pprint's workhorse _safe_repr() function took time quadratic in the # of
elements when crunching a list, dict or tuple. Now takes linear time
instead -- huge speedup for even moderately large containers, and the
code is notably simpler too.
Added some basic "is the output correct?" tests to test_pprint.
diff --git a/Lib/pprint.py b/Lib/pprint.py
index 48efb33..351323b 100644
--- a/Lib/pprint.py
+++ b/Lib/pprint.py
@@ -188,66 +188,55 @@
# Return triple (repr_string, isreadable, isrecursive).
def _safe_repr(object, context, maxlevels=None, level=0):
- level = level + 1
+ level += 1
typ = type(object)
if not (typ in (DictType, ListType, TupleType) and object):
rep = `object`
return rep, (rep and (rep[0] != '<')), 0
+
if context.has_key(id(object)):
return `_Recursion(object)`, 0, 1
objid = id(object)
context[objid] = 1
+
readable = 1
recursive = 0
- if typ is DictType:
- if maxlevels and level >= maxlevels:
- s = "{...}"
- readable = 0
- else:
- items = object.items()
- k, v = items[0]
+ startchar, endchar = {ListType: "[]",
+ TupleType: "()",
+ DictType: "{}"}[typ]
+ if maxlevels and level > maxlevels:
+ with_commas = "..."
+ readable = 0
+
+ elif typ is DictType:
+ components = []
+ for k, v in object.iteritems():
krepr, kreadable, krecur = _safe_repr(k, context, maxlevels,
level)
vrepr, vreadable, vrecur = _safe_repr(v, context, maxlevels,
level)
+ components.append("%s: %s" % (krepr, vrepr))
readable = readable and kreadable and vreadable
recursive = recursive or krecur or vrecur
- s = "{%s: %s" % (krepr, vrepr)
- for k, v in items[1:]:
- krepr, kreadable, krecur = _safe_repr(k, context, maxlevels,
- level)
- vrepr, vreadable, vrecur = _safe_repr(v, context, maxlevels,
- level)
- readable = readable and kreadable and vreadable
- recursive = recursive or krecur or vrecur
- s = "%s, %s: %s" % (s, krepr, vrepr)
- s = s + "}"
- else:
- s, term = (typ is ListType) and ('[', ']') or ('(', ')')
- if maxlevels and level >= maxlevels:
- s = s + "..."
- readable = 0
- else:
+ with_commas = ", ".join(components)
+
+ else: # list or tuple
+ assert typ in (ListType, TupleType)
+ components = []
+ for element in object:
subrepr, subreadable, subrecur = _safe_repr(
- object[0], context, maxlevels, level)
+ element, context, maxlevels, level)
+ components.append(subrepr)
readable = readable and subreadable
recursive = recursive or subrecur
- s = s + subrepr
- tail = object[1:]
- if not tail:
- if typ is TupleType:
- s = s + ','
- for ent in tail:
- subrepr, subreadable, subrecur = _safe_repr(
- ent, context, maxlevels, level)
- readable = readable and subreadable
- recursive = recursive or subrecur
- s = "%s, %s" % (s, subrepr)
- s = s + term
+ if len(components) == 1 and typ is TupleType:
+ components[0] += ","
+ with_commas = ", ".join(components)
+
+ s = "%s%s%s" % (startchar, with_commas, endchar)
del context[objid]
return s, readable and not recursive, recursive
-
class _Recursion:
# represent a recursive relationship; really only used for the __repr__()
# method...