def match(self, segments: Tuple[BaseSegment, ...],
parse_context: ParseContext) -> MatchResult:
"""Match against any of the elements a relevant number of times.
If it matches multiple, it returns the longest, and if any are the same
length it returns the first (unless we explicitly just match first).
"""
# First if we have an *exclude* option, we should check that
# which would prevent the rest of this grammar from matching.
if self.exclude:
with parse_context.deeper_match() as ctx:
if self.exclude.match(segments, parse_context=ctx):
return MatchResult.from_unmatched(segments)
# Match on each of the options
matched_segments: MatchResult = MatchResult.from_empty()
unmatched_segments: Tuple[BaseSegment, ...] = segments
n_matches = 0
while True:
if self.max_times and n_matches >= self.max_times:
# We've matched as many times as we can
return MatchResult(matched_segments.matched_segments,
unmatched_segments)
# Is there anything left to match?
if len(unmatched_segments) == 0:
# No...
if n_matches >= self.min_times:
return MatchResult(matched_segments.matched_segments,
unmatched_segments)
else:
# We didn't meet the hurdle
return MatchResult.from_unmatched(unmatched_segments)
# If we've already matched once...
if n_matches > 0 and self.allow_gaps:
# Consume any non-code if there is any
pre_seg, mid_seg, post_seg = trim_non_code_segments(
unmatched_segments)
unmatched_segments = mid_seg + post_seg
else:
pre_seg = () # empty tuple
match = self._match_once(unmatched_segments,
parse_context=parse_context)
if match:
matched_segments += pre_seg + match.matched_segments
unmatched_segments = match.unmatched_segments
n_matches += 1
else:
# If we get here, then we've not managed to match. And the next
# unmatched segments are meaningful, i.e. they're not what we're
# looking for.
if n_matches >= self.min_times:
return MatchResult(matched_segments.matched_segments,
pre_seg + unmatched_segments)
else:
# We didn't meet the hurdle
return MatchResult.from_unmatched(unmatched_segments)
def test__parser__helper_trim_non_code_segments(
token_list,
pre_len,
mid_len,
post_len,
generate_test_segments,
):
"""Test trim_non_code_segments."""
seg_list = generate_test_segments(token_list)
pre, mid, post = trim_non_code_segments(seg_list)
# Assert lengths
assert (len(pre), len(mid), len(post)) == (pre_len, mid_len, post_len)
# Assert content
assert [elem.raw for elem in pre] == list(token_list[:pre_len])
assert [elem.raw for elem in mid] == list(token_list[pre_len : pre_len + mid_len])
assert [elem.raw for elem in post] == list(token_list[len(seg_list) - post_len :])
def parse(self, parse_context=None, parse_grammar=None):
"""Use the parse grammar to find subsegments within this segment.
A large chunk of the logic around this can be found in the `expand` method.
Use the parse setting in the context for testing, mostly to check how deep to go.
True/False for yes or no, an integer allows a certain number of levels.
Optionally, this method allows a custom parse grammar to be
provided which will override any existing parse grammar
on the segment.
"""
# Clear the blacklist cache so avoid missteps
if parse_context:
parse_context.blacklist.clear()
# the parse_depth and recurse kwargs control how deep we will recurse for testing.
if not self.segments:
# This means we're a root segment, just return an unmutated self
return self
# Check the Parse Grammar
parse_grammar = parse_grammar or self.parse_grammar
if parse_grammar is None:
# No parse grammar, go straight to expansion
parse_context.logger.debug(
"{0}.parse: no grammar. Going straight to expansion".format(
self.__class__.__name__))
else:
# For debugging purposes. Ensure that we don't have non-code elements
# at the start or end of the segments. They should always in the middle,
# or in the parent expression.
segments = self.segments
if self.can_start_end_non_code:
pre_nc, segments, post_nc = trim_non_code_segments(segments)
else:
pre_nc = ()
post_nc = ()
if (not segments[0].is_code) and (not segments[0].is_meta):
raise ValueError(
"Segment {0} starts with non code segment: {1!r}.\n{2!r}"
.format(self, segments[0].raw, segments))
if (not segments[-1].is_code) and (not segments[-1].is_meta):
raise ValueError(
"Segment {0} ends with non code segment: {1!r}.\n{2!r}"
.format(self, segments[-1].raw, segments))
# NOTE: No match_depth kwarg, because this is the start of the matching.
with parse_context.matching_segment(
self.__class__.__name__) as ctx:
m = parse_grammar.match(segments=segments, parse_context=ctx)
if not isinstance(m, MatchResult):
raise TypeError(
"[PD:{0}] {1}.match. Result is {2}, not a MatchResult!".
