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slice.go
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slice.go
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package template
import (
"fmt"
"reflect"
"github.com/coveo/gotemplate/collections"
"github.com/coveo/gotemplate/errors"
)
func safeIndex(value interface{}, index int, def interface{}) (result interface{}, err error) {
defer func() { err = errors.Trap(err, recover()) }()
valueOf := reflect.ValueOf(value)
switch valueOf.Kind() {
case reflect.Slice, reflect.Array, reflect.String:
if index < 0 || index >= valueOf.Len() {
return def, nil
}
return valueOf.Index(index).Interface(), nil
default:
return nil, fmt.Errorf("First argument is not indexable %T", value)
}
}
func slice(value interface{}, args ...interface{}) (result interface{}, err error) {
return sliceInternal(value, false, args...)
}
func extract(value interface{}, args ...interface{}) (result interface{}, err error) {
return sliceInternal(value, true, args...)
}
func sliceInternal(value interface{}, extract bool, args ...interface{}) (result interface{}, err error) {
defer func() { err = errors.Trap(err, recover()) }()
args = convertArgs(nil, args...).AsArray()
valueOf := reflect.ValueOf(value)
switch valueOf.Kind() {
case reflect.Slice, reflect.Array, reflect.String:
switch len(args) {
case 0:
return valueOf.Interface(), nil
case 1:
return selectElement(valueOf, toInt(args[0])), nil
case 2:
if !extract {
return sliceList(valueOf, args...)
}
fallthrough
default:
if !extract {
return nil, fmt.Errorf("To many parameters")
}
result := collections.AsList(value).Create(len(args))
for i := range args {
result.Set(i, selectElement(valueOf, toInt(args[i])))
}
if valueOf.Kind() == reflect.String {
return fmt.Sprint(result.AsArray()...), nil
}
return result, nil
}
case reflect.Map:
return sliceMap(value, extract, args...)
default:
return nil, fmt.Errorf("Cannot apply slice on type %s", reflect.TypeOf(value))
}
}
func sliceMap(value interface{}, extract bool, args ...interface{}) (interface{}, error) {
dict := collections.AsDictionary(value)
switch len(args) {
case 0:
return nil, nil
case 1:
return dict.Get(args[0]), nil
case 2:
if !extract {
keys := dict.GetKeys()
k1, k2 := fmt.Sprint(args[0]), fmt.Sprint(args[1])
if k1 > k2 {
keys = keys.Reverse()
k1, k2 = k2, k1
}
results := dict.CreateList(0, dict.Len()*20)
for i := 0; i < keys.Len(); i++ {
k := fmt.Sprint(keys.Get(i))
if k >= k1 && k <= k2 {
results = results.Append(dict.Get(k))
}
}
return results, nil
}
fallthrough
default:
if !extract {
return nil, fmt.Errorf("Slice cannot have more that two parts")
}
results := dict.CreateList(len(args))
for i, key := range args {
results.Set(i, dict.Get(key))
}
return results, nil
}
}
func sliceList(value reflect.Value, args ...interface{}) (result interface{}, err error) {
length := value.Len()
begin := toInt(args[0])
begin = iif(begin < 0, length+begin+1, begin).(int)
end := toInt(args[1])
end = iif(end < 0, length+end+1, end).(int)
// Check if we should reverse the section
reverse := end < begin
if reverse {
end, begin = begin, end
}
// For slice operation, there is no error if the index are of limit
end = int(min(end, length).(int64))
begin = int(max(begin, 0).(int64))
if value.Kind() == reflect.String {
// String slices are returned as string instead of array of runes
result := value.String()[begin:end]
if reverse {
return reverseString(result), nil
}
return result, nil
}
if begin > length {
// Begin is after the end
return collections.AsList(value.Interface()).Create(), nil
}
results := collections.AsList(value.Interface()).Create(end - begin)
for i := range results.AsArray() {
results.Set(i, value.Index(i+begin).Interface())
}
if reverse {
return results.Reverse(), nil
}
return results, nil
}
func selectElement(value reflect.Value, index int) interface{} {
index = iif(index < 0, value.Len()+index, index).(int)
if value.Kind() == reflect.String {
return value.String()[index : index+1]
}
return value.Index(index).Interface()
}
func getSingleMapElement(m interface{}) (key, value interface{}, err error) {
err = fmt.Errorf("Argument must be a map with a single key")
if m == nil {
return
}
t := reflect.TypeOf(m)
v := reflect.ValueOf(m)
switch t.Kind() {
case reflect.Map:
keys := v.MapKeys()
if len(keys) != 1 {
return
}
return keys[0].Interface(), v.MapIndex(keys[0]).Interface(), nil
case reflect.Slice:
length := v.Len()
keys := make([]interface{}, length)
values := make([]interface{}, length)
for i := range keys {
if keys[i], values[i], err = getSingleMapElement(v.Index(i).Interface()); err != nil {
return
}
}
results := make(dictionary)
for i := range keys {
results[fmt.Sprint(keys[i])] = values[i]
}
return keys, results, nil
default:
return
}
}
// Reverse returns its argument string reversed rune-wise left to right.
func reverseString(s string) string {
r := []rune(s)
for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
r[i], r[j] = r[j], r[i]
}
return string(r)
}