10.12., 9:00 - 11:00: Due to updates GitLab may be unavailable for some minutes between 09:00 and 11:00.

syntaxtree.py 20.4 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.
"""

Eckhart Arnold's avatar
Eckhart Arnold committed
19
import collections.abc
20
import copy
21
import os
22
from functools import partial
23
from typing import Any, Callable, cast, Iterator, List, Union, Tuple, Hashable, Optional
24

25
from DHParser.error import Error, linebreaks, line_col
26
from DHParser.stringview import StringView
27
from DHParser.toolkit import is_logging, log_dir, identity, re
28

29 30 31 32 33 34 35
__all__ = ('ParserBase',
           'WHITESPACE_PTYPE',
           'TOKEN_PTYPE',
           'MockParser',
           'ZombieParser',
           'ZOMBIE_PARSER',
           'Node',
36 37
           'mock_syntax_tree',
           'TransformationFunc')
Eckhart Arnold's avatar
Eckhart Arnold committed
38 39


40 41 42 43 44 45 46 47 48 49 50 51 52 53
#######################################################################
#
# 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()):
54
        self._name = name  # type: str
55 56 57 58 59 60 61 62
        self._ptype = ':' + self.__class__.__name__  # type: str

    def __repr__(self):
        return self.name + self.ptype

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

63 64 65
    def __call__(self, text: StringView) -> Tuple[Optional['Node'], StringView]:
        return None, text

66 67 68 69
    @property
    def name(self):
        return self._name

70 71 72 73 74 75 76 77
    @property
    def ptype(self) -> str:
        return self._ptype

    @property
    def repr(self) -> str:
        return self.name if self.name else repr(self)

78 79 80 81 82 83 84 85 86
    def reset(self):
        pass

    def grammar(self) -> 'Grammar':
        return None

    def apply(self, func: Callable) -> bool:
        return False

87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103

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] == ':'
104
        super().__init__(name)
105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146
        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
#
#######################################################################


147
ChildrenType = Tuple['Node', ...]
Eckhart Arnold's avatar
Eckhart Arnold committed
148
NoChildren = cast(ChildrenType, ())  # type: ChildrenType
149 150
StrictResultType = Union[ChildrenType, StringView, str]
ResultType = Union[ChildrenType, 'Node', StringView, str, None]
151 152


Eckhart Arnold's avatar
Eckhart Arnold committed
153 154
def flatten_sxpr(sxpr: str) -> str:
    """Returns S-expression `sxpr` as a one-liner without unnecessary
Eckhart Arnold's avatar
Eckhart Arnold committed
155 156 157
    whitespace.

    Example:
Eckhart Arnold's avatar
Eckhart Arnold committed
158
    >>> flatten_sxpr('(a\\n    (b\\n        c\\n    )\\n)\\n')
Eckhart Arnold's avatar
Eckhart Arnold committed
159 160 161 162 163
    '(a (b c))'
    """
    return re.sub('\s(?=\))', '', re.sub('\s+', ' ', sxpr)).strip()


Eckhart Arnold's avatar
Eckhart Arnold committed
164
class Node(collections.abc.Sized):
165 166 167
    """
    Represents a node in the concrete or abstract syntax tree.

168
    Attributes and Properties:
169 170 171 172 173 174 175
        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!
Eckhart Arnold's avatar
Eckhart Arnold committed
176
        parser (Parser):  The parser which generated this node.
177 178
            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
179 180
            rely on this being a real parser object in any phase after
            parsing (i.e. AST-transformation and compiling), for
181
            example by calling ``isinstance(node.parer, ...)``.
182 183
        errors (list):  A list of parser- or compiler-errors:
            tuple(position, string) attached to this node
184 185 186
        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.
187 188 189 190 191 192 193
        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.

Eckhart Arnold's avatar
Eckhart Arnold committed
194
            The value of ``pos`` is -1 meaning invalid by default.
195
            Setting this value will set the positions of all child
Eckhart Arnold's avatar
Eckhart Arnold committed
196
            nodes relative to this value.
197 198

            To set the pos values of all nodes in a syntax tree, the
Eckhart Arnold's avatar
Eckhart Arnold committed
199
            pos value of the root node should be set to 0 right
200 201
            after parsing.

Eckhart Arnold's avatar
Eckhart Arnold committed
202
            Other than that, this value should be considered READ ONLY.
203 204 205 206
            At any rate, it should only be reassigned only during
            parsing stage and never during or after the
            AST-transformation.
    """
207

208 209
    __slots__ = ['_result', 'children', '_errors', '_len', '_pos', 'parser', 'error_flag']