format(parse_context.parse_depth, self.__class__.__name__,
type(m)))
# Basic Validation, that we haven't dropped anything.
check_still_complete(segments, m.matched_segments,
m.unmatched_segments)
if m.has_match():
if m.is_complete():
# Complete match, happy days!
self.segments = pre_nc + m.matched_segments + post_nc
else:
# Incomplete match.
# For now this means the parsing has failed. Lets add the unmatched bit at the
# end as something unparsable.
# TODO: Do something more intelligent here.
self.segments = (
pre_nc + m.matched_segments + (UnparsableSegment(
segments=m.unmatched_segments + post_nc,
expected="Nothing...",
), ))
elif self.allow_empty and not segments:
# Very edge case, but some segments are allowed to be empty other than non-code
self.segments = pre_nc + post_nc
else:
# If there's no match at this stage, then it's unparsable. That's
# a problem at this stage so wrap it in an unparsable segment and carry on.
self.segments = (
pre_nc + (
UnparsableSegment(
segments=segments,
expected=self.name,
), # NB: tuple
) + post_nc)
bencher = BenchIt() # starts the timer
bencher("Parse complete of {0!r}".format(self.__class__.__name__))
# Recurse if allowed (using the expand method to deal with the expansion)
parse_context.logger.debug(
"{0}.parse: Done Parse. Plotting Recursion. Recurse={1!r}".format(
self.__class__.__name__, parse_context.recurse))
parse_depth_msg = "###\n#\n# Beginning Parse Depth {0}: {1}\n#\n###\nInitial Structure:\n{2}".format(
parse_context.parse_depth + 1, self.__class__.__name__,
self.stringify())
if parse_context.may_recurse():
parse_context.logger.debug(parse_depth_msg)
with parse_context.deeper_parse() as ctx:
self.segments = self.expand(self.segments, parse_context=ctx)
return self
def _longest_trimmed_match(
cls,
segments: Tuple["BaseSegment", ...],
matchers: List["MatchableType"],
parse_context: ParseContext,
trim_noncode=True,
) -> Tuple[MatchResult, Optional["MatchableType"]]:
"""Return longest match from a selection of matchers.
Prioritise the first match, and if multiple match at the same point the longest.
If two matches of the same length match at the same time, then it's the first in
the iterable of matchers.
Returns:
`tuple` of (match_object, matcher).
"""
# Have we been passed an empty list?
if len(segments) == 0:
return MatchResult.from_empty(), None
# If gaps are allowed, trim the ends.
if trim_noncode:
pre_nc, segments, post_nc = trim_non_code_segments(segments)
best_match_length = 0
# iterate at this position across all the matchers
for matcher in matchers:
# MyPy seems to require a type hint here. Not quite sure why.
res_match: MatchResult = matcher.match(
segments, parse_context=parse_context
)
if res_match.is_complete():
# Just return it! (WITH THE RIGHT OTHER STUFF)
if trim_noncode:
return (
MatchResult.from_matched(
pre_nc + res_match.matched_segments + post_nc
),
matcher,
)
else:
return res_match, matcher
elif res_match:
# We've got an incomplete match, if it's the best so far keep it.
if res_match.matched_length > best_match_length:
best_match = res_match, matcher
best_match_length = res_match.matched_length
# If we get here, then there wasn't a complete match. If we
# has a best_match, return that.
if best_match_length > 0:
if trim_noncode:
return (
MatchResult(
pre_nc + best_match[0].matched_segments,
best_match[0].unmatched_segments + post_nc,
),
best_match[1],
)
else:
return best_match
# If no match at all, return nothing
return MatchResult.from_unmatched(segments), None
def match(self, segments, parse_context):
"""Match a specific sequence of elements."""
if isinstance(segments, BaseSegment):
segments = tuple(segments)
matched_segments = MatchResult.from_empty()
unmatched_segments = segments
# Buffers of uninstantiated meta segments.
meta_pre_nc = ()
meta_post_nc = ()
early_break = False
for idx, elem in enumerate(self._elements):
# Check for an early break.
if early_break:
break
while True:
# Consume non-code if appropriate
if self.allow_gaps:
pre_nc, mid_seg, post_nc = trim_non_code_segments(
unmatched_segments)
else:
pre_nc = ()
mid_seg = unmatched_segments
post_nc = ()
# Is it an indent or dedent?
if elem.is_meta:
# Elements with a negative indent value come AFTER
# the whitespace. Positive or neutral come BEFORE.
if elem.indent_val < 0:
meta_post_nc += (elem(), )
else:
meta_pre_nc += (elem(), )
break
# Is it a conditional? If so is it active
if isinstance(
elem,
Conditional) and not elem.is_enabled(parse_context):
# If it's not active, skip it.
break
if len(pre_nc + mid_seg + post_nc) == 0:
