syntaxtree.py 49.1 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
# syntaxtree.py - syntax tree classes for DHParser
#
# Copyright 2016  by Eckhart Arnold (arnold@badw.de)
#                 Bavarian Academy of Sciences an Humanities (badw.de)
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.  See the License for the specific language governing
# permissions and limitations under the License.
17
18
19


"""
20
21
Module ``syntaxtree`` defines the ``Node``-class for syntax trees as well
as an abstract base class for parser-objects. The latter is defined
eckhart's avatar
eckhart committed
22
here, because node-objects refer to parser-objects. All concrete
23
24
25
parser classes are defined in the ``parse`` module.
"""

26
from collections import OrderedDict
eckhart's avatar
eckhart committed
27
import copy
28
import json
29
from typing import Callable, cast, Iterator, List, AbstractSet, Set, Union, Tuple, Optional, Dict
30

eckhart's avatar
eckhart committed
31
from DHParser.error import Error, ErrorCode, linebreaks, line_col
32
from DHParser.stringview import StringView
33
from DHParser.toolkit import get_config_value, re
di68kap's avatar
di68kap committed
34

35

di68kap's avatar
di68kap committed
36
__all__ = ('WHITESPACE_PTYPE',
37
           'TOKEN_PTYPE',
38
39
           'ZOMBIE_TAG',
           'PLACEHOLDER',
eckhart's avatar
eckhart committed
40
41
42
           'ResultType',
           'StrictResultType',
           'ChildrenType',
43
           'Node',
44
           'serialize',
45
           'FrozenNode',
46
           'tree_sanity_check',
di68kap's avatar
di68kap committed
47
           'RootNode',
48
           'parse_sxpr',
49
           'parse_xml',
eckhart's avatar
eckhart committed
50
           'parse_tree',
51
52
           'flatten_sxpr',
           'flatten_xml')
Eckhart Arnold's avatar
Eckhart Arnold committed
53
54


55
56
57
58
59
60
61
62
#######################################################################
#
# parser base and mock parsers
#
#######################################################################


WHITESPACE_PTYPE = ':Whitespace'
63
TOKEN_PTYPE = ':Token'
64

65
ZOMBIE_TAG = "__ZOMBIE__"
66

67
68
69
70
71
72
73
#######################################################################
#
# syntaxtree nodes
#
#######################################################################


74
def flatten_sxpr(sxpr: str, threshold: int = -1) -> str:
75
76
    """
    Returns S-expression ``sxpr`` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
77
78
    whitespace.

79
80
81
82
83
84
85
    The ``threshold`` value is a maximum number of
    characters allowed in the flattened expression. If this number
    is exceeded the the unflattened S-expression is returned. A
    negative number means that the S-expression will always be
    flattened. Zero or (any postive integer <= 3) essentially means
    that the expression will not be flattened.

Eckhart Arnold's avatar
Eckhart Arnold committed
86
    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
87
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
88
89
    '(a (b c))'
    """
90

91
92
93
94
    flat = re.sub(r'\s(?=\))', '', re.sub(r'\s+', ' ', sxpr)).strip()
    if threshold >= 0 and len(flat) > threshold:
        return sxpr.strip()
    return flat
Eckhart Arnold's avatar
Eckhart Arnold committed
95
96


97
def flatten_xml(xml: str) -> str:
98
99
    """
    Returns an XML-tree as a one liner without unnecessary whitespace,
100
    i.e. only whitespace within leaf-nodes is preserved.
101
102
    A more precise alternative to `flatten_xml` is to use Node.as_xml()
    ans passing a set containing the top level tag to parameter `inline_tags`.
103
    """
104

105
106
107
108
    # works only with regex
    # return re.sub(r'\s+(?=<\w)', '', re.sub(r'(?<=</\w+>)\s+', '', xml))
    def tag_only(m):
        return m.groupdict()['closing_tag']
109
    return re.sub(r'\s+(?=<[\w:])', '', re.sub(r'(?P<closing_tag></:?\w+>)\s+', tag_only, xml))
110
111


112
113
114
115
116
ChildrenType = Tuple['Node', ...]
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
StrictResultType = Union[ChildrenType, StringView, str]
ResultType = Union[ChildrenType, 'Node', StringView, str, None]

eckhart's avatar
eckhart committed
117
RX_AMP = re.compile(r'&(?!\w+;)')
118
119


Eckhart Arnold's avatar
Eckhart Arnold committed
120
class Node:  # (collections.abc.Sized): Base class omitted for cython-compatibility
121
122
123
    """
    Represents a node in the concrete or abstract syntax tree.

124
125
    TODO: Add some documentation and doc-tests here...

126
    Attributes:
127
128
        tag_name (str):  The name of the node, which is either its
            parser's name or, if that is empty, the parser's class name
129

130
131
132
        result (str or tuple):  The result of the parser which
            generated this node, which can be either a string or a
            tuple of child nodes.
133

134
135
        children (tuple):  The tuple of child nodes or an empty tuple
            if there are no child nodes. READ ONLY!
136

eckhart's avatar
eckhart committed
137
138
139
140
        content (str):  Yields the contents of the tree as string. The
            difference to ``str(node)`` is that ``node.content`` does
            not add the error messages to the returned string.

