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import math
import re
from collections import Counter
from itertools import groupby
DIFF_CONTEXT = ' '
DIFF_ADDITION = '+'
DIFF_DELETION = '-'
DIFF_NO_NEWLINE = '\\'
def parse_range_str(range_str):
if ',' in range_str:
begin, end = range_str.split(',', 1)
return int(begin), int(end)
return int(range_str), 1
def _format_range(start, count):
if count == 1:
return str(start)
return '%d,%d' % (start, count)
def _format_hunk_header(old_start, old_count, new_start, new_count, heading=''):
return '@@ -{} +{} @@{}\n'.format(
_format_range(old_start, old_count),
_format_range(new_start, new_count),
heading,
)
def digits(number):
"""Return the number of digits needed to display a number"""
if number >= 0:
result = int(math.log10(number)) + 1
else:
result = 1
return result
class LineCounter:
"""Keep track of a diff range's values"""
def __init__(self, value=0, max_value=-1):
self.count = 0 # Absolute count of additions/removals/...
self.value = value # Current line number counter.
self.max_value = max_value
self._initial_max_value = max_value
def reset(self):
"""Reset the max counter and return self for convenience"""
self.count = 0
self.max_value = self._initial_max_value
return self
def parse(self, range_str):
"""Parse a diff range and setup internal state"""
start, count = parse_range_str(range_str)
self.value = start
self.max_value = max(start + count - 1, self.max_value)
def tick(self, amount=1):
"""Return the current value and increment to the next"""
value = self.value
self.value += amount
self.count += amount
return value
class DiffLines:
"""Parse diffs and gather line numbers"""
EMPTY = -1
DASH = -2
def __init__(self):
self.merge = False
# diff <old> <new>
# merge <ours> <theirs> <new>
self.old = LineCounter()
self.new = LineCounter()
self.ours = LineCounter()
self.theirs = LineCounter()
self.additions = LineCounter()
self.removals = LineCounter()
def digits(self):
return digits(
max(
self.old.max_value,
self.new.max_value,
self.ours.max_value,
self.theirs.max_value,
)
)
def parse(self, diff_text):
lines = []
diff_state = 1
state = initial_state = 0
merge = self.merge = False
no_newline = r'\ No newline at end of file'
old = self.old.reset()
new = self.new.reset()
ours = self.ours.reset()
theirs = self.theirs.reset()
additions = self.additions.reset()
removals = self.removals.reset()
for text in diff_text.split('\n'):
if text.startswith('@@ -'):
parts = text.split(' ', 4)
if parts[0] == '@@' and parts[3] == '@@':
state = diff_state
old.parse(parts[1][1:])
new.parse(parts[2][1:])
lines.append((self.DASH, self.DASH))
continue
if text.startswith('@@@ -'):
self.merge = merge = True
parts = text.split(' ', 5)
if parts[0] == '@@@' and parts[4] == '@@@':
state = diff_state
ours.parse(parts[1][1:])
theirs.parse(parts[2][1:])
new.parse(parts[3][1:])
lines.append((self.DASH, self.DASH, self.DASH))
continue
if state == initial_state or text.rstrip() == no_newline:
if merge:
lines.append((self.EMPTY, self.EMPTY, self.EMPTY))
else:
lines.append((self.EMPTY, self.EMPTY))
elif not merge and text.startswith('-'):
removals.tick()
lines.append((old.tick(), self.EMPTY))
elif merge and text.startswith('- '):
removals.tick()
lines.append((ours.tick(), self.EMPTY, self.EMPTY))
elif merge and text.startswith(' -'):
removals.tick()
lines.append((self.EMPTY, theirs.tick(), self.EMPTY))
elif merge and text.startswith('--'):
