syntaxtree.py 36 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

Eckhart Arnold's avatar
Eckhart Arnold committed
27
import collections.abc
28
from collections import OrderedDict
29
import copy
30

31
from DHParser.error import Error, linebreaks, line_col
32
from DHParser.stringview import StringView
eckhart's avatar
eckhart committed
33
from DHParser.toolkit import re, typing
eckhart's avatar
eckhart committed
34
from typing import Callable, cast, Iterator, List, AbstractSet, Set, Union, Tuple, Optional
di68kap's avatar
di68kap committed
35

36

37
38
__all__ = ('ParserBase',
           'WHITESPACE_PTYPE',
di68kap's avatar
di68kap committed
39
           'PLAINTEXT_PTYPE',
40
41
42
43
           'TOKEN_PTYPE',
           'MockParser',
           'ZombieParser',
           'ZOMBIE_PARSER',
eckhart's avatar
eckhart committed
44
           'ZOMBIE_NODE',
45
           'Node',
di68kap's avatar
di68kap committed
46
           'RootNode',
47
           'parse_sxpr',
48
49
50
           'parse_xml',
           'flatten_sxpr',
           'flatten_xml')
Eckhart Arnold's avatar
Eckhart Arnold committed
51
52


53
54
55
56
57
58
59
60
61
62
63
64
65
66
#######################################################################
#
# parser base and mock parsers
#
#######################################################################


class ParserBase:
    """
    ParserBase is the base class for all real and mock parser classes.
    It is defined here, because Node objects require a parser object
    for instantiation.
    """
    def __init__(self, name=''):  # , pbases=frozenset()):
67
        self._name = name  # type: str
68
69
70
        self._ptype = ':' + self.__class__.__name__  # type: str

    def __repr__(self):
di68kap's avatar
di68kap committed
71
         return self.name + self.ptype
72
73
74
75

    def __str__(self):
        return self.name + (' = ' if self.name else '') + repr(self)

76
77
78
    def __call__(self, text: StringView) -> Tuple[Optional['Node'], StringView]:
        return None, text

79
80
    @property
    def name(self):
81
82
        """Returns the name of the parser or the empty string '' for unnamed
        parsers."""
83
84
        return self._name

85
86
    @property
    def ptype(self) -> str:
87
88
        """Returns the type of the parser. By default this is the parser's
        class name preceded by a colon, e.g. ':ZeroOrMore'."""
89
90
91
92
        return self._ptype

    @property
    def repr(self) -> str:
di68kap's avatar
di68kap committed
93
        """Returns the parser's name if it has a name and repr()"""
94
95
        return self.name if self.name else repr(self)

96
    def reset(self):
97
        """Resets any parser variables. (Should be overridden.)"""
98
99
        pass

eckhart's avatar
eckhart committed
100
    def grammar(self) -> Optional[object]:
101
102
        """Returns the Grammar object to which the parser belongs. If not
        yet connected to any Grammar object, None is returned."""
103
104
105
        return None

    def apply(self, func: Callable) -> bool:
eckhart's avatar
eckhart committed
106
        """Applies the function `func` to the parser. Returns False, if
107
        - for whatever reason - the functions has not been applied, True
eckhart's avatar
eckhart committed
108
        otherwise."""
109
110
        return False

111
112

WHITESPACE_PTYPE = ':Whitespace'
di68kap's avatar
di68kap committed
113
PLAINTEXT_PTYPE = ':PlainText'
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
TOKEN_PTYPE = ':Token'


class MockParser(ParserBase):
    """
    MockParser objects can be used to reconstruct syntax trees from a
    serialized form like S-expressions or XML. Mock objects can mimic
    different parser types by assigning them a ptype on initialization.

    Mock objects should not be used for anything other than
    syntax tree (re-)construction. In all other cases where a parser
    object substitute is needed, chose the singleton ZOMBIE_PARSER.
    """
    def __init__(self, name='', ptype=''):  # , pbases=frozenset()):
        assert not ptype or ptype[0] == ':'
129
        super().__init__(name)
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
        self._ptype = ptype or ':' + self.__class__.__name__


class ZombieParser(MockParser):
    """
    Serves as a substitute for a Parser instance.

