python - 如何使用 Python 将更改应用于源文件？

Question

我正在使用 Clang 编译器 (cindex) 的 Python 绑定(bind)重构 C++ 代码。使用它，我分析 AST 并准备更改。我最终得到类似于以下的操作列表:

DELETE line 10
INSERT line 5 column 32: <<  "tofu"
REPLACE from line 31 colum 6 to line 33 column 82 with: std::cout << "Thanks SO"
...

我的问题是如何将这些转化为实际的文件更改。

直接用 python 做似乎很乏味:需要以正确的顺序应用补丁并检查一致性。看起来很难，而且容易出错。

我也找不到一个好的库来提供帮助(clang 确实有一个叫做重写器的东西，但它没有包装在 Python 中。如果可能的话，我真的很想避免使用 C++ 进行重构)。

也许一个想法是生成补丁并用 git 应用它们，也许吧？但即使那样似乎也有点乏味。

有什么想法吗？

Answer 1

所以我推出了自己的。该代码几乎肯定存在错误并且不是很漂亮，但我将其发布是希望在找到更好的解决方案之前它能对某人有所帮助。

class PatchRecord(object):
    """ Record patches, validate them, order them, and apply them """

    def __init__(self):
        # output of readlines for each patched file
        self.lines = {}
        # list of patches for each patched file
        self.patches = {}

    class Patch(object):
        """ Abstract base class for editing operations """

        def __init__(self, filename, start, end):
            self.filename = filename
            self.start = start
            self.end = end

        def __repr__(self):
            return "{op}: {filename} {start}/{end} {what}".format(
                op=self.__class__.__name__.upper(),
                filename=self.filename,
                start=format_place(self.start),
                end=format_place(self.end),
                what=getattr(self, "what", ""))

        def apply(self, lines):
            print "Warning: applying no-op patch"

    class Delete(Patch):

        def __init__(self, filename, extent):
            super(PatchRecord.Delete, self).__init__(
                filename, extent.start, extent.end)
            print "DELETE: {file} {extent}".format(file=self.filename,
                                                   extent=format_extent(extent))

        def apply(self, lines):
            lines[self.start.line - 1:self.end.line] = [
                lines[self.start.line - 1][:self.start.column - 1] +
                lines[self.end.line - 1][self.end.column:]]

    class Insert(Patch):

        def __init__(self, filename, start, what):
            super(PatchRecord.Insert, self).__init__(filename, start, start)
            self.what = what
            print "INSERT {where} {what}".format(what=what, where=format_place(self.start))

        def apply(self, lines):
            line = lines[self.start.line - 1]
            lines[self.start.line - 1] = "%s%s%s" % (
                line[:self.start.column],
                self.what,
                line[self.start.column:])

    class Replace(Patch):

        def __init__(self, filename, extent, what):
            super(PatchRecord.Replace, self).__init__(
                filename, extent.start, extent.end)
            self.what = what
            print "REPLACE: {where} {what}".format(what=what,
                                                   where=format_extent(extent))

        def apply(self, lines):
            lines[self.start.line - 1:self.end.line] = [
                lines[self.start.line - 1][:self.start.column - 1] +
                self.what +
                lines[self.end.line - 1][self.end.column - 1:]]

    # Convenience functions for creating patches
    def delete(self, filename, extent):
        self.patches[filename] = self.patches.get(
            filename, []) + [self.Delete(filename, extent)]

    def insert(self, filename, where, what):
        self.patches[filename] = self.patches.get(
            filename, []) + [self.Insert(filename, where, what)]

    def replace(self, filename, extent, what):
        self.patches[filename] = self.patches.get(
            filename, []) + [self.Replace(filename, extent, what)]

    def _pos_to_tuple(self, position):
        """ Convert a source location to a tuple for use as a sorting key """
        return (position.line, position.column)

    def sort(self, filename):
        """ Sort patches by extent start """
        self.patches[filename].sort(key=lambda p: self._pos_to_tuple(p.start))

    def validate(self, filename):
        """Try to insure patches are consistent"""
        print "Checking patches for %s" % filename
        self.sort(filename)
        previous = self.patches[filename][0]
        for p in self.patches[filename][1:]:
            assert(self._pos_to_tuple(p.start) >
                   self._pos_to_tuple(previous.start))

    def _apply(self, filename):
        self.sort(filename)
        lines = self._getlines(filename)
        for p in reversed(self.patches[filename]):
            print p
            p.apply(lines)

    def _getlines(self, filename):
        """ Get source file lines for editing """
        if not filename in self.lines:
            with open(filename) as f:
                self.lines[filename] = f.readlines()
        return self.lines[filename]

    def apply(self):
        for filename in self.patches:
            self.validate(filename)
            self._apply(filename)
            # with open(filename+".patched","w") as output:
            with open(filename, "w") as output:
                output.write("".join(self._getlines(filename)))

只需创建一个 PatchRecord 对象，使用 create、replace 和 delete 方法添加更改，然后应用当您准备好时，使用 apply 将它们应用。