// substr extracts parts of a string, beginning at the character at the specified
// position, and returns the specified number of characters.
//
// It normally takes two parameters: start and length.
// It can also take one parameter: start, i.e. length is omitted, in which case
// the substring starting from start until the end of the string will be returned.
//
// To extract characters from the end of the string, use a negative start number.
//
// In addition, borrowing from the extended behavior described at http://php.net/substr,
// if length is given and is negative, then that many characters will be omitted from
// the end of string.
func substr(a interface{}, nums ...interface{}) (string, error) {
aStr, err := cast.ToStringE(a)
if err != nil {
return "", err
}
var start, length int
asRunes := []rune(aStr)
switch len(nums) {
case 0:
return "", errors.New("too less arguments")
case 1:
if start, err = cast.ToIntE(nums[0]); err != nil {
return "", errors.New("start argument must be integer")
}
length = len(asRunes)
case 2:
if start, err = cast.ToIntE(nums[0]); err != nil {
return "", errors.New("start argument must be integer")
}
if length, err = cast.ToIntE(nums[1]); err != nil {
return "", errors.New("length argument must be integer")
}
default:
return "", errors.New("too many arguments")
}
if start < -len(asRunes) {
start = 0
}
if start > len(asRunes) {
return "", fmt.Errorf("start position out of bounds for %d-byte string", len(aStr))
}
var s, e int
if start >= 0 && length >= 0 {
s = start
e = start + length
} else if start < 0 && length >= 0 {
s = len(asRunes) + start - length + 1
e = len(asRunes) + start + 1
} else if start >= 0 && length < 0 {
s = start
e = len(asRunes) + length
} else {
s = len(asRunes) + start
e = len(asRunes) + length
}
if s > e {
return "", fmt.Errorf("calculated start position greater than end position: %d > %d", s, e)
}
if e > len(asRunes) {
e = len(asRunes)
}
return string(asRunes[s:e]), nil
}
// After is exposed to templates, to iterate over all the items after N in a
// rangeable list. It's meant to accompany First
func After(index interface{}, seq interface{}) (interface{}, error) {
if index == nil || seq == nil {
return nil, errors.New("both limit and seq must be provided")
}
indexv, err := cast.ToIntE(index)
if err != nil {
return nil, err
}
if indexv < 1 {
return nil, errors.New("can't return negative/empty count of items from sequence")
}
seqv := reflect.ValueOf(seq)
seqv, isNil := indirect(seqv)
if isNil {
return nil, errors.New("can't iterate over a nil value")
}
switch seqv.Kind() {
case reflect.Array, reflect.Slice, reflect.String:
// okay
default:
return nil, errors.New("can't iterate over " + reflect.ValueOf(seq).Type().String())
}
if indexv >= seqv.Len() {
return nil, errors.New("no items left")
}
return seqv.Slice(indexv, seqv.Len()).Interface(), nil
}
func (self *Options) Int(key string) int {
value, err := cast.ToIntE(self.Interface(key))
if err != nil {
self.log.Printf("%s for key '%s'", err.Error(), key)
}
return value
}
// First is exposed to templates, to iterate over the first N items in a
// rangeable list.
func First(limit interface{}, seq interface{}) (interface{}, error) {
limitv, err := cast.ToIntE(limit)
if err != nil {
return nil, err
}
if limitv < 1 {
return nil, errors.New("can't return negative/empty count of items from sequence")
}
seqv := reflect.ValueOf(seq)
seqv, isNil := indirect(seqv)
if isNil {
return nil, errors.New("can't iterate over a nil value")
}
switch seqv.Kind() {
case reflect.Array, reflect.Slice, reflect.String:
// okay
default:
return nil, errors.New("can't iterate over " + reflect.ValueOf(seq).Type().String())
}
if limitv > seqv.Len() {
limitv = seqv.Len()
}
return seqv.Slice(0, limitv).Interface(), nil
}
func (c *Configr) Int(key string) (int, error) {
val, err := c.Get(key)
if err != nil {
return 0, err
}
return cast.ToIntE(val)
}
// First is exposed to templates, to iterate over the first N items in a
// rangeable list.
func First(limit interface{}, seq interface{}) (interface{}, error) {
limitv, err := cast.ToIntE(limit)
if err != nil {
return nil, err
}
if limitv < 1 {
return nil, errors.New("can't return negative/empty count of items from sequence")
}
seqv := reflect.ValueOf(seq)
// this is better than my first pass; ripped from text/template/exec.go indirect():
for ; seqv.Kind() == reflect.Ptr || seqv.Kind() == reflect.Interface; seqv = seqv.Elem() {
if seqv.IsNil() {
return nil, errors.New("can't iterate over a nil value")
}
if seqv.Kind() == reflect.Interface && seqv.NumMethod() > 0 {
break
}
}
switch seqv.Kind() {
case reflect.Array, reflect.Slice, reflect.String:
// okay
default:
return nil, errors.New("can't iterate over " + reflect.ValueOf(seq).Type().String())
}
if limitv > seqv.Len() {
limitv = seqv.Len()
}
return seqv.Slice(0, limitv).Interface(), nil
}
// slicestr slices a string by specifying a half-open range with
// two indices, start and end. 1 and 4 creates a slice including elements 1 through 3.
// The end index can be omitted, it defaults to the string's length.
func slicestr(a interface{}, startEnd ...interface{}) (string, error) {
aStr, err := cast.ToStringE(a)
if err != nil {
return "", err
}
var argStart, argEnd int
argNum := len(startEnd)
if argNum > 0 {
if argStart, err = cast.ToIntE(startEnd[0]); err != nil {
return "", errors.New("start argument must be integer")
}
}
if argNum > 1 {
if argEnd, err = cast.ToIntE(startEnd[1]); err != nil {
return "", errors.New("end argument must be integer")
}
}
if argNum > 2 {
return "", errors.New("too many arguments")
}
asRunes := []rune(aStr)
if argNum > 0 && (argStart < 0 || argStart >= len(asRunes)) {
return "", errors.New("slice bounds out of range")
}
if argNum == 2 {
if argEnd < 0 || argEnd > len(asRunes) {
return "", errors.New("slice bounds out of range")
}
return string(asRunes[argStart:argEnd]), nil
} else if argNum == 1 {
return string(asRunes[argStart:]), nil
} else {
return string(asRunes[:]), nil
}
}
// GetInt takes the name of an argument and returns an integer and an error
func (args Args) GetInt(name string) (int, error) {
v, ok := args[name]
if !ok {
return -1 << 7, ErrNoArg
}
i, err := cast.ToIntE(v)
if err != nil {
return -1 << 7, err
}
return i, nil
}
func resolvePagerSize(options ...interface{}) (int, error) {
if len(options) == 0 {
return viper.GetInt("paginate"), nil
}
if len(options) > 1 {
return -1, errors.New("too many arguments, 'pager size' is currently the only option")
}
pas, err := cast.ToIntE(options[0])
if err != nil || pas <= 0 {
return -1, errors.New(("'pager size' must be a positive integer"))
}
return pas, nil
}