Eckhart Arnold's avatar
Eckhart Arnold committed
141
        parser (Parser):  The parser which generated this node.
142
143
            WARNING: In case you use mock syntax trees for testing or
            parser replacement during the AST-transformation: DO NOT
Eckhart Arnold's avatar
Eckhart Arnold committed
144
145
            rely on this being a real parser object in any phase after
            parsing (i.e. AST-transformation and compiling), for
146
            example by calling ``isinstance(node.parer, ...)``.
147

148
149
150
        len (int):  The full length of the node's string result if the
            node is a leaf node or, otherwise, the concatenated string
            result's of its descendants. The figure always represents
151
            the length before AST-transformation and will never change
152
            through AST-transformation. READ ONLY!
153

154
155
        pos (int):  the position of the node within the parsed text.

Eckhart Arnold's avatar
Eckhart Arnold committed
156
            The value of ``pos`` is -1 meaning invalid by default.
157
            Setting this value will set the positions of all child
Eckhart Arnold's avatar
Eckhart Arnold committed
158
            nodes relative to this value.
159
160

            To set the pos values of all nodes in a syntax tree, the
Eckhart Arnold's avatar
Eckhart Arnold committed
161
            pos value of the root node should be set to 0 right
162
163
            after parsing.

Eckhart Arnold's avatar
Eckhart Arnold committed
164
            Other than that, this value should be considered READ ONLY.
165
166
            At any rate, it should only be reassigned during the parsing
            stage and never during or after the AST-transformation.
167

168
169
        attr (dict): An optional dictionary of XML-attr. This
            dictionary is created lazily upon first usage. The attr
170
171
            will only be shown in the XML-Representation, not in the
            S-Expression-output.
172
    """
173

174
    __slots__ = '_result', 'children', '_pos', 'tag_name', '_xml_attr'
175

176
    def __init__(self, tag_name: str, result: ResultType, leafhint: bool = False) -> None:
177
178
        """
        Initializes the ``Node``-object with the ``Parser``-Instance
179
180
        that generated the node and the parser's result.
        """
eckhart's avatar
eckhart committed
181
        self._pos = -1                  # type: int
182
        # Assignment to self.result initializes the attr _result, children and _len
di68kap's avatar
di68kap committed
183
        # The following if-clause is merely an optimization, i.e. a fast-path for leaf-Nodes
184
        if leafhint:
eckhart's avatar
eckhart committed
185
            self._result = result       # type: StrictResultType  # cast(StrictResultType, result)
186
187
188
            self.children = NoChildren  # type: ChildrenType
        else:
            self.result = result
189
        self.tag_name = tag_name        # type: str
190

eckhart's avatar
eckhart committed
191
192
    def __deepcopy__(self, memo):
        if self.children:
193
            duplicate = self.__class__(self.tag_name, copy.deepcopy(self.children), False)
eckhart's avatar
eckhart committed
194
        else:
195
            duplicate = self.__class__(self.tag_name, self.result, True)
eckhart's avatar
eckhart committed
196
        duplicate._pos = self._pos
eckhart's avatar
eckhart committed
197
        if self.attr_active():
di68kap's avatar
di68kap committed
198
199
            duplicate.attr.update(copy.deepcopy(self._xml_attr))
            # duplicate._xml_attr = copy.deepcopy(self._xml_attr)  # this is not cython compatible
eckhart's avatar
eckhart committed
200
        return duplicate
Eckhart Arnold's avatar
Eckhart Arnold committed
201

202
    def __str__(self):
203
204
        if isinstance(self, RootNode):
            root = cast(RootNode, self)
205
            errors = root.errors_sorted
206
207
            if errors:
                e_pos = errors[0].pos
Eckhart Arnold's avatar
Eckhart Arnold committed
208
209
                content = self.content
                return content[:e_pos] + \
210
                   ' <<< Error on "%s" | %s >>> ' % \
Eckhart Arnold's avatar
Eckhart Arnold committed
211
                   (content[e_pos - self.pos:], '; '.join(e.message for e in errors))
212
        return self.content
Eckhart Arnold's avatar
Eckhart Arnold committed
213

214
    def __repr__(self):
215
        # mpargs = {'name': self.parser.name, 'ptype': self.parser.ptype}
216
217
        # name, ptype = (self._tag_name.split(':') + [''])[:2]
        # parg = "MockParser({name}, {ptype})".format(name=name, ptype=ptype)
218
        rarg = str(self) if not self.children else \
219
            "(" + ", ".join(child.__repr__() for child in self.children) + ")"
220
        return "Node(%s, %s)" % (self.tag_name, rarg)
221

Eckhart Arnold's avatar
Eckhart Arnold committed
222

223
    def __len__(self):
224
225
        return (sum(len(child) for child in self.children)
                if self.children else len(self._result))
226
227
228


    def __bool__(self):
229
230
231
232
        """Returns the bool value of a node, which is always True. The reason
        for this is that a boolean test on a variable that can contain a node
        or None will only yield `False` in case of None.
        """
233
234
235
        return True