210

211
    def __init__(self, parser, result: ResultType, leafhint: bool=False) -> None:
212 213 214
        """Initializes the ``Node``-object with the ``Parser``-Instance
        that generated the node and the parser's result.
        """
215 216 217 218 219 220 221 222 223
        # self._result = ''             # type: StrictResultType
        # self.children = ()            # type: ChildrenType
        self.error_flag = 0             # type: int
        self._errors = []               # type: List[Error]
        if leafhint:
            self._result = result       # type: StrictResultType
            self.children = NoChildren  # type: ChildrenType
        else:
            self.result = result
Eckhart Arnold's avatar
Eckhart Arnold committed
224
        self._len = len(self._result) if not self.children else \
225
            sum(child._len for child in self.children)  # type: int
Eckhart Arnold's avatar
Eckhart Arnold committed
226
        # self.pos: int  = 0  # continuous updating of pos values wastes a lot of time
227
        self._pos = -1  # type: int
228 229
        self.parser = parser or ZOMBIE_PARSER

Eckhart Arnold's avatar
Eckhart Arnold committed
230

231 232
    def __str__(self):
        if self.children:
233
            return "".join(str(child) for child in self.children)
234 235 236
        elif isinstance(self.result, StringView):
            self.result = str(self.result)
        return self.result
237

Eckhart Arnold's avatar
Eckhart Arnold committed
238

239 240 241 242 243 244
    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)
245

Eckhart Arnold's avatar
Eckhart Arnold committed
246

247 248 249 250 251 252 253 254 255
    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


256
    def __eq__(self, other):
257 258
        # return str(self.parser) == str(other.parser) and self.result == other.result
        return self.tag_name == other.tag_name and self.result == other.result
259

Eckhart Arnold's avatar
Eckhart Arnold committed
260

261
    def __hash__(self):
262
        return hash(self.tag_name)
263

Eckhart Arnold's avatar
Eckhart Arnold committed
264

265 266 267 268 269 270
    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
271

272
    @property   # this needs to be a (dynamic) property, in case sef.parser gets updated
273
    def tag_name(self) -> str:
274
        return self.parser.name or self.parser.ptype
275

Eckhart Arnold's avatar
Eckhart Arnold committed
276

277
    @property
Eckhart Arnold's avatar
Eckhart Arnold committed
278
    def result(self) -> StrictResultType:
279 280 281
        return self._result

    @result.setter
Eckhart Arnold's avatar
Eckhart Arnold committed
282
    def result(self, result: ResultType):
Eckhart Arnold's avatar
Eckhart Arnold committed
283
        # # made obsolete by static type checking with mypy
284 285 286
        # 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
287 288
        # Possible optimization: Do not allow single nodes as argument:
        # assert not isinstance(result, Node)
289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311

        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 ''
                if self.children and not self.error_flag:
                    self.error_flag = max(child.error_flag for child in self.children)
            else:
                self.children = NoChildren
                self._result = result

        # # shorter but slower:
        # self._result = (result,) if isinstance(result, Node) else result or ''  # type: StrictResultType
        # self.children = cast(ChildrenType, self._result) \
        #     if isinstance(self._result, tuple) else NoChildren  # type: ChildrenType
        # if self.children:
        #     self.error_flag = max(self.error_flag,
        #                           max(child.error_flag for child in self.children))  # type: bool

312 313

    @property
314
    def pos(self) -> int:
315 316 317 318
        assert self._pos >= 0, "position value not initialized!"
        return self._pos

    @pos.setter
319
    def pos(self, pos: int):
320 321
        self._pos = pos
        offset = 0
322
        # recursively adjust pos-values of all children
323 324
        for child in self.children:
            child.pos = pos + offset
325
            offset += len(child)
326 327 328
        # add pos-values to Error-objects
        for err in self._errors:
            err.pos = pos
329

Eckhart Arnold's avatar
Eckhart Arnold committed
330

331
    @property
332
    def errors(self) -> List[Error]:
333 334
        return self._errors.copy()

335

336
    def add_error(self, message: str, level: int = Error.ERROR, code: Hashable = 0) -> 'Node':
Eckhart Arnold's avatar
Eckhart Arnold committed
337
        self._errors.append(Error(message, level, code))
338
        self.error_flag = max(self.error_flag, self._errors[-1].level)
Eckhart Arnold's avatar
Eckhart Arnold committed
339 340
        return self

341

342 343
    def collect_errors(self, document: Union[StringView, str] = '', clear_errors=False) \
            -> List[Error]:
Eckhart Arnold's avatar
Eckhart Arnold committed
344
        """
345
        Recursively adds line- and column-numbers to all error objects.
Eckhart Arnold's avatar
Eckhart Arnold committed
346 347 348 349
        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.
        """
350 351 352 353 354 355
        if self.error_flag:
            lbreaks = linebreaks(document) if document else []
            return self._collect_errors(lbreaks, clear_errors)
        else:
            return []

356
    def _collect_errors(self, lbreaks: List[int]=[], clear_errors=False) -> List[Error]:
357 358 359 360 361 362 363 364 365 366 367 368 369 370 371
        if self.error_flag:
            errors = self.errors
            if lbreaks:
                for err in errors:
                    err.pos = self.pos
                    err.line, err.column = line_col(lbreaks, err.pos)
            if clear_errors:
                self._errors = []
                self.error_flag = 0
            if self.children:
                for child in self.children:
                    errors.extend(child._collect_errors(lbreaks, clear_errors))
            return errors
        else:
            return []
372

Eckhart Arnold's avatar
Eckhart Arnold committed
373

374
    def _tree_repr(self, tab, openF, closeF, dataF=identity, density=0) -> str:
375 376 377 378 379 380 381 382
        """
        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.

