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expr_string_char_entry.go
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/
expr_string_char_entry.go
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package rel
import (
"fmt"
"github.com/arr-ai/wbnf/parser"
)
// StringCharTupleExpr represents an expr that evaluates to a StringCharTuple.
type StringCharTupleExpr struct {
ExprScanner
at, char Expr
}
// NewStringCharTupleExpr returns a new dictEntryTupleExpr.
func NewStringCharTupleExpr(scanner parser.Scanner, at, char Expr) StringCharTupleExpr {
// TODO: Optimise for literals.
// if at, ok := at.(Value); ok {
// if char, ok := char.(Value); ok {
// return NewDictTuple(at, char)
// }
// }
return StringCharTupleExpr{ExprScanner: ExprScanner{Src: scanner}, at: at, char: char}
}
// String returns a string representation of the expression.
func (e StringCharTupleExpr) String() string {
return fmt.Sprintf("(@: %v, %s: %v)", e.at, StringCharAttr, e.char)
}
// Eval returns the subject
func (e StringCharTupleExpr) Eval(local Scope) (_ Value, err error) {
defer wrapPanic(e, &err, local)
at, err := e.at.Eval(local)
if err != nil {
return nil, wrapContext(err, e, local)
}
char, err := e.char.Eval(local)
if err != nil {
return nil, wrapContext(err, e, local)
}
return NewStringCharTuple(int(at.(Number).Float64()), rune(char.(Number).Float64())), nil
}