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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 vcs
import (
"encoding/xml"
"fmt"
"io"
"strings"
)
// charsetReader returns a reader that converts from the given charset to UTF-8.
// 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 "utf-8", "ascii":
return input, nil
default:
return nil, fmt.Errorf("can't decode XML document using charset %q", charset)
}
}
// 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, mod ModuleMode) ([]metaImport, error) {
d := xml.NewDecoder(r)
d.CharsetReader = charsetReader
d.Strict = false
var imports []metaImport
for {
t, err := d.RawToken()
if err != nil {
if err != io.EOF && len(imports) == 0 {
return nil, err
}
break
}
if e, ok := t.(xml.StartElement); ok && strings.EqualFold(e.Name.Local, "body") {
break
}
if e, ok := t.(xml.EndElement); ok && strings.EqualFold(e.Name.Local, "head") {
break
}
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],
})
}
}
// Extract mod entries if we are paying attention to them.
var list []metaImport
var have map[string]bool
if mod == PreferMod {
have = make(map[string]bool)
for _, m := range imports {
if m.VCS == "mod" {
have[m.Prefix] = true
list = append(list, m)
}
}
}
// Append non-mod entries, ignoring those superseded by a mod entry.
for _, m := range imports {
if m.VCS != "mod" && !have[m.Prefix] {
list = append(list, m)
}
}
return list, nil
}
// 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 ""
}
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