Python3之美化打印pprint源码

青旅半醒 2022-05-24 03:21 138阅读 0赞

# Author: Fred L. Drake, Jr.
    # fdrake@acm.org
    #
    # This is a simple little module I wrote to make life easier. I didn't
    # see anything quite like it in the library, though I may have overlooked
    # something. I wrote this when I was trying to read some heavily nested
    # tuples with fairly non-descriptive content. This is modeled very much
    # after Lisp/Scheme - style pretty-printing of lists. If you find it
    # useful, thank small children who sleep at night.
    
    """Support to pretty-print lists, tuples, & dictionaries recursively. Very simple, but useful, especially in debugging data structures. Classes ------- PrettyPrinter() Handle pretty-printing operations onto a stream using a configured set of formatting parameters. Functions --------- pformat() Format a Python object into a pretty-printed representation. pprint() Pretty-print a Python object to a stream [default is sys.stdout]. saferepr() Generate a 'standard' repr()-like value, but protect against recursive data structures. """
    
    import collections as _collections
    import re
    import sys as _sys
    import types as _types
    from io import StringIO as _StringIO
    
    __all__ = ["pprint","pformat","isreadable","isrecursive","saferepr",
               "PrettyPrinter"]
    
    
    def pprint(object, stream=None, indent=1, width=80, depth=None, *, compact=False):
        """Pretty-print a Python object to a stream [default is sys.stdout]."""
        printer = PrettyPrinter(
            stream=stream, indent=indent, width=width, depth=depth,
            compact=compact)
        printer.pprint(object)
    
    def pformat(object, indent=1, width=80, depth=None, *, compact=False):
        """Format a Python object into a pretty-printed representation."""
        return PrettyPrinter(indent=indent, width=width, depth=depth,
                             compact=compact).pformat(object)
    
    def saferepr(object):
        """Version of repr() which can handle recursive data structures."""
        return _safe_repr(object, {}, None, 0)[0]
    
    def isreadable(object):
        """Determine if saferepr(object) is readable by eval()."""
        return _safe_repr(object, {}, None, 0)[1]
    
    def isrecursive(object):
        """Determine if object requires a recursive representation."""
        return _safe_repr(object, {}, None, 0)[2]
    
    class _safe_key:
        """Helper function for key functions when sorting unorderable objects. The wrapped-object will fallback to a Py2.x style comparison for unorderable types (sorting first comparing the type name and then by the obj ids). Does not work recursively, so dict.items() must have _safe_key applied to both the key and the value. """
    
        __slots__ = ['obj']
    
        def __init__(self, obj):
            self.obj = obj
    
        def __lt__(self, other):
            try:
                return self.obj < other.obj
            except TypeError:
                return ((str(type(self.obj)), id(self.obj)) < \
                        (str(type(other.obj)), id(other.obj)))
    
    def _safe_tuple(t):
        "Helper function for comparing 2-tuples"
        return _safe_key(t[0]), _safe_key(t[1])
    
    class PrettyPrinter:
        def __init__(self, indent=1, width=80, depth=None, stream=None, *, compact=False):
            """Handle pretty printing operations onto a stream using a set of configured parameters. indent Number of spaces to indent for each level of nesting. width Attempted maximum number of columns in the output. depth The maximum depth to print out nested structures. stream The desired output stream. If omitted (or false), the standard output stream available at construction will be used. compact If true, several items will be combined in one line. """
            indent = int(indent)
            width = int(width)
            if indent < 0:
                raise ValueError('indent must be >= 0')
            if depth is not None and depth <= 0:
                raise ValueError('depth must be > 0')
            if not width:
                raise ValueError('width must be != 0')
            self._depth = depth
            self._indent_per_level = indent
            self._width = width
            if stream is not None:
                self._stream = stream
            else:
                self._stream = _sys.stdout
            self._compact = bool(compact)
    
        def pprint(self, object):
            self._format(object, self._stream, 0, 0, {}, 0)
            self._stream.write("\n")
    
        def pformat(self, object):
            sio = _StringIO()
            self._format(object, sio, 0, 0, {}, 0)
            return sio.getvalue()
    
        def isrecursive(self, object):
            return self.format(object, {}, 0, 0)[2]
    
        def isreadable(self, object):
            s, readable, recursive = self.format(object, {}, 0, 0)
            return readable and not recursive
    
        def _format(self, object, stream, indent, allowance, context, level):
            objid = id(object)
            if objid in context:
                stream.write(_recursion(object))
                self._recursive = True
                self._readable = False
                return
            rep = self._repr(object, context, level)
            max_width = self._width - indent - allowance
            if len(rep) > max_width:
                p = self._dispatch.get(type(object).__repr__, None)
                if p is not None:
                    context[objid] = 1
                    p(self, object, stream, indent, allowance, context, level + 1)
                    del context[objid]
                    return
                elif isinstance(object, dict):
                    context[objid] = 1
                    self._pprint_dict(object, stream, indent, allowance,
                                      context, level + 1)
                    del context[objid]
                    return
            stream.write(rep)
    