    ``ZombieParser`` is the class of the singelton object
    ``ZOMBIE_PARSER``. The  ``ZOMBIE_PARSER`` has a name and can be
    called, but it never matches. It serves as a substitute where only
    these (or one of these properties) is needed, but no real Parser-
    object is instantiated.
    """
    alive = False

    def __init__(self):
        super(ZombieParser, self).__init__("__ZOMBIE__")
        assert not self.__class__.alive, "There can be only one!"
        assert self.__class__ == ZombieParser, "No derivatives, please!"
        self.__class__.alive = True

    def __copy__(self):
        return self

    def __deepcopy__(self, memo):
        return self

    def __call__(self, text):
        """Better call Saul ;-)"""
        return None, text


ZOMBIE_PARSER = ZombieParser()


#######################################################################
#
# syntaxtree nodes
#
#######################################################################


172
ChildrenType = Tuple['Node', ...]
Eckhart Arnold's avatar
Eckhart Arnold committed
173
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
eckhart's avatar
eckhart committed
174
StrictResultType = Union[ChildrenType, StringView, str]
175
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
176
177


Eckhart Arnold's avatar
Eckhart Arnold committed
178
def flatten_sxpr(sxpr: str) -> str:
179
    """Returns S-expression ``sxpr`` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
180
181
182
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
183
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
184
185
    '(a (b c))'
    """
186
    return re.sub(r'\s(?=\))', '', re.sub(r'\s+', ' ', sxpr)).strip()
Eckhart Arnold's avatar
Eckhart Arnold committed
187
188


189
190
191
192
193
194
195
def flatten_xml(xml: str) -> str:
    """Returns an XML-tree as a one linter without unnecessary whitespace,
    i.e. only whitespace within leaf-nodes is preserved.
    """
    return re.sub(r'\s+(?=<\w)', '', re.sub(r'(?<=</\w+>)\s+', '', xml))


Eckhart Arnold's avatar
Eckhart Arnold committed
196
class Node(collections.abc.Sized):
197
198
199
    """
    Represents a node in the concrete or abstract syntax tree.

200
    Attributes:
201
202
        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
203

204
205
206
        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.
207

208
209
        children (tuple):  The tuple of child nodes or an empty tuple
            if there are no child nodes. READ ONLY!
210

eckhart's avatar
eckhart committed
211
212
213
214
        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
215
        parser (Parser):  The parser which generated this node.
216
217
            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
218
219
            rely on this being a real parser object in any phase after
            parsing (i.e. AST-transformation and compiling), for
220
            example by calling ``isinstance(node.parer, ...)``.
221

222
223
224
        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
225
            the length before AST-transformation and will never change
226
            through AST-transformation. READ ONLY!
227

228
229
        pos (int):  the position of the node within the parsed text.

Eckhart Arnold's avatar
Eckhart Arnold committed
230
            The value of ``pos`` is -1 meaning invalid by default.
231
            Setting this value will set the positions of all child
Eckhart Arnold's avatar
Eckhart Arnold committed
232
            nodes relative to this value.
233
234

            To set the pos values of all nodes in a syntax tree, the
Eckhart Arnold's avatar
Eckhart Arnold committed
235
            pos value of the root node should be set to 0 right
236
237
            after parsing.

Eckhart Arnold's avatar
Eckhart Arnold committed
238
            Other than that, this value should be considered READ ONLY.
239
240
            At any rate, it should only be reassigned during the parsing
            stage and never during or after the AST-transformation.
241

242
243
        errors (list):  A list of all errors that occured on this node.

244
        attributes (dict): An optional dictionary of XML-attributes. This
245
246
247
            dictionary is created lazily upon first usage. The attributes
            will only be shown in the XML-Representation, not in the
            S-Expression-output.
248
    """
249

eckhart's avatar
eckhart committed
250
    __slots__ = ['_result', 'children', '_len', '_pos', 'parser', 'errors', '_xml_attr', '_content']
251

252
253
254
    def __init__(self, parser, result: ResultType, leafhint: bool = False) -> None:
        """
        Initializes the ``Node``-object with the ``Parser``-Instance
255
256
        that generated the node and the parser's result.
        """
eckhart's avatar
eckhart committed
257
        self.errors = []               # type: List[Error]
eckhart's avatar
eckhart committed
258
        self._pos = -1                  # type: int
di68kap's avatar
di68kap committed
259
260
        # Assignment to self.result initializes the attributes _result, children and _len
        # The following if-clause is merely an optimization, i.e. a fast-path for leaf-Nodes
261
        if leafhint:
eckhart's avatar
eckhart committed
262
            self._result = result       # type: StrictResultType
eckhart's avatar
eckhart committed
263
            self._content = None        # type: Optional[str]
264
            self.children = NoChildren  # type: ChildrenType
265
            self._len = -1              # type: int  # lazy evaluation
266
267
        else:
            self.result = result
268
269
        self.parser = parser or ZOMBIE_PARSER

