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package objects
import (
"strconv"
"github.com/d5/tengo"
"github.com/d5/tengo/compiler/token"
)
// String represents a string value.
type String struct {
Value string
runeStr []rune
}
// TypeName returns the name of the type.
func (o *String) TypeName() string {
return "string"
}
func (o *String) String() string {
return strconv.Quote(o.Value)
}
// BinaryOp returns another object that is the result of
// a given binary operator and a right-hand side object.
func (o *String) BinaryOp(op token.Token, rhs Object) (Object, error) {
switch op {
case token.Add:
switch rhs := rhs.(type) {
case *String:
if len(o.Value)+len(rhs.Value) > tengo.MaxStringLen {
return nil, ErrStringLimit
}
return &String{Value: o.Value + rhs.Value}, nil
default:
rhsStr := rhs.String()
if len(o.Value)+len(rhsStr) > tengo.MaxStringLen {
return nil, ErrStringLimit
}
return &String{Value: o.Value + rhsStr}, nil
}
}
return nil, ErrInvalidOperator
}
// IsFalsy returns true if the value of the type is falsy.
func (o *String) IsFalsy() bool {
return len(o.Value) == 0
}
// Copy returns a copy of the type.
func (o *String) Copy() Object {
return &String{Value: o.Value}
}
// Equals returns true if the value of the type
// is equal to the value of another object.
func (o *String) Equals(x Object) bool {
t, ok := x.(*String)
if !ok {
return false
}
return o.Value == t.Value
}
// IndexGet returns a character at a given index.
func (o *String) IndexGet(index Object) (res Object, err error) {
intIdx, ok := index.(*Int)
if !ok {
err = ErrInvalidIndexType
return
}
idxVal := int(intIdx.Value)
if o.runeStr == nil {
o.runeStr = []rune(o.Value)
}
if idxVal < 0 || idxVal >= len(o.runeStr) {
res = UndefinedValue
return
}
res = &Char{Value: o.runeStr[idxVal]}
return
}
// Iterate creates a string iterator.
func (o *String) Iterate() Iterator {
if o.runeStr == nil {
o.runeStr = []rune(o.Value)
}
return &StringIterator{
v: o.runeStr,
l: len(o.runeStr),
}
}
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