227 lines
9.6 KiB
Python
227 lines
9.6 KiB
Python
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#!/usr/bin/env python
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# encoding: utf-8
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"""Commands to compare text objects and to guess how to transform from one to
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another."""
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from collections import defaultdict
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import sys
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from UltiSnips import _vim
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from UltiSnips.position import Position
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def is_complete_edit(initial_line, original, wanted, cmds):
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"""Returns true if 'original' is changed to 'wanted' with the edit commands
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in 'cmds'.
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Initial line is to change the line numbers in 'cmds'.
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"""
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buf = original[:]
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for cmd in cmds:
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ctype, line, col, char = cmd
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line -= initial_line
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if ctype == 'D':
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if char != '\n':
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buf[line] = buf[line][:col] + buf[line][col + len(char):]
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else:
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if line + 1 < len(buf):
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buf[line] = buf[line] + buf[line + 1]
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del buf[line + 1]
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else:
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del buf[line]
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elif ctype == 'I':
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buf[line] = buf[line][:col] + char + buf[line][col:]
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buf = '\n'.join(buf).split('\n')
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return (len(buf) == len(wanted) and
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all(j == k for j, k in zip(buf, wanted)))
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def guess_edit(initial_line, last_text, current_text, vim_state):
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"""Try to guess what the user might have done by heuristically looking at
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cursor movement, number of changed lines and if they got longer or shorter.
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This will detect most simple movements like insertion, deletion of a line
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or carriage return. 'initial_text' is the index of where the comparison
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starts, 'last_text' is the last text of the snippet, 'current_text' is the
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current text of the snippet and 'vim_state' is the cached vim state.
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Returns (True, edit_cmds) when the edit could be guessed, (False,
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None) otherwise.
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"""
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if not len(last_text) and not len(current_text):
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return True, ()
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pos = vim_state.pos
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ppos = vim_state.ppos
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# All text deleted?
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if (len(last_text) and
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(not current_text or
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(len(current_text) == 1 and not current_text[0]))
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):
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es = []
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if not current_text:
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current_text = ['']
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for i in last_text:
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es.append(('D', initial_line, 0, i))
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es.append(('D', initial_line, 0, '\n'))
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es.pop() # Remove final \n because it is not really removed
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if is_complete_edit(initial_line, last_text, current_text, es):
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return True, es
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if ppos.mode == 'v': # Maybe selectmode?
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sv = list(map(int, _vim.eval("""getpos("'<")""")))
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sv = Position(sv[1] - 1, sv[2] - 1)
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ev = list(map(int, _vim.eval("""getpos("'>")""")))
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ev = Position(ev[1] - 1, ev[2] - 1)
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if 'exclusive' in _vim.eval('&selection'):
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ppos.col -= 1 # We want to be inclusive, sorry.
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ev.col -= 1
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es = []
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if sv.line == ev.line:
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es.append(('D', sv.line, sv.col,
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last_text[sv.line - initial_line][sv.col:ev.col + 1]))
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if sv != pos and sv.line == pos.line:
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es.append(('I', sv.line, sv.col,
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current_text[sv.line - initial_line][sv.col:pos.col + 1]))
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if is_complete_edit(initial_line, last_text, current_text, es):
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return True, es
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if pos.line == ppos.line:
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if len(last_text) == len(current_text): # Movement only in one line
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llen = len(last_text[ppos.line - initial_line])
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clen = len(current_text[pos.line - initial_line])
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if ppos < pos and clen > llen: # maybe only chars have been added
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es = (
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('I', ppos.line, ppos.col,
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current_text[ppos.line - initial_line]
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[ppos.col:pos.col]),
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)
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if is_complete_edit(initial_line, last_text, current_text, es):
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return True, es
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if clen < llen:
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if ppos == pos: # 'x' or DEL or dt or something
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es = (
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('D', pos.line, pos.col,
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last_text[ppos.line - initial_line]
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[ppos.col:ppos.col + (llen - clen)]),
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)
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if is_complete_edit(initial_line, last_text,
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current_text, es):
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return True, es
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if pos < ppos: # Backspacing or dT dF?