Eckhart Arnold's avatar
Eckhart Arnold committed
270

271
    def __str__(self):
272
        s = "".join(str(child) for child in self.children) if self.children else self.content
eckhart's avatar
eckhart committed
273
        if self.errors:
274
            return ' <<< Error on "%s" | %s >>> ' % \
eckhart's avatar
eckhart committed
275
                   (s, '; '.join(e.message for e in self.errors))
276
        return s
277

Eckhart Arnold's avatar
Eckhart Arnold committed
278

279
280
281
282
283
284
    def __repr__(self):
        mpargs = {'name': self.parser.name, 'ptype': self.parser.ptype}
        parg = "MockParser({name}, {ptype})".format(**mpargs)
        rarg = str(self) if not self.children else \
               "(" + ", ".join(repr(child) for child in self.children) + ")"
        return "Node(%s, %s)" % (parg, rarg)
285

Eckhart Arnold's avatar
Eckhart Arnold committed
286

287
    def __len__(self):
288
        if self._len < 0:
di68kap's avatar
di68kap committed
289
            self._len = sum(len(child) for child in self.children) \
290
                if self.children else len(self._result)
291
292
293
294
295
296
297
298
        return self._len


    def __bool__(self):
        # A node that is not None is always True, even if it's empty
        return True


299
    def __eq__(self, other):
300
301
302
303
        """
        Equality of nodes: Two nodes are considered as equal, if their tag
        name is the same and if their results are equal.
        """
304
        return self.tag_name == other.tag_name and self.result == other.result
305

Eckhart Arnold's avatar
Eckhart Arnold committed
306

307
    def __hash__(self):
308
        return hash(self.tag_name)
309

Eckhart Arnold's avatar
Eckhart Arnold committed
310

311
312
313
    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
314
        an integer or the first child node with the given tag name. Examples::
315

316
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
317
318
            >>> flatten_sxpr(tree[0].as_sxpr())
            '(b "X")'
319
320
            >>> flatten_sxpr(tree["X"].as_sxpr())
            '(X (c "d"))'
321
322
323
324

        Args:
            index_or_tagname(str): Either an index of a child node or a
                tag name.
325
        Returns:
326
327
            Node: All nodes which have a given tag name.
        """
328
329
330
        if self.children:
            if isinstance(index_or_tagname, int):
                return self.children[index_or_tagname]
331
            else:
332
333
334
335
336
                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!')
337
338
339
340


    def __contains__(self, tag_name: str) -> bool:
        """
341
        Returns true if a child with the given tag name exists.
342
        Args:
343
344
            tag_name (str): tag_name which will be searched among to immediate
                descendants of this node.
345
346
347
348
        Returns:
            bool:  True, if at least one descendant node with the given tag
                name exists, False otherwise
        """
349
350
351
352
353
        # assert isinstance(tag_name, str)
        if self.children:
            for child in self.children:
                if child.tag_name == tag_name:
                    return True
354
            return False
355
        raise ValueError('Leave node cannot contain other nodes')
356
        # generator = self.select_by_tag(tag_name, False)
357
358
359
360
361
        # try:
        #     generator.__next__()
        #     return True
        # except StopIteration:
        #     return False
362
363


364
    @property   # this needs to be a (dynamic) property, in case sef.parser gets updated
365
    def tag_name(self) -> str:
366
367
368
369
370
371
        """
        Returns the tage name of Node, i.e. the name for XML or
        S-expression representation. By default the tag name is the
        name of the node's parser or, if the node's parser is unnamed, the
        node's parser's `ptype`.
        """
372
        return self.parser.name or self.parser.ptype
373

Eckhart Arnold's avatar
Eckhart Arnold committed
374

375
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
376
    def result(self) -> StrictResultType:
377
378
379
380
381
        """
        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.
        """
382
383
        return self._result

384

385
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
386
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
387
        # # made obsolete by static type checking with mypy
388
389
390
        # assert ((isinstance(result, tuple) and all(isinstance(child, Node) for child in result))
        #         or isinstance(result, Node)
        #         or isinstance(result, str)), str(result)
Eckhart Arnold's avatar
Eckhart Arnold committed
391
392
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
393
394
        self._len = -1        # lazy evaluation
        self._content = None
395
396
397
398
399
400
401
402
403
        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
404
                self._result = result
405

