1 {
+		return parts[0], ""
+	}
+	if len(parts) != 2 {
+		return "", ""
+	}
+
+	key = parts[0]
+	val = strings.Trim(parts[1], "\"")
+
+	return key, val
+
+}