        _dispatch = {}
    
        def _pprint_dict(self, object, stream, indent, allowance, context, level):
            write = stream.write
            write('{')
            if self._indent_per_level > 1:
                write((self._indent_per_level - 1) * ' ')
            length = len(object)
            if length:
                items = sorted(object.items(), key=_safe_tuple)
                self._format_dict_items(items, stream, indent, allowance + 1,
                                        context, level)
            write('}')
    
        _dispatch[dict.__repr__] = _pprint_dict
    
        def _pprint_ordered_dict(self, object, stream, indent, allowance, context, level):
            if not len(object):
                stream.write(repr(object))
                return
            cls = object.__class__
            stream.write(cls.__name__ + '(')
            self._format(list(object.items()), stream,
                         indent + len(cls.__name__) + 1, allowance + 1,
                         context, level)
            stream.write(')')
    
        _dispatch[_collections.OrderedDict.__repr__] = _pprint_ordered_dict
    
        def _pprint_list(self, object, stream, indent, allowance, context, level):
            stream.write('[')
            self._format_items(object, stream, indent, allowance + 1,
                               context, level)
            stream.write(']')
    
        _dispatch[list.__repr__] = _pprint_list
    
        def _pprint_tuple(self, object, stream, indent, allowance, context, level):
            stream.write('(')
            endchar = ',)' if len(object) == 1 else ')'
            self._format_items(object, stream, indent, allowance + len(endchar),
                               context, level)
            stream.write(endchar)
    
        _dispatch[tuple.__repr__] = _pprint_tuple
    
        def _pprint_set(self, object, stream, indent, allowance, context, level):
            if not len(object):
                stream.write(repr(object))
                return
            typ = object.__class__
            if typ is set:
                stream.write('{')
                endchar = '}'
            else:
                stream.write(typ.__name__ + '({')
                endchar = '})'
                indent += len(typ.__name__) + 1
            object = sorted(object, key=_safe_key)
            self._format_items(object, stream, indent, allowance + len(endchar),
                               context, level)
            stream.write(endchar)
    
        _dispatch[set.__repr__] = _pprint_set
        _dispatch[frozenset.__repr__] = _pprint_set
    
        def _pprint_str(self, object, stream, indent, allowance, context, level):
            write = stream.write
            if not len(object):
                write(repr(object))
                return
            chunks = []
            lines = object.splitlines(True)
            if level == 1:
                indent += 1
                allowance += 1
            max_width1 = max_width = self._width - indent
            for i, line in enumerate(lines):
                rep = repr(line)
                if i == len(lines) - 1:
                    max_width1 -= allowance
                if len(rep) <= max_width1:
                    chunks.append(rep)
                else:
                    # A list of alternating (non-space, space) strings
                    parts = re.findall(r'\S*\s*', line)
                    assert parts
                    assert not parts[-1]
                    parts.pop()  # drop empty last part
                    max_width2 = max_width
                    current = ''
                    for j, part in enumerate(parts):
                        candidate = current + part
                        if j == len(parts) - 1 and i == len(lines) - 1:
                            max_width2 -= allowance
                        if len(repr(candidate)) > max_width2:
                            if current:
                                chunks.append(repr(current))
                            current = part
                        else:
                            current = candidate
                    if current:
                        chunks.append(repr(current))
            if len(chunks) == 1:
                write(rep)
                return
            if level == 1:
                write('(')
            for i, rep in enumerate(chunks):
                if i > 0:
                    write('\n' + ' '*indent)
                write(rep)
            if level == 1:
                write(')')
    
        _dispatch[str.__repr__] = _pprint_str
    
        def _pprint_bytes(self, object, stream, indent, allowance, context, level):
            write = stream.write
            if len(object) <= 4:
                write(repr(object))
                return
            parens = level == 1
            if parens:
                indent += 1
                allowance += 1
                write('(')
            delim = ''
            for rep in _wrap_bytes_repr(object, self._width - indent, allowance):
                write(delim)
                write(rep)
                if not delim:
                    delim = '\n' + ' '*indent
            if parens:
                write(')')
    