406
407

    @property
eckhart's avatar
eckhart committed
408
    def content(self) -> str:
409
        """
410
        Returns content as string, omitting error messages.
411
        """
412
413
414
415
        if self._content is None:
            if self.children:
                self._content = "".join(child.content for child in self.children)
            else:
416
                # self._content = self._result
417
418
419
                self._content = str(self._result)
                self._result = self._content  # self._result might be more efficient as a string!?
        return self._content
420
421
422
423
424
425
426
427
428
429
430


    @property
    def structure(self) -> str:
        """
        Return structure (and content) as S-expression on a single line
        without any line breaks.
        """
        return flatten_sxpr(self.as_sxpr(showerrors=False))


431
    @property
432
    def pos(self) -> int:
eckhart's avatar
eckhart committed
433
434
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
435
            raise AssertionError("Position value not initialized!")
436
437
        return self._pos

eckhart's avatar
eckhart committed
438

eckhart's avatar
eckhart committed
439
    def init_pos(self, pos: int) -> 'Node':
eckhart's avatar
eckhart committed
440
441
442
443
444
445
446
447
448
        """
        (Re-)initialize position value. Usually, the parser guard
        (`parsers.add_parser_guard()`) takes care of assigning the
        position in the document to newly created nodes. However,
        where Nodes are created outside the reach of the parser
        guard, their document-position must be assigned manually.
        This function recursively reassigns the position values
        of the child nodes, too.
        """
eckhart's avatar
eckhart committed
449
450
        assert self._pos < 0 or self.pos == pos, str("pos mismatch %i != %i" % (self._pos, pos))
        self._pos = pos
451
        # recursively adjust pos-values of all children
eckhart's avatar
eckhart committed
452
        offset = self.pos
453
        for child in self.children:
eckhart's avatar
eckhart committed
454
            child.init_pos(offset)
eckhart's avatar
eckhart committed
455
456
457
            offset = child.pos + len(child)
        return self

458

459
460
    @property
    def attributes(self):
461
462
463
        """
        Returns a dictionary of XML-Attributes attached to the Node.
        """
464
465
466
467
        if not hasattr(self, '_xml_attr'):
            self._xml_attr = OrderedDict()
        return self._xml_attr

Eckhart Arnold's avatar
Eckhart Arnold committed
468

469
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i, density=0) -> str:
470
471
472
473
474
475
476
477
        """
        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.

478
        Args:
479
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
480
            open_fn:   (Node->str) A function that returns an opening
481
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
482
            close_fn:  (Node->str) A function that returns a closeF
483
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
484
            data_fn:   (str->str) A function that filters the data string
485
486
487
488
489
490
                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
491
492
        head = open_fn(self)
        tail = close_fn(self)
493
494

        if not self.result:
495
            return head.rstrip() + tail.lstrip()
496

eckhart's avatar
eckhart committed
497
        tail = tail.lstrip(None if density & 2 else '')
498

499
500
501
        sep, inner_tab = ('', '') if hasattr(self, '_xml_attr') and '_inline' in self.attributes \
            else ('\n', tab)

502
503
        if self.children:
            content = []
504
            for child in self.children:
eckhart's avatar
eckhart committed
505
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn, density).split('\n')
506
507
                content.append((sep + inner_tab).join(s for s in subtree))
            return head + tab + (sep + inner_tab).join(content) + tail
508

509
        res = cast(str, self.result)  # safe, because if there are no children, result is a string
510
511
512
        if density & 1 and res.find('\n') < 0:  # and head[0] == "<":
            # except for XML, add a gap between opening statement and content
            gap = ' ' if head.rstrip()[-1] != '>' else ''
eckhart's avatar
eckhart committed
513
            return head.rstrip() + gap + data_fn(self.result) + tail.lstrip()
514
        else:
eckhart's avatar
eckhart committed
515
            return head + '\n'.join([tab + data_fn(s) for s in res.split('\n')]) + tail
516

Eckhart Arnold's avatar
Eckhart Arnold committed
517

518
519
    def as_sxpr(self, src: str = None, compact: bool = False, showerrors: bool = True,
                indentation: int = 2) -> str:
520
521
522
        """
        Returns content as S-expression, i.e. in lisp-like form.

