Load YAML mappings as ordered dictionaries

OrderedYAML.py

import yaml
import yaml.constructor

def load(data):
    
    try:
        # included in standard lib from Python 2.7
        from collections import OrderedDict
    except ImportError:
        # try importing the backported drop-in replacement
        # it's available on PyPI
        from ordereddict import OrderedDict

    class OrderedDictYAMLLoader(yaml.Loader):
        """
        A YAML loader that loads mappings into ordered dictionaries.
        """

        def __init__(self, *args, **kwargs):
            yaml.Loader.__init__(self, *args, **kwargs)

            self.add_constructor(u'tag:yaml.org,2002:map', type(self).construct_yaml_map)
            self.add_constructor(u'tag:yaml.org,2002:omap', type(self).construct_yaml_map)

        def construct_yaml_map(self, node):
            data = OrderedDict()
            yield data
            value = self.construct_mapping(node)
            data.update(value)

        def construct_mapping(self, node, deep=False):
            if isinstance(node, yaml.MappingNode):
                self.flatten_mapping(node)
            else:
                raise yaml.constructor.ConstructorError(None, None,
                    'expected a mapping node, but found %s' % node.id, node.start_mark)

            mapping = OrderedDict()
            for key_node, value_node in node.value:
                key = self.construct_object(key_node, deep=deep)
                try:
                    hash(key)
                except TypeError, exc:
                    raise yaml.constructor.ConstructorError('while constructing a mapping',
                        node.start_mark, 'found unacceptable key (%s)' % exc, key_node.start_mark)
                value = self.construct_object(value_node, deep=deep)
                mapping[key] = value
            return mapping
    
    
    
    return yaml.load(data, OrderedDictYAMLLoader)


### Usage:
#import OrderedYAML
#data = ...
#ydoc = OrderedYAML.load(data)

Slight modification of the original: changed it to make it easy to use as module (see usage note inside).