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