From 916cad6803f8be9259b736c231d2c66852bf7694 Mon Sep 17 00:00:00 2001
From: Raj Nishtala <rnishtala@sumologic.com>
Date: Mon, 21 Aug 2023 11:48:48 -0400
Subject: [PATCH] Removing the check for the ottlarg struct tag

---
 pkg/ottl/expression.go               | 10 +---------
 pkg/ottl/expression_test.go          | 17 -----------------
 pkg/ottl/functions.go                | 24 ++----------------------
 pkg/ottl/ottlfuncs/func_substring.go |  4 ++--
 4 files changed, 5 insertions(+), 50 deletions(-)

diff --git a/pkg/ottl/expression.go b/pkg/ottl/expression.go
index 82e9b0407ebcb..bd885afd22566 100644
--- a/pkg/ottl/expression.go
+++ b/pkg/ottl/expression.go
@@ -279,15 +279,7 @@ func (g StandardFunctionGetter[K]) Get(args Arguments) (Expr[K], error) {
 	}
 	for i := 0; i < fArgsVal.NumField(); i++ {
 		field := argsVal.Field(i)
-		argIndex, err := getArgumentIndex(i, argsVal)
-		if err != nil {
-			return Expr[K]{}, err
-		}
-		fArgIndex, err := getArgumentIndex(argIndex, fArgsVal)
-		if err != nil {
-			return Expr[K]{}, err
-		}
-		fArgsVal.Field(fArgIndex).Set(field)
+		fArgsVal.Field(i).Set(field)
 	}
 	fn, err := g.fact.CreateFunction(g.fCtx, fArgs)
 	if err != nil {
diff --git a/pkg/ottl/expression_test.go b/pkg/ottl/expression_test.go
index b9d2451e81aa2..bdb36c07a1278 100644
--- a/pkg/ottl/expression_test.go
+++ b/pkg/ottl/expression_test.go
@@ -688,11 +688,6 @@ func Test_FunctionGetter(t *testing.T) {
 			&multipleArgsArguments{},
 			functionWithStringGetter,
 		),
-		createFactory[any](
-			"no_struct_tag",
-			&noStructTagFunctionArguments{},
-			functionWithStringGetter,
-		),
 		NewFactory(
 			"cannot_create_function",
 			&stringGetterArguments{},
@@ -751,18 +746,6 @@ func Test_FunctionGetter(t *testing.T) {
 			valid:            false,
 			expectedErrorMsg: "incorrect number of arguments. Expected: 4 Received: 1",
 		},
-		{
-			name: "Invalid Arguments struct tag",
-			getter: StandardStringGetter[interface{}]{
-				Getter: func(ctx context.Context, tCtx interface{}) (interface{}, error) {
-					return nil, nil
-				},
-			},
-			function:         StandardFunctionGetter[any]{fCtx: FunctionContext{Set: componenttest.NewNopTelemetrySettings()}, fact: functions["no_struct_tag"]},
-			want:             "anything",
-			valid:            false,
-			expectedErrorMsg: "no `ottlarg` struct tag on Arguments field \"StringArg\"",
-		},
 		{
 			name: "Cannot create function",
 			getter: StandardStringGetter[interface{}]{
diff --git a/pkg/ottl/functions.go b/pkg/ottl/functions.go
index 967f804533637..730410e169dbf 100644
--- a/pkg/ottl/functions.go
+++ b/pkg/ottl/functions.go
@@ -7,7 +7,6 @@ import (
 	"errors"
 	"fmt"
 	"reflect"
-	"strconv"
 	"strings"
 )
 
@@ -47,22 +46,6 @@ func (p *Parser[K]) newFunctionCall(ed editor) (Expr[K], error) {
 	return Expr[K]{exprFunc: fn}, err
 }
 
-func getArgumentIndex(index int, args reflect.Value) (int, error) {
-	argsType := args.Type()
-	fieldTag, ok := argsType.Field(index).Tag.Lookup("ottlarg")
-	if !ok {
-		return 0, fmt.Errorf("no `ottlarg` struct tag on Arguments field %q", argsType.Field(index).Name)
-	}
-	argNum, err := strconv.Atoi(fieldTag)
-	if err != nil {
-		return 0, fmt.Errorf("ottlarg struct tag on field %q is not a valid integer: %w", argsType.Field(index).Name, err)
-	}
-	if argNum < 0 || argNum >= args.NumField() {
-		return 0, fmt.Errorf("ottlarg struct tag on field %q has value %d, but must be between 0 and %d", argsType.Field(index).Name, argNum, args.NumField())
-	}
-	return argNum, nil
-}
-
 func (p *Parser[K]) buildArgs(ed editor, argsVal reflect.Value) error {
 	if len(ed.Arguments) != argsVal.NumField() {
 		return fmt.Errorf("incorrect number of arguments. Expected: %d Received: %d", argsVal.NumField(), len(ed.Arguments))
@@ -71,12 +54,9 @@ func (p *Parser[K]) buildArgs(ed editor, argsVal reflect.Value) error {
 	for i := 0; i < argsVal.NumField(); i++ {
 		field := argsVal.Field(i)
 		fieldType := field.Type()
-		argNum, err := getArgumentIndex(i, argsVal)
-		if err != nil {
-			return err
-		}
-		argVal := ed.Arguments[argNum]
+		argVal := ed.Arguments[i]
 		var val any
+		var err error
 		switch {
 		case strings.HasPrefix(fieldType.Name(), "FunctionGetter"):
 			var name string
diff --git a/pkg/ottl/ottlfuncs/func_substring.go b/pkg/ottl/ottlfuncs/func_substring.go
index ef35fa9896fac..974a110b8716c 100644
--- a/pkg/ottl/ottlfuncs/func_substring.go
+++ b/pkg/ottl/ottlfuncs/func_substring.go
@@ -12,8 +12,8 @@ import (
 
 type SubstringArguments[K any] struct {
 	Target ottl.StringGetter[K]
-	Start  int64
-	Length int64
+	Start  ottl.IntGetter[K]
+	Length ottl.IntGetter[K]
 }
 
 func NewSubstringFactory[K any]() ottl.Factory[K] {