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/
discovery.go
83 lines (76 loc) · 2.26 KB
/
discovery.go
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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gps
// This code is taken from cmd/go/discovery.go; it is the logic go get itself
// uses to interpret meta imports information.
import (
"encoding/xml"
"fmt"
"io"
"strings"
)
// charsetReader returns a reader for the given charset. Currently
// it only supports UTF-8 and ASCII. Otherwise, it returns a meaningful
// error which is printed by go get, so the user can find why the package
// wasn't downloaded if the encoding is not supported. Note that, in
// order to reduce potential errors, ASCII is treated as UTF-8 (i.e. characters
// greater than 0x7f are not rejected).
func charsetReader(charset string, input io.Reader) (io.Reader, error) {
switch strings.ToLower(charset) {
case "ascii":
return input, nil
default:
return nil, fmt.Errorf("can't decode XML document using charset %q", charset)
}
}
type metaImport struct {
Prefix, VCS, RepoRoot string
}
// parseMetaGoImports returns meta imports from the HTML in r.
// Parsing ends at the end of the <head> section or the beginning of the <body>.
func parseMetaGoImports(r io.Reader) (imports []metaImport, err error) {
d := xml.NewDecoder(r)
d.CharsetReader = charsetReader
d.Strict = false
var t xml.Token
for {
t, err = d.RawToken()
if err != nil {
if err == io.EOF || len(imports) > 0 {
err = nil
}
return
}
if e, ok := t.(xml.StartElement); ok && strings.EqualFold(e.Name.Local, "body") {
return
}
if e, ok := t.(xml.EndElement); ok && strings.EqualFold(e.Name.Local, "head") {
return
}
e, ok := t.(xml.StartElement)
if !ok || !strings.EqualFold(e.Name.Local, "meta") {
continue
}
if attrValue(e.Attr, "name") != "go-import" {
continue
}
if f := strings.Fields(attrValue(e.Attr, "content")); len(f) == 3 {
imports = append(imports, metaImport{
Prefix: f[0],
VCS: f[1],
RepoRoot: f[2],
})
}
}
}
// attrValue returns the attribute value for the case-insensitive key
// `name', or the empty string if nothing is found.
func attrValue(attrs []xml.Attr, name string) string {
for _, a := range attrs {
if strings.EqualFold(a.Name.Local, name) {
return a.Value
}
}
return ""
}