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package etreeutils
import (
"sort"
"strings"
"github.com/beevik/etree"
)
// TransformExcC14n transforms the passed element into xml-exc-c14n form.
func TransformExcC14n(el *etree.Element, inclusiveNamespacesPrefixList string) error {
prefixes := strings.Fields(inclusiveNamespacesPrefixList)
prefixSet := make(map[string]struct{}, len(prefixes))
for _, prefix := range prefixes {
prefixSet[prefix] = struct{}{}
}
err := transformExcC14n(DefaultNSContext, DefaultNSContext, el, prefixSet)
if err != nil {
return err
}
return nil
}
func transformExcC14n(ctx, declared NSContext, el *etree.Element, inclusiveNamespaces map[string]struct{}) error {
scope, err := ctx.SubContext(el)
if err != nil {
return err
}
visiblyUtilizedPrefixes := map[string]struct{}{
el.Space: struct{}{},
}
filteredAttrs := []etree.Attr{}
// Filter out all namespace declarations
for _, attr := range el.Attr {
switch {
case attr.Space == xmlnsPrefix:
if _, ok := inclusiveNamespaces[attr.Key]; ok {
visiblyUtilizedPrefixes[attr.Key] = struct{}{}
}
case attr.Space == defaultPrefix && attr.Key == xmlnsPrefix:
if _, ok := inclusiveNamespaces[defaultPrefix]; ok {
visiblyUtilizedPrefixes[defaultPrefix] = struct{}{}
}
default:
if attr.Space != defaultPrefix {
visiblyUtilizedPrefixes[attr.Space] = struct{}{}
}
filteredAttrs = append(filteredAttrs, attr)
}
}
el.Attr = filteredAttrs
declared = declared.Copy()
// Declare all visibly utilized prefixes that are in-scope but haven't
// been declared in the canonicalized form yet. These might have been
// declared on this element but then filtered out above, or they might
// have been declared on an ancestor (before canonicalization) which
// didn't visibly utilize and thus had them removed.
for prefix := range visiblyUtilizedPrefixes {
// Skip redundant declarations - they have to already have the same
// value.
if declaredNamespace, ok := declared.prefixes[prefix]; ok {
if value, ok := scope.prefixes[prefix]; ok && declaredNamespace == value {
continue
}
}
namespace, err := scope.LookupPrefix(prefix)
if err != nil {
return err
}
el.Attr = append(el.Attr, declared.declare(prefix, namespace))
}
sort.Sort(SortedAttrs(el.Attr))
// Transform child elements
for _, child := range el.ChildElements() {
err := transformExcC14n(scope, declared, child, inclusiveNamespaces)
if err != nil {
return err
}
}
return nil
}
|
