expr/func-base.go

// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
// All rights reserved.

// func-builtins.go
package expr

import (
	"math"
	"strconv"
)

func isNilFunc(ctx ExprContext, name string, args []any) (result any, err error) {
	if len(args) == 1 {
		result = args[0] == nil
	} else {
		err = errOneParam(name)
	}
	return
}

func intFunc(ctx ExprContext, name string, args []any) (result any, err error) {
	if len(args) == 1 {
		switch v := args[0].(type) {
		case int64:
			result = v
		case float64:
			result = int64(math.Trunc(v))
		case bool:
			if v {
				result = int64(1)
			} else {
				result = int64(0)
			}
		case string:
			var i int
			if i, err = strconv.Atoi(v); err == nil {
				result = int64(i)
			}
		default:
			err = errCantConvert(name, v, "int")
		}
	} else {
		err = errOneParam(name)
	}
	return
}

func iteratorFunc(ctx ExprContext, name string, args []any) (result any, err error) {
	return
}

func ImportBuiltinsFuncs(ctx ExprContext) {
	ctx.RegisterFunc("isNil", &simpleFunctor{f: isNilFunc}, 1, -1)
	ctx.RegisterFunc("int", &simpleFunctor{f: intFunc}, 1, -1)
}

func init() {
	registerImport("base", ImportBuiltinsFuncs, "Base expression tools like isNil(), int(), etc.")
}