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range.go
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range.go
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// 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.
// Range object
package py
// A python Range object
// FIXME one day support BigInts too!
type Range struct {
Start Int
Stop Int
Step Int
//Length Object
}
// A python Range iterator
type RangeIterator struct {
Range
Index Int
}
var RangeType = NewTypeX("range", `range(stop) -> range object
range(start, stop[, step]) -> range object
Return a virtual sequence of numbers from start to stop by step.`,
RangeNew, nil)
var RangeIteratorType = NewType("range_iterator", `range_iterator object`)
// Type of this object
func (o *Range) Type() *Type {
return RangeType
}
// Type of this object
func (o *RangeIterator) Type() *Type {
return RangeIteratorType
}
// RangeNew
func RangeNew(metatype *Type, args Tuple, kwargs StringDict) (Object, error) {
var start Object
var stop Object
var step Object = Int(1)
err := UnpackTuple(args, kwargs, "range", 1, 3, &start, &stop, &step)
if err != nil {
return nil, err
}
startIndex, err := Index(start)
if err != nil {
return nil, err
}
if len(args) == 1 {
return &Range{
Start: Int(0),
Stop: startIndex,
Step: Int(1),
}, nil
}
stopIndex, err := Index(stop)
if err != nil {
return nil, err
}
stepIndex, err := Index(step)
if err != nil {
return nil, err
}
return &Range{
Start: startIndex,
Stop: stopIndex,
Step: stepIndex,
}, nil
}
// Make a range iterator from a range
func (r *Range) M__iter__() (Object, error) {
return &RangeIterator{
Range: *r,
Index: r.Start,
}, nil
}
// Range iterator
func (it *RangeIterator) M__iter__() (Object, error) {
return it, nil
}
// Range iterator next
func (it *RangeIterator) M__next__() (Object, error) {
r := it.Index
if r >= it.Stop {
return nil, StopIteration
}
it.Index += it.Step
return r, nil
}
// Check interface is satisfied
var _ I__iter__ = (*Range)(nil)
var _ I_iterator = (*RangeIterator)(nil)