# We've run our of sequence without matching everything.
# Do only optional or meta elements remain?
if all(e.is_optional() or e.is_meta
or isinstance(elem, Conditional)
for e in self._elements[idx:]):
# then it's ok, and we can return what we've got so far.
# No need to deal with anything left over because we're at the end,
# unless it's a meta segment.
# We'll add those meta segments after any existing ones. So
# the go on the meta_post_nc stack.
for e in self._elements[idx:]:
# If it's meta, instantiate it.
if e.is_meta:
meta_post_nc += (e(), )
# If it's conditional and it's enabled, match it.
if isinstance(e, Conditional) and e.is_enabled(
parse_context):
meta_match = e.match(tuple(), parse_context)
if meta_match:
meta_post_nc += meta_match.matched_segments
# Early break to exit via the happy match path.
early_break = True
break
else:
# we've got to the end of the sequence without matching all
# required elements.
return MatchResult.from_unmatched(segments)
else:
# We've already dealt with potential whitespace above, so carry on to matching
with parse_context.deeper_match() as ctx:
elem_match = elem.match(mid_seg, parse_context=ctx)
if elem_match.has_match():
# We're expecting mostly partial matches here, but complete
# matches are possible. Don't be greedy with whitespace!
matched_segments += (meta_pre_nc + pre_nc +
meta_post_nc +
elem_match.matched_segments)
meta_pre_nc = ()
meta_post_nc = ()
unmatched_segments = elem_match.unmatched_segments + post_nc
# Each time we do this, we do a sense check to make sure we haven't
# dropped anything. (Because it's happened before!).
check_still_complete(
segments,
matched_segments.matched_segments,
unmatched_segments,
)
# Break out of the while loop and move to the next element.
break
else:
# If we can't match an element, we should ascertain whether it's
# required. If so then fine, move on, but otherwise we should crash
# out without a match. We have not matched the sequence.
if elem.is_optional():
# This will crash us out of the while loop and move us
# onto the next matching element
break
else:
return MatchResult.from_unmatched(segments)
# If we get to here, we've matched all of the elements (or skipped them)
# but still have some segments left (or perhaps have precisely zero left).
# In either case, we're golden. Return successfully, with any leftovers as
# the unmatched elements. Meta all go at the end regardless of wny trailing
# whitespace.
return MatchResult(
BaseSegment._position_segments(
matched_segments.matched_segments + meta_pre_nc +
meta_post_nc, ),
unmatched_segments,
)
def match(self, segments: Tuple["BaseSegment", ...],
parse_context: ParseContext) -> MatchResult:
"""Match if this is a bracketed sequence, with content that matches one of the elements.
1. work forwards to find the first bracket.
If we find something other that whitespace, then fail out.
2. Once we have the first bracket, we need to bracket count forward to find its partner.
3. Assuming we find its partner then we try and match what goes between them
using the match method of Sequence.
If we match, great. If not, then we return an empty match.
If we never find its partner then we return an empty match but should probably
log a parsing warning, or error?
"""
# Trim ends if allowed.
if self.allow_gaps:
pre_nc, seg_buff, post_nc = trim_non_code_segments(segments)
else:
seg_buff = segments
# Rehydrate the bracket segments in question.
start_bracket, end_bracket = self.get_bracket_from_dialect(
parse_context)
# Allow optional override for special bracket-like things
start_bracket = self.start_bracket or start_bracket
end_bracket = self.end_bracket or end_bracket
# Look for the first bracket
with parse_context.deeper_match() as ctx:
start_match = start_bracket.match(seg_buff, parse_context=ctx)
if start_match:
seg_buff = start_match.unmatched_segments
else:
# Can't find the opening bracket. No Match.
return MatchResult.from_unmatched(segments)
# Look for the closing bracket
content_segs, end_match, _ = self._bracket_sensitive_look_ahead_match(
segments=seg_buff,
matchers=[end_bracket],
parse_context=parse_context,
start_bracket=start_bracket,
end_bracket=end_bracket,
bracket_pairs_set=self.bracket_pairs_set,
)
if not end_match:
raise SQLParseError(
"Couldn't find closing bracket for opening bracket.",
segment=start_match.matched_segments[0],
)