236
    def __hash__(self):
237
        return hash(self.tag_name)
238

Eckhart Arnold's avatar
Eckhart Arnold committed
239

240
241
242
    def __getitem__(self, index_or_tagname: Union[int, str]) -> Union['Node', Iterator['Node']]:
        """
        Returns the child node with the given index if ``index_or_tagname`` is
243
        an integer or the first child node with the given tag name. Examples::
244

245
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
246
247
            >>> flatten_sxpr(tree[0].as_sxpr())
            '(b "X")'
248
249
            >>> flatten_sxpr(tree["X"].as_sxpr())
            '(X (c "d"))'
250
251
252
253

        Args:
            index_or_tagname(str): Either an index of a child node or a
                tag name.
254
        Returns:
255
256
            Node: All nodes which have a given tag name.
        """
257
258
259
        if self.children:
            if isinstance(index_or_tagname, int):
                return self.children[index_or_tagname]
260
            else:
261
262
263
264
265
                for child in self.children:
                    if child.tag_name == index_or_tagname:
                        return child
                raise KeyError(index_or_tagname)
        raise ValueError('Leave nodes have no children that can be indexed!')
266
267
268
269


    def __contains__(self, tag_name: str) -> bool:
        """
270
        Returns true if a child with the given tag name exists.
271
        Args:
272
273
            tag_name (str): tag_name which will be searched among to immediate
                descendants of this node.
274
275
276
277
        Returns:
            bool:  True, if at least one descendant node with the given tag
                name exists, False otherwise
        """
278
279
280
281
282
        # assert isinstance(tag_name, str)
        if self.children:
            for child in self.children:
                if child.tag_name == tag_name:
                    return True
283
            return False
284
        raise ValueError('Leave node cannot contain other nodes')
285
286


287
    def equals(self, other: 'Node') -> bool:
288
        """
289
290
291
292
293
294
        Equality of value: Two nodes are considered as having the same value,
        if their tag name is the same, if their results are equal and
        if their attributes and attribute values are the same.

        Returns True, if the tree originating in node `self` is equal by
        value to the tree originating in node `other`.
295
296
297
298
299
300
301
302
303
304
        """
        if self.tag_name == other.tag_name and self.compare_attr(other):
            if self.children:
                return (len(self.children) == len(other.children)
                        and all(a.equals(b) for a, b in zip(self.children, other.children)))
            else:
                return self.result == other.result
        return False


305
306
307
308
309
310
311
312
313
314
315
316
317
318
    def get(self, index_or_tagname: Union[int, str],
            surrogate: Union['Node', Iterator['Node']]) -> Union['Node', Iterator['Node']]:
        """Returns the child node with the given index if ``index_or_tagname``
        is an integer or the first child node with the given tag name. If no
        child with the given index or tag_name exists, the ``surrogate`` is
        returned instead. This mimics the behaviour of Python's dictionary's
        get-method.
        """
        try:
            return self[index_or_tagname]
        except KeyError:
            return surrogate


319
    def is_anonymous(self) -> bool:
Eckhart Arnold's avatar
Eckhart Arnold committed
320
        return not self.tag_name or self.tag_name[0] == ':'
321

Eckhart Arnold's avatar
Eckhart Arnold committed
322

323
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
324
    def result(self) -> StrictResultType:
325
326
327
328
329
        """
        Returns the result from the parser that created the node.
        Error messages are not included in the result. Use `self.content()`
        if the result plus any error messages is needed.
        """
330
331
        return self._result

332

333
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
334
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
335
        # # made obsolete by static type checking with mypy
Eckhart Arnold's avatar
Eckhart Arnold committed
336
337
338
339
        assert ((isinstance(result, tuple) and all(isinstance(child, Node) for child in result))
                or isinstance(result, Node)
                or isinstance(result, str)
                or isinstance(result, StringView)), "%s (%s)" % (str(result), str(type(result)))
Eckhart Arnold's avatar
Eckhart Arnold committed
340
341
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
342
        # self._content = None
343
344
345
346
347
348
349
350
351
        if isinstance(result, Node):
            self.children = (result,)
            self._result = self.children
        else:
            if isinstance(result, tuple):
                self.children = result
                self._result = result or ''
            else:
                self.children = NoChildren
eckhart's avatar
eckhart committed
352
                self._result = result  # cast(StrictResultType, result)
353

354

355
356
357
358
359
360
361
362
363
364
365
366
    def _content(self) -> List[str]:
        """
        Returns string content as list of string fragments
        that are gathered from all child nodes in order.
        """
        if self.children:
            fragments = []
            for child in self.children:
                fragments.extend(child._content())
            return fragments
        self._result = str(self._result)
        return [self._result]
367

368

369
    @property
eckhart's avatar
eckhart committed
370
    def content(self) -> str:
371
        """
372
373
374
        Returns content as string. If the node has child-nodes, the
        string content of the child-nodes is recursively read and then
        concatenated.
375
        """
376
377
378
379
380
381
382
383
        if self.children:
            fragments = []
            for child in self.children:
                fragments.extend(child._content())
            return ''.join(fragments)
        self._result = str(self._result)
        return self._result
        # unoptimized
Eckhart Arnold's avatar
Eckhart Arnold committed
384
385
        # return "".join(child.content for child in self.children) if self.children \
        #     else str(self._result)
di68kap's avatar
di68kap committed
386
387


