| 1 | |
|---|
| 2 | __all__ = ['Composer', 'ComposerError'] |
|---|
| 3 | |
|---|
| 4 | from error import MarkedYAMLError |
|---|
| 5 | from events import * |
|---|
| 6 | from nodes import * |
|---|
| 7 | |
|---|
| 8 | class ComposerError(MarkedYAMLError): |
|---|
| 9 | pass |
|---|
| 10 | |
|---|
| 11 | class Composer: |
|---|
| 12 | |
|---|
| 13 | def __init__(self): |
|---|
| 14 | self.anchors = {} |
|---|
| 15 | |
|---|
| 16 | def check_node(self): |
|---|
| 17 | # If there are more documents available? |
|---|
| 18 | return not self.check_event(StreamEndEvent) |
|---|
| 19 | |
|---|
| 20 | def get_node(self): |
|---|
| 21 | # Get the root node of the next document. |
|---|
| 22 | if not self.check_event(StreamEndEvent): |
|---|
| 23 | return self.compose_document() |
|---|
| 24 | |
|---|
| 25 | def __iter__(self): |
|---|
| 26 | # Iterator protocol. |
|---|
| 27 | while not self.check_event(StreamEndEvent): |
|---|
| 28 | yield self.compose_document() |
|---|
| 29 | |
|---|
| 30 | def compose_document(self): |
|---|
| 31 | |
|---|
| 32 | # Drop the STREAM-START event. |
|---|
| 33 | if self.check_event(StreamStartEvent): |
|---|
| 34 | self.get_event() |
|---|
| 35 | |
|---|
| 36 | # Drop the DOCUMENT-START event. |
|---|
| 37 | self.get_event() |
|---|
| 38 | |
|---|
| 39 | # Compose the root node. |
|---|
| 40 | node = self.compose_node(None, None) |
|---|
| 41 | |
|---|
| 42 | # Drop the DOCUMENT-END event. |
|---|
| 43 | self.get_event() |
|---|
| 44 | |
|---|
| 45 | self.complete_anchors = {} |
|---|
| 46 | return node |
|---|
| 47 | |
|---|
| 48 | def compose_node(self, parent, index): |
|---|
| 49 | if self.check_event(AliasEvent): |
|---|
| 50 | event = self.get_event() |
|---|
| 51 | anchor = event.anchor |
|---|
| 52 | if anchor not in self.anchors: |
|---|
| 53 | raise ComposerError(None, None, "found undefined alias %r" |
|---|
| 54 | % anchor.encode('utf-8'), event.start_mark) |
|---|
| 55 | return self.anchors[anchor] |
|---|
| 56 | event = self.peek_event() |
|---|
| 57 | anchor = event.anchor |
|---|
| 58 | if anchor is not None: |
|---|
| 59 | if anchor in self.anchors: |
|---|
| 60 | raise ComposerError("found duplicate anchor %r; first occurence" |
|---|
| 61 | % anchor.encode('utf-8'), self.anchors[anchor].start_mark, |
|---|
| 62 | "second occurence", event.start_mark) |
|---|
| 63 | self.descend_resolver(parent, index) |
|---|
| 64 | if self.check_event(ScalarEvent): |
|---|
| 65 | node = self.compose_scalar_node(anchor) |
|---|
| 66 | elif self.check_event(SequenceStartEvent): |
|---|
| 67 | node = self.compose_sequence_node(anchor) |
|---|
| 68 | elif self.check_event(MappingStartEvent): |
|---|
| 69 | node = self.compose_mapping_node(anchor) |
|---|
| 70 | self.ascend_resolver() |
|---|
| 71 | return node |
|---|
| 72 | |
|---|
| 73 | def compose_scalar_node(self, anchor): |
|---|
| 74 | event = self.get_event() |
|---|
| 75 | tag = event.tag |
|---|
| 76 | if tag is None or tag == u'!': |
|---|
| 77 | tag = self.resolve(ScalarNode, event.value, event.implicit) |
|---|
| 78 | node = ScalarNode(tag, event.value, |
|---|
| 79 | event.start_mark, event.end_mark, style=event.style) |
|---|
| 80 | if anchor is not None: |
|---|
| 81 | self.anchors[anchor] = node |
|---|
| 82 | return node |
|---|
| 83 | |
|---|
| 84 | def compose_sequence_node(self, anchor): |
|---|
| 85 | start_event = self.get_event() |
|---|
| 86 | tag = start_event.tag |
|---|
| 87 | if tag is None or tag == u'!': |
|---|
| 88 | tag = self.resolve(SequenceNode, None, start_event.implicit) |
|---|
| 89 | node = SequenceNode(tag, [], |
|---|
| 90 | start_event.start_mark, None, |
|---|
| 91 | flow_style=start_event.flow_style) |
|---|
| 92 | if anchor is not None: |
|---|
| 93 | self.anchors[anchor] = node |
|---|
| 94 | index = 0 |
|---|
| 95 | while not self.check_event(SequenceEndEvent): |
|---|
| 96 | node.value.append(self.compose_node(node, index)) |
|---|
| 97 | index += 1 |
|---|
| 98 | end_event = self.get_event() |
|---|
| 99 | node.end_mark = end_event.end_mark |
|---|
| 100 | return node |
|---|
| 101 | |
|---|
| 102 | def compose_mapping_node(self, anchor): |
|---|
| 103 | start_event = self.get_event() |
|---|
| 104 | tag = start_event.tag |
|---|
| 105 | if tag is None or tag == u'!': |
|---|
| 106 | tag = self.resolve(MappingNode, None, start_event.implicit) |
|---|
| 107 | node = MappingNode(tag, {}, |
|---|
| 108 | start_event.start_mark, None, |
|---|
| 109 | flow_style=start_event.flow_style) |
|---|
| 110 | if anchor is not None: |
|---|
| 111 | self.anchors[anchor] = node |
|---|
| 112 | while not self.check_event(MappingEndEvent): |
|---|
| 113 | key_event = self.peek_event() |
|---|
| 114 | item_key = self.compose_node(node, None) |
|---|
| 115 | if item_key in node.value: |
|---|
| 116 | raise ComposerError("while composing a mapping", start_event.start_mark, |
|---|
| 117 | "found duplicate key", key_event.start_mark) |
|---|
| 118 | item_value = self.compose_node(node, item_key) |
|---|
| 119 | node.value[item_key] = item_value |
|---|
| 120 | end_event = self.get_event() |
|---|
| 121 | node.end_mark = end_event.end_mark |
|---|
| 122 | return node |
|---|
| 123 | |
|---|
