mirror of
https://github.com/python/cpython.git
synced 2024-12-18 22:34:08 +08:00
315 lines
10 KiB
Python
315 lines
10 KiB
Python
# 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.sydout].
|
|
|
|
saferepr()
|
|
Generate a 'standard' repr()-like value, but protect against recursive
|
|
data structures.
|
|
|
|
"""
|
|
|
|
from types import DictType, ListType, TupleType, StringType
|
|
import sys
|
|
|
|
try:
|
|
from cStringIO import StringIO
|
|
except ImportError:
|
|
from StringIO import StringIO
|
|
|
|
__all__ = ["pprint","pformat","isreadable","isrecursive","saferepr",
|
|
"PrettyPrinter"]
|
|
|
|
# cache these for faster access:
|
|
_commajoin = ", ".join
|
|
_sys_modules = sys.modules
|
|
_id = id
|
|
_len = len
|
|
_type = type
|
|
|
|
|
|
def pprint(object, stream=None):
|
|
"""Pretty-print a Python object to a stream [default is sys.sydout]."""
|
|
printer = PrettyPrinter(stream=stream)
|
|
printer.pprint(object)
|
|
|
|
def pformat(object):
|
|
"""Format a Python object into a pretty-printed representation."""
|
|
return PrettyPrinter().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 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
|
|
assert depth is None or depth > 0, "depth must be > 0"
|
|
assert width
|
|
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._stream.write(self.pformat(object) + "\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)[2]
|
|
|
|
def isreadable(self, object):
|
|
s, readable, recursive = self.format(object, {}, 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 sepLines:
|
|
if typ is DictType:
|
|
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 = object.items()
|
|
items.sort()
|
|
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)
|
|
write(',\n%s%s: ' % (' '*indent, 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 typ is ListType or typ is TupleType:
|
|
if typ is ListType:
|
|
write('[')
|
|
endchar = ']'
|
|
else:
|
|
write('(')
|
|
endchar = ')'
|
|
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
|
|
self._format(object[0], stream, indent, allowance + 1,
|
|
context, level)
|
|
if length > 1:
|
|
for ent in object[1:]:
|
|
write(',\n' + ' '*indent)
|
|
self._format(ent, stream, indent,
|
|
allowance + 1, context, level)
|
|
indent = indent - self._indent_per_level
|
|
del context[objid]
|
|
if typ is TupleType 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 StringType:
|
|
if 'locale' not in _sys_modules:
|
|
return `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, `char`[1:-1]))
|
|
return ("%s%s%s" % (closure, sio.getvalue(), closure)), True, False
|
|
|
|
if typ is DictType:
|
|
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 object.iteritems():
|
|
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 typ is ListType or typ is TupleType:
|
|
if typ is ListType:
|
|
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 = `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()
|