388
389
390
391
392
393
    @property
    def structure(self) -> str:
        """
        Return structure (and content) as S-expression on a single line
        without any line breaks.
        """
394
        return flatten_sxpr(self.as_sxpr())
395
396


397
    @property
398
    def pos(self) -> int:
eckhart's avatar
eckhart committed
399
400
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
Eckhart Arnold's avatar
Eckhart Arnold committed
401
            raise AssertionError("Position value not initialized! Use Node.with_pos()")
402
403
        return self._pos

eckhart's avatar
eckhart committed
404

Eckhart Arnold's avatar
Eckhart Arnold committed
405
    def with_pos(self, pos: int) -> 'Node':
eckhart's avatar
eckhart committed
406
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
407
        Initialize position value. Usually, the parser guard
eckhart's avatar
eckhart committed
408
409
        (`parsers.add_parser_guard()`) takes care of assigning the
        position in the document to newly created nodes. However,
Eckhart Arnold's avatar
Eckhart Arnold committed
410
        when Nodes are created outside the reach of the parser
eckhart's avatar
eckhart committed
411
        guard, their document-position must be assigned manually.
Eckhart Arnold's avatar
Eckhart Arnold committed
412
413
        Position values of the child nodes are assigned recursively, too.
        Returns the node itself for convenience.
eckhart's avatar
eckhart committed
414
        """
415
416
417
418
        # condition self.pos == pos cannot be assumed when tokens or whitespace
        # are dropped early!
        # assert self._pos < 0 or self.pos == pos, ("pos mismatch %i != %i at Node: %s"
        #                                           % (self._pos, pos, repr(self)))
Eckhart Arnold's avatar
Eckhart Arnold committed
419
420
421
422
423
424
425
426
427
428
        if pos != self._pos >= 0:
            raise AssertionError("Position value cannot be reassigned to a different value!")
        if self._pos < 0:
            self._pos = pos
            # recursively adjust pos-values of all children
            offset = self.pos
            for child in self.children:
                if child._pos < 0:
                    child.with_pos(offset)
                offset = child.pos + len(child)
eckhart's avatar
eckhart committed
429
430
        return self

431

432
433
434
435
436
437
438
439
440
441
442
443
444
    @property
    def attr(self):
        """
        Returns a dictionary of XML-attr attached to the node.
        """
        try:
            if self._xml_attr is None:          # cython compatibility
                self._xml_attr = OrderedDict()
        except AttributeError:
            self._xml_attr = OrderedDict()
        return self._xml_attr


eckhart's avatar
eckhart committed
445
446
447
448
449
450
451
452
453
454
455
456
457
    def attr_active(self) -> bool:
        """
        Returns True, if XML-Attributes of this node have ever been set
        or queried, even if unsuccessfully.
        """
        try:
            if self._xml_attr is not None:
                return True
        except AttributeError:
            pass
        return False


458
    def compare_attr(self, other: 'Node') -> bool:
459
        """
460
461
        Returns True, if `self` and `other` have the same attributes with the
        same attribute values.
462
        """
463
464
465
466
467
468
469
470
471
        if self.attr_active():
            if other.attr_active():
                return self.attr == other.attr
            return len(self.attr) == 0
            # self has empty dictionary and other has no attributes
        elif other.attr_active():
            return len(other.attr) == 0
            # other has empty attribute dictionary and self as no attributes
        return True  # neither self nor other have any attributes
472

Eckhart Arnold's avatar
Eckhart Arnold committed
473

474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
    def select(self, match_function: Callable, include_root: bool = False, reverse: bool = False) \
            -> Iterator['Node']:
        """
        Finds nodes in the tree that fulfill a given criterion.

        `select` is a generator that yields all nodes for which the
        given `match_function` evaluates to True. The tree is
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.

        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
            reverse (bool): If True, the tree will be walked in reverse
                order, i.e. last children first.
        Yields:
            Node: All nodes of the tree for which
            ``match_function(node)`` returns True
        """
        if include_root and match_function(self):
            yield self
        child_iterator = reversed(self.children) if reverse else self.children
        for child in child_iterator:
            if match_function(child):
                yield child
            yield from child.select(match_function, False, reverse)
        # The above variant is slightly faster
        # for child in child_iterator:
        #     yield from child.select(match_function, True, reverse)


    def select_by_tag(self, tag_names: Union[str, AbstractSet[str]],
                      include_root: bool = False) -> Iterator['Node']:
        """
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::

            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
            ['(X (c "d"))', '(X "F")']
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
            ['(b "X")', '(X (c "d"))', '(X "F")']
            >>> any(tree.select_by_tag('a', False))
            False
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
            ['(a (b "X") (X (c "d")) (e (X "F")))']
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'

        Args:
            tag_name(set): A tag name or set of tag names that is being
                searched for
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
        Yields:
            Node: All nodes which have a given tag name.
        """
        if isinstance(tag_names, str):
            tag_names = frozenset({tag_names})
        return self.select(lambda node: node.tag_name in tag_names, include_root)


    def pick(self, tag_names: Union[str, Set[str]]) -> Optional['Node']:
        """
        Picks the first descendant with one of the given tag_names.

