syntaxtree.py 29.1 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

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

30
from DHParser.error import Error, linebreaks, line_col
31
from DHParser.stringview import StringView
eckhart's avatar
eckhart committed
32
from DHParser.toolkit import re, typing
33
from typing import Callable, cast, Iterator, List, Set, Union, Tuple, Optional
di68kap's avatar
di68kap committed
34

35

36
37
38
39
40
41
__all__ = ('ParserBase',
           'WHITESPACE_PTYPE',
           'TOKEN_PTYPE',
           'MockParser',
           'ZombieParser',
           'ZOMBIE_PARSER',
eckhart's avatar
eckhart committed
42
           'ZOMBIE_NODE',
43
           'Node',
44
           'mock_syntax_tree',
45
           'flatten_sxpr')
Eckhart Arnold's avatar
Eckhart Arnold committed
46
47


48
49
50
51
52
53
54
55
56
57
58
59
60
61
#######################################################################
#
# 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()):
62
        self._name = name  # type: str
63
64
65
        self._ptype = ':' + self.__class__.__name__  # type: str

    def __repr__(self):
di68kap's avatar
di68kap committed
66
         return self.name + self.ptype
67
68
69
70

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

71
72
73
    def __call__(self, text: StringView) -> Tuple[Optional['Node'], StringView]:
        return None, text

74
75
    @property
    def name(self):
76
77
        """Returns the name of the parser or the empty string '' for unnamed
        parsers."""
78
79
        return self._name

80
81
    @property
    def ptype(self) -> str:
82
83
        """Returns the type of the parser. By default this is the parser's
        class name preceded by a colon, e.g. ':ZeroOrMore'."""
84
85
86
87
        return self._ptype

    @property
    def repr(self) -> str:
di68kap's avatar
di68kap committed
88
        """Returns the parser's name if it has a name and repr()"""
89
90
        return self.name if self.name else repr(self)

91
    def reset(self):
92
        """Resets any parser variables. (Should be overridden.)"""
93
94
        pass

eckhart's avatar
eckhart committed
95
    def grammar(self) -> Optional[object]:
96
97
        """Returns the Grammar object to which the parser belongs. If not
        yet connected to any Grammar object, None is returned."""
98
99
100
        return None

    def apply(self, func: Callable) -> bool:
eckhart's avatar
eckhart committed
101
        """Applies the function `func` to the parser. Returns False, if
102
        - for whatever reason - the functions has not been applied, True
eckhart's avatar
eckhart committed
103
        otherwise."""
104
105
        return False

106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122

WHITESPACE_PTYPE = ':Whitespace'
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] == ':'
123
        super().__init__(name)
124
125
126
127
128
129
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
        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
#
#######################################################################


166
ChildrenType = Tuple['Node', ...]
Eckhart Arnold's avatar
Eckhart Arnold committed
167
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
eckhart's avatar
eckhart committed
168
StrictResultType = Union[ChildrenType, StringView, str]
169
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
170
171


Eckhart Arnold's avatar
Eckhart Arnold committed
172
def flatten_sxpr(sxpr: str) -> str:
173
    """Returns S-expression ``sxpr`` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
174
175
176
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
177
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
178
179
    '(a (b c))'
    """
180
    return re.sub(r'\s(?=\))', '', re.sub(r'\s+', ' ', sxpr)).strip()
Eckhart Arnold's avatar
Eckhart Arnold committed
181
182


Eckhart Arnold's avatar
Eckhart Arnold committed
183
class Node(collections.abc.Sized):
184
185
186
    """
    Represents a node in the concrete or abstract syntax tree.

187
    Attributes:
188
189
        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
190

191
192
193
        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.
194

195
196
        children (tuple):  The tuple of child nodes or an empty tuple
            if there are no child nodes. READ ONLY!
197

eckhart's avatar
eckhart committed
198
199
200
201
        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
202
        parser (Parser):  The parser which generated this node.
203
204
            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
205
206
            rely on this being a real parser object in any phase after
            parsing (i.e. AST-transformation and compiling), for
207
            example by calling ``isinstance(node.parer, ...)``.
208

209
210
        errors (list):  A list of parser- or compiler-errors:
            tuple(position, string) attached to this node
211

212
213
214
        error_flag (int):  0 if no error occurred in either the node
            itself or any of its descendants. Otherwise contains the
            highest warning or error level or all errors that occurred.
215

216
217
218
        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
219
            the length before AST-transformation and will never change
220
            through AST-transformation. READ ONLY!
221

222
223
        pos (int):  the position of the node within the parsed text.