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es = (
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('D', pos.line, pos.col,
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last_text[pos.line - initial_line]
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[pos.col:pos.col + llen - clen]),
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)
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if is_complete_edit(initial_line, last_text,
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current_text, es):
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return True, es
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elif len(current_text) < len(last_text):
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# where some lines deleted? (dd or so)
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es = []
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for i in range(len(last_text) - len(current_text)):
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es.append(('D', pos.line, 0,
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last_text[pos.line - initial_line + i]))
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es.append(('D', pos.line, 0, '\n'))
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if is_complete_edit(initial_line, last_text,
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current_text, es):
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return True, es
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else:
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# Movement in more than one line
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if ppos.line + 1 == pos.line and pos.col == 0: # Carriage return?
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es = (('I', ppos.line, ppos.col, '\n'),)
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if is_complete_edit(initial_line, last_text,
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current_text, es):
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return True, es
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return False, None
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def diff(a, b, sline=0):
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"""
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Return a list of deletions and insertions that will turn 'a' into 'b'. This
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is done by traversing an implicit edit graph and searching for the shortest
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route. The basic idea is as follows:
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- Matching a character is free as long as there was no
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deletion/insertion before. Then, matching will be seen as delete +
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insert [1].
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- Deleting one character has the same cost everywhere. Each additional
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character costs only have of the first deletion.
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- Insertion is cheaper the earlier it happens. The first character is
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more expensive that any later [2].
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[1] This is that world -> aolsa will be "D" world + "I" aolsa instead of
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"D" w , "D" rld, "I" a, "I" lsa
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[2] This is that "hello\n\n" -> "hello\n\n\n" will insert a newline after
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hello and not after \n
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"""
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d = defaultdict(list) # pylint:disable=invalid-name
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seen = defaultdict(lambda: sys.maxsize)
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d[0] = [(0, 0, sline, 0, ())]
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cost = 0
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deletion_cost = len(a) + len(b)
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insertion_cost = len(a) + len(b)
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while True:
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while len(d[cost]):
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x, y, line, col, what = d[cost].pop()
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if a[x:] == b[y:]:
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return what
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if x < len(a) and y < len(b) and a[x] == b[y]:
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ncol = col + 1
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nline = line
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if a[x] == '\n':
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ncol = 0
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nline += 1
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lcost = cost + 1
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if (what and what[-1][0] == 'D' and what[-1][1] == line and
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what[-1][2] == col and a[x] != '\n'):
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# Matching directly after a deletion should be as costly as
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# DELETE + INSERT + a bit
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lcost = (deletion_cost + insertion_cost) * 1.5
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if seen[x + 1, y + 1] > lcost:
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d[lcost].append((x + 1, y + 1, nline, ncol, what))
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seen[x + 1, y + 1] = lcost
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if y < len(b): # INSERT
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ncol = col + 1
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nline = line
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if b[y] == '\n':
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ncol = 0
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nline += 1
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if (what and what[-1][0] == 'I' and what[-1][1] == nline and
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what[-1][2] + len(what[-1][-1]) == col and b[y] != '\n' and
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seen[x, y + 1] > cost + (insertion_cost + ncol) // 2
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):
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seen[x, y + 1] = cost + (insertion_cost + ncol) // 2
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d[cost + (insertion_cost + ncol) // 2].append(
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(x, y + 1, line, ncol, what[:-1] + (
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('I', what[-1][1], what[-1][2],
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what[-1][-1] + b[y]),)
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)
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)
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elif seen[x, y + 1] > cost + insertion_cost + ncol:
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seen[x, y + 1] = cost + insertion_cost + ncol
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d[cost + ncol + insertion_cost].append((x, y + 1, nline, ncol,
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what + (('I', line, col, b[y]),))
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)
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if x < len(a): # DELETE
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if (what and what[-1][0] == 'D' and what[-1][1] == line and
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what[-1][2] == col and a[x] != '\n' and
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what[-1][-1] != '\n' and
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seen[x + 1, y] > cost + deletion_cost // 2
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):
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seen[x + 1, y] = cost + deletion_cost // 2
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d[cost + deletion_cost // 2].append(
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(x + 1, y, line, col, what[:-1] + (
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('D', line, col, what[-1][-1] + a[x]),))
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)
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elif seen[x + 1, y] > cost + deletion_cost:
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seen[x + 1, y] = cost + deletion_cost
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d[cost + deletion_cost].append((x + 1, y, line, col, what +
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(('D', line, col, a[x]),))
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)
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cost += 1
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