        This function is mostly just syntactic sugar for
        ``next(node.select_by_tag(tag_names, False))``. However, rather than
        raising a StopIterationError if no descendant with the given tag-name
        exists, it returns None.
        """
        try:
            return next(self.select_by_tag(tag_names, False))
        except StopIteration:
            return None


    def tree_size(self) -> int:
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
        return sum(child.tree_size() for child in self.children) + 1

    #
    # serialization methods
    #

566
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i,
567
                   density=0, inline=False, inline_fn=lambda node: False) -> str:
568
569
570
571
572
573
574
575
        """
        Generates a tree representation of this node and its children
        in string from.

        The kind ot tree-representation that is determined by several
        function parameters. This could be an XML-representation or a
        lisp-like S-expression.

576
        Args:
577
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
578
            open_fn:   (Node->str) A function that returns an opening
579
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
580
            close_fn:  (Node->str) A function that returns a closeF
581
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
582
            data_fn:   (str->str) A function that filters the data string
583
584
585
586
587
588
                before printing, e.g. to add quotation marks

        Returns (str):
            A string that contains a (serialized) tree representation
            of the node and its children.
        """
eckhart's avatar
eckhart committed
589
590
        head = open_fn(self)
        tail = close_fn(self)
591
592

        if not self.result:
593
            return head.rstrip() + tail.lstrip()
594

eckhart's avatar
eckhart committed
595
        tail = tail.lstrip(None if density & 2 else '')
596

597
        inline = inline or inline_fn(self)
598
599
600
601
602
        if inline:
            head = head.rstrip()
            tail = tail.lstrip()
            usetab, sep = '', ''
        else:
eckhart's avatar
eckhart committed
603
604
            usetab = tab if head else ''    # no indentation if tag is already omitted
            sep = '\n'
605

606
607
        if self.children:
            content = []
608
            for child in self.children:
609
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn,
610
                                           density, inline, inline_fn)
eckhart's avatar
eckhart committed
611
                if subtree:
eckhart's avatar
eckhart committed
612
613
                    st = [subtree] if inline else subtree.split('\n')
                    content.append((sep + usetab).join(s for s in st))
614
            return head + usetab + (sep + usetab).join(content) + tail
615

eckhart's avatar
eckhart committed
616
        res = self.content
eckhart's avatar
eckhart committed
617
        if not inline and not head:
eckhart's avatar
eckhart committed
618
            # strip whitespace for omitted non inline node, e.g. CharData in mixed elements
eckhart's avatar
eckhart committed
619
            res = res.strip()
620
621
        if density & 1 and res.find('\n') < 0:  # and head[0] == "<":
            # except for XML, add a gap between opening statement and content
622
            gap = ' ' if not inline and head and head.rstrip()[-1:] != '>' else ''
eckhart's avatar
eckhart committed
623
            return head.rstrip() + gap + data_fn(res) + tail.lstrip()
624
        else:
625
            return head + '\n'.join([usetab + data_fn(s) for s in res.split('\n')]) + tail
626

Eckhart Arnold's avatar
Eckhart Arnold committed
627

628
629
    def as_sxpr(self, src: str = None,
                indentation: int = 2,
630
631
                compact: bool = False,
                flatten_threshold: int = 0) -> str:
632
        """
633
634
        Returns content as S-expression, i.e. in lisp-like form. If this
        method is callad on a RootNode-object,
635

636
        Args:
637
638
639
            src:  The source text or `None`. In case the source text is
                given the position of the element in the text will be
                reported as line and column.
640
641
            indentation: The number of whitespaces for indentation
            compact:  If True, a compact representation is returned where
642
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
643
                tree structure.
644
645
646
            flatten_threshold:  Return the S-expression in flattened form if
                the flattened expression does not exceed the threshold length.
                A negative number means that it will always be flattened.
647
648
        """

eckhart's avatar
eckhart committed
649
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
eckhart's avatar
eckhart committed
650
        lbreaks = linebreaks(src) if src else []  # type: List[int]
651
        root = cast(RootNode, self) if isinstance(self, RootNode) else None  # type: Optional[RootNode]
652

653
        def opening(node: Node) -> str:
eckhart's avatar
eckhart committed
654
            """Returns the opening string for the representation of `node`."""
eckhart's avatar
eckhart committed
655
            txt = [left_bracket, node.tag_name]
656
            # s += " '(pos %i)" % node.add_pos
657
            # txt.append(str(id(node)))  # for debugging
eckhart's avatar
eckhart committed
658
            if node.attr_active():
659
                txt.extend(' `(%s "%s")' % (k, v) for k, v in node.attr.items())
660
            if src:
661
662
                line, col = line_col(lbreaks, node.pos)
                txt.append(" `(pos %i %i %i)" % (node.pos, line, col))
663
664
            if root and id(node) in root.error_nodes:
                txt.append(" `(err `%s)" % ' '.join(str(err) for err in root.get_errors(node)))
665
            return "".join(txt) + '\n'
666

667
        def closing(node: Node) -> str:
eckhart's avatar
eckhart committed
668
669
            """Returns the closing string for the representation of `node`."""
            return right_bracket
670

