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package link
import (
"net/http"
"regexp"
"strings"
)
var (
commaRegexp = regexp.MustCompile(`,\s{0,}`)
valueCommaRegexp = regexp.MustCompile(`([^"]),`)
equalRegexp = regexp.MustCompile(` *= *`)
keyRegexp = regexp.MustCompile(`[a-z*]+`)
linkRegexp = regexp.MustCompile(`\A<(.+)>;(.+)\z`)
semiRegexp = regexp.MustCompile(`; +`)
valRegexp = regexp.MustCompile(`"+([^"]+)"+`)
)
// Group returned by Parse, contains multiple links indexed by "rel"
type Group map[string]*Link
// Link contains a Link item with URI, Rel, and other non-URI components in Extra.
type Link struct {
URI string
Rel string
Extra map[string]string
}
// String returns the URI
func (l *Link) String() string {
return l.URI
}
// ParseRequest parses the provided *http.Request into a Group
func ParseRequest(req *http.Request) Group {
if req == nil {
return nil
}
return ParseHeader(req.Header)
}
// ParseResponse parses the provided *http.Response into a Group
func ParseResponse(resp *http.Response) Group {
if resp == nil {
return nil
}
return ParseHeader(resp.Header)
}
// ParseHeader retrieves the Link header from the provided http.Header and parses it into a Group
func ParseHeader(h http.Header) Group {
if headers, found := h["Link"]; found {
return Parse(strings.Join(headers, ", "))
}
return nil
}
// Parse parses the provided string into a Group
func Parse(s string) Group {
if s == "" {
return nil
}
s = valueCommaRegexp.ReplaceAllString(s, "$1")
group := Group{}
for _, l := range commaRegexp.Split(s, -1) {
linkMatches := linkRegexp.FindAllStringSubmatch(l, -1)
if len(linkMatches) == 0 {
return nil
}
pieces := linkMatches[0]
link := &Link{URI: pieces[1], Extra: map[string]string{}}
for _, extra := range semiRegexp.Split(pieces[2], -1) {
vals := equalRegexp.Split(extra, -1)
key := keyRegexp.FindString(vals[0])
val := valRegexp.FindStringSubmatch(vals[1])[1]
if key == "rel" {
vals := strings.Split(val, " ")
rels := []string{vals[0]}
if len(vals) > 1 {
for _, v := range vals[1:] {
if !strings.HasPrefix(v, "http") {
rels = append(rels, v)
}
}
}
rel := strings.Join(rels, " ")
link.Rel = rel
group[rel] = link
} else {
link.Extra[key] = val
}
}
}
return group
}
|
