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- import difflib
- import itertools
- # one line diff functions.
- def one_line_diff_str(before,after,mx=15,pre=2):
- """
- Return a summary of the differences between two strings, concatenated.
- Parameters:
- before - string before.
- after - after string.
- mx - the max number of strings.
- pre - number of characters to show before diff (context)
- Returns a string no longer than 'mx'.
- """
- old = one_line_diff(before,after)
- result = ''
- firstEl = True
- # TODO instead of using +addition+ and -subtraction- it'd be nice to be able
- # to highlight the change w/o requiring the +/- chars.
- for v in old:
- # if the first element doesn't have a change, then don't include it.
- v = escape_returns(v)
- if firstEl:
- firstEl = False
- # add in pre character context:
- if not (v.startswith('+') or v.startswith('-')) and result == '':
- v = v[-pre:]
- # when we're going to be bigger than our max limit, lets ensure that the
- # trailing +/- appears in the text:
- if len(result) + len(v) > mx:
- if v.startswith('+') or v.startswith('-'):
- result += v[:mx - len(result) - 1]
- result += v[0]
- break
- result += v
- return result
- def escape_returns(result):
- return result.replace('\n','\\n').replace('\r','\\r').replace('\t','\\t')
- def one_line_diff(before, after):
- """
- Return a summary of the differences between two arbitrary strings.
- Returns a list of strings, summarizing all the changes.
- """
- a, b, result = [], [], []
- for line in itertools.chain(itertools.islice(
- difflib.unified_diff(before.splitlines(),
- after.splitlines()), 2, None), ['@@']):
- if line.startswith('@@'):
- result.extend(one_line_diff_raw('\n'.join(a), '\n'.join(b)))
- a, b = [], []
- continue
- if not line.startswith('+'):
- a.append(line[1:])
- if not line.startswith('-'):
- b.append(line[1:])
- if after.endswith('\n') and not before.endswith('\n'):
- if result:
- result[-1] = result[-1][:-1] + '\n+'
- else:
- result = ['+\n+']
- return result
- def one_line_diff_raw(before,after):
- s = difflib.SequenceMatcher(None,before,after)
- results = []
- for tag, i1, i2, j1, j2 in s.get_opcodes():
- #print ("%7s a[%d:%d] (%s) b[%d:%d] (%s)" % (tag, i1, i2, before[i1:i2], j1, j2, after[j1:j2]))
- if tag == 'equal':
- _append_result(results,{
- 'equal': after[j1:j2]
- })
- if tag == 'insert':
- _append_result(results,{
- 'plus': after[j1:j2]
- })
- elif tag == 'delete':
- _append_result(results,{
- 'minus': before[i1:i2]
- })
- elif tag == 'replace':
- _append_result(results,{
- 'minus': before[j1:j2],
- 'plus': after[j1:j2]
- })
- final_results = []
- # finally, create a human readable string of information.
- for v in results:
- if 'minus' in v and 'plus' in v and len(v['minus']) > 0 and len(v['plus']) > 0:
- final_results.append("-%s-+%s+"% (v['minus'],v['plus']))
- elif 'minus' in v and len(v['minus']) > 0:
- final_results.append("-%s-"% (v['minus']))
- elif 'plus' in v and len(v['plus']) > 0:
- final_results.append("+%s+"% (v['plus']))
- elif 'equal' in v:
- final_results.append("%s"% (v['equal']))
- return final_results
- def _append_result(results,val):
- results.append(val)
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