# Match the content now we've confirmed the brackets.
# First deal with the case of TOTALLY EMPTY BRACKETS e.g. "()"
if not content_segs:
# If it's allowed, return a match.
if not self._elements or all(e.is_optional()
for e in self._elements):
return MatchResult(
start_match.matched_segments + end_match.matched_segments,
end_match.unmatched_segments,
)
# If not, don't.
else:
return MatchResult.from_unmatched(segments)
# Then trim whitespace and deal with the case of no code content e.g. "( )"
if self.allow_gaps:
pre_nc, content_segs, post_nc = trim_non_code_segments(
content_segs)
else:
pre_nc = ()
post_nc = ()
# If we don't have anything left after trimming, act accordingly.
if not content_segs:
if not self._elements or (all(e.is_optional()
for e in self._elements)
and self.allow_gaps):
return MatchResult(
start_match.matched_segments + pre_nc + post_nc +
end_match.matched_segments,
end_match.unmatched_segments,
)
else:
return MatchResult.from_unmatched(segments)
# Match using super. Sequence will interpret the content of the elements.
with parse_context.deeper_match() as ctx:
content_match = super().match(content_segs, parse_context=ctx)
# We require a complete match for the content (hopefully for obvious reasons)
if content_match.is_complete():
# Append some indent and dedent tokens at the start and the end.
return MatchResult(
# We need to realign the meta segments so the pos markers are correct.
BaseSegment._position_segments(
(
# NB: The nc segments go *outside* the indents.
start_match.matched_segments +
(Indent(), ) # Add a meta indent here
+ pre_nc + content_match.matched_segments + post_nc +
(Dedent(), ) # Add a meta indent here
+ end_match.matched_segments), ),
end_match.unmatched_segments,
)
# No complete match. Fail.
else:
return MatchResult.from_unmatched(segments)
def greedy_match(
cls,
segments,
parse_context,
matchers,
enforce_whitespace_preceeding_terminator,
include_terminator=False,
):
"""Matching for GreedyUntil works just how you'd expect."""
seg_buff = segments
seg_bank = () # Empty tuple
# If no terminators then just return the whole thing.
if matchers == [None]:
return MatchResult.from_matched(segments)
while True:
with parse_context.deeper_match() as ctx:
pre, mat, matcher = cls._bracket_sensitive_look_ahead_match(
seg_buff, matchers, parse_context=ctx)
# Do we have a match?
if mat:
# Do we need to enforce whitespace preceding?
if enforce_whitespace_preceeding_terminator:
# Does the match include some whitespace already?
# Work forward
idx = 0
while True:
elem = mat.matched_segments[idx]
if elem.is_meta:
idx += 1
continue
elif elem.is_type("whitespace", "newline"):
allowable_match = True
break
else:
# No whitespace before. Not allowed.
allowable_match = False
break
# If we're not ok yet, work backward to the preceding sections.
if not allowable_match:
idx = -1
while True:
if len(pre) < abs(idx):
# If we're at the start, it's ok
allowable_match = True
break
if pre[idx].is_meta:
idx -= 1
continue
elif pre[idx].is_type("whitespace", "newline"):
allowable_match = True
break
else:
# No whitespace before. Not allowed.
allowable_match = False
break
# If this match isn't preceded by whitespace and that is
# a requirement, then we can't use it. Carry on...
if not allowable_match:
# Update our buffers and continue onward
seg_bank = pre + mat.matched_segments
seg_buff = mat.unmatched_segments
# Loop around, don't return yet
continue
# Depending on whether we found a terminator or not we treat
# the result slightly differently. If no terminator was found,
# we just use the whole unmatched segment. If we did find one,
# we match up until (but not including [unless self.include_terminator
# is true]) that terminator.
if mat:
# Return everything up to the match unless it's a gap matcher.
if include_terminator:
return MatchResult(
seg_bank + pre + mat.matched_segments,
mat.unmatched_segments,
)
# We can't claim any non-code segments, so we trim them off the end.
leading_nc, pre_seg_mid, trailing_nc = trim_non_code_segments(
seg_bank + pre)
return MatchResult(
leading_nc + pre_seg_mid,
trailing_nc + mat.all_segments(),
)
# No terminator, just return the whole thing.
return MatchResult.from_matched(mat.unmatched_segments)
else:
# Return everything
return MatchResult.from_matched(segments)
def trimmed_matched_length(self) -> int:
"""Return the length of the match in characters, trimming whitespace."""