Eckhart Arnold's avatar
Eckhart Arnold committed
224
            The value of ``pos`` is -1 meaning invalid by default.
225
            Setting this value will set the positions of all child
Eckhart Arnold's avatar
Eckhart Arnold committed
226
            nodes relative to this value.
227
228

            To set the pos values of all nodes in a syntax tree, the
Eckhart Arnold's avatar
Eckhart Arnold committed
229
            pos value of the root node should be set to 0 right
230
231
            after parsing.

Eckhart Arnold's avatar
Eckhart Arnold committed
232
            Other than that, this value should be considered READ ONLY.
233
234
            At any rate, it should only be reassigned during the parsing
            stage and never during or after the AST-transformation.
235

236
        attributes (dict): An optional dictionary of XML-attributes. This
237
238
239
            dictionary is created lazily upon first usage. The attributes
            will only be shown in the XML-Representation, not in the
            S-Expression-output.
eckhart's avatar
eckhart committed
240
241
242


        _parent (Node): SLOT RESERVED FOR FUTURE USE!
243
    """
244

di68kap's avatar
di68kap committed
245
    __slots__ = ['_result', 'children', '_errors', '_len', '_pos', 'parser', 'error_flag',
246
                 '_xml_attr', '_content', '_parent']
247

248
249
250
    def __init__(self, parser, result: ResultType, leafhint: bool = False) -> None:
        """
        Initializes the ``Node``-object with the ``Parser``-Instance
251
252
        that generated the node and the parser's result.
        """
253
254
        self.error_flag = 0             # type: int
        self._errors = []               # type: List[Error]
eckhart's avatar
eckhart committed
255
        self._pos = -1                  # type: int
di68kap's avatar
di68kap committed
256
257
        # 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
258
        if leafhint:
eckhart's avatar
eckhart committed
259
            self._result = result       # type: StrictResultType
260
            self._content = None        # type: str
261
            self.children = NoChildren  # type: ChildrenType
262
            self._len = -1              # type: int  # lazy evaluation
263
264
        else:
            self.result = result
265
266
        self.parser = parser or ZOMBIE_PARSER

Eckhart Arnold's avatar
Eckhart Arnold committed
267

268
    def __str__(self):
269
        s = "".join(str(child) for child in self.children) if self.children else self.content
270
271
272
273
        if self._errors:
            return ' <<< Error on "%s" | %s >>> ' % \
                   (s, '; '.join(e.message for e in self._errors))
        return s
274

Eckhart Arnold's avatar
Eckhart Arnold committed
275

276
277
278
279
280
281
    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)
282

Eckhart Arnold's avatar
Eckhart Arnold committed
283

284
    def __len__(self):
285
        if self._len < 0:
di68kap's avatar
di68kap committed
286
            self._len = sum(len(child) for child in self.children) \
287
                if self.children else len(self._result)
288
289
290
291
292
293
294
295
        return self._len


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


296
    def __eq__(self, other):
297
298
299
300
        """
        Equality of nodes: Two nodes are considered as equal, if their tag
        name is the same and if their results are equal.
        """
301
        return self.tag_name == other.tag_name and self.result == other.result
302

Eckhart Arnold's avatar
Eckhart Arnold committed
303

304
    def __hash__(self):
305
        return hash(self.tag_name)
306

Eckhart Arnold's avatar
Eckhart Arnold committed
307

308
309
310
311
312
313
    def __deepcopy__(self, memodict={}):
        result = copy.deepcopy(self.result)
        other = Node(self.parser, result)
        other._pos = self._pos
        return other

Eckhart Arnold's avatar
Eckhart Arnold committed
314

315
316
317
    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
318
        an integer or the first child node with the given tag name. Examples::
319

