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