383
        Args:
384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399
            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:
400
            return head.rstrip() + tail.lstrip()
401

402
        D = None if density & 2 else ''
403 404 405

        if self.children:
            content = []
406
            for child in self.children:
407
                subtree = child._tree_repr(tab, openF, closeF, dataF, density).split('\n')
408
                content.append('\n'.join((tab + s) for s in subtree))
409
            return head + '\n'.join(content) + tail.lstrip(D)
410

411
        res = cast(str, self.result)  # safe, because if there are no children, result is a string
412 413 414 415
        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()
416
        else:
417
            return head + '\n'.join([tab + dataF(s) for s in res.split('\n')]) + tail.lstrip(D)
418

Eckhart Arnold's avatar
Eckhart Arnold committed
419

420
    def as_sxpr(self, src: str=None, compact: bool=False) -> str:
421 422 423
        """
        Returns content as S-expression, i.e. in lisp-like form.

424
        Args:
425 426 427
            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
428 429 430
            compact:  If True a compact representation is returned where
                brackets are ommited and only the indentation indicates the
                tree structure.
431 432
        """

433 434
        lB, rB, D = ('', '', 1) if compact else ('(', '\n)', 0)

435
        def opening(node) -> str:
436
            s = lB + node.tag_name
437 438
            # s += " '(pos %i)" % node.pos
            if src:
439
                s += " '(pos %i " % node.pos  # + " %i %i)" % line_col(src, node.pos)
440 441 442
            if node.errors:
                s += " '(err '(%s))" % ' '.join(str(err).replace('"', r'\"')
                                                for err in node.errors)
443
            return s + '\n'
444 445 446 447 448 449

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

450
        return self._tree_repr('    ', opening, lambda node: rB, pretty, density=D)
451

Eckhart Arnold's avatar
Eckhart Arnold committed
452

453
    def as_xml(self, src: str=None) -> str:
454 455 456
        """
        Returns content as XML-tree.

457
        Args:
458 459 460 461 462
            src:  The source text or `None`. In case the source text is
                given the position will also be reported as line and
                column.
        """

463
        def opening(node) -> str:
464 465 466 467 468 469
            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)
470
            return s + ">\n"
471 472

        def closing(node):
473
            return '\n</' + node.tag_name + '>'
474

475
        return self._tree_repr('    ', opening, closing, density=1)
476

Eckhart Arnold's avatar
Eckhart Arnold committed
477

Eckhart Arnold's avatar
Eckhart Arnold committed
478 479 480
    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
481 482
        return flatten_sxpr(self.as_sxpr())

483

Eckhart Arnold's avatar
Eckhart Arnold committed
484
    def content(self) -> str:
485
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
486 487
        Returns content as string, inserting error messages where
        errors occurred.
488
        """
Eckhart Arnold's avatar
Eckhart Arnold committed
489 490
        s = "".join(child.content() for child in self.children) if self.children \
            else str(self.result)
491 492
        return (' <<< Error on "%s" | %s >>> '
                % (s, '; '.join(e.message for e in self._errors))) if self._errors else s
493

Eckhart Arnold's avatar
Eckhart Arnold committed
494

495
    def find(self, match_function: Callable) -> Iterator['Node']:
496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515
        """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
516

517 518 519 520 521
    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
522
    def log(self, log_file_name):
523
        if is_logging():
Eckhart Arnold's avatar
Eckhart Arnold committed
524 525 526 527
            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:
528
                f.write(self.as_sxpr())
Eckhart Arnold's avatar
Eckhart Arnold committed
529

530

531
def mock_syntax_tree(sxpr):
532 533 534 535 536 537 538 539 540 541 542 543 544 545
    """
    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
546
            k = 1
547
            while level > 0:
548
                if s[k] == '(':
549
                    level += 1
550
                elif s[k] == ')':
551
                    level -= 1
552 553 554
                k += 1
            yield s[:k]
            s = s[k:].strip()
555

556 557 558 559 560 561 562 563 564
    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))
565 566
    else:
        lines = []
567
        while sxpr and sxpr[0] != ')':
568
            for qm in ['"""', "'''", '"', "'"]:
569
                m = re.match(qm + r'.*?' + qm, sxpr, re.DOTALL)
570 571
                if m:
                    i = len(qm)
572 573
                    lines.append(sxpr[i:m.end() - i])
                    sxpr = sxpr[m.end():].strip()
574 575
                    break
            else:
576 577 578
                m = re.match(r'(?:(?!\)).)*', sxpr, re.DOTALL)
                lines.append(sxpr[:m.end()])
                sxpr = sxpr[m.end():]
579 580 581 582
        result = "\n".join(lines)
    return Node(MockParser(name, ':' + class_name), result)


583
TransformationFunc = Union[Callable[[Node], Any], partial]
584

585 586 587 588 589

# 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())