523
        Args:
524
525
526
            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.
Eckhart Arnold's avatar
Eckhart Arnold committed
527
            compact:  If True a compact representation is returned where
528
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
529
                tree structure.
530
531
        """

eckhart's avatar
eckhart committed
532
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
eckhart's avatar
eckhart committed
533
        lbreaks = linebreaks(src) if src else []  # type: List[int]
534

535
        def opening(node) -> str:
eckhart's avatar
eckhart committed
536
            """Returns the opening string for the representation of `node`."""
537
            txt = [left_bracket,  node.tag_name]
538
            # s += " '(pos %i)" % node.add_pos
539
            if hasattr(node, '_xml_attr'):
540
541
                txt.extend(' `(%s "%s")' % (k, v)
                           for k, v in node.attributes.items() if k != '_inline')
542
            if src:
eckhart's avatar
eckhart committed
543
                txt.append(" `(pos %i %i %i)" % (node.pos, *line_col(lbreaks, node.pos)))
di68kap's avatar
di68kap committed
544
545
            # if node.error_flag:   # just for debugging error collecting
            #     txt += " HAS ERRORS"
546
            if showerrors and node.errors:
547
                txt.append(" `(err `%s)" % ' '.join(str(err) for err in node.errors))
548
            return "".join(txt) + '\n'
549

eckhart's avatar
eckhart committed
550
551
552
        def closing(node) -> str:
            """Returns the closing string for the representation of `node`."""
            return right_bracket
553

eckhart's avatar
eckhart committed
554
555
556
557
558
        def pretty(strg):
            """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'\"')
559

560
        return self._tree_repr(' ' * indentation, opening, closing, pretty, density=density)
Eckhart Arnold's avatar
Eckhart Arnold committed
561

eckhart's avatar
eckhart committed
562

563
    def as_xml(self, src: str = None, showerrors: bool = True, indentation: int = 2) -> str:
564
565
566
        """
        Returns content as XML-tree.

567
        Args:
568
569
570
571
572
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
        """

573
        def opening(node) -> str:
eckhart's avatar
eckhart committed
574
            """Returns the opening string for the representation of `node`."""            
eckhart's avatar
eckhart committed
575
            txt = ['<', node.tag_name]
576
577
            has_reserved_attrs = hasattr(node, '_xml_attr') \
                and any (r in node.attributes for r in {'err', 'line', 'col'})
di68kap's avatar
di68kap committed
578
            if hasattr(node, '_xml_attr'):
579
580
                txt.extend(' %s="%s"' % (k, v)
                           for k, v in node.attributes.items() if k != '_inline')
581
            if src and not has_reserved_attrs:
eckhart's avatar
eckhart committed
582
                txt.append(' line="%i" col="%i"' % line_col(line_breaks, node.pos))
583
            if showerrors and node.errors and not has_reserved_attrs:
eckhart's avatar
eckhart committed
584
585
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
                                                 for err in node.errors))
586
            return "".join(txt + [">\n"])
587
588

        def closing(node):
eckhart's avatar
eckhart committed
589
            """Returns the closing string for the representation of `node`."""            
590
            return ('\n</') + node.tag_name + '>'
591

592
        line_breaks = linebreaks(src) if src else []
593
        return self._tree_repr(' ' * indentation, opening, closing, density=1)
594

Eckhart Arnold's avatar
Eckhart Arnold committed
595

596
    def select(self, match_function: Callable, include_root: bool=False) -> Iterator['Node']:
eckhart's avatar
eckhart committed
597
        """
598
        Finds nodes in the tree that fulfill a given criterion.
eckhart's avatar
eckhart committed
599

600
        `select` is a generator that yields all nodes for which the
di68kap's avatar
di68kap committed
601
        given `match_function` evaluates to True. The tree is
602
603
604
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.
eckhart's avatar
eckhart committed
605

606
607
608
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
609
610
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
611
        Yields:
612
            Node: All nodes of the tree for which
613
614
            ``match_function(node)`` returns True
        """
615
        if include_root and match_function(self):
616
            yield self
eckhart's avatar
eckhart committed
617
618
619
        for child in self.children:
            for node in child.select(match_function, True):
                yield node
620

Eckhart Arnold's avatar
Eckhart Arnold committed
621

eckhart's avatar
eckhart committed
622
    def select_by_tag(self, tag_names: Union[str, AbstractSet[str]],
623
                      include_root: bool=False) -> Iterator['Node']:
624
        """
625
626
627
628
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::
629

630
            >>> tree = parse_sxpr('(a (b "X") (X (c "d")) (e (X "F")))')
631
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
632
            ['(X (c "d"))', '(X "F")']
633
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
634
            ['(b "X")', '(X (c "d"))', '(X "F")']
635
            >>> any(tree.select_by_tag('a', False))
636
            False
637
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
638
            ['(a (b "X") (X (c "d")) (e (X "F")))']
639
640
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'
641
642

