syntaxtree.py 19.4 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.
"""

19
import copy
20
import os
21
22
from functools import partial

23
24
25
26
try:
    import regex as re
except ImportError:
    import re
27
28
29
30
31
32
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
33

34
from DHParser.toolkit import is_logging, log_dir, StringView, line_col, identity
35

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


Eckhart Arnold's avatar
Eckhart Arnold committed
47
48
49
50
51
52
53
54
55
56
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

57
58
59
    def __repr__(self):
        return self.name + self.ptype

Eckhart Arnold's avatar
Eckhart Arnold committed
60
    def __str__(self):
61
        return self.name + (' = ' if self.name else '') + repr(self)
Eckhart Arnold's avatar
Eckhart Arnold committed
62
63
64
65
66

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

67
68
69
    @property
    def repr(self) -> str:
        return self.name if self.name else repr(self)
Eckhart Arnold's avatar
Eckhart Arnold committed
70

71

72
73
74
75
WHITESPACE_PTYPE = ':Whitespace'
TOKEN_PTYPE = ':Token'


Eckhart Arnold's avatar
Eckhart Arnold committed
76
class MockParser(ParserBase):
77
78
    """
    MockParser objects can be used to reconstruct syntax trees from a
Eckhart Arnold's avatar
Eckhart Arnold committed
79
80
    serialized form like S-expressions or XML. Mock objects can mimic
    different parser types by assigning them a ptype on initialization.
81
82
83
84
85
    
    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
86
    def __init__(self, name='', ptype=''):  # , pbases=frozenset()):
87
        assert not ptype or ptype[0] == ':'
Eckhart Arnold's avatar
Eckhart Arnold committed
88
        super(MockParser, self).__init__(name)
89
        self.name = name
Eckhart Arnold's avatar
Eckhart Arnold committed
90
        self._ptype = ptype or ':' + self.__class__.__name__
91
92
93


class ZombieParser(MockParser):
94
95
96
97
98
99
100
101
102
103
104
105
    """
    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):
106
        super(ZombieParser, self).__init__("__ZOMBIE__")
107
108
109
110
        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
111
112
113
114
115
116
    def __copy__(self):
        return self

    def __deepcopy__(self, memo):
        return self

117
118
119
120
    def __call__(self, text):
        """Better call Saul ;-)"""
        return None, text

121
122
123
124

ZOMBIE_PARSER = ZombieParser()


125
126
127
128
129
# # Python 3.6:
# class Error(NamedTuple):
#     pos: int
#     msg: str
Error = NamedTuple('Error', [('pos', int), ('msg', str)])
130

131
ChildrenType = Tuple['Node', ...]
132
133
StrictResultType = Union[ChildrenType, StringView, str]
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
134
135


Eckhart Arnold's avatar
Eckhart Arnold committed
136
137
def flatten_sxpr(sxpr: str) -> str:
    """Returns S-expression `sxpr` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
138
139
140
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
141
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
142
143
144
145
146
    '(a (b c))'
    """
    return re.sub('\s(?=\))', '', re.sub('\s+', ' ', sxpr)).strip()


147
148
149
150
151
152
153
154
155
156
157
158
class Node:
    """
    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!
159
160
161
162
163
164
        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, ...)``.
165
166
        errors (list):  A list of parser- or compiler-errors:
            tuple(position, string) attached to this node
Eckhart Arnold's avatar
Eckhart Arnold committed
167
168
        error_flag (bool):  True, if either the node or any of its
            descendants has errors.
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
        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.
    """
189

190
191
    __slots__ = ['_result', 'children', '_errors', '_len', '_pos', 'parser', 'error_flag']

192

Eckhart Arnold's avatar
Eckhart Arnold committed
193
    def __init__(self, parser, result: ResultType) -> None:
194
195
196
        """Initializes the ``Node``-object with the ``Parser``-Instance
        that generated the node and the parser's result.
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
197
        # self._result = ''  # type: StrictResultType
198
        # self.children = ()  # type: ChildrenType
199
        # self.error_flag = False  # type: bool
200
        self._errors = []  # type: List[str]
201
        self.result = result
202
203
        self._len = len(result) if not self.children else \
            sum(child._len for child in self.children)  # type: int
Eckhart Arnold's avatar
Eckhart Arnold committed
204
        # self.pos: int  = 0  # continuous updating of pos values wastes a lot of time
205
        self._pos = -1  # type: int
206
207
        self.parser = parser or ZOMBIE_PARSER

