builtin: Implement enumerate feature

Now, gpython supports enumerate feature

Author: corona10

builtin/builtin.go

@@ -74,7 +74,7 @@ func init(){
 "classmethod": py.ClassMethodType,
 "complex": py.ComplexType,
 "dict": py.StringDictType, // FIXME
-// "enumerate": py.EnumType,
+"enumerate": py.EnumerateType,
 // "filter": py.FilterType,
 "float": py.FloatType,
 "frozenset": py.FrozenSetType,

builtin/tests/builtin.py

@@ -32,6 +32,11 @@
 doc="divmod"
 assertdivmod(34,7) == (4, 6)
 
+doc="enumerate"
+a= [3, 4, 5, 6, 7]
+foridx, valueinenumerate(a):
+assertvalue==a[idx]
+
 doc="eval"
 # smoke test only - see vm/tests/builtin.py for more tests
 asserteval("1+2") ==3

py/enumerate.go

@@ -0,0 +1,88 @@
+// Copyright 2018 The go-python Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package py
+
+// A python Enumerate object
+typeEnumeratestruct{
+IterableObject
+StartInt
+}
+
+// A python Enumerate iterator
+typeEnumerateIteratorstruct{
+Enumerate
+IndexInt
+}
+
+varEnumerateType=NewTypeX("enumerate", `enumerate(iterable, start=0)
+
+Return an enumerate object.`,
+EnumerateNew, nil)
+
+varEnumerateIteratorType=NewType("enumerate_iterator", `enumerate_iterator object`)
+
+// Type of this object
+func (o*Enumerate) Type() *Type{
+returnEnumerateType
+}
+
+// Type of this object
+func (o*EnumerateIterator) Type() *Type{
+returnEnumerateIteratorType
+}
+
+// EnumerateTypeNew
+funcEnumerateNew(metatype*Type, argsTuple, kwargsStringDict) (Object, error){
+variterableObject
+varstartObject
+err:=UnpackTuple(args, kwargs, "enumerate", 1, 2, &iterable, &start)
+iferr!=nil{
+returnnil, err
+ }
+
+ifstart==nil{
+start=Int(0)
+ }
+startIndex, err:=Index(start)
+iferr!=nil{
+returnnil, err
+ }
+iter, err:=Iter(iterable)
+iferr!=nil{
+returnnil, err
+ }
+
+return&Enumerate{Iterable: iter, Start: startIndex}, nil
+}
+
+// Enumerate iterator
+func (it*Enumerate) M__iter__() (Object, error){
+return&EnumerateIterator{
+Enumerate: *it,
+Index: it.Start,
+ }, nil
+}
+
+// EnumerateIterator iterator
+func (it*EnumerateIterator) M__iter__() (Object, error){
+returnit, nil
+}
+
+// EnumerateIterator iterator next
+func (iter*EnumerateIterator) M__next__() (Object, error){
+value, err:=Next(iter.Enumerate.Iterable)
+iferr!=nil{
+returnnil, err
+ }
+res:=make(Tuple, 2)
+res[0] =iter.Index
+res[1] =value
+iter.Index+=1
+returnres, nil
+}
+
+// Check interface is satisfied
+var_I__iter__= (*Enumerate)(nil)
+var_I_iterator= (*EnumerateIterator)(nil)

py/tests/list.py

@@ -14,4 +14,12 @@
 assertrepr([1,[2,3],4]) =="[1, [2, 3], 4]"
 assertrepr(["1",[2.5,17,[]]]) =="['1', [2.5, 17, []]]"
 
+doc="enumerate"
+a= [eforeinenumerate([3,4,5,6,7], 4)]
+idxs= [4, 5, 6, 7, 8]
+values= [3, 4, 5, 6, 7]
+foridx, valueinenumerate(values):
+assertidxs[idx] ==a[idx][0]
+assertvalues[idx] ==a[idx][1]
+
 doc="finished"