        Args:
643
644
645
646
            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.
647
648
649
        Yields:
            Node: All nodes which have a given tag name.
        """
650
        if isinstance(tag_names, str):
eckhart's avatar
eckhart committed
651
            tag_names = frozenset({tag_names})
652
        return self.select(lambda node: node.tag_name in tag_names, include_root)
653
654


655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
    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 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


670
    def tree_size(self) -> int:
eckhart's avatar
eckhart committed
671
672
673
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
674
675
676
        return sum(child.tree_size() for child in self.children) + 1


di68kap's avatar
di68kap committed
677
class RootNode(Node):
678
    """TODO: Add Documentation!!!
di68kap's avatar
di68kap committed
679

680
681
682
        errors (list):  A list of all errors that have occured so far during
                processing (i.e. parsing, AST-transformation, compiling)
                of this tree.
di68kap's avatar
di68kap committed
683

684
685
        error_flag (int):  the highest warning or error level of all errors
                that occurred.
di68kap's avatar
di68kap committed
686
    """
eckhart's avatar
eckhart committed
687
    def __init__(self, node: Optional[Node] = None) -> 'RootNode':
di68kap's avatar
di68kap committed
688
        super().__init__(ZOMBIE_PARSER, '')
689
        self.all_errors = []
eckhart's avatar
eckhart committed
690
        self.err_nodes_keep = []
di68kap's avatar
di68kap committed
691
        self.error_flag = 0
eckhart's avatar
eckhart committed
692
693
        if node is not None:
            self.swallow(node)
di68kap's avatar
di68kap committed
694

695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
    # def _propagate_errors(self):
    #     if not self.all_errors or not self.error_propagation:
    #         return
    #     self.all_errors.sort(key=lambda e: e.pos)
    #     i = 0
    #     for leaf in self.select(lambda nd: not nd.children, False):
    #         leaf.errors = []
    #         while i < len(self.all_errors) \
    #                 and leaf.pos <= self.all_errors[i].add_pos < leaf.add_pos + leaf.len:
    #             leaf._errors.append(self.all_errors[i])
    #             i += 1
    #         if i >= len(self.all_errors):
    #             break
    #
    # def _propagate_new_error(self, error):
    #     if self.error_propagation:
    #         for leaf in self.select(lambda nd: not nd.children, True):
    #             if leaf.pos <= error.add_pos < leaf.add_pos + leaf.len:
    #                 leaf._errors.append(error)
    #                 break
    #         else:
    #             assert False, "Error %s at pos %i out of bounds" % (str(error), error.add_pos)

    def swallow(self, node: Node) -> 'RootNode':
di68kap's avatar
di68kap committed
719
720
721
722
723
        self._result = node._result
        self.children = node.children
        self._len = node._len
        self._pos = node._pos
        self.parser = node.parser
724
725
        if hasattr(node, '_xml_attr'):
            self._xml_attr = node._xml_attr
di68kap's avatar
di68kap committed
726
        self._content = node._content
727
        return self
di68kap's avatar
di68kap committed
728

eckhart's avatar
eckhart committed
729
730
    def add_error(self, node: Node, error: Error) -> 'RootNode':
        """Adds an Error object to the tree, locating it at a specific node."""
di68kap's avatar
di68kap committed
731
732
733
734
735
736
        self.all_errors.append(error)
        self.error_flag = max(self.error_flag, error.code)
        node.errors.append(error)
        self.err_nodes_keep.append(node)
        return self

eckhart's avatar
eckhart committed
737
    def new_error(self,
738
                  node: Node,
di68kap's avatar
di68kap committed
739
                  message: str,
di68kap's avatar
di68kap committed
740
                  code: int = Error.ERROR) -> 'RootNode':
di68kap's avatar
di68kap committed
741
        """
eckhart's avatar
eckhart committed
742
        Adds an error to this tree, locating it at a specific node.
di68kap's avatar
di68kap committed
743
744
745
746
747
        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's avatar
eckhart committed
748
        error = Error(message, code, node=node)
eckhart's avatar
eckhart committed
749
750
        self.add_error(node, error)
        return self
di68kap's avatar
di68kap committed
751

