• Gustavo Niemeyer's avatar
    xml: major Go 1 fixup · 1627b46e
    Gustavo Niemeyer authored
    This CL improves the xml package in the following ways:
    
    - makes its interface match established conventions
    - brings Marshal and Unmarshal closer together
    - fixes a large number of bugs and adds tests
    - improves speed significantly
    - organizes and simplifies the code
    
    Fixes #2426.
    Fixes #2406.
    Fixes #1989.
    
    What follows is a detailed list of those changes.
    
    - All matching is case sensitive without special processing
      to the field name or xml tag in an attempt to match them.
      Customize the field tag as desired to match the correct XML
      elements.
    
    - Flags are ",flag" rather than "flag". The names "attr",
      "chardata", etc, may be used to name actual XML elements.
    
    - Overriding of attribute names is possible with "name,attr".
    
    - Attribute fields are marshalled properly if they have
      non-string types. Previously they were unmarshalled, but were
      ignored at marshalling time.
    
    - Comment fields tagged with ",comment" are marshalled properly,
      rather than being marshalled as normal fields.
    
    - The handling of the Any field has been replaced by the ",any"
      flag to avoid unexpected results when using the field name for
      other purposes, and has also been fixed to interact properly
      with name paths. Previously the feature would not function
      if any field in the type had a name path in its tag.
    
    - Embedded struct support fixed and cleaned so it works when
      marshalling and also when using field paths deeper than one level.
    
    - Conflict reporting on field names have been expanded to cover
      all fields. Previously it'd catch only conflicts of paths
      deeper than one level. Also interacts correctly with embedded
      structs now.
    
    - A trailing '>' is disallowed in xml tags. It used to be
      supported for removing the ambiguity between "attr" and "attr>",
      but the marshalling support for that was broken, and it's now
      unnecessary. Use "name" instead of "name>".
    
    - Fixed docs to point out that a XMLName doesn't have to be
      an xml.Name (e.g. a struct{} is a good fit too). The code was
      already working like that.
    
    - Fixed asymmetry in the precedence of XML element names between
      marshalling and unmarshalling. Marshal would consider the XMLName
      of the field type before the field tag, while unmarshalling would
      do the opposite. Now both respect the tag of the XMLName field
      first, and a nice error message is provided in case an attempt
      is made to name a field with its tag in a way that would
      conflict with the underlying type's XMLName field.
    
    - Do not marshal broken "<???>" tags when in doubt. Use the type
      name, and error out if that's not possible.
    
    - Do not break down unmarshalling if there's an interface{} field
      in a struct.
    
    - Significant speed boost due to caching of type metadata and
      overall allocation clean ups. The following timings reflect
      processing of the the atom test data:
    
      Old:
    
      BenchmarkMarshal           50000             48798 ns/op
      BenchmarkUnmarshal          5000            357174 ns/op
    
      New:
    
      BenchmarkMarshal          100000             19799 ns/op
      BenchmarkUnmarshal         10000            128525 ns/op
    
    R=cw, gustavo, kevlar, adg, rogpeppe, fullung, christoph, rsc
    CC=golang-dev
    https://golang.org/cl/5503078
    1627b46e
atom_test.go 1.51 KB