320
            >>> tree = mock_syntax_tree('(a (b "X") (X (c "d")) (e (X "F")))')
321
322
            >>> flatten_sxpr(tree[0].as_sxpr())
            '(b "X")'
323
324
            >>> flatten_sxpr(tree["X"].as_sxpr())
            '(X (c "d"))'
325
326
327
328

        Args:
            index_or_tagname(str): Either an index of a child node or a
                tag name.
329
        Returns:
330
331
            Node: All nodes which have a given tag name.
        """
332
333
334
        if self.children:
            if isinstance(index_or_tagname, int):
                return self.children[index_or_tagname]
335
            else:
336
337
338
339
340
                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!')
341
342
343
344


    def __contains__(self, tag_name: str) -> bool:
        """
345
        Returns true if a child with the given tag name exists.
346
        Args:
347
348
            tag_name (str): tag_name which will be searched among to immediate
                descendants of this node.
349
350
351
352
        Returns:
            bool:  True, if at least one descendant node with the given tag
                name exists, False otherwise
        """
353
354
355
356
357
        # assert isinstance(tag_name, str)
        if self.children:
            for child in self.children:
                if child.tag_name == tag_name:
                    return True
358
            return False
359
        raise ValueError('Leave node cannot contain other nodes')
360
        # generator = self.select_by_tag(tag_name, False)
361
362
363
364
365
        # try:
        #     generator.__next__()
        #     return True
        # except StopIteration:
        #     return False
366
367


368
    @property   # this needs to be a (dynamic) property, in case sef.parser gets updated
369
    def tag_name(self) -> str:
370
371
372
373
374
375
        """
        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`.
        """
376
        return self.parser.name or self.parser.ptype
377

Eckhart Arnold's avatar
Eckhart Arnold committed
378

379
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
380
    def result(self) -> StrictResultType:
381
382
383
384
385
        """
        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.
        """
386
387
        return self._result

388

389
    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
390
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
391
        # # made obsolete by static type checking with mypy
392
393
394
        # 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
395
396
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
397
398
        self._len = -1        # lazy evaluation
        self._content = None
399
400
401
402
403
404
405
406
        if isinstance(result, Node):
            self.children = (result,)
            self._result = self.children
            self.error_flag = result.error_flag
        else:
            if isinstance(result, tuple):
                self.children = result
                self._result = result or ''
407
408
409
                if result:
                    if self.error_flag == 0:
                        self.error_flag = max(child.error_flag for child in self.children)
410
411
            else:
                self.children = NoChildren
412
                self._result = result
413

414
415

    @property
416
    def content(self) -> Union[StringView, str]:
417
        """
418
        Returns content as string, omitting error messages.
419
        """
420
421
422
423
        if self._content is None:
            if self.children:
                self._content = "".join(child.content for child in self.children)
            else:
424
                # self._content = self._result
425
426
427
                self._content = str(self._result)
                self._result = self._content  # self._result might be more efficient as a string!?
        return self._content
428
429
430
431
432
433
434
435
436
437
438


    @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))


439
    @property
440
    def pos(self) -> int:
eckhart's avatar
eckhart committed
441
442
        """Returns the position of the Node's content in the source text."""
        if self._pos < 0:
443
            raise AssertionError("Position value not initialized!")
444
445
        return self._pos

eckhart's avatar
eckhart committed
446

eckhart's avatar
eckhart committed
447
    def init_pos(self, pos: int, overwrite: bool = False) -> 'Node':
eckhart's avatar
eckhart committed
448
449
450
451
452
453
454
455
456
        """
        (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
457
458
459
460
461
462
        if overwrite or self._pos < 0:
            self._pos = pos
            for err in self._errors:
                err.pos = pos
        else:
            assert self._pos == pos, str("%i != %i" % (self._pos, pos))
463
        # recursively adjust pos-values of all children
eckhart's avatar
eckhart committed
464
        offset = self.pos
465
        for child in self.children:
eckhart's avatar
eckhart committed
466
            child.init_pos(offset, overwrite)
eckhart's avatar
eckhart committed
467
468
469
            offset = child.pos + len(child)
        return self

470
471

    @property
472
    def errors(self) -> List[Error]:
eckhart's avatar
eckhart committed
473
        """
474
        Returns the errors that occurred at this Node,
eckhart's avatar
eckhart committed
475
476
        not including any errors from child nodes.
        """
477
478
        return self._errors.copy()

