feat: allow sorting directives WithDirectiveRunOrder

context.go

@@ -5,4 +5,5 @@ type contextKey int
 const (
 	ckNamespace contextKey = iota
 	ckResolveNestedDirectives
+	ckDirectiveRunOrder
 )

option.go

@@ -41,3 +41,14 @@ func WithValue(key, value interface{}) Option {
 func WithNestedDirectivesEnabled(resolve bool) Option {
 	return WithValue(ckResolveNestedDirectives, resolve)
 }
+
+type DirectiveRunOrder func(*Directive, *Directive) bool
+
+// WithDirectiveRunOrder sets the order of execution for directives.
+//
+// When used in New, the directives will be sorted at the tree building stage.
+//
+// When Used in Resolve or Scan, a copy of the directives will be sorted and used.
+func WithDirectiveRunOrder(runOrder DirectiveRunOrder) Option {
+	return WithValue(ckDirectiveRunOrder, runOrder)
+}

resolver.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"reflect"
+	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -55,6 +56,7 @@ func New(structValue interface{}, opts ...Option) (*Resolver, error) {
 	// Apply the context to each resolver.
 	tree.Iterate(func(r *Resolver) error {
 		r.Context = ctx
+		r.Directives = getSortedDirectives(ctx, r.Directives)
 		return nil
 	})
 
@@ -317,7 +319,7 @@ func (r *Resolver) runDirectives(ctx context.Context, rv reflect.Value) error {
 		ns = nsOverriden.(*Namespace)
 	}
 
-	for _, directive := range r.Directives {
+	for _, directive := range getSortedDirectives(ctx, r.Directives) {
 		dirRuntime := &DirectiveRuntime{
 			Directive: directive,
 			Resolver:  r,
@@ -345,6 +347,18 @@ func (r *Resolver) runDirectives(ctx context.Context, rv reflect.Value) error {
 	return nil
 }
 
+func getSortedDirectives(ctx context.Context, directives []*Directive) []*Directive {
+	if directiveRunOrder := ctx.Value(ckDirectiveRunOrder); directiveRunOrder != nil {
+		var directivesCopy []*Directive
+		directivesCopy = append(directivesCopy, directives...)
+		sort.SliceStable(directivesCopy, func(i, j int) bool {
+			return directiveRunOrder.(DirectiveRunOrder)(directivesCopy[i], directivesCopy[j])
+		})
+		return directivesCopy
+	}
+	return directives // the original one
+}
+
 func (r *Resolver) DebugLayoutText(depth int) string {
 	var sb strings.Builder
 	sb.WriteString(r.String())

resolver_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 	"reflect"
+	"strings"
 	"testing"
 
 	"github.com/ggicci/owl"
@@ -840,6 +841,76 @@ func TestWithNestedDirectivesEnabled_definitionOfNestedDirectives(t *testing.T)
 	}, tracker.Executed.ExecutedDirectives(), "tell the difference between nested and non-nested directives")
 }
 
+func TestWithDirectiveRunOrder_buildtime(t *testing.T) {
+	type Record struct {
+		R1 string `owl:"DOTA=2;csgo=1"`
+		R2 string `owl:"apple=green;pear;Grape=purple"`
+	}
+
+	tree, err := owl.New(Record{}, owl.WithDirectiveRunOrder(func(d1, d2 *owl.Directive) bool {
+		return strings.ToLower(d1.Name) < strings.ToLower(d2.Name) // sort directives by name (alphabetical order)
+	}))
+
+	assert.NoError(t, err)
+	assert.NotNil(t, tree)
+	suite.Run(t, NewBuildResolverTreeTestSuite(
+		tree,
+		[]*expectedResolver{
+			{
+				Index:      []int{0},
+				LookupPath: "R1",
+				NumFields:  0,
+				Directives: []*owl.Directive{
+					owl.NewDirective("csgo", "1"),
+					owl.NewDirective("DOTA", "2"),
+				},
+				Leaf: true,
+			},
+			{
+				Index:      []int{1},
+				LookupPath: "R2",
+				NumFields:  0,
+				Directives: []*owl.Directive{
+					owl.NewDirective("