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Diffstat (limited to 'bitbake/lib/simplediff/__init__.py')
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1 files changed, 198 insertions, 0 deletions
diff --git a/bitbake/lib/simplediff/__init__.py b/bitbake/lib/simplediff/__init__.py new file mode 100644 index 0000000000..57ee3c5c40 --- /dev/null +++ b/bitbake/lib/simplediff/__init__.py @@ -0,0 +1,198 @@ +''' +Simple Diff for Python version 1.0 + +Annotate two versions of a list with the values that have been +changed between the versions, similar to unix's `diff` but with +a dead-simple Python interface. + +(C) Paul Butler 2008-2012 <http://www.paulbutler.org/> +May be used and distributed under the zlib/libpng license +<http://www.opensource.org/licenses/zlib-license.php> +''' + +__all__ = ['diff', 'string_diff', 'html_diff'] +__version__ = '1.0' + + +def diff(old, new): + ''' + Find the differences between two lists. Returns a list of pairs, where the + first value is in ['+','-','='] and represents an insertion, deletion, or + no change for that list. The second value of the pair is the list + of elements. + + Params: + old the old list of immutable, comparable values (ie. a list + of strings) + new the new list of immutable, comparable values + + Returns: + A list of pairs, with the first part of the pair being one of three + strings ('-', '+', '=') and the second part being a list of values from + the original old and/or new lists. The first part of the pair + corresponds to whether the list of values is a deletion, insertion, or + unchanged, respectively. + + Examples: + >>> diff([1,2,3,4],[1,3,4]) + [('=', [1]), ('-', [2]), ('=', [3, 4])] + + >>> diff([1,2,3,4],[2,3,4,1]) + [('-', [1]), ('=', [2, 3, 4]), ('+', [1])] + + >>> diff('The quick brown fox jumps over the lazy dog'.split(), + ... 'The slow blue cheese drips over the lazy carrot'.split()) + ... # doctest: +NORMALIZE_WHITESPACE + [('=', ['The']), + ('-', ['quick', 'brown', 'fox', 'jumps']), + ('+', ['slow', 'blue', 'cheese', 'drips']), + ('=', ['over', 'the', 'lazy']), + ('-', ['dog']), + ('+', ['carrot'])] + + ''' + + # Create a map from old values to their indices + old_index_map = dict() + for i, val in enumerate(old): + old_index_map.setdefault(val,list()).append(i) + + # Find the largest substring common to old and new. + # We use a dynamic programming approach here. + # + # We iterate over each value in the `new` list, calling the + # index `inew`. At each iteration, `overlap[i]` is the + # length of the largest suffix of `old[:i]` equal to a suffix + # of `new[:inew]` (or unset when `old[i]` != `new[inew]`). + # + # At each stage of iteration, the new `overlap` (called + # `_overlap` until the original `overlap` is no longer needed) + # is built from the old one. + # + # If the length of overlap exceeds the largest substring + # seen so far (`sub_length`), we update the largest substring + # to the overlapping strings. + + overlap = dict() + # `sub_start_old` is the index of the beginning of the largest overlapping + # substring in the old list. `sub_start_new` is the index of the beginning + # of the same substring in the new list. `sub_length` is the length that + # overlaps in both. + # These track the largest overlapping substring seen so far, so naturally + # we start with a 0-length substring. + sub_start_old = 0 + sub_start_new = 0 + sub_length = 0 + + for inew, val in enumerate(new): + _overlap = dict() + for iold in old_index_map.get(val,list()): + # now we are considering all values of iold such that + # `old[iold] == new[inew]`. + _overlap[iold] = (iold and overlap.get(iold - 1, 0)) + 1 + if(_overlap[iold] > sub_length): + # this is the largest substring seen so far, so store its + # indices + sub_length = _overlap[iold] + sub_start_old = iold - sub_length + 1 + sub_start_new = inew - sub_length + 1 + overlap = _overlap + + if sub_length == 0: + # If no common substring is found, we return an insert and delete... + return (old and [('-', old)] or []) + (new and [('+', new)] or []) + else: + # ...otherwise, the common substring is unchanged and we recursively + # diff the text before and after that substring + return diff(old[ : sub_start_old], new[ : sub_start_new]) + \ + [('=', new[sub_start_new : sub_start_new + sub_length])] + \ + diff(old[sub_start_old + sub_length : ], + new[sub_start_new + sub_length : ]) + + +def string_diff(old, new): + ''' + Returns the difference between the old and new strings when split on + whitespace. Considers punctuation a part of the word + + This function is intended as an example; you'll probably want + a more sophisticated wrapper in practice. + + Params: + old the old string + new the new string + + Returns: + the output of `diff` on the two strings after splitting them + on whitespace (a list of change instructions; see the docstring + of `diff`) + + Examples: + >>> string_diff('The quick brown fox', 'The fast blue fox') + ... # doctest: +NORMALIZE_WHITESPACE + [('=', ['The']), + ('-', ['quick', 'brown']), + ('+', ['fast', 'blue']), + ('=', ['fox'])] + + ''' + return diff(old.split(), new.split()) + + +def html_diff(old, new): + ''' + Returns the difference between two strings (as in stringDiff) in + HTML format. HTML code in the strings is NOT escaped, so you + will get weird results if the strings contain HTML. + + This function is intended as an example; you'll probably want + a more sophisticated wrapper in practice. + + Params: + old the old string + new the new string + + Returns: + the output of the diff expressed with HTML <ins> and <del> + tags. + + Examples: + >>> html_diff('The quick brown fox', 'The fast blue fox') + 'The <del>quick brown</del> <ins>fast blue</ins> fox' + ''' + con = {'=': (lambda x: x), + '+': (lambda x: "<ins>" + x + "</ins>"), + '-': (lambda x: "<del>" + x + "</del>")} + return " ".join([(con[a])(" ".join(b)) for a, b in string_diff(old, new)]) + + +def check_diff(old, new): + ''' + This tests that diffs returned by `diff` are valid. You probably won't + want to use this function, but it's provided for documentation and + testing. + + A diff should satisfy the property that the old input is equal to the + elements of the result annotated with '-' or '=' concatenated together. + Likewise, the new input is equal to the elements of the result annotated + with '+' or '=' concatenated together. This function compares `old`, + `new`, and the results of `diff(old, new)` to ensure this is true. + + Tests: + >>> check_diff('ABCBA', 'CBABA') + >>> check_diff('Foobarbaz', 'Foobarbaz') + >>> check_diff('Foobarbaz', 'Boobazbam') + >>> check_diff('The quick brown fox', 'Some quick brown car') + >>> check_diff('A thick red book', 'A quick blue book') + >>> check_diff('dafhjkdashfkhasfjsdafdasfsda', 'asdfaskjfhksahkfjsdha') + >>> check_diff('88288822828828288282828', '88288882882828282882828') + >>> check_diff('1234567890', '24689') + ''' + old = list(old) + new = list(new) + result = diff(old, new) + _old = [val for (a, vals) in result if (a in '=-') for val in vals] + assert old == _old, 'Expected %s, got %s' % (old, _old) + _new = [val for (a, vals) in result if (a in '=+') for val in vals] + assert new == _new, 'Expected %s, got %s' % (new, _new) + |