49 lines
1.4 KiB
Python
49 lines
1.4 KiB
Python
import io
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import difflib
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def sumLen(lines):
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return sum(map(len, lines))
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def diff(old, new, limit=False):
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matcher = difflib.SequenceMatcher(None, old, new)
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actions = []
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size = 0
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for tag, old_from, old_to, new_from, new_to in matcher.get_opcodes():
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if tag == "insert":
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new_line = new[new_from:new_to]
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actions.append(("+", new_line))
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size += sum(map(len, new_line))
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elif tag == "equal":
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actions.append(("=", sumLen(old[old_from:old_to])))
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elif tag == "delete":
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actions.append(("-", sumLen(old[old_from:old_to])))
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elif tag == "replace":
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actions.append(("-", sumLen(old[old_from:old_to])))
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new_lines = new[new_from:new_to]
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actions.append(("+", new_lines))
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size += sumLen(new_lines)
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if limit and size > limit:
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return False
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return actions
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def patch(old_f, actions):
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new_f = io.BytesIO()
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for action, param in actions:
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if type(action) is bytes:
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action = action.decode()
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if action == "=": # Same lines
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new_f.write(old_f.read(param))
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elif action == "-": # Delete lines
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old_f.seek(param, 1) # Seek from current position
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continue
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elif action == "+": # Add lines
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for add_line in param:
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new_f.write(add_line)
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else:
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raise "Unknown action: %s" % action
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return new_f
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