_, segs, _ = trim_non_code_segments(self.matched_segments)
return sum(seg.matched_length for seg in segs)
def match(self, segments: Tuple["BaseSegment", ...],
parse_context: ParseContext) -> MatchResult:
"""Match if a bracketed sequence, with content that matches one of the elements.
1. work forwards to find the first bracket.
If we find something other that whitespace, then fail out.
2. Once we have the first bracket, we need to bracket count forward to find its
partner.
3. Assuming we find its partner then we try and match what goes between them
using the match method of Sequence.
If we match, great. If not, then we return an empty match.
If we never find its partner then we return an empty match but should
probably log a parsing warning, or error?
"""
# Trim ends if allowed.
if self.allow_gaps:
pre_nc, seg_buff, post_nc = trim_non_code_segments(segments)
else:
seg_buff = segments # pragma: no cover TODO?
# Rehydrate the bracket segments in question.
# bracket_persits controls whether we make a BracketedSegment or not.
start_bracket, end_bracket, bracket_persists = self.get_bracket_from_dialect(
parse_context)
# Allow optional override for special bracket-like things
start_bracket = self.start_bracket or start_bracket
end_bracket = self.end_bracket or end_bracket
# Are we dealing with a pre-existing BracketSegment?
if seg_buff[0].is_type("bracketed"):
seg: BracketedSegment = cast(BracketedSegment, seg_buff[0])
content_segs = seg.segments[len(seg.start_bracket
):-len(seg.end_bracket)]
bracket_segment = seg
trailing_segments = seg_buff[1:]
# Otherwise try and match the segments directly.
else:
# Look for the first bracket
with parse_context.deeper_match() as ctx:
start_match = start_bracket.match(seg_buff, parse_context=ctx)
if start_match:
seg_buff = start_match.unmatched_segments
else:
# Can't find the opening bracket. No Match.
return MatchResult.from_unmatched(segments)
# Look for the closing bracket
content_segs, end_match, _ = self._bracket_sensitive_look_ahead_match(
segments=seg_buff,
matchers=[end_bracket],
parse_context=parse_context,
start_bracket=start_bracket,
end_bracket=end_bracket,
bracket_pairs_set=self.bracket_pairs_set,
)
if not end_match: # pragma: no cover
raise SQLParseError(
"Couldn't find closing bracket for opening bracket.",
segment=start_match.matched_segments[0],
)
# Construct a bracket segment
bracket_segment = BracketedSegment(
segments=(start_match.matched_segments + content_segs +
end_match.matched_segments),
start_bracket=start_match.matched_segments,
end_bracket=end_match.matched_segments,
)
trailing_segments = end_match.unmatched_segments
# Then trim whitespace and deal with the case of non-code content e.g. "( )"
if self.allow_gaps:
pre_segs, content_segs, post_segs = trim_non_code_segments(
content_segs)
else: # pragma: no cover TODO?
pre_segs = ()
post_segs = ()
# If we've got a case of empty brackets check whether that is allowed.
if not content_segs:
if not self._elements or (all(e.is_optional()
for e in self._elements) and
(self.allow_gaps or
(not pre_segs and not post_segs))):
return MatchResult(
(bracket_segment, )
if bracket_persists else bracket_segment.segments,
trailing_segments,
)
else:
return MatchResult.from_unmatched(segments)
# Match the content using super. Sequence will interpret the content of the
# elements.
with parse_context.deeper_match() as ctx:
content_match = super().match(content_segs, parse_context=ctx)
# We require a complete match for the content (hopefully for obvious reasons)
if content_match.is_complete():
# Reconstruct the bracket segment post match.
# We need to realign the meta segments so the pos markers are correct.
# Have we already got indents?
meta_idx = None
for idx, seg in enumerate(bracket_segment.segments):
if (seg.is_meta and cast(MetaSegment, seg).indent_val > 0
and not cast(MetaSegment, seg).is_template):
meta_idx = idx
break
# If we've already got indents, don't add more.
if meta_idx:
bracket_segment.segments = BaseSegment._position_segments(
bracket_segment.start_bracket + pre_segs +
content_match.all_segments() + post_segs +
bracket_segment.end_bracket)
# Append some indent and dedent tokens at the start and the end.
else:
bracket_segment.segments = BaseSegment._position_segments(
# NB: The nc segments go *outside* the indents.
bracket_segment.start_bracket +
(Indent(), ) # Add a meta indent here
+ pre_segs + content_match.all_segments() + post_segs +
(Dedent(), ) # Add a meta indent here
+ bracket_segment.end_bracket)
return MatchResult(
(bracket_segment, )
if bracket_persists else bracket_segment.segments,
trailing_segments,
)
# No complete match. Fail.
else:
return MatchResult.from_unmatched(segments)
def match(
self, segments: Tuple[BaseSegment, ...], parse_context: ParseContext
) -> MatchResult:
"""Match an arbitrary number of elements separated by a delimiter.
