| # 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 sys as _sys | |
| import warnings | |
| from cStringIO import StringIO as _StringIO | |
| __all__ = ["pprint","pformat","isreadable","isrecursive","saferepr", | |
| "PrettyPrinter"] | |
| # cache these for faster access: | |
| _commajoin = ", ".join | |
| _id = id | |
| _len = len | |
| _type = type | |
| def pprint(object, stream=None, indent=1, width=80, depth=None): | |
| """Pretty-print a Python object to a stream [default is sys.stdout].""" | |
| printer = PrettyPrinter( | |
| stream=stream, indent=indent, width=width, depth=depth) | |
| printer.pprint(object) | |
| def pformat(object, indent=1, width=80, depth=None): | |
| """Format a Python object into a pretty-printed representation.""" | |
| return PrettyPrinter(indent=indent, width=width, depth=depth).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] | |
| def _sorted(iterable): | |
| with warnings.catch_warnings(): | |
| if _sys.py3kwarning: | |
| warnings.filterwarnings("ignore", "comparing unequal types " | |
| "not supported", DeprecationWarning) | |
| return sorted(iterable) | |
| class PrettyPrinter: | |
| def __init__(self, indent=1, width=80, depth=None, stream=None): | |
| """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. | |
| """ | |
| indent = int(indent) | |
| width = int(width) | |
| assert indent >= 0, "indent must be >= 0" | |
| assert depth is None or depth > 0, "depth must be > 0" | |
| assert width, "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 | |
| 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): | |
| level = level + 1 | |
| objid = _id(object) | |
| if objid in context: | |
| stream.write(_recursion(object)) | |
| self._recursive = True | |
| self._readable = False | |
| return | |
| rep = self._repr(object, context, level - 1) | |
| typ = _type(object) | |
| sepLines = _len(rep) > (self._width - 1 - indent - allowance) | |
| write = stream.write | |
| if self._depth and level > self._depth: | |
| write(rep) | |
| return | |
| r = getattr(typ, "__repr__", None) | |
| if issubclass(typ, dict) and r is dict.__repr__: | |
| write('{') | |
| if self._indent_per_level > 1: | |
| write((self._indent_per_level - 1) * ' ') | |
| length = _len(object) | |
| if length: | |
| context[objid] = 1 | |
| indent = indent + self._indent_per_level | |
| items = _sorted(object.items()) | |
| key, ent = items[0] | |
| rep = self._repr(key, context, level) | |
| write(rep) | |
| write(': ') | |
| self._format(ent, stream, indent + _len(rep) + 2, | |
| allowance + 1, context, level) | |
| if length > 1: | |
| for key, ent in items[1:]: | |
| rep = self._repr(key, context, level) | |
| if sepLines: | |
| write(',\n%s%s: ' % (' '*indent, rep)) | |
| else: | |
| write(', %s: ' % rep) | |
| self._format(ent, stream, indent + _len(rep) + 2, | |
| allowance + 1, context, level) | |
| indent = indent - self._indent_per_level | |
| del context[objid] | |
| write('}') | |
| return | |
| if ((issubclass(typ, list) and r is list.__repr__) or | |
| (issubclass(typ, tuple) and r is tuple.__repr__) or | |
| (issubclass(typ, set) and r is set.__repr__) or | |
| (issubclass(typ, frozenset) and r is frozenset.__repr__) | |
| ): | |
| length = _len(object) | |
| if issubclass(typ, list): | |
| write('[') | |
| endchar = ']' | |
| elif issubclass(typ, set): | |
| if not length: | |
| write('set()') | |
| return | |
| write('set([') | |
| endchar = '])' | |
| object = _sorted(object) | |
| indent += 4 | |
| elif issubclass(typ, frozenset): | |
| if not length: | |
| write('frozenset()') | |
| return | |
| write('frozenset([') | |
| endchar = '])' | |
| object = _sorted(object) | |
| indent += 10 | |
| else: | |
| write('(') | |
| endchar = ')' | |
| if self._indent_per_level > 1 and sepLines: | |
| write((self._indent_per_level - 1) * ' ') | |
| if length: | |
| context[objid] = 1 | |
| indent = indent + self._indent_per_level | |
| self._format(object[0], stream, indent, allowance + 1, | |
| context, level) | |
| if length > 1: | |
| for ent in object[1:]: | |
| if sepLines: | |
| write(',\n' + ' '*indent) | |
| else: | |
| write(', ') | |
| self._format(ent, stream, indent, | |
| allowance + 1, context, level) | |
| indent = indent - self._indent_per_level | |
| del context[objid] | |
| if issubclass(typ, tuple) and length == 1: | |
| write(',') | |
| write(endchar) | |
| return | |
| write(rep) | |
| 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) | |
| # Return triple (repr_string, isreadable, isrecursive). | |
| def _safe_repr(object, context, maxlevels, level): | |
| typ = _type(object) | |
| if typ is str: | |
| if 'locale' not in _sys.modules: | |
| return repr(object), True, False | |
| if "'" in object and '"' not in object: | |
| closure = '"' | |
| quotes = {'"': '\\"'} | |
| else: | |
| closure = "'" | |
| quotes = {"'": "\\'"} | |
| qget = quotes.get | |
| sio = _StringIO() | |
| write = sio.write | |
| for char in object: | |
| if char.isalpha(): | |
| write(char) | |
| else: | |
| write(qget(char, repr(char)[1:-1])) | |
| return ("%s%s%s" % (closure, sio.getvalue(), closure)), 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 | |
| for k, v in _sorted(object.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}" % _commajoin(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 % _commajoin(components), readable, recursive | |
| rep = repr(object) | |
| return rep, (rep and not rep.startswith('<')), False | |
| 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 | |
| if __name__ == "__main__": | |
| _perfcheck() |