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iterators.go
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iterators.go
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package plush
import (
"reflect"
"github.com/pkg/errors"
)
// Iterator type can be implemented and used by the `for` command to build loops in templates
type Iterator interface {
Next() interface{}
}
type ranger struct {
pos int
end int
}
func (r *ranger) Next() interface{} {
if r.pos < r.end {
r.pos++
return r.pos
}
return nil
}
func rangeHelper(a, b int) Iterator {
return &ranger{pos: a - 1, end: b}
}
func betweenHelper(a, b int) Iterator {
return &ranger{pos: a, end: b - 1}
}
func untilHelper(a int) Iterator {
return &ranger{pos: -1, end: a - 1}
}
func groupByHelper(size int, underlying interface{}) (*groupBy, error) {
if size <= 0 {
return nil, errors.New("size must be greater than zero")
}
u := reflect.Indirect(reflect.ValueOf(underlying))
group := []reflect.Value{}
switch u.Kind() {
case reflect.Array, reflect.Slice:
if u.Len() == size {
return &groupBy{
group: []reflect.Value{u},
}, nil
}
groupSize := u.Len() / size
if u.Len()%size != 0 {
groupSize++
}
pos := 0
for pos < u.Len() {
e := pos + groupSize
if e > u.Len() {
e = u.Len()
}
group = append(group, u.Slice(pos, e))
pos += groupSize
}
default:
return nil, errors.Errorf("can not use %T in groupBy", underlying)
}
g := &groupBy{
group: group,
}
return g, nil
}
type groupBy struct {
pos int
group []reflect.Value
}
func (g *groupBy) Next() interface{} {
if g.pos >= len(g.group) {
return nil
}
v := g.group[g.pos]
g.pos++
return v.Interface()
}