Note that if there are multiple elements passed in that they will be treated
as different options of what can be delimited, rather than a sequence.
"""
# Have we been passed an empty list?
if len(segments) == 0:
return MatchResult.from_empty()
# Make some buffers
seg_buff = segments
matched_segments = MatchResult.from_empty()
# delimiters is a list of tuples containing delimiter segments as we find them.
delimiters: List[BaseSegment] = []
# First iterate through all the segments, looking for the delimiter.
# Second, split the list on each of the delimiters, and ensure that
# each sublist in turn matches one of the elements.
# In more detail, match against delimiter, if we match, put a slice
# up to that point onto a list of slices. Carry on.
while True:
# Check to see whether we've exhausted the buffer, either by iterating through it,
# or by consuming all the non-code segments already.
# NB: If we're here then we've already tried matching the remaining segments against
# the content, so we must be in a trailing case.
if len(seg_buff) == 0:
# Append the remaining buffer in case we're in the not is_code case.
matched_segments += seg_buff
# Nothing left, this is potentially a trailing case?
if self.allow_trailing and (
self.min_delimiters is None
or len(delimiters) >= self.min_delimiters
):
# It is! (nothing left so no unmatched segments to append)
return MatchResult.from_matched(matched_segments.matched_segments)
else:
return MatchResult.from_unmatched(segments)
# We rely on _bracket_sensitive_look_ahead_match to do the bracket counting
# element of this now. We look ahead to find a delimiter or terminator.
matchers = [self.delimiter]
if self.terminator:
matchers.append(self.terminator)
# If gaps aren't allowed, a gap (or non-code segment), acts like a terminator.
if not self.allow_gaps:
matchers.append(NonCodeMatcher())
with parse_context.deeper_match() as ctx:
(
pre_content,
delimiter_match,
delimiter_matcher,
) = self._bracket_sensitive_look_ahead_match(
seg_buff,
matchers,
parse_context=ctx,
bracket_pairs_set=self.bracket_pairs_set,
)
# Store the mutated segments to reuse.
mutated_segments = pre_content + delimiter_match.all_segments()
# Have we found a delimiter or terminator looking forward?
if delimiter_match:
if delimiter_matcher is self.delimiter:
# Yes. Store it and then match the contents up to now.
delimiters.append(delimiter_match.matched_segments)
# We now test the intervening section as to whether it matches one
# of the things we're looking for. NB: If it's of zero length then
# we return without trying it.
if len(pre_content) > 0:
pre_non_code, pre_content, post_non_code = trim_non_code_segments(
pre_content
)
# Check for whitespace gaps.
# We do this explicitly here rather than relying on an
# untrimmed match so we can handle _whitespace_ explicitly
# compared to other non code segments like placeholders.
if not self.allow_gaps and any(
seg.is_whitespace for seg in pre_non_code + post_non_code
):
return MatchResult.from_unmatched(mutated_segments)
with parse_context.deeper_match() as ctx:
match, _ = self._longest_trimmed_match(
segments=pre_content,
matchers=self._elements,
parse_context=ctx,
# We've already trimmed
trim_noncode=False,
)
# No match, or an incomplete match: Not allowed
if not match or not match.is_complete():
return MatchResult.from_unmatched(mutated_segments)
# We have a complete match!
# First add the segment up to the delimiter to the matched segments
matched_segments += (
pre_non_code + match.matched_segments + post_non_code
)
# Then it depends what we matched.
# Delimiter
if delimiter_matcher is self.delimiter:
# Then add the delimiter to the matched segments
matched_segments += delimiter_match.matched_segments
# Break this for loop and move on, looking for the next delimiter
seg_buff = delimiter_match.unmatched_segments
# Still got some buffer left. Carry on.
continue
# Terminator (or the gap terminator).
elif delimiter_matcher is self.terminator or isinstance(
delimiter_matcher, NonCodeMatcher
):
