| [53] | 1 | |
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| 2 | from error import MarkedYAMLError |
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| 3 | from events import * |
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| 4 | from nodes import * |
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| 5 | |
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| 6 | class ComposerError(MarkedYAMLError): |
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| 7 | pass |
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| 8 | |
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| 9 | class Composer: |
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| 10 | |
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| 11 | def __init__(self, parser): |
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| 12 | self.parser = parser |
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| 13 | self.all_anchors = {} |
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| 14 | self.complete_anchors = {} |
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| 15 | |
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| 16 | def check(self): |
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| 17 | # If there are more documents available? |
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| 18 | return not self.parser.check(StreamEndEvent) |
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| 19 | |
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| 20 | def get(self): |
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| 21 | # Get the root node of the next document. |
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| 22 | if not self.parser.check(StreamEndEvent): |
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| 23 | return self.compose_document() |
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| 24 | |
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| 25 | def __iter__(self): |
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| 26 | # Iterator protocol. |
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| 27 | while not self.parser.check(StreamEndEvent): |
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| 28 | yield self.compose_document() |
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| 29 | |
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| 30 | def compose_document(self): |
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| 31 | node = self.compose_node() |
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| 32 | self.all_anchors = {} |
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| 33 | self.complete_anchors = {} |
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| 34 | return node |
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| 35 | |
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| 36 | def compose_node(self): |
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| 37 | if self.parser.check(AliasEvent): |
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| 38 | event = self.parser.get() |
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| 39 | anchor = event.anchor |
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| 40 | if anchor not in self.all_anchors: |
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| 41 | raise ComposerError(None, None, "found undefined alias %r" |
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| 42 | % anchor.encode('utf-8'), event.start_marker) |
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| 43 | if anchor not in self.complete_anchors: |
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| 44 | collection_event = self.all_anchors[anchor] |
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| 45 | raise ComposerError("while composing a collection", |
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| 46 | collection_event.start_marker, |
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| 47 | "found recursive anchor %r" % anchor.encode('utf-8'), |
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| 48 | event.start_marker) |
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| 49 | return self.complete_anchors[anchor] |
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| 50 | event = self.parser.peek() |
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| 51 | anchor = event.anchor |
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| 52 | if anchor is not None: |
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| 53 | if anchor in self.all_anchors: |
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| 54 | raise ComposerError("found duplicate anchor %r; first occurence" |
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| 55 | % anchor.encode('utf-8'), self.all_anchors[anchor].start_marker, |
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| 56 | "second occurence", event.start_marker) |
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| 57 | self.all_anchors[anchor] = event |
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| 58 | if self.parser.check(ScalarEvent): |
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| 59 | node = self.compose_scalar_node() |
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| 60 | elif self.parser.check(SequenceEvent): |
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| 61 | node = self.compose_sequence_node() |
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| 62 | elif self.parser.check(MappingEvent): |
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| 63 | node = self.compose_mapping_node() |
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| 64 | if anchor is not None: |
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| 65 | self.complete_anchors[anchor] = node |
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| 66 | return node |
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| 67 | |
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| 68 | def compose_scalar_node(self): |
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| 69 | event = self.parser.get() |
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| 70 | return ScalarNode(event.tag, event.value, |
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| 71 | event.start_marker, event.end_marker) |
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| 72 | |
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| 73 | def compose_sequence_node(self): |
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| 74 | start_event = self.parser.get() |
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| 75 | value = [] |
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| 76 | while not self.parser.check(CollectionEndEvent): |
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| 77 | value.append(self.compose_node()) |
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| 78 | end_event = self.parser.get() |
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| 79 | return SequenceNode(start_event.tag, value, |
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| 80 | start_event.start_marker, end_event.end_marker) |
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| 81 | |
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| 82 | def compose_mapping_node(self): |
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| 83 | start_event = self.parser.get() |
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| 84 | value = [] |
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| 85 | while not self.parser.check(CollectionEndEvent): |
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| 86 | item_key = self.compose_node() |
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| 87 | item_value = self.compose_node() |
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| 88 | value.append((item_key, item_value)) |
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| 89 | end_event = self.parser.get() |
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| 90 | return MappingNode(start_event.tag, value, |
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| 91 | start_event.start_marker, end_event.end_marker) |
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| 92 | |
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