75 lines
1.5 KiB
Go
75 lines
1.5 KiB
Go
// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
|
|
// All rights reserved.
|
|
|
|
// operator-map.go
|
|
package expr
|
|
|
|
import (
|
|
"fmt"
|
|
"io"
|
|
|
|
"git.portale-stac.it/go-pkg/expr/kern"
|
|
"git.portale-stac.it/go-pkg/expr/scan"
|
|
)
|
|
|
|
//-------- map term
|
|
|
|
func newMapTerm(tk *scan.Token) (inst *scan.Term) {
|
|
return &scan.Term{
|
|
Tk: *tk,
|
|
Children: make([]*scan.Term, 0, 2),
|
|
Position: scan.PosInfix,
|
|
Priority: scan.PriIterOp,
|
|
EvalFunc: evalMap,
|
|
}
|
|
}
|
|
|
|
func evalMap(ctx kern.ExprContext, opTerm *scan.Term) (v any, err error) {
|
|
var leftValue, rightValue any
|
|
var it kern.Iterator
|
|
var item any
|
|
var ok bool
|
|
|
|
if err = opTerm.CheckOperands(); err != nil {
|
|
return
|
|
}
|
|
|
|
if leftValue, err = opTerm.Children[0].Compute(ctx); err != nil {
|
|
return
|
|
}
|
|
|
|
if it, ok = leftValue.(kern.Iterator); !ok {
|
|
if it, err = NewIterator(ctx, leftValue, nil); err != nil {
|
|
return nil, fmt.Errorf("left operand of MAP must be an iterable data-source; got %s", kern.TypeName(leftValue))
|
|
}
|
|
}
|
|
|
|
values := kern.NewListA()
|
|
for item, err = it.Next(); err == nil; item, err = it.Next() {
|
|
ctx.SetVar("_", item)
|
|
ctx.SetVar("__", it.Index())
|
|
ctx.SetVar("_#", it.Count())
|
|
if rightValue, err = opTerm.Children[1].Compute(ctx); err == nil {
|
|
values.AppendItem(rightValue)
|
|
}
|
|
ctx.DeleteVar("_#")
|
|
ctx.DeleteVar("__")
|
|
ctx.DeleteVar("_")
|
|
if err != nil {
|
|
break
|
|
}
|
|
}
|
|
if err == io.EOF {
|
|
err = nil
|
|
}
|
|
if err == nil {
|
|
v = values
|
|
}
|
|
return
|
|
}
|
|
|
|
// init
|
|
func init() {
|
|
scan.RegisterTermConstructor(scan.SymKwMap, newMapTerm)
|
|
}
|