# We just return straight away here. We don't add the terminator to
# this match, it should go with the unmatched parts.
# First check we've had enough delimiters
if (
self.min_delimiters
and len(delimiters) < self.min_delimiters
):
return MatchResult.from_unmatched(mutated_segments)
else:
return MatchResult(
matched_segments.matched_segments,
delimiter_match.all_segments(),
)
else:
raise RuntimeError(
(
"I don't know how I got here. Matched instead on {}, which "
"doesn't appear to be delimiter or terminator"
).format(delimiter_matcher)
)
else:
# Zero length section between delimiters, or zero code
# elements if appropriate. Return unmatched.
return MatchResult.from_unmatched(mutated_segments)
else:
# No match for a delimiter looking forward, this means we're
# at the end. In this case we look for a potential partial match
# looking forward. We know it's a non-zero length section because
# we checked that up front.
# First check we're had enough delimiters, because if we haven't then
# there's no sense to try matching
if self.min_delimiters and len(delimiters) < self.min_delimiters:
return MatchResult.from_unmatched(mutated_segments)
# We use the whitespace padded match to hoover up whitespace if enabled,
# and default to the longest matcher. We don't care which one matches.
pre_non_code, trimmed_segments, post_non_code = trim_non_code_segments(
mutated_segments
)
# Check for whitespace gaps.
# We do this explicitly here rather than relying on an
# untrimmed match so we can handle _whitespace_ explicitly
# compared to other non code segments like placeholders.
if not self.allow_gaps and any(
seg.is_whitespace for seg in pre_non_code + post_non_code
):
return MatchResult.from_unmatched(mutated_segments)
with parse_context.deeper_match() as ctx:
mat, _ = self._longest_trimmed_match(
trimmed_segments,
self._elements,
parse_context=ctx,
# We've already trimmed
trim_noncode=False,
)
if mat:
# We've got something at the end. Return!
if mat.unmatched_segments:
# We have something unmatched and so we should let it also have the trailing elements
return MatchResult(
matched_segments.matched_segments
+ pre_non_code
+ mat.matched_segments,
mat.unmatched_segments + post_non_code,
)
else:
# If there's nothing unmatched in the most recent match, then we can consume the trailing
# non code segments
return MatchResult.from_matched(
matched_segments.matched_segments
+ pre_non_code
+ mat.matched_segments
+ post_non_code,
)
else:
# No match at the end, are we allowed to trail? If we are then return,
# otherwise we fail because we can't match the last element.
if self.allow_trailing:
return MatchResult(matched_segments.matched_segments, seg_buff)
else:
return MatchResult.from_unmatched(mutated_segments)
def match(
self,
segments: Tuple[BaseSegment, ...],
parse_context: ParseContext,
) -> MatchResult:
"""Match an arbitrary number of elements separated by a delimiter.
Note that if there are multiple elements passed in that they will be treated
as different options of what can be delimited, rather than a sequence.
"""
# Have we been passed an empty list?
if len(segments) == 0:
return MatchResult.from_empty()
# Make some buffers
seg_buff = segments
matched_segments: Tuple[BaseSegment, ...] = ()
unmatched_segments: Tuple[BaseSegment, ...] = ()
cached_matched_segments: Tuple[BaseSegment, ...] = ()
cached_unmatched_segments: Tuple[BaseSegment, ...] = ()
delimiters = 0
matched_delimiter = False
# We want to render progress bar only for the main matching loop,
# so disable it when in deeper parsing.
disable_progress_bar = (
parse_context.parse_depth > 0
or progress_bar_configuration.disable_progress_bar)
# We use amount of `NewLineSegment` to estimate how many steps could be in
# a big file. It's not perfect, but should do a job in most cases.
new_line_segments = [
s for s in segments if isinstance(s, NewlineSegment)
]
progressbar_matching = tqdm(
total=len(new_line_segments),
desc="matching",
miniters=30,
disable=disable_progress_bar,
leave=False,
)
seeking_delimiter = False
has_matched_segs = False
terminated = False
delimiter_matchers = [self.delimiter]
terminator_matchers = []
if self.terminator:
terminator_matchers.append(self.terminator)