671
        def pretty(strg: str) -> str:
eckhart's avatar
eckhart committed
672
673
674
675
            """Encloses `strg` with the right kind of quotation marks."""
            return '"%s"' % strg if strg.find('"') < 0 \
                else "'%s'" % strg if strg.find("'") < 0 \
                else '"%s"' % strg.replace('"', r'\"')
676

677
678
        sxpr = self._tree_repr(' ' * indentation, opening, closing, pretty, density=density)
        return flatten_sxpr(sxpr, flatten_threshold)
Eckhart Arnold's avatar
Eckhart Arnold committed
679

eckhart's avatar
eckhart committed
680

681
682
    def as_xml(self, src: str = None,
               indentation: int = 2,
eckhart's avatar
eckhart committed
683
684
685
               inline_tags: Set[str] = set(),
               omit_tags: Set[str] = set(),
               empty_tags: Set[str] = set()) -> str:
686
687
688
        """
        Returns content as XML-tree.

689
        Args:
690
691
692
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
693
            indentation: The number of whitespaces for indentation
694
695
696
            inline_tags:  A set of tag names, the content of which will always be written
                on a single line, unless it contains explicit line feeds ('\n').
            omit_tags:  A set of tags from which only the content will be printed, but
697
                neither the opening tag nor its attr nor the closing tag. This
698
699
700
                allows producing a mix of plain text and child tags in the output,
                which otherwise is not supported by the Node object, because it
                requires its content to be either a tuple of children or string content.
701
702
            empty_tags:  A set of tags which shall be rendered as empty elements, e.g.
                "<empty/>" instead of "<empty><empty>".
703
        """
704
        root = cast(RootNode, self) if isinstance(self, RootNode) else None  # type: Optional[RootNode]
705

706
        def opening(node: Node) -> str:
707
708
709
            """Returns the opening string for the representation of `node`."""
            if node.tag_name in omit_tags:
                return ''
eckhart's avatar
eckhart committed
710
            txt = ['<', node.tag_name]
eckhart's avatar
eckhart committed
711
            has_reserved_attrs = node.attr_active() \
eckhart's avatar
eckhart committed
712
                and any(r in node.attr for r in {'err', 'line', 'col'})
eckhart's avatar
eckhart committed
713
            if node.attr_active():
714
                txt.extend(' %s="%s"' % (k, v) for k, v in node.attr.items())
715
            if src and not has_reserved_attrs:
eckhart's avatar
eckhart committed
716
                txt.append(' line="%i" col="%i"' % line_col(line_breaks, node.pos))
717
            if root and id(node) in root.error_nodes and not has_reserved_attrs:
eckhart's avatar
eckhart committed
718
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
eckhart's avatar
eckhart committed
719
                                                 for err in root.get_errors(node)))
720
721
722
            if node.tag_name in empty_tags:
                assert not node.result, ("Node %s with content %s is not an empty element!" %
                                         (node.tag_name, str(node)))
eckhart's avatar
eckhart committed
723
                ending = "/>\n" if not node.tag_name[0] == '?' else "?>\n"
724
725
726
            else:
                ending = ">\n"
            return "".join(txt + [ending])
727

728
        def closing(node: Node):
729
            """Returns the closing string for the representation of `node`."""
730
            if node.tag_name in omit_tags or node.tag_name in empty_tags:
731
                return ''
732
            return ('\n</') + node.tag_name + '>'
733

734
735
736
737
738
739
        def sanitizer(content: str) -> str:
            """Substitute "&", "<", ">" in XML-content by the respective entities."""
            content = RX_AMP.sub('&amp;', content)
            content = content.replace('<', '&lt;').replace('>', '&gt;')
            return content

740
        def inlining(node: Node):
741
742
743
744
            """Returns True, if `node`'s tag name is contained in `inline_tags`,
            thereby signalling that the children of this node shall not be
            printed on several lines to avoid unwanted gaps in the output.
            """
eckhart's avatar
eckhart committed
745
            return node.tag_name in inline_tags \
eckhart's avatar
eckhart committed
746
                or (node.attr_active()
eckhart's avatar
eckhart committed
747
                    and node.attr.get('xml:space', 'default') == 'preserve')
748

749
        line_breaks = linebreaks(src) if src else []
750
        return self._tree_repr(' ' * indentation, opening, closing, sanitizer,
751
                               density=1, inline_fn=inlining)
752

Eckhart Arnold's avatar
Eckhart Arnold committed
753

754
    def to_json_obj(self) -> Dict:
755
        """Seralize a node or tree as json-object"""
756
757
758
759
760
761
762
763
764
        data = [ self.tag_name,
                [child.to_json_obj() for child in self.children] if self.children
                else str(self._result)]
        has_attr = self.attr_active()
        if self._pos >= 0 or has_attr:
            data.append(self._pos)
        if has_attr:
            data.append(dict(self._xml_attr))
        return { '__class__': 'DHParser.Node', 'data': data }
765
766


