syntaxtree.py 19.6 KB
Newer Older
1
"""syntaxtree.py - syntax tree classes for DHParser
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

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.
"""

Eckhart Arnold's avatar
Eckhart Arnold committed
19
import collections.abc
20
import copy
21
import os
22
23
from functools import partial

24
25
26
27
try:
    import regex as re
except ImportError:
    import re
28
29
30
31
32
33
try:
    from typing import AbstractSet, Any, ByteString, Callable, cast, Container, Dict, \
        Iterator, List, NamedTuple, Sequence, Union, Text, Tuple
except ImportError:
    from .typing34 import AbstractSet, Any, ByteString, Callable, cast, Container, Dict, \
        Iterator, List, NamedTuple, Sequence, Union, Text, Tuple
34

35
from DHParser.toolkit import is_logging, log_dir, StringView, line_col, identity
36

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


Eckhart Arnold's avatar
Eckhart Arnold committed
48
49
50
51
52
53
54
55
56
57
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()):
        self.name = name  # type: str
        self._ptype = ':' + self.__class__.__name__  # type: str

58
59
60
    def __repr__(self):
        return self.name + self.ptype

Eckhart Arnold's avatar
Eckhart Arnold committed
61
    def __str__(self):
62
        return self.name + (' = ' if self.name else '') + repr(self)
Eckhart Arnold's avatar
Eckhart Arnold committed
63
64
65
66
67

    @property
    def ptype(self) -> str:
        return self._ptype

68
69
70
    @property
    def repr(self) -> str:
        return self.name if self.name else repr(self)
Eckhart Arnold's avatar
Eckhart Arnold committed
71

72

73
74
75
76
WHITESPACE_PTYPE = ':Whitespace'
TOKEN_PTYPE = ':Token'


Eckhart Arnold's avatar
Eckhart Arnold committed
77
class MockParser(ParserBase):
78
79
    """
    MockParser objects can be used to reconstruct syntax trees from a
Eckhart Arnold's avatar
Eckhart Arnold committed
80
81
    serialized form like S-expressions or XML. Mock objects can mimic
    different parser types by assigning them a ptype on initialization.
82
83
84
85
86
    
    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.
    """
Eckhart Arnold's avatar
Eckhart Arnold committed
87
    def __init__(self, name='', ptype=''):  # , pbases=frozenset()):
88
        assert not ptype or ptype[0] == ':'
Eckhart Arnold's avatar
Eckhart Arnold committed
89
        super(MockParser, self).__init__(name)
90
        self.name = name
Eckhart Arnold's avatar
Eckhart Arnold committed
91
        self._ptype = ptype or ':' + self.__class__.__name__
92
93
94


class ZombieParser(MockParser):
95
96
97
98
99
100
101
102
103
104
105
106
    """
    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):
107
        super(ZombieParser, self).__init__("__ZOMBIE__")
108
109
110
111
        assert not self.__class__.alive, "There can be only one!"
        assert self.__class__ == ZombieParser, "No derivatives, please!"
        self.__class__.alive = True

Eckhart Arnold's avatar
Eckhart Arnold committed
112
113
114
115
116
117
    def __copy__(self):
        return self

    def __deepcopy__(self, memo):
        return self

118
119
120
121
    def __call__(self, text):
        """Better call Saul ;-)"""
        return None, text

122
123
124
125

ZOMBIE_PARSER = ZombieParser()


126
127
128
129
130
# # Python 3.6:
# class Error(NamedTuple):
#     pos: int
#     msg: str
Error = NamedTuple('Error', [('pos', int), ('msg', str)])
131

132
ChildrenType = Tuple['Node', ...]
133
134
StrictResultType = Union[ChildrenType, StringView, str]
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
135
136


Eckhart Arnold's avatar
Eckhart Arnold committed
137
138
def flatten_sxpr(sxpr: str) -> str:
    """Returns S-expression `sxpr` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
139
140
141
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
142
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
143
144
145
146
147
    '(a (b c))'
    """
    return re.sub('\s(?=\))', '', re.sub('\s+', ' ', sxpr)).strip()


Eckhart Arnold's avatar
Eckhart Arnold committed
148
class Node(collections.abc.Sized):
149
150
151
152
153
154
155
156
157
158
159
    """
    Represents a node in the concrete or abstract syntax tree.

    Attributes:
        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
        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.
        children (tuple):  The tuple of child nodes or an empty tuple
            if there are no child nodes. READ ONLY!
160
161
162
163
164
165
        parser (Parser):  The parser which generated this node. 
            WARNING: In case you use mock syntax trees for testing or
            parser replacement during the AST-transformation: DO NOT
            rely on this being a real parser object in any phase after 
            parsing (i.e. AST-transformation and compiling), for 
            example by calling ``isinstance(node.parer, ...)``.
166
167
        errors (list):  A list of parser- or compiler-errors:
            tuple(position, string) attached to this node
Eckhart Arnold's avatar
Eckhart Arnold committed
168
169
        error_flag (bool):  True, if either the node or any of its
            descendants has errors.
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
        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
            the length before AST-transformation ans will never change
            through AST-transformation. READ ONLY!
        pos (int):  the position of the node within the parsed text.

            The value of ``pos`` is -1 meaning invalid by default. 
            Setting this value will set the positions of all child
            nodes relative to this value.  

            To set the pos values of all nodes in a syntax tree, the
            pos value of the root node should be set to 0 right 
            after parsing.

            Other than that, this value should be considered READ ONLY. 
            At any rate, it should only be reassigned only during
            parsing stage and never during or after the
            AST-transformation.
    """
190

191
192
    __slots__ = ['_result', 'children', '_errors', '_len', '_pos', 'parser', 'error_flag']

193

Eckhart Arnold's avatar
Eckhart Arnold committed
194
    def __init__(self, parser, result: ResultType) -> None:
195
196
197
        """Initializes the ``Node``-object with the ``Parser``-Instance
        that generated the node and the parser's result.
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
198
        # self._result = ''  # type: StrictResultType
199
        # self.children = ()  # type: ChildrenType
200
        # self.error_flag = False  # type: bool
201
        self._errors = []  # type: List[str]
202
        self.result = result
Eckhart Arnold's avatar
Eckhart Arnold committed
203
        self._len = len(self._result) if not self.children else \
204
            sum(child._len for child in self.children)  # type: int
Eckhart Arnold's avatar
Eckhart Arnold committed
205
        # self.pos: int  = 0  # continuous updating of pos values wastes a lot of time
206
        self._pos = -1  # type: int
207
208
        self.parser = parser or ZOMBIE_PARSER

Eckhart Arnold's avatar
Eckhart Arnold committed
209

210
211
    def __str__(self):
        if self.children:
212
            return "".join(str(child) for child in self.children)
213
214
        return str(self.result)

Eckhart Arnold's avatar
Eckhart Arnold committed
215

216
217
218
219
220
221
    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)
222

Eckhart Arnold's avatar
Eckhart Arnold committed
223

224
225
226
227
228
229
230
231
232
    def __len__(self):
        return self._len


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


233
    def __eq__(self, other):
234
235
        # return str(self.parser) == str(other.parser) and self.result == other.result
        return self.tag_name == other.tag_name and self.result == other.result
236

Eckhart Arnold's avatar
Eckhart Arnold committed
237

238
    def __hash__(self):
239
        return hash(self.tag_name)
240

Eckhart Arnold's avatar
Eckhart Arnold committed
241

242
243
244
245
246
247
    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
248

249
    @property   # this needs to be a (dynamic) property, in case sef.parser gets updated
250
    def tag_name(self) -> str:
251
        return self.parser.name or self.parser.ptype
252

Eckhart Arnold's avatar
Eckhart Arnold committed
253

254
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
255
    def result(self) -> StrictResultType:
256
257
258
        return self._result

    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
259
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
260
        # # made obsolete by static type checking with mypy
261
262
263
        # 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
264
265
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
266
        self._result = (result,) if isinstance(result, Node) else str(result) \
267
            if isinstance(result, StringView) else result or ''  # type: StrictResultType
268
        self.children = cast(ChildrenType, self._result) \
Eckhart Arnold's avatar
Eckhart Arnold committed
269
            if isinstance(self._result, tuple) else cast(ChildrenType, ())  # type: ChildrenType
270
        self.error_flag = any(r.error_flag for r in self.children)  # type: bool
271
272

    @property
273
    def pos(self) -> int:
274
275
276
277
        assert self._pos >= 0, "position value not initialized!"
        return self._pos

    @pos.setter
278
279
    def pos(self, pos: int):
        # assert isinstance(pos, int)
280
281
282
283
        self._pos = pos
        offset = 0
        for child in self.children:
            child.pos = pos + offset
284
            offset += len(child)
285

Eckhart Arnold's avatar
Eckhart Arnold committed
286

287
    @property
288
    def errors(self) -> List[Error]:
289
290
        return [Error(self.pos, err) for err in self._errors]

Eckhart Arnold's avatar
Eckhart Arnold committed
291

292
293
    def add_error(self, error_str: str) -> 'Node':
        assert isinstance(error_str, str)
Eckhart Arnold's avatar
Eckhart Arnold committed
294
295
296
297
        self._errors.append(error_str)
        self.error_flag = True
        return self

Eckhart Arnold's avatar
Eckhart Arnold committed
298

Eckhart Arnold's avatar
Eckhart Arnold committed
299
300
301
302
303
304
305
306
307
308
309
310
311
312
    def collect_errors(self, clear_errors=False) -> List[Error]:
        """
        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.
        """
        errors = self.errors
        if clear_errors:
            self._errors = []
            self.error_flag = False
        if self.children:
            for child in self.children:
                errors.extend(child.collect_errors(clear_errors))
        return errors
313

Eckhart Arnold's avatar
Eckhart Arnold committed
314

315
    def _tree_repr(self, tab, openF, closeF, dataF=identity, density=0) -> str:
316
317
318
319
320
321
322
323
        """
        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.

324
        Args:
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
            tab (str):  The indentation string, e.g. '\t' or '    '
            openF:  (Node->str) A function that returns an opening
                string (e.g. an XML-tag_name) for a given node
            closeF:  (Node->str) A function that returns a closeF
                string (e.g. an XML-tag_name) for a given node.
            dataF:  (str->str) A function that filters the data string
                before printing, e.g. to add quotation marks

        Returns (str):
            A string that contains a (serialized) tree representation
            of the node and its children.
        """
        head = openF(self)
        tail = closeF(self)

        if not self.result:
341
            return head.rstrip() + tail.lstrip()
342

343
        D = None if density & 2 else ''
344
345
346

        if self.children:
            content = []
347
            for child in self.children:
348
                subtree = child._tree_repr(tab, openF, closeF, dataF, density).split('\n')
349
                content.append('\n'.join((tab + s) for s in subtree))
350
            return head + '\n'.join(content) + tail.lstrip(D)
351

352
        res = cast(str, self.result)  # safe, because if there are no children, result is a string
353
354
355
356
        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 ''
            return head.rstrip() + gap + dataF(self.result) + tail.lstrip()
357
        else:
358
            return head + '\n'.join([tab + dataF(s) for s in res.split('\n')]) + tail.lstrip(D)
359

Eckhart Arnold's avatar
Eckhart Arnold committed
360

361
    def as_sxpr(self, src: str=None, compact: bool=False) -> str:
362
363
364
        """
        Returns content as S-expression, i.e. in lisp-like form.

365
        Args:
366
367
368
369
370
            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.
        """

371
372
        lB, rB, D = ('', '', 1) if compact else ('(', '\n)', 0)

373
        def opening(node) -> str:
374
            s = lB + node.tag_name
375
376
            # s += " '(pos %i)" % node.pos
            if src:
Eckhart Arnold's avatar
Eckhart Arnold committed
377
                s += " '(pos %i " % node.pos + " %i %i)" % line_col(src, node.pos)
378
379
380
            if node.errors:
                s += " '(err '(%s))" % ' '.join(str(err).replace('"', r'\"')
                                                for err in node.errors)
381
            return s + '\n'
382
383
384
385
386
387

        def pretty(s):
            return '"%s"' % s if s.find('"') < 0 \
                else "'%s'" % s if s.find("'") < 0 \
                else '"%s"' % s.replace('"', r'\"')

388
        return self._tree_repr('    ', opening, lambda node: rB, pretty, density=D)
389

Eckhart Arnold's avatar
Eckhart Arnold committed
390

391
    def as_xml(self, src: str=None) -> str:
392
393
394
        """
        Returns content as XML-tree.

395
        Args:
396
397
398
399
400
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
        """

401
        def opening(node) -> str:
402
403
404
405
406
407
            s = '<' + node.tag_name
            # s += ' pos="%i"' % node.pos
            if src:
                s += ' line="%i" col="%i"' % line_col(src, node.pos)
            if node.errors:
                s += ' err="%s"' % ''.join(str(err).replace('"', r'\"') for err in node.errors)
408
            return s + ">\n"
409
410

        def closing(node):
411
            return '\n</' + node.tag_name + '>'
412

413
        return self._tree_repr('    ', opening, closing, density=1)
414

Eckhart Arnold's avatar
Eckhart Arnold committed
415

Eckhart Arnold's avatar
Eckhart Arnold committed
416
417
418
    def structure(self) -> str:
        """Return structure (and content) as S-expression on a single line
        without any line breaks."""
Eckhart Arnold's avatar
Eckhart Arnold committed
419
420
        return flatten_sxpr(self.as_sxpr())

421

Eckhart Arnold's avatar
Eckhart Arnold committed
422
    def content(self) -> str:
423
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
424
425
        Returns content as string, inserting error messages where
        errors occurred.
426
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
427
428
429
430
        s = "".join(child.content() for child in self.children) if self.children \
            else str(self.result)
        return (
        ' <<< Error on "%s" | %s >>> ' % (s, '; '.join(self._errors))) if self._errors else s
431

Eckhart Arnold's avatar
Eckhart Arnold committed
432

433
    def find(self, match_function: Callable) -> Iterator['Node']:
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
        """Finds nodes in the tree that match a specific criterion.
        
        ``find`` is a generator that yields all nodes for which the
        given ``match_function`` evaluates to True. The tree is 
        traversed pre-order.
        
        Args:
            match_function (function): A function  that takes as Node
                object as argument and returns True or False
        Yields:
            Node: all nodes of the tree for which 
            ``match_function(node)`` returns True
        """
        if match_function(self):
            yield self
        else:
            for child in self.children:
                for nd in child.find(match_function):
                    yield nd

Eckhart Arnold's avatar
Eckhart Arnold committed
454

455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
    # def range(self, match_first, match_last):
    #     """Iterates over the range of nodes, starting from the first
    #     node for which ``match_first`` becomes True until the first node
    #     after this one for which ``match_last`` becomes true or until
    #     the end if it never does.
    #
    #     Args:
    #         match_first (function): A function  that takes as Node
    #             object as argument and returns True or False
    #         match_last (function): A function  that takes as Node
    #             object as argument and returns True or False
    #     Yields:
    #         Node: all nodes of the tree for which
    #         ``match_function(node)`` returns True
    #     """


472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
    # def navigate(self, path):
    #     """Yields the results of all descendant elements matched by
    #     ``path``, e.g.
    #     'd/s' yields 'l' from (d (s l)(e (r x1) (r x2))
    #     'e/r' yields 'x1', then 'x2'
    #     'e'   yields (r x1)(r x2)
    #
    #     Args:
    #         path (str):  The path of the object, e.g. 'a/b/c'. The
    #             components of ``path`` can be regular expressions
    #
    #     Returns:
    #         The object at the path, either a string or a Node or
    #         ``None``, if the path did not match.
    #     """
    #     def nav(node, pl):
    #         if pl:
    #             return itertools.chain(nav(child, pl[1:]) for child in node.children
    #                                    if re.match(pl[0], child.tag_name))
    #         else:
    #             return self.result,
    #     return nav(path.split('/'))
494

Eckhart Arnold's avatar
Eckhart Arnold committed
495

496
497
498
499
500
    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


Eckhart Arnold's avatar
Eckhart Arnold committed
501
    def log(self, log_file_name):
502
        if is_logging():
Eckhart Arnold's avatar
Eckhart Arnold committed
503
504
505
506
            path = os.path.join(log_dir(), log_file_name)
            if os.path.exists(path):
                print('WARNING: Log-file "%s" already exists and will be overwritten!' % path)
            with open(path, "w", encoding="utf-8") as f:
507
                f.write(self.as_sxpr())
Eckhart Arnold's avatar
Eckhart Arnold committed
508

509

510
def mock_syntax_tree(sxpr):
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
    """
    Generates a tree of nodes from an S-expression.

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

    def next_block(s):
        s = s.strip()
        while s[0] != ')':
            if s[0] != '(': raise ValueError('"(" expected, not ' + s[:10])
            # assert s[0] == '(', s
            level = 1
            i = 1
            while level > 0:
                if s[i] == '(':
                    level += 1
                elif s[i] == ')':
                    level -= 1
                i += 1
            yield s[:i]
            s = s[i:].strip()

535
536
537
538
539
540
541
542
543
    sxpr = sxpr.strip()
    if sxpr[0] != '(': raise ValueError('"(" expected, not ' + sxpr[:10])
    # assert sxpr[0] == '(', sxpr
    sxpr = sxpr[1:].strip()
    m = re.match('[\w:]+', sxpr)
    name, class_name = (sxpr[:m.end()].split(':') + [''])[:2]
    sxpr = sxpr[m.end():].strip()
    if sxpr[0] == '(':
        result = tuple(mock_syntax_tree(block) for block in next_block(sxpr))
544
545
    else:
        lines = []
546
        while sxpr and sxpr[0] != ')':
547
            for qm in ['"""', "'''", '"', "'"]:
548
                m = re.match(qm + r'.*?' + qm, sxpr, re.DOTALL)
549
550
                if m:
                    i = len(qm)
551
552
                    lines.append(sxpr[i:m.end() - i])
                    sxpr = sxpr[m.end():].strip()
553
554
                    break
            else:
555
556
557
                m = re.match(r'(?:(?!\)).)*', sxpr, re.DOTALL)
                lines.append(sxpr[:m.end()])
                sxpr = sxpr[m.end():]
558
559
560
561
        result = "\n".join(lines)
    return Node(MockParser(name, ':' + class_name), result)


562
TransformationFunc = Union[Callable[[Node], Any], partial]
563

564
565
566
567
568

# 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())