eckhart's avatar
eckhart committed
752
    def collect_errors(self) -> List[Error]:
di68kap's avatar
di68kap committed
753
754
        """Returns the list of errors, ordered bv their position.
        """
eckhart's avatar
eckhart committed
755
756
757
        # for node in self.err_nodes:  # lazy evaluation of positions
        #     for err in node.errors:  # moved to error.Error.pos
        #         err.pos = node.pos
758
        self.all_errors.sort(key=lambda e: e.pos)
eckhart's avatar
eckhart committed
759
760
        for node in self.err_nodes_keep:  # redundant: consider removing Error.Error._node_keep
            for error in node.errors:
eckhart's avatar
eckhart committed
761
                assert error._pos < 0 or node.pos <= error._pos <= node.pos + len(node)
762
763
                if error._pos < 0:
                    error._pos = node.pos
eckhart's avatar
eckhart committed
764
        self.err_nodes_keep = []
765
        errors = self.all_errors
eckhart's avatar
eckhart committed
766
767
        # for error in self.all_errors:
        #     _ = error.pos
di68kap's avatar
di68kap committed
768
769
770
        return errors


eckhart's avatar
eckhart committed
771
772
773
ZOMBIE_NODE = Node(ZOMBIE_PARSER, '')


774
def parse_sxpr(sxpr: str) -> Node:
775
    """
776
777
778
779
780
    Generates a tree of nodes from an S-expression.

    This can - among other things - be used for deserialization of trees that
    have been serialized with `Node.as_sxpr()` or as a convenient way to
    generate test data.
781
782

    Example:
783
    >>> parse_sxpr("(a (b c))").as_sxpr()
784
785
    '(a\\n    (b\\n        "c"\\n    )\\n)'
    """
786
787
    sxpr = StringView(sxpr).strip()
    mock_parsers = dict()
788

789
    def next_block(s: StringView):
eckhart's avatar
eckhart committed
790
791
792
        """Generator that yields all characters until the next closing bracket
        that does not match an opening bracket matched earlier within the same
        package."""
793
        s = s.strip()
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
        try:
            while s[0] != ')':
                if s[0] != '(':
                    raise ValueError('"(" expected, not ' + s[:10])
                # assert s[0] == '(', s
                level = 1
                k = 1
                while level > 0:
                    if s[k] == '(':
                        level += 1
                    elif s[k] == ')':
                        level -= 1
                    k += 1
                yield s[:k]
                s = s[k:].strip()
        except IndexError:
            errmsg = ('Malformed S-expression. Unprocessed part: "%s"' % s) if s \
                else 'Malformed S-expression. Closing bracket(s) ")" missing.'
            raise AssertionError(errmsg)
813

814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
    def inner_parser(sxpr: StringView) -> Node:
        if sxpr[0] != '(':
            raise ValueError('"(" expected, not ' + sxpr[:10])
        # assert sxpr[0] == '(', sxpr
        sxpr = sxpr[1:].strip()
        match = sxpr.match(re.compile(r'[\w:]+'))
        if match is None:
            raise AssertionError('Malformed S-expression Node-tagname or identifier expected, '
                                 'not "%s"' % sxpr[:40].replace('\n', ''))
        end = match.end() - sxpr.begin
        tagname = sxpr[:end]
        name, class_name = (tagname.split(':') + [''])[:2]
        sxpr = sxpr[end:].strip()
        attributes = OrderedDict()
        if sxpr[0] == '(':
            result = tuple(inner_parser(block) for block in next_block(sxpr))
        else:
            lines = []
            while sxpr and sxpr[0:1] != ')':
                # parse attributes
                while sxpr[:2] == "`(":
                    i = sxpr.find('"')
                    k = sxpr.find(')')
                    # read very special attribute pos
                    if sxpr[2:5] == "pos" and 0 < i < k:
                        pos = int(sxpr[5:k].strip().split(' ')[0])
                    # ignore very special attribute err
                    elif sxpr[2:5] == "err" and 0 <= sxpr.find('`', 5) < k:
                        m = sxpr.find('(', 5)
                        while m >= 0 and m < k:
                            m = sxpr.find('(', k)
                            k = max(k, sxpr.find(')', max(m, 0)))
                    # read attributes
                    else:
                        attr = sxpr[2:i].strip()
                        value = sxpr[i:k].strip()[1:-1]
                        attributes[attr] = value
                    sxpr = sxpr[k+1:].strip()
                # parse content
                for qtmark in ['"""', "'''", '"', "'"]:
                    match = sxpr.match(re.compile(qtmark + r'.*?' + qtmark, re.DOTALL))
                    if match:
                        end = match.end() - sxpr.begin
                        i = len(qtmark)
                        lines.append(str(sxpr[i:end - i]))
                        sxpr = sxpr[end:].strip()
                        break
861
                else:
862
863
864
865
866
867
868
869
870
871
872
873
874
                    match = sxpr.match(re.compile(r'(?:(?!\)).)*', re.DOTALL))
                    end = match.end() - sxpr.begin
                    lines.append(str(sxpr[:end]))
                    sxpr = sxpr[end:]
            result = "\n".join(lines)
        node = Node(mock_parsers.setdefault(tagname, MockParser(name, ':' + class_name)), result)
        if attributes:
            node.attributes.update(attributes)
        return node

    return inner_parser(sxpr)


di68kap's avatar
di68kap committed
875
876
877
RX_WHITESPACE_TAIL = re.compile(r'\s*$')