        _dispatch[bytes.__repr__] = _pprint_bytes
    
        def _pprint_bytearray(self, object, stream, indent, allowance, context, level):
            write = stream.write
            write('bytearray(')
            self._pprint_bytes(bytes(object), stream, indent + 10,
                               allowance + 1, context, level + 1)
            write(')')
    
        _dispatch[bytearray.__repr__] = _pprint_bytearray
    
        def _pprint_mappingproxy(self, object, stream, indent, allowance, context, level):
            stream.write('mappingproxy(')
            self._format(object.copy(), stream, indent + 13, allowance + 1,
                         context, level)
            stream.write(')')
    
        _dispatch[_types.MappingProxyType.__repr__] = _pprint_mappingproxy
    
        def _format_dict_items(self, items, stream, indent, allowance, context, level):
            write = stream.write
            indent += self._indent_per_level
            delimnl = ',\n' + ' ' * indent
            last_index = len(items) - 1
            for i, (key, ent) in enumerate(items):
                last = i == last_index
                rep = self._repr(key, context, level)
                write(rep)
                write(': ')
                self._format(ent, stream, indent + len(rep) + 2,
                             allowance if last else 1,
                             context, level)
                if not last:
                    write(delimnl)
    
        def _format_items(self, items, stream, indent, allowance, context, level):
            write = stream.write
            indent += self._indent_per_level
            if self._indent_per_level > 1:
                write((self._indent_per_level - 1) * ' ')
            delimnl = ',\n' + ' ' * indent
            delim = ''
            width = max_width = self._width - indent + 1
            it = iter(items)
            try:
                next_ent = next(it)
            except StopIteration:
                return
            last = False
            while not last:
                ent = next_ent
                try:
                    next_ent = next(it)
                except StopIteration:
                    last = True
                    max_width -= allowance
                    width -= allowance
                if self._compact:
                    rep = self._repr(ent, context, level)
                    w = len(rep) + 2
                    if width < w:
                        width = max_width
                        if delim:
                            delim = delimnl
                    if width >= w:
                        width -= w
                        write(delim)
                        delim = ', '
                        write(rep)
                        continue
                write(delim)
                delim = delimnl
                self._format(ent, stream, indent,
                             allowance if last else 1,
                             context, level)
    
        def _repr(self, object, context, level):
            repr, readable, recursive = self.format(object, context.copy(),
                                                    self._depth, level)
            if not readable:
                self._readable = False
            if recursive:
                self._recursive = True
            return repr
    
        def format(self, object, context, maxlevels, level):
            """Format object for a specific context, returning a string and flags indicating whether the representation is 'readable' and whether the object represents a recursive construct. """
            return _safe_repr(object, context, maxlevels, level)
    
        def _pprint_default_dict(self, object, stream, indent, allowance, context, level):
            if not len(object):
                stream.write(repr(object))
                return
            rdf = self._repr(object.default_factory, context, level)
            cls = object.__class__
            indent += len(cls.__name__) + 1
            stream.write('%s(%s,\n%s' % (cls.__name__, rdf, ' ' * indent))
            self._pprint_dict(object, stream, indent, allowance + 1, context, level)
            stream.write(')')
    
        _dispatch[_collections.defaultdict.__repr__] = _pprint_default_dict
    
        def _pprint_counter(self, object, stream, indent, allowance, context, level):
            if not len(object):
                stream.write(repr(object))
                return
            cls = object.__class__
            stream.write(cls.__name__ + '({')
            if self._indent_per_level > 1:
                stream.write((self._indent_per_level - 1) * ' ')
            items = object.most_common()
            self._format_dict_items(items, stream,
                                    indent + len(cls.__name__) + 1, allowance + 2,
                                    context, level)
            stream.write('})')
    
        _dispatch[_collections.Counter.__repr__] = _pprint_counter
    
        def _pprint_chain_map(self, object, stream, indent, allowance, context, level):
            if not len(object.maps):
                stream.write(repr(object))
                return
            cls = object.__class__
            stream.write(cls.__name__ + '(')
            indent += len(cls.__name__) + 1
            for i, m in enumerate(object.maps):
                if i == len(object.maps) - 1:
                    self._format(m, stream, indent, allowance + 1, context, level)
                    stream.write(')')
                else:
                    self._format(m, stream, indent, 1, context, level)
                    stream.write(',\n' + ' ' * indent)
    