removals.tick()
lines.append((ours.tick(), theirs.tick(), self.EMPTY))
elif not merge and text.startswith('+'):
additions.tick()
lines.append((self.EMPTY, new.tick()))
elif merge and text.startswith('++'):
additions.tick()
lines.append((self.EMPTY, self.EMPTY, new.tick()))
elif merge and text.startswith('+ '):
additions.tick()
lines.append((self.EMPTY, theirs.tick(), new.tick()))
elif merge and text.startswith(' +'):
additions.tick()
lines.append((ours.tick(), self.EMPTY, new.tick()))
elif not merge and text.startswith(' '):
lines.append((old.tick(), new.tick()))
elif merge and text.startswith(' '):
lines.append((ours.tick(), theirs.tick(), new.tick()))
elif not text:
new.tick()
old.tick()
ours.tick()
theirs.tick()
else:
state = initial_state
if merge:
lines.append((self.EMPTY, self.EMPTY, self.EMPTY))
else:
lines.append((self.EMPTY, self.EMPTY))
return lines
class FormatDigits:
"""Format numbers for use in diff line numbers"""
DASH = DiffLines.DASH
EMPTY = DiffLines.EMPTY
def __init__(self, dash='', empty=''):
self.fmt = ''
self.empty = ''
self.dash = ''
self._dash = dash or chr(0xB7)
self._empty = empty or ' '
def set_digits(self, value):
self.fmt = '%%0%dd' % value
self.empty = self._empty * value
self.dash = self._dash * value
def value(self, old, new):
old_str = self._format(old)
new_str = self._format(new)
return f'{old_str} {new_str}'
def merge_value(self, old, base, new):
old_str = self._format(old)
base_str = self._format(base)
new_str = self._format(new)
return f'{old_str} {base_str} {new_str}'
def number(self, value):
return self.fmt % value
def _format(self, value):
if value == self.DASH:
result = self.dash
elif value == self.EMPTY:
result = self.empty
else:
result = self.number(value)
return result
class _HunkGrouper:
_HUNK_HEADER_RE = re.compile(r'^@@ -([0-9,]+) \+([0-9,]+) @@(.*)')
def __init__(self):
self.match = None
def __call__(self, line):
match = self._HUNK_HEADER_RE.match(line)
if match is not None:
self.match = match
return self.match
class _DiffHunk:
def __init__(self, old_start, start_offset, heading, content_lines):
type_counts = Counter(line[:1] for line in content_lines)
self.old_count = type_counts[DIFF_CONTEXT] + type_counts[DIFF_DELETION]
self.new_count = type_counts[DIFF_CONTEXT] + type_counts[DIFF_ADDITION]
if self.old_count == 0:
self.old_start = 0
else:
self.old_start = old_start
if self.new_count == 0:
self.new_start = 0
elif self.old_start == 0:
self.new_start = 1
else:
self.new_start = self.old_start + start_offset
self.heading = heading
self.lines = [
_format_hunk_header(
self.old_start,
self.old_count,
self.new_start,
self.new_count,
heading,
),
*content_lines,
]
self.content_lines = content_lines
self.changes = type_counts[DIFF_DELETION] + type_counts[DIFF_ADDITION]
def has_changes(self):
return bool(self.changes)
def line_delta(self):
return self.new_count - self.old_count
class Patch:
"""Parse and rewrite diffs to produce edited patches
This parser is used for modifying the worktree and index by constructing
temporary patches that are applied using "git apply".
"""
def __init__(self, filename, hunks, header_line_count=0):
self.filename = filename
self.hunks = hunks
self.header_line_count = header_line_count
@classmethod
def parse(cls, filename, diff_text):
header_line_count = 0
hunks = []
start_offset = 0
for match, hunk_lines in groupby(diff_text.split('\n'), _HunkGrouper()):
if match is not None:
