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140 lines
4.8 KiB
Python
140 lines
4.8 KiB
Python
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__all__ = ['Composer', 'ComposerError']
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from .error import MarkedYAMLError
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from .events import *
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from .nodes import *
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class ComposerError(MarkedYAMLError):
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pass
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class Composer:
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def __init__(self):
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self.anchors = {}
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def check_node(self):
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# Drop the STREAM-START event.
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if self.check_event(StreamStartEvent):
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self.get_event()
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# If there are more documents available?
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return not self.check_event(StreamEndEvent)
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def get_node(self):
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# Get the root node of the next document.
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if not self.check_event(StreamEndEvent):
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return self.compose_document()
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def get_single_node(self):
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# Drop the STREAM-START event.
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self.get_event()
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# Compose a document if the stream is not empty.
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document = None
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if not self.check_event(StreamEndEvent):
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document = self.compose_document()
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# Ensure that the stream contains no more documents.
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if not self.check_event(StreamEndEvent):
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event = self.get_event()
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raise ComposerError("expected a single document in the stream",
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document.start_mark, "but found another document",
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event.start_mark)
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# Drop the STREAM-END event.
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self.get_event()
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return document
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def compose_document(self):
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# Drop the DOCUMENT-START event.
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self.get_event()
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# Compose the root node.
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node = self.compose_node(None, None)
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# Drop the DOCUMENT-END event.
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self.get_event()
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self.anchors = {}
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return node
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def compose_node(self, parent, index):
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if self.check_event(AliasEvent):
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event = self.get_event()
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anchor = event.anchor
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if anchor not in self.anchors:
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raise ComposerError(None, None, "found undefined alias %r"
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% anchor, event.start_mark)
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return self.anchors[anchor]
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event = self.peek_event()
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anchor = event.anchor
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if anchor is not None:
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if anchor in self.anchors:
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raise ComposerError("found duplicate anchor %r; first occurrence"
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% anchor, self.anchors[anchor].start_mark,
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"second occurrence", event.start_mark)
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self.descend_resolver(parent, index)
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if self.check_event(ScalarEvent):
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node = self.compose_scalar_node(anchor)
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elif self.check_event(SequenceStartEvent):
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node = self.compose_sequence_node(anchor)
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elif self.check_event(MappingStartEvent):
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node = self.compose_mapping_node(anchor)
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self.ascend_resolver()
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return node
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def compose_scalar_node(self, anchor):
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event = self.get_event()
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tag = event.tag
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if tag is None or tag == '!':
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tag = self.resolve(ScalarNode, event.value, event.implicit)
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node = ScalarNode(tag, event.value,
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event.start_mark, event.end_mark, style=event.style)
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if anchor is not None:
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self.anchors[anchor] = node
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return node
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def compose_sequence_node(self, anchor):
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start_event = self.get_event()
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tag = start_event.tag
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if tag is None or tag == '!':
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tag = self.resolve(SequenceNode, None, start_event.implicit)
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node = SequenceNode(tag, [],
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start_event.start_mark, None,
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flow_style=start_event.flow_style)
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if anchor is not None:
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self.anchors[anchor] = node
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index = 0
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while not self.check_event(SequenceEndEvent):
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node.value.append(self.compose_node(node, index))
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index += 1
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end_event = self.get_event()
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node.end_mark = end_event.end_mark
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return node
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def compose_mapping_node(self, anchor):
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start_event = self.get_event()
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tag = start_event.tag
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if tag is None or tag == '!':
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tag = self.resolve(MappingNode, None, start_event.implicit)
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node = MappingNode(tag, [],
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start_event.start_mark, None,
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flow_style=start_event.flow_style)
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if anchor is not None:
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self.anchors[anchor] = node
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while not self.check_event(MappingEndEvent):
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#key_event = self.peek_event()
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item_key = self.compose_node(node, None)
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#if item_key in node.value:
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# raise ComposerError("while composing a mapping", start_event.start_mark,
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# "found duplicate key", key_event.start_mark)
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item_value = self.compose_node(node, item_key)
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#node.value[item_key] = item_value
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node.value.append((item_key, item_value))
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end_event = self.get_event()
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node.end_mark = end_event.end_mark
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return node
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