        _dispatch[_collections.ChainMap.__repr__] = _pprint_chain_map
    
        def _pprint_deque(self, object, stream, indent, allowance, context, level):
            if not len(object):
                stream.write(repr(object))
                return
            cls = object.__class__
            stream.write(cls.__name__ + '(')
            indent += len(cls.__name__) + 1
            stream.write('[')
            if object.maxlen is None:
                self._format_items(object, stream, indent, allowance + 2,
                                   context, level)
                stream.write('])')
            else:
                self._format_items(object, stream, indent, 2,
                                   context, level)
                rml = self._repr(object.maxlen, context, level)
                stream.write('],\n%smaxlen=%s)' % (' ' * indent, rml))
    
        _dispatch[_collections.deque.__repr__] = _pprint_deque
    
        def _pprint_user_dict(self, object, stream, indent, allowance, context, level):
            self._format(object.data, stream, indent, allowance, context, level - 1)
    
        _dispatch[_collections.UserDict.__repr__] = _pprint_user_dict
    
        def _pprint_user_list(self, object, stream, indent, allowance, context, level):
            self._format(object.data, stream, indent, allowance, context, level - 1)
    
        _dispatch[_collections.UserList.__repr__] = _pprint_user_list
    
        def _pprint_user_string(self, object, stream, indent, allowance, context, level):
            self._format(object.data, stream, indent, allowance, context, level - 1)
    
        _dispatch[_collections.UserString.__repr__] = _pprint_user_string
    
    # Return triple (repr_string, isreadable, isrecursive).
    
    def _safe_repr(object, context, maxlevels, level):
        typ = type(object)
        if typ in _builtin_scalars:
            return repr(object), True, False
    
        r = getattr(typ, "__repr__", None)
        if issubclass(typ, dict) and r is dict.__repr__:
            if not object:
                return "{}", True, False
            objid = id(object)
            if maxlevels and level >= maxlevels:
                return "{...}", False, objid in context
            if objid in context:
                return _recursion(object), False, True
            context[objid] = 1
            readable = True
            recursive = False
            components = []
            append = components.append
            level += 1
            saferepr = _safe_repr
            items = sorted(object.items(), key=_safe_tuple)
            for k, v in items:
                krepr, kreadable, krecur = saferepr(k, context, maxlevels, level)
                vrepr, vreadable, vrecur = saferepr(v, context, maxlevels, level)
                append("%s: %s" % (krepr, vrepr))
                readable = readable and kreadable and vreadable
                if krecur or vrecur:
                    recursive = True
            del context[objid]
            return "{%s}" % ", ".join(components), readable, recursive
    
        if (issubclass(typ, list) and r is list.__repr__) or \
           (issubclass(typ, tuple) and r is tuple.__repr__):
            if issubclass(typ, list):
                if not object:
                    return "[]", True, False
                format = "[%s]"
            elif len(object) == 1:
                format = "(%s,)"
            else:
                if not object:
                    return "()", True, False
                format = "(%s)"
            objid = id(object)
            if maxlevels and level >= maxlevels:
                return format % "...", False, objid in context
            if objid in context:
                return _recursion(object), False, True
            context[objid] = 1
            readable = True
            recursive = False
            components = []
            append = components.append
            level += 1
            for o in object:
                orepr, oreadable, orecur = _safe_repr(o, context, maxlevels, level)
                append(orepr)
                if not oreadable:
                    readable = False
                if orecur:
                    recursive = True
            del context[objid]
            return format % ", ".join(components), readable, recursive
    
        rep = repr(object)
        return rep, (rep and not rep.startswith('<')), False
    
    _builtin_scalars = frozenset({str, bytes, bytearray, int, float, complex,
                                  bool, type(None)})
    
    def _recursion(object):
        return ("<Recursion on %s with id=%s>"
                % (type(object).__name__, id(object)))
    
    
    def _perfcheck(object=None):
        import time
        if object is None:
            object = [("string", (1, 2), [3, 4], {
       5: 6, 7: 8})] * 100000
        p = PrettyPrinter()
        t1 = time.time()
        _safe_repr(object, {}, None, 0)
        t2 = time.time()
        p.pformat(object)
        t3 = time.time()
        print("_safe_repr:", t2 - t1)
        print("pformat:", t3 - t2)
    
    def _wrap_bytes_repr(object, width, allowance):
        current = b''
        last = len(object) // 4 * 4
        for i in range(0, len(object), 4):
            part = object[i: i+4]
            candidate = current + part
            if i == last:
                width -= allowance
            if len(repr(candidate)) > width:
                if current:
                    yield repr(current)
                current = part
            else:
                current = candidate
        if current:
            yield repr(current)
    
    if __name__ == "__main__":
        _perfcheck()