767
768
    @staticmethod
    def from_json_obj(json_obj: Dict) -> 'Node':
769
770
771
772
773
774
        """Convert a json object representing a node (or tree) back into a
        Node object. Raises a ValueError, if `json_obj` does not represent
        a node."""
        if json_obj.get('__class__', '') != 'DHParser.Node':
            raise ValueError('JSON object: ' + str(json_obj) +
                             ' does not represent a Node object.')
775
        tag_name, result, pos, attr = (json_obj['data'] + [-1, None])[:4]
776
        if isinstance(result, str):
777
778
779
780
781
782
783
            leafhint = True
        else:
            leafhint = False
            result = tuple(Node.from_json_obj(child) for child in result)
        node = Node(tag_name, result, leafhint)
        node._pos = pos
        if attr:
784
            node.attr.update(attr)
785
        return node
786

787
788
789
790
    def as_json(self, indent: Optional[int] = 2, ensure_ascii=False) -> str:
        return json.dumps(self.to_json_obj(), indent=indent, ensure_ascii=ensure_ascii,
                          separators=(', ', ': ') if indent is not None else (',', ':'))

791

792
793
def serialize(node: Node, how: str='default') -> str:
    """
794
    Serializes the tree starting with `node` either as S-expression, XML, JSON,
795
    or in compact form. Possible values for `how` are 'S-expression',
796
    'XML', 'JSON', 'compact' accordingly, or 'AST', 'CST', 'default' in which case
797
798
799
800
801
802
803
804
805
806
807
808
809
    the value of respective configuration variable determines the
    serialization format. (See module `configuration.py`.)
    """
    switch = how.lower()

    if switch == 'ast':
        switch = get_config_value('ast_serialization').lower()
    elif switch == 'cst':
        switch = get_config_value('cst_serialization').lower()
    elif switch == 'default':
        switch = get_config_value('default_serialization').lower()

    if switch == 's-expression':
810
        return node.as_sxpr(flatten_threshold=get_config_value('flatten_sxpr_threshold'))
811
812
    elif switch == 'xml':
        return node.as_xml()
813
814
    elif switch == 'json':
        return node.as_json()
815
816
817
818
819
820
    elif switch == 'compact':
        return node.as_sxpr(compact=True)
    else:
        raise ValueError('Unknown serialization %s, %s' % (how, switch))


821
class FrozenNode(Node):
822
823
824
825
826
827
828
829
830
831
    """
    FrozenNode is an immutable kind of Node, i.e. it must not be changed
    after initialization. The purpose is mainly to allow certain kinds of
    optimization, like not having to instantiate empty nodes (because they
    are always the same and will be dropped while parsing, anyway).

    Frozen nodes must be used only temporarily during parsing or
    tree-transformation and should not occur in the product of the
    transformation any more. This can be verified with `tree_sanity_check()`.
    """
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848

    def __init__(self, tag_name: str, result: ResultType) -> None:
        if isinstance(result, str) or isinstance(result, StringView):
            result = str(result)
        else:
            raise TypeError('FrozenNode only accepts string as results. '
                            '(Only leaf-nodes can be frozen nodes.)')
        super(FrozenNode, self).__init__(tag_name, result, True)

    @property
    def result(self) -> StrictResultType:
        return self._result

    @result.setter
    def result(self, result: ResultType):
        raise TypeError('FrozenNode does not allow re-assignment of results.')

eckhart's avatar
eckhart committed
849
850
851
852
    @property
    def attr(self):
        raise AssertionError("Attributes cannot be accessed on a frozen node")

Eckhart Arnold's avatar
Eckhart Arnold committed
853
    def with_pos(self, pos: int) -> 'Node':
854
855
856
        pass


857
PLACEHOLDER = FrozenNode('__PLACEHOLDER__', '')
di68kap's avatar
di68kap committed
858
859


860
def tree_sanity_check(tree: Node) -> bool:
861
862
863
864
865
866
867
868
869
    """
    Sanity check for syntax trees: One and the same node must never appear
    twice in the syntax tree. Frozen Nodes (EMTPY_NODE, PLACEHOLDER)
    should only exist temporarily and must have been dropped or eliminated
    before any kind of tree generation (i.e. parsing) or transformation
    is finished.
    :param tree: the root of the tree to be checked
    :return: True, if the tree is `sane`, False otherwise.
    """
870
    node_set = set()  # type: Set[Node]
871
    for node in tree.select(lambda nd: True, include_root=True):
872
        if node in node_set or isinstance(Node, FrozenNode):
873
874
875
876
877
            return False
        node_set.add(node)
    return True


di68kap's avatar
di68kap committed
878
class RootNode(Node):
879
880
881
882
883
884
885
886
887
888
889
890
    """The root node for the syntax tree is a special kind of node that keeps
    and manages global properties of the tree as a whole. These are first and
    foremost the list off errors that occurred during tree generation
    (i.e. parsing) or any transformation of the tree. Other properties concern
    the customization of the XML-serialization.