479

eckhart's avatar
eckhart committed
480
481
    def add_error(self,
                  message: str,
482
                  code: int = Error.ERROR) -> 'Node':
eckhart's avatar
eckhart committed
483
484
485
        """
        Adds an error to this Node.
        Parameters:
eckhart's avatar
eckhart committed
486
487
            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
488
        """
489
490
        self._errors.append(Error(message, code))
        self.error_flag = max(self.error_flag, self._errors[-1].code)
Eckhart Arnold's avatar
Eckhart Arnold committed
491
492
        return self

493

494
    def collect_errors(self, clear_errors=False) -> List[Error]:
Eckhart Arnold's avatar
Eckhart Arnold committed
495
        """
496
        Recursively adds line- and column-numbers to all error objects.
Eckhart Arnold's avatar
Eckhart Arnold committed
497
498
499
500
        Returns all errors of this node or any child node in the form
        of a set of tuples (position, error_message), where position
        is always relative to this node.
        """
501
        errors = self.errors
502
503
        for err in errors:
            err.pos = self.pos
504
505
        if self.children:
            for child in self.children:
506
                errors.extend(child.collect_errors(clear_errors))
507
508
509
        if clear_errors:
            self._errors = []
            self.error_flag = 0
510
        else:
511
512
513
514
515
516
517
            if self._errors:
                self.error_flag = max(err.code for err in self.errors)
            if self.children:
                max_child_error = max(child.error_flag for child in self.children)
                self.error_flag = max(self.error_flag, max_child_error)
        return errors

518

Eckhart Arnold's avatar
Eckhart Arnold committed
519

520
    def _tree_repr(self, tab, open_fn, close_fn, data_fn=lambda i: i, density=0) -> str:
521
522
523
524
525
526
527
528
        """
        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.

529
        Args:
530
            tab (str):  The indentation string, e.g. '\t' or '    '
eckhart's avatar
eckhart committed
531
            open_fn:   (Node->str) A function that returns an opening
532
                string (e.g. an XML-tag_name) for a given node
eckhart's avatar
eckhart committed
533
            close_fn:  (Node->str) A function that returns a closeF
534
                string (e.g. an XML-tag_name) for a given node.
eckhart's avatar
eckhart committed
535
            data_fn:   (str->str) A function that filters the data string
536
537
538
539
540
541
                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
542
543
        head = open_fn(self)
        tail = close_fn(self)
544
545

        if not self.result:
546
            return head.rstrip() + tail.lstrip()
547

eckhart's avatar
eckhart committed
548
        tail = tail.lstrip(None if density & 2 else '')
549
550
551

        if self.children:
            content = []
552
            for child in self.children:
eckhart's avatar
eckhart committed
553
                subtree = child._tree_repr(tab, open_fn, close_fn, data_fn, density).split('\n')
554
                content.append('\n'.join((tab + s) for s in subtree))
eckhart's avatar
eckhart committed
555
            return head + '\n'.join(content) + tail
556

557
        res = cast(str, self.result)  # safe, because if there are no children, result is a string
558
559
560
        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
561
            return head.rstrip() + gap + data_fn(self.result) + tail.lstrip()
562
        else:
eckhart's avatar
eckhart committed
563
            return head + '\n'.join([tab + data_fn(s) for s in res.split('\n')]) + tail
564

Eckhart Arnold's avatar
Eckhart Arnold committed
565

566
    def as_sxpr(self, src: str = None, compact: bool = False, showerrors: bool = True) -> str:
567
568
569
        """
        Returns content as S-expression, i.e. in lisp-like form.