878
879
880
881
882
def parse_xml(xml: str) -> Node:
    """
    Generates a tree of nodes from a (Pseudo-)XML-source.
    """
    xml = StringView(xml)
di68kap's avatar
di68kap committed
883
884
    PlainText = MockParser('', PLAINTEXT_PTYPE)
    mock_parsers = {PLAINTEXT_PTYPE: PlainText}
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904

    def parse_attributes(s: StringView) -> Tuple[StringView, OrderedDict]:
        """Parses a sqeuence of XML-Attributes. Returns the string-slice
        beginning after the end of the attributes."""
        attributes = OrderedDict()
        restart = 0
        for match in s.finditer(re.compile(r'\s*(?P<attr>\w+)\s*=\s*"(?P<value>.*)"\s*')):
            d = match.groupdict()
            attributes[d['attr']] = d['value']
            restart = match.end() - s.begin
        return (s[restart:], attributes)

    def parse_opening_tag(s: StringView) -> Tuple[StringView, str, OrderedDict, bool]:
        """Parses an opening tag. Returns the string segment following the
        the opening tag, the tag name, a dictionary of attributes and
        a flag indicating whether the tag is actually a solitary tag as
        indicated by a slash at the end, i.e. <br/>."""
        match = s.match(re.compile(r'<\s*(?P<tagname>[\w:]+)\s*'))
        assert match
        tagname = match.groupdict()['tagname']
di68kap's avatar
di68kap committed
905
906
        section = s[match.end() - s.begin:]
        s, attributes = parse_attributes(section)
907
908
        i = s.find('>')
        assert i >= 0
909
        return s[i+1:], tagname, attributes, s[i-1] == "/"
910
911

    def parse_closing_tag(s: StringView) -> Tuple[StringView, str]:
912
        """Parses a closing tag and returns the string segment, just after
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
        the closing tag."""
        match = s.match(re.compile(r'</\s*(?P<tagname>[\w:]+)>'))
        assert match
        tagname = match.groupdict()['tagname']
        return s[match.end() - s.begin:], tagname

    def parse_leaf_content(s: StringView) -> Tuple[StringView, str]:
        """Parses a piece of the content of a tag, just until the next opening,
        closing or solitary tag is reached."""
        i = 0
        while s[i] != "<" or s[max(0, i-1)] == "\\":
            i = s.find("<", i)
        return s[i:], s[:i]

    def parse_full_content(s: StringView) -> Tuple[StringView, Node]:
        """Parses the full content of a tag, starting right at the beginning
        of the opening tag and ending right after the closing tag.
        """
        result = []
        s, tagname, attributes, solitary = parse_opening_tag(s)
        name, class_name = (tagname.split(":") + [''])[:2]
        if not solitary:
            while s and not s[:2] == "</":
                s, leaf = parse_leaf_content(s)
di68kap's avatar
di68kap committed
937
                if not leaf.match(RX_WHITESPACE_TAIL):
938
939
940
941
942
943
                    result.append(Node(PlainText, leaf))
                if s[:1] == "<" and s[:2] != "</":
                    s, child = parse_full_content(s)
                    result.append(child)
            s, closing_tagname = parse_closing_tag(s)
            assert tagname == closing_tagname
di68kap's avatar
di68kap committed
944
        if len(result) == 1 and result[0].parser.ptype == PLAINTEXT_PTYPE:
945
946
947
            result = result[0].result
        else:
            result = tuple(result)
di68kap's avatar
di68kap committed
948
        return s, Node(mock_parsers.setdefault(tagname, MockParser(name, ":" + class_name)), result)
949

950
951
    match_header = xml.search(re.compile(r'<(?!\?)'))
    start = match_header.start() if match_header else 0
di68kap's avatar
di68kap committed
952
953
954
    _, tree = parse_full_content(xml[start:])
    assert _.match(RX_WHITESPACE_TAIL)
    return tree
955

956
# if __name__ == "__main__":
957
#     st = parse_sxpr("(alpha (beta (gamma i\nj\nk) (delta y)) (epsilon z))")
958
959
#     print(st.as_sxpr())
#     print(st.as_xml())