restructure project

internal/builtins/find.go

@@ -0,0 +1,52 @@
+package builtins
+
+import (
+	"monkey/internal/object"
+	"monkey/internal/typing"
+	"sort"
+)
+
+import (
+	"strings"
+)
+
+// Find ...
+func Find(args ...object.Object) object.Object {
+	if err := typing.Check(
+		"find", args,
+		typing.ExactArgs(2),
+	); err != nil {
+		return newError(err.Error())
+	}
+
+	// find substring in string
+	if haystack, ok := args[0].(*object.String); ok {
+		if err := typing.Check(
+			"find", args,
+			typing.WithTypes(object.STRING_OBJ, object.STRING_OBJ),
+		); err != nil {
+			return newError(err.Error())
+		}
+
+		needle := args[1].(*object.String)
+		index := strings.Index(haystack.Value, needle.Value)
+		return &object.Integer{Value: int64(index)}
+	}
+
+	// find in array
+	if haystack, ok := args[0].(*object.Array); ok {
+		needle := args[1].(object.Comparable)
+		i := sort.Search(len(haystack.Elements), func(i int) bool {
+			return needle.Compare(haystack.Elements[i]) == 0
+		})
+		if i < len(haystack.Elements) && needle.Compare(haystack.Elements[i]) == 0 {
+			return &object.Integer{Value: int64(i)}
+		}
+		return &object.Integer{Value: -1}
+	}
+
+	return newError(
+		"TypeError: find() expected argument #1 to be `array` or `str` got `%s`",
+		args[0].Type(),
+	)
+}