570
        Args:
571
572
573
            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
574
            compact:  If True a compact representation is returned where
575
                brackets are omitted and only the indentation indicates the
Eckhart Arnold's avatar
Eckhart Arnold committed
576
                tree structure.
577
578
        """

eckhart's avatar
eckhart committed
579
        left_bracket, right_bracket, density = ('', '', 1) if compact else ('(', '\n)', 0)
580

581
        def opening(node) -> str:
eckhart's avatar
eckhart committed
582
583
            """Returns the opening string for the representation of `node`."""
            txt = left_bracket + node.tag_name
584
585
            # s += " '(pos %i)" % node.pos
            if src:
eckhart's avatar
eckhart committed
586
                txt += " '(pos %i " % node.pos  # + " %i %i)" % line_col(src, node.pos)
di68kap's avatar
di68kap committed
587
588
            # if node.error_flag:   # just for debugging error collecting
            #     txt += " HAS ERRORS"
589
            if showerrors and node.errors:
eckhart's avatar
eckhart committed
590
591
592
                txt += " '(err '(%s))" % ' '.join(str(err).replace('"', r'\"')
                                                  for err in node.errors)
            return txt + '\n'
593

eckhart's avatar
eckhart committed
594
595
596
        def closing(node) -> str:
            """Returns the closing string for the representation of `node`."""
            return right_bracket
597

eckhart's avatar
eckhart committed
598
599
600
601
602
        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'\"')
603

eckhart's avatar
eckhart committed
604
        return self._tree_repr('    ', opening, closing, pretty, density=density)
Eckhart Arnold's avatar
Eckhart Arnold committed
605

eckhart's avatar
eckhart committed
606

eckhart's avatar
eckhart committed
607
    @property
608
    def attributes(self):
eckhart's avatar
eckhart committed
609
610
611
612
613
614
        """Returns a dictionary of XML-Attributes attached to the Node."""
        if not hasattr(self, '_xml_attr'):
            self._xml_attr = dict()
        return self._xml_attr


615
    def as_xml(self, src: str = None, showerrors: bool = True) -> str:
616
617
618
        """
        Returns content as XML-tree.

619
        Args:
620
621
622
623
624
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
        """

625
        def opening(node) -> str:
eckhart's avatar
eckhart committed
626
            """Returns the opening string for the representation of `node`."""            
eckhart's avatar
eckhart committed
627
            txt = ['<', node.tag_name]
628
            # s += ' pos="%i"' % node.pos
di68kap's avatar
di68kap committed
629
            if hasattr(node, '_xml_attr'):
630
                txt.extend(' %s="%s"' % (k, v) for k, v in node.attributes.items())
631
            if src:
eckhart's avatar
eckhart committed
632
                txt.append(' line="%i" col="%i"' % line_col(line_breaks, node.pos))
633
            if showerrors and node.errors:
eckhart's avatar
eckhart committed
634
635
636
                txt.append(' err="%s"' % ''.join(str(err).replace('"', r'\"')
                                                 for err in node.errors))
            return "".join(txt + [">\n"])
637
638

        def closing(node):
eckhart's avatar
eckhart committed
639
            """Returns the closing string for the representation of `node`."""            
640
            return '\n</' + node.tag_name + '>'
641

642
        line_breaks = linebreaks(src) if src else []
643
        return self._tree_repr('    ', opening, closing, density=1)
644

Eckhart Arnold's avatar
Eckhart Arnold committed
645

646
    def select(self, match_function: Callable, include_root: bool=True) -> Iterator['Node']:
eckhart's avatar
eckhart committed
647
        """
648
        Finds nodes in the tree that fulfill a given criterion.
eckhart's avatar
eckhart committed
649

650
        `select` is a generator that yields all nodes for which the
di68kap's avatar
di68kap committed
651
        given `match_function` evaluates to True. The tree is
652
653
654
        traversed pre-order.

        See function `Node.select_by_tag` for some examples.
eckhart's avatar
eckhart committed
655

656
657
658
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
659
660
            include_root (bool): If False, only descendant nodes will be
                checked for a match.
661
        Yields:
662
            Node: All nodes of the tree for which
663
664
            ``match_function(node)`` returns True
        """
665
        if include_root and match_function(self):
666
667
668
            yield self
        else:
            for child in self.children:
669
                for node in child.select(match_function, True):
eckhart's avatar
eckhart committed
670
                    yield node
671

Eckhart Arnold's avatar
Eckhart Arnold committed
672

673
674
    def select_by_tag(self, tag_names: Union[str, Set[str]],
                      include_root: bool=True) -> Iterator['Node']:
675
        """
676
677
678
679
        Returns an iterator that runs through all descendants that have one
        of the given tag names.

