parseyaml.py

from collections import namedtuple
import yaml

from annotations import Annotation, AnnotatedValue
from parser import Parser

class YAMLParser(Parser):
    def parse(self):
        tree = yaml.compose(self.fileobj)
        self._constructor = yaml.constructor.SafeConstructor()
        return self._annotate(tree)
    
    def _annotate(self, node):
        ann = Annotation(self.filename,
                         node.start_mark.line + 1, node.end_mark.line + 1)
        if isinstance(node, yaml.SequenceNode):
            value = [self._annotate(n) for n in node.value]
        elif isinstance(node, yaml.MappingNode):
            value = dict((self._annotate(n) for n in l) for l in node.value)
        elif isinstance(node, yaml.ScalarNode):
            value = self._constructor.construct_object(node)
        else:
            raise RuntimeError("unhandled node type")
        
        return AnnotatedValue(value, ann)
    
    def get_description(self, annotation):
        return "in file {}, line"