    The root node can be instantiated before the tree is fully parsed. This is
    necessary, because the root node is needed for managing error messages
    during the parsing process, already. In order to connect the root node to
    the tree, when parsing is finished, the swallow()-method must be called.

        errors (list):  A list of all errors that have occurred so far during
891
892
                processing (i.e. parsing, AST-transformation, compiling)
                of this tree.
di68kap's avatar
di68kap committed
893

894
895
896
897
898
899
        error_nodes (dict): A mapping of node-ids to a list of errors that
                occurred on the node with the respective id.

        error_positions (dict): A mapping of locations to a set of ids of
                nodes that contain an error at that particular location

900
901
        error_flag (int):  the highest warning or error level of all errors
                that occurred.
902
903
904
905
906
907

        inline_tags (set of strings): see `Node.as_xml()` for an explanation.

        omit_tags (set of strings): see `Node.as_xml()` for an explanation.

        empty_tags (set oif strings): see `Node.as_xml()` for an explanation.
di68kap's avatar
di68kap committed
908
    """
909

eckhart's avatar
eckhart committed
910
    def __init__(self, node: Optional[Node] = None):
911
        super().__init__('__not_yet_ready__', '')
912
        self.errors = []               # type: List[Error]
913
914
        self.error_nodes = dict()      # type: Dict[int, List[Error]]  # id(node) -> error list
        self.error_positions = dict()  # type: Dict[int, Set[int]]  # pos -> set of id(node)
di68kap's avatar
di68kap committed
915
        self.error_flag = 0
eckhart's avatar
eckhart committed
916
917
        if node is not None:
            self.swallow(node)
918
        # customization for XML-Representation
eckhart's avatar
eckhart committed
919
        self.inline_tags = set()  # type: Set[str]
920
921
        self.omit_tags = set()    # type: Set[str]
        self.empty_tags = set()   # type: Set[str]
di68kap's avatar
di68kap committed
922

923
924
925
926
927
928
929
930
931
    def __deepcopy__(self, memodict={}):
        duplicate = self.__class__(None)
        if self.children:
            duplicate.children = copy.deepcopy(self.children)
            duplicate._result = duplicate.children
        else:
            duplicate.children = NoChildren
            duplicate._result = self._result
        duplicate._pos = self._pos
eckhart's avatar
eckhart committed
932
        if self.attr_active():
di68kap's avatar
di68kap committed
933
            duplicate.attr.update(copy.deepcopy(self._xml_attr))
934
            # duplicate._xml_attr = copy.deepcopy(self._xml_attr)  # this is blocked by cython
935
        duplicate.errors = copy.copy(self.errors)
936
937
        duplicate.error_nodes = copy.copy(self.error_nodes)
        duplicate.error_positions = copy.deepcopy(self.error_positions)
938
939
940
941
        duplicate.error_flag = self.error_flag
        duplicate.inline_tags = self.inline_tags
        duplicate.omit_tags = self.omit_tags
        duplicate.empty_tags = self.empty_tags
942
        duplicate.tag_name = self.tag_name
943
944
945
        return duplicate


946
    def swallow(self, node: Node) -> 'RootNode':
947
948
        """
        Put `self` in the place of `node` by copying all its data.
949
950
951
952
953
954
955
956
957
        Returns self.

        This is done by the parse.Grammar object after
        parsing has finished, so that the Grammar object always
        returns a syntax tree rooted in a RootNode object.

        It is possible to add errors to a RootNode object, before it
        has actually swallowed the root of the syntax tree.
        """
di68kap's avatar
di68kap committed
958
959
960
        self._result = node._result
        self.children = node.children
        self._pos = node._pos
961
        self.tag_name = node.tag_name
eckhart's avatar
eckhart committed
962
        if node.attr_active():
963
            self._xml_attr = node._xml_attr
964
        # self._content = node._content
965
966
        if id(node) in self.error_nodes:
            self.error_nodes[id(self)] = self.error_nodes[id(node)]
967
        return self
di68kap's avatar
di68kap committed
968

969
    def add_error(self, node: Optional[Node], error: Error) -> 'RootNode':
970
971
972
        """
        Adds an Error object to the tree, locating it at a specific node.
        """
973
974
        if not node:
            node = Node(ZOMBIE_TAG, '').with_pos(error.pos)
975
        assert node.pos == error.pos or isinstance(node, FrozenNode)
976
        self.error_nodes.setdefault(id(node), []).append(error)
977
        self.error_positions.setdefault(error.pos, set()).add(id(node))
978
979
        self.errors.append(error)
        self.error_flag = max(self.error_flag, error.code)
di68kap's avatar
di68kap committed
980
981
        return self

eckhart's avatar
eckhart committed
982
    def new_error(self,
983
                  node: Node,
di68kap's avatar
di68kap committed
984
                  message: str,
eckhart's avatar
eckhart committed
985
                  code: ErrorCode = Error.ERROR) -> 'RootNode':
di68kap's avatar
di68kap committed
986
        """
eckhart's avatar
eckhart committed
987
        Adds an error to this tree, locating it at a specific node.
di68kap's avatar
di68kap committed
988
989
990
991
992
        Parameters:
            pos(int):     The position of the error in the source text
            message(str): A string with the error message.abs
            code(int):    An error code to identify the kind of error
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
993
        error = Error(message, node.pos, code)
eckhart's avatar
eckhart committed
994
995
        self.add_error(node, error)
        return self
di68kap's avatar
di68kap committed
996

997
998
    def get_errors(self, node: Node) -> List[Error]:
        """