# If gaps aren't allowed, a gap (or non-code segment), acts like a terminator.
if not self.allow_gaps:
terminator_matchers.append(NonCodeMatcher())
while True:
progressbar_matching.update(n=1)
if seeking_delimiter:
elements = delimiter_matchers
else:
elements = self._elements
if len(seg_buff) > 0:
pre_non_code, seg_content, post_non_code = trim_non_code_segments(
seg_buff)
if not self.allow_gaps and any(seg.is_whitespace
for seg in pre_non_code):
unmatched_segments = seg_buff
break
if not seg_content: # pragma: no cover
matched_segments += pre_non_code
break
# Check whether there is a terminator before checking for content
with parse_context.deeper_match() as ctx:
match, _ = self._longest_trimmed_match(
segments=seg_content,
matchers=terminator_matchers,
parse_context=ctx,
# We've already trimmed
trim_noncode=False,
)
if match:
terminated = True
unmatched_segments = (pre_non_code +
match.all_segments() +
post_non_code)
break
with parse_context.deeper_match() as ctx:
match, _ = self._longest_trimmed_match(
segments=seg_content,
matchers=elements,
parse_context=ctx,
# We've already trimmed
trim_noncode=False,
terminators=delimiter_matchers
if elements != delimiter_matchers else None,
)
if match:
if elements == delimiter_matchers:
delimiters += 1
matched_delimiter = True
cached_matched_segments = matched_segments
cached_unmatched_segments = seg_buff
else:
matched_delimiter = False
has_matched_segs = True
seg_buff = match.unmatched_segments + post_non_code
unmatched_segments = match.unmatched_segments
if match.is_complete():
matched_segments += (pre_non_code +
match.matched_segments +
post_non_code)
unmatched_segments = match.unmatched_segments
break
matched_segments += pre_non_code + match.matched_segments
seeking_delimiter = not seeking_delimiter
else:
matched_segments += pre_non_code
unmatched_segments = match.unmatched_segments + post_non_code
break
else:
break # pragma: no cover
if self.min_delimiters:
if delimiters < self.min_delimiters:
return MatchResult.from_unmatched(matched_segments +
unmatched_segments)
if terminated:
if has_matched_segs:
return MatchResult(matched_segments, unmatched_segments)
else:
return MatchResult.from_unmatched(matched_segments +
unmatched_segments)
if matched_delimiter and not self.allow_trailing:
if not unmatched_segments:
return MatchResult.from_unmatched(matched_segments +
unmatched_segments)
else:
return MatchResult(cached_matched_segments,
cached_unmatched_segments)
if not has_matched_segs:
return MatchResult.from_unmatched(matched_segments +
unmatched_segments)
if not unmatched_segments:
return MatchResult.from_matched(matched_segments)
return MatchResult(matched_segments, unmatched_segments)
def _longest_trimmed_match(
cls,
segments: Tuple[BaseSegment, ...],
matchers: List[MatchableType],
parse_context: ParseContext,
trim_noncode=True,
terminators: List[MatchableType] = None,
) -> Tuple[MatchResult, Optional[MatchableType]]:
"""Return longest match from a selection of matchers.
Prioritise the first match, and if multiple match at the same point the longest.
If two matches of the same length match at the same time, then it's the first in
the iterable of matchers.
Returns:
`tuple` of (match_object, matcher).
"""
terminated = False
# Have we been passed an empty list?
if len(segments) == 0: # pragma: no cover
return MatchResult.from_empty(), None
# If gaps are allowed, trim the ends.
if trim_noncode:
pre_nc, segments, post_nc = trim_non_code_segments(segments)
best_match_length = 0
# iterate at this position across all the matchers
for matcher in matchers:
# MyPy seems to require a type hint here. Not quite sure why.
res_match: MatchResult = matcher.match(segments,
parse_context=parse_context)
if res_match.is_complete():
# Just return it! (WITH THE RIGHT OTHER STUFF)
if trim_noncode:
return (
MatchResult.from_matched(pre_nc +
res_match.matched_segments +
post_nc),
matcher,
)
else:
return res_match, matcher
elif res_match:
# We've got an incomplete match, if it's the best so far keep it.
if res_match.trimmed_matched_length > best_match_length:
best_match = res_match, matcher
best_match_length = res_match.trimmed_matched_length
if terminators:
_, segs, _ = trim_non_code_segments(
best_match[0].unmatched_segments)
for terminator in terminators:
terminator_match: MatchResult = terminator.match(
segs, parse_context=parse_context)
if terminator_match.matched_segments:
terminated = True
break
if terminated:
break
# We could stash segments here, but given we might have some successful
# matches here, we shouldn't, because they'll be mutated in the wrong way.
# Eventually there might be a performance gain from doing that sensibly
# here.
# If we get here, then there wasn't a complete match. If we
# has a best_match, return that.
if best_match_length > 0:
if trim_noncode:
return (
MatchResult(
pre_nc + best_match[0].matched_segments,
best_match[0].unmatched_segments + post_nc,
),
best_match[1],
)
else:
return best_match
# If no match at all, return nothing
return MatchResult.from_unmatched(segments), None