| 1 | # SPDX-License-Identifier: MIT |
| 2 | |
| 3 | __all__ = ['Composer', 'ComposerError'] |
| 4 | |
| 5 | from .error import MarkedYAMLError |
| 6 | from .events import * |
| 7 | from .nodes import * |
| 8 | |
| 9 | class ComposerError(MarkedYAMLError): |
| 10 | pass |
| 11 | |
| 12 | class Composer: |
| 13 | |
| 14 | def __init__(self): |
| 15 | self.anchors = {} |
| 16 | |
| 17 | def check_node(self): |
| 18 | # Drop the STREAM-START event. |
| 19 | if self.check_event(StreamStartEvent): |
| 20 | self.get_event() |
| 21 | |
| 22 | # If there are more documents available? |
| 23 | return not self.check_event(StreamEndEvent) |
| 24 | |
| 25 | def get_node(self): |
| 26 | # Get the root node of the next document. |
| 27 | if not self.check_event(StreamEndEvent): |
| 28 | return self.compose_document() |
| 29 | |
| 30 | def get_single_node(self): |
| 31 | # Drop the STREAM-START event. |
| 32 | self.get_event() |
| 33 | |
| 34 | # Compose a document if the stream is not empty. |
| 35 | document = None |
| 36 | if not self.check_event(StreamEndEvent): |
| 37 | document = self.compose_document() |
| 38 | |
| 39 | # Ensure that the stream contains no more documents. |
| 40 | if not self.check_event(StreamEndEvent): |
| 41 | event = self.get_event() |
| 42 | raise ComposerError("expected a single document in the stream", |
| 43 | document.start_mark, "but found another document", |
| 44 | event.start_mark) |
| 45 | |
| 46 | # Drop the STREAM-END event. |
| 47 | self.get_event() |
| 48 | |
| 49 | return document |
| 50 | |
| 51 | def compose_document(self): |
| 52 | # Drop the DOCUMENT-START event. |
| 53 | self.get_event() |
| 54 | |
| 55 | # Compose the root node. |
| 56 | node = self.compose_node(None, None) |
| 57 | |
| 58 | # Drop the DOCUMENT-END event. |
| 59 | self.get_event() |
| 60 | |
| 61 | self.anchors = {} |
| 62 | return node |
| 63 | |
| 64 | def compose_node(self, parent, index): |
| 65 | if self.check_event(AliasEvent): |
| 66 | event = self.get_event() |
| 67 | anchor = event.anchor |
| 68 | if anchor not in self.anchors: |
| 69 | raise ComposerError(None, None, "found undefined alias %r" |
| 70 | % anchor, event.start_mark) |
| 71 | return self.anchors[anchor] |
| 72 | event = self.peek_event() |
| 73 | anchor = event.anchor |
| 74 | if anchor is not None: |
| 75 | if anchor in self.anchors: |
| 76 | raise ComposerError("found duplicate anchor %r; first occurence" |
| 77 | % anchor, self.anchors[anchor].start_mark, |
| 78 | "second occurence", event.start_mark) |
| 79 | self.descend_resolver(parent, index) |
| 80 | if self.check_event(ScalarEvent): |
| 81 | node = self.compose_scalar_node(anchor) |
| 82 | elif self.check_event(SequenceStartEvent): |
| 83 | node = self.compose_sequence_node(anchor) |
| 84 | elif self.check_event(MappingStartEvent): |
| 85 | node = self.compose_mapping_node(anchor) |
| 86 | self.ascend_resolver() |
| 87 | return node |
| 88 | |
| 89 | def compose_scalar_node(self, anchor): |
| 90 | event = self.get_event() |
| 91 | tag = event.tag |
| 92 | if tag is None or tag == '!': |
| 93 | tag = self.resolve(ScalarNode, event.value, event.implicit) |
| 94 | node = ScalarNode(tag, event.value, |
| 95 | event.start_mark, event.end_mark, style=event.style) |
| 96 | if anchor is not None: |
| 97 | self.anchors[anchor] = node |
| 98 | return node |
| 99 | |
| 100 | def compose_sequence_node(self, anchor): |
| 101 | start_event = self.get_event() |
| 102 | tag = start_event.tag |
| 103 | if tag is None or tag == '!': |
| 104 | tag = self.resolve(SequenceNode, None, start_event.implicit) |
| 105 | node = SequenceNode(tag, [], |
| 106 | start_event.start_mark, None, |
| 107 | flow_style=start_event.flow_style) |
| 108 | if anchor is not None: |
| 109 | self.anchors[anchor] = node |
| 110 | index = 0 |
| 111 | while not self.check_event(SequenceEndEvent): |
| 112 | node.value.append(self.compose_node(node, index)) |
| 113 | index += 1 |
| 114 | end_event = self.get_event() |
| 115 | node.end_mark = end_event.end_mark |
| 116 | return node |
| 117 | |
| 118 | def compose_mapping_node(self, anchor): |
| 119 | start_event = self.get_event() |
| 120 | tag = start_event.tag |
| 121 | if tag is None or tag == '!': |
| 122 | tag = self.resolve(MappingNode, None, start_event.implicit) |
| 123 | node = MappingNode(tag, [], |
| 124 | start_event.start_mark, None, |
| 125 | flow_style=start_event.flow_style) |
| 126 | if anchor is not None: |
| 127 | self.anchors[anchor] = node |
| 128 | while not self.check_event(MappingEndEvent): |
| 129 | #key_event = self.peek_event() |
| 130 | item_key = self.compose_node(node, None) |
| 131 | #if item_key in node.value: |
| 132 | # raise ComposerError("while composing a mapping", start_event.start_mark, |
| 133 | # "found duplicate key", key_event.start_mark) |
| 134 | item_value = self.compose_node(node, item_key) |
| 135 | #node.value[item_key] = item_value |
| 136 | node.value.append((item_key, item_value)) |
| 137 | end_event = self.get_event() |
| 138 | node.end_mark = end_event.end_mark |
| 139 | return node |
| 140 |