        Examples::
680
681

            >>> tree = mock_syntax_tree('(a (b "X") (X (c "d")) (e (X "F")))')
682
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag("X", False))
683
            ['(X (c "d"))', '(X "F")']
684
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag({"X", "b"}, False))
685
            ['(b "X")', '(X (c "d"))', '(X "F")']
686
            >>> any(tree.select_by_tag('a', False))
687
            False
688
            >>> list(flatten_sxpr(item.as_sxpr()) for item in tree.select_by_tag('a', True))
689
            ['(a (b "X") (X (c "d")) (e (X "F")))']
690
691
            >>> flatten_sxpr(next(tree.select_by_tag("X", False)).as_sxpr())
            '(X (c "d"))'
692
693

        Args:
694
695
696
697
            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.
698
699
700
        Yields:
            Node: All nodes which have a given tag name.
        """
701
702
703
        if isinstance(tag_names, str):
            tag_names = frozenset(tag_names)
        return self.select(lambda node: node.tag_name in tag_names, include_root)
704
705


706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
    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


721
    def tree_size(self) -> int:
eckhart's avatar
eckhart committed
722
723
724
        """
        Recursively counts the number of nodes in the tree including the root node.
        """
725
726
727
        return sum(child.tree_size() for child in self.children) + 1


eckhart's avatar
eckhart committed
728
729
730
ZOMBIE_NODE = Node(ZOMBIE_PARSER, '')


731
def mock_syntax_tree(sxpr):
732
    """
di68kap's avatar
di68kap committed
733
734
    Generates a tree of nodes from an S-expression. The main purpose of this is
    to generate test data.
735
736
737
738
739
740
741

    Example:
    >>> mock_syntax_tree("(a (b c))").as_sxpr()
    '(a\\n    (b\\n        "c"\\n    )\\n)'
    """

    def next_block(s):
eckhart's avatar
eckhart committed
742
743
744
        """Generator that yields all characters until the next closing bracket
        that does not match an opening bracket matched earlier within the same
        package."""
745
        s = s.strip()
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
        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)
765

766
    sxpr = sxpr.strip()
eckhart's avatar
eckhart committed
767
768
    if sxpr[0] != '(':
        raise ValueError('"(" expected, not ' + sxpr[:10])
769
770
    # assert sxpr[0] == '(', sxpr
    sxpr = sxpr[1:].strip()
eckhart's avatar
eckhart committed
771
    match = re.match(r'[\w:]+', sxpr)
772
773
774
    if match is None:
        raise AssertionError('Malformed S-expression Node-tagname or identifier expected, '
                             'not "%s"' % sxpr[:40].replace('\n', ''))
eckhart's avatar
eckhart committed
775
776
    name, class_name = (sxpr[:match.end()].split(':') + [''])[:2]
    sxpr = sxpr[match.end():].strip()
777
778
    if sxpr[0] == '(':
        result = tuple(mock_syntax_tree(block) for block in next_block(sxpr))
779
780
781
782
        pos = 0
        for node in result:
            node._pos = pos
            pos += len(node)
783
784
    else:
        lines = []
785
        while sxpr and sxpr[0] != ')':
eckhart's avatar
eckhart committed
786
787
788
789
790
791
            for qtmark in ['"""', "'''", '"', "'"]:
                match = re.match(qtmark + r'.*?' + qtmark, sxpr, re.DOTALL)
                if match:
                    i = len(qtmark)
                    lines.append(sxpr[i:match.end() - i])
                    sxpr = sxpr[match.end():].strip()
792
793
                    break
            else:
eckhart's avatar
eckhart committed
794
795
796
                match = re.match(r'(?:(?!\)).)*', sxpr, re.DOTALL)
                lines.append(sxpr[:match.end()])
                sxpr = sxpr[match.end():]
797
        result = "\n".join(lines)
798
799
800
    node = Node(MockParser(name, ':' + class_name), result)
    node._pos = 0
    return node
801

802
803
804
805
# if __name__ == "__main__":
#     st = mock_syntax_tree("(alpha (beta (gamma i\nj\nk) (delta y)) (epsilon z))")
#     print(st.as_sxpr())
#     print(st.as_xml())