# Skip the hunk range header line as it will be regenerated by the
# _DiffHunk.
next(hunk_lines)
hunk = _DiffHunk(
old_start=parse_range_str(match.group(1))[0],
start_offset=start_offset,
heading=match.group(3),
content_lines=[line + '\n' for line in hunk_lines if line],
)
if hunk.has_changes():
hunks.append(hunk)
start_offset += hunk.line_delta()
else:
header_line_count = len(list(hunk_lines))
return cls(filename, hunks, header_line_count)
def has_changes(self):
return bool(self.hunks)
def as_text(self, *, file_headers=True):
lines = []
if self.hunks:
if file_headers:
lines.append('--- a/%s\n' % self.filename)
lines.append('+++ b/%s\n' % self.filename)
for hunk in self.hunks:
lines.extend(hunk.lines)
return ''.join(lines)
def _hunk_iter(self):
hunk_last_line_idx = self.header_line_count - 1
for hunk in self.hunks:
hunk_first_line_idx = hunk_last_line_idx + 1
hunk_last_line_idx += len(hunk.lines)
yield hunk_first_line_idx, hunk_last_line_idx, hunk
@staticmethod
def _reverse_content_lines(content_lines):
# Normally in a diff, deletions come before additions. In order to preserve
# this property in reverse patches, when this function encounters a deletion
# line and switches it to addition, it appends the line to the pending_additions
# list, while additions that get switched to deletions are appended directly to
# the content_lines list. Each time a context line is encountered, any pending
# additions are then appended to the content_lines list immediately before the
# context line and the pending_additions list is cleared.
new_content_lines = []
pending_additions = []
line_type = None
for line in content_lines:
prev_line_type = line_type
line_type = line[:1]
if line_type == DIFF_ADDITION:
new_content_lines.append(DIFF_DELETION + line[1:])
elif line_type == DIFF_DELETION:
pending_additions.append(DIFF_ADDITION + line[1:])
elif line_type == DIFF_NO_NEWLINE:
if prev_line_type == DIFF_DELETION:
# Previous line was a deletion that was switched to an
# addition, so the "No newline" line goes with it.
pending_additions.append(line)
else:
new_content_lines.append(line)
else:
new_content_lines.extend(pending_additions)
new_content_lines.append(line)
pending_additions = []
new_content_lines.extend(pending_additions)
return new_content_lines
def extract_subset(self, first_line_idx, last_line_idx, *, reverse=False):
new_hunks = []
start_offset = 0
for hunk_first_line_idx, hunk_last_line_idx, hunk in self._hunk_iter():
# Skip hunks until reaching the one that contains the first selected line.
if hunk_last_line_idx < first_line_idx:
continue
# Stop once the hunk that contains the last selected line has been
# processed.
if hunk_first_line_idx > last_line_idx:
break
content_lines = []
prev_skipped = False
for hunk_line_idx, line in enumerate(
hunk.content_lines, start=hunk_first_line_idx + 1
):
line_type = line[:1]
if not first_line_idx <= hunk_line_idx <= last_line_idx:
if line_type == DIFF_ADDITION:
if reverse:
# Change unselected additions to context for reverse diffs.
line = DIFF_CONTEXT + line[1:]
else:
# Skip unselected additions for normal diffs.
prev_skipped = True
continue
elif line_type == DIFF_DELETION:
if not reverse:
# Change unselected deletions to context for normal diffs.
line = DIFF_CONTEXT + line[1:]
else:
# Skip unselected deletions for reverse diffs.
prev_skipped = True
continue
if line_type == DIFF_NO_NEWLINE and prev_skipped:
# If the line immediately before a "No newline" line was skipped
# (e.g. because it was an unselected addition) skip the "No
# newline" line as well
continue
content_lines.append(line)
if reverse:
old_start = hunk.new_start
content_lines = self._reverse_content_lines(content_lines)
else:
old_start = hunk.old_start
new_hunk = _DiffHunk(
old_start=old_start,
start_offset=start_offset,
heading=hunk.heading,
content_lines=content_lines,
)
if new_hunk.has_changes():
new_hunks.append(new_hunk)
start_offset += new_hunk.line_delta()
return Patch(self.filename, new_hunks)
def extract_hunk(self, line_idx, *, reverse=False):
"""Return a new patch containing only the hunk containing the specified line"""
new_hunks = []
for _, hunk_last_line_idx, hunk in self._hunk_iter():
if line_idx <= hunk_last_line_idx:
if reverse:
old_start = hunk.new_start
content_lines = self._reverse_content_lines(hunk.content_lines)
else:
old_start = hunk.old_start
content_lines = hunk.content_lines
new_hunks = [
_DiffHunk(
old_start=old_start,
start_offset=0,
heading=hunk.heading,
content_lines=content_lines,
)
]
break
return Patch(self.filename, new_hunks)
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