Eckhart Arnold's avatar
Eckhart Arnold committed
208

209
210
    def __str__(self):
        if self.children:
211
            return "".join(str(child) for child in self.children)
212
213
        return str(self.result)

Eckhart Arnold's avatar
Eckhart Arnold committed
214

215
216
217
218
219
220
    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)
221

Eckhart Arnold's avatar
Eckhart Arnold committed
222

223
    def __eq__(self, other):
224
225
        # return str(self.parser) == str(other.parser) and self.result == other.result
        return self.tag_name == other.tag_name and self.result == other.result
226

Eckhart Arnold's avatar
Eckhart Arnold committed
227

228
    def __hash__(self):
229
        return hash(self.tag_name)
230

Eckhart Arnold's avatar
Eckhart Arnold committed
231

232
233
234
235
236
237
    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
238

239
    @property   # this needs to be a (dynamic) property, in case sef.parser gets updated
240
    def tag_name(self) -> str:
241
        return self.parser.name or self.parser.ptype
242

Eckhart Arnold's avatar
Eckhart Arnold committed
243

244
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
245
    def result(self) -> StrictResultType:
246
247
248
        return self._result

    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
249
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
250
        # # made obsolete by static type checking with mypy
251
252
253
        # assert ((isinstance(result, tuple) and all(isinstance(child, Node) for child in result))
        #         or isinstance(result, Node)
        #         or isinstance(result, str)), str(result)
254
        self._result = (result,) if isinstance(result, Node) else str(result) \
255
            if isinstance(result, StringView) else result or ''  # type: StrictResultType
256
        self.children = cast(ChildrenType, self._result) \
Eckhart Arnold's avatar
Eckhart Arnold committed
257
            if isinstance(self._result, tuple) else cast(ChildrenType, ())  # type: ChildrenType
258
        self.error_flag = any(r.error_flag for r in self.children)  # type: bool
259

Eckhart Arnold's avatar
Eckhart Arnold committed
260

261
    @property
262
    def len(self) -> int:
263
        # DEBUGGING:  print(self.tag_name, str(self.pos), str(self._len), str(self)[:10].replace('\n','.'))
264
265
        return self._len

Eckhart Arnold's avatar
Eckhart Arnold committed
266

267
    @property
268
    def pos(self) -> int:
269
270
271
272
        assert self._pos >= 0, "position value not initialized!"
        return self._pos

    @pos.setter
273
274
    def pos(self, pos: int):
        # assert isinstance(pos, int)
275
276
277
278
279
280
        self._pos = pos
        offset = 0
        for child in self.children:
            child.pos = pos + offset
            offset += child.len

Eckhart Arnold's avatar
Eckhart Arnold committed
281

282
    @property
283
    def errors(self) -> List[Error]:
284
285
        return [Error(self.pos, err) for err in self._errors]

Eckhart Arnold's avatar
Eckhart Arnold committed
286

287
288
    def add_error(self, error_str: str) -> 'Node':
        assert isinstance(error_str, str)
Eckhart Arnold's avatar
Eckhart Arnold committed
289
290
291
292
        self._errors.append(error_str)
        self.error_flag = True
        return self

Eckhart Arnold's avatar
Eckhart Arnold committed
293

Eckhart Arnold's avatar
Eckhart Arnold committed
294
295
296
297
298
299
300
301
302
303
304
305
306
307
    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
308

Eckhart Arnold's avatar
Eckhart Arnold committed
309

310
    def _tree_repr(self, tab, openF, closeF, dataF=identity, density=0) -> str:
311
312
313
314
315
316
317
318
        """
        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.

319
        Args:
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
            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:
336
            return head.rstrip() + tail.lstrip()
337

338
        D = None if density & 2 else ''
339
340
341

        if self.children:
            content = []
342
            for child in self.children:
343
                subtree = child._tree_repr(tab, openF, closeF, dataF, density).split('\n')
344
                content.append('\n'.join((tab + s) for s in subtree))
345
            return head + '\n'.join(content) + tail.lstrip(D)
346

347
        res = cast(str, self.result)  # safe, because if there are no children, result is a string
348
349
350
351
        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()
352
        else:
353
            return head + '\n'.join([tab + dataF(s) for s in res.split('\n')]) + tail.lstrip(D)
354

Eckhart Arnold's avatar
Eckhart Arnold committed
355

356
    def as_sxpr(self, src: str=None) -> str:
357
358
359
        """
        Returns content as S-expression, i.e. in lisp-like form.

360
        Args:
361
362
363
364
365
            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.
        """

366
        def opening(node) -> str:
367
368
369
            s = '(' + node.tag_name
            # s += " '(pos %i)" % node.pos
            if src:
Eckhart Arnold's avatar
Eckhart Arnold committed
370
                s += " '(pos %i " % node.pos + " %i %i)" % line_col(src, node.pos)
371
372
373
            if node.errors:
                s += " '(err '(%s))" % ' '.join(str(err).replace('"', r'\"')
                                                for err in node.errors)
374
            return s + '\n'
375
376
377
378
379
380

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

381
        return self._tree_repr('    ', opening, lambda node: '\n)', pretty, density=0)
382

Eckhart Arnold's avatar
Eckhart Arnold committed
383

384
    def as_xml(self, src: str=None) -> str:
385
386
387
        """
        Returns content as XML-tree.

388
        Args:
389
390
391
392
393
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
        """

394
        def opening(node) -> str:
395
396
397
398
399
400
            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)
401
            return s + ">\n"
402
403

        def closing(node):
404
            return '\n</' + node.tag_name + '>'
405

406
        return self._tree_repr('    ', opening, closing, density=1)
407

Eckhart Arnold's avatar
Eckhart Arnold committed
408

Eckhart Arnold's avatar
Eckhart Arnold committed
409
410
411
    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
412
413
        return flatten_sxpr(self.as_sxpr())

414

Eckhart Arnold's avatar
Eckhart Arnold committed
415
    def content(self) -> str:
416
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
417
418
        Returns content as string, inserting error messages where
        errors occurred.
419
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
420
421
422
423
        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
424

Eckhart Arnold's avatar
Eckhart Arnold committed
425

426
    def find(self, match_function: Callable) -> Iterator['Node']:
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
        """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
447

448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
    # 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
    #     """


465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
    # 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('/'))
487

Eckhart Arnold's avatar
Eckhart Arnold committed
488

489
490
491
492
493
    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
494
    def log(self, log_file_name):
495
        if is_logging():
Eckhart Arnold's avatar
Eckhart Arnold committed
496
497
498
499
            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:
500
                f.write(self.as_sxpr())
Eckhart Arnold's avatar
Eckhart Arnold committed
501

502

503
def mock_syntax_tree(sxpr):
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
    """
    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()

528
529
530
531
532
533
534
535
536
    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))
537
538
    else:
        lines = []
539
        while sxpr and sxpr[0] != ')':
540
            for qm in ['"""', "'''", '"', "'"]:
541
                m = re.match(qm + r'.*?' + qm, sxpr, re.DOTALL)
542
543
                if m:
                    i = len(qm)
544
545
                    lines.append(sxpr[i:m.end() - i])
                    sxpr = sxpr[m.end():].strip()
546
547
                    break
            else:
548
549
550
                m = re.match(r'(?:(?!\)).)*', sxpr, re.DOTALL)
                lines.append(sxpr[:m.end()])
                sxpr = sxpr[m.end():]
551
552
553
554
        result = "\n".join(lines)
    return Node(MockParser(name, ':' + class_name), result)


555
TransformationFunc = Union[Callable[[Node], Any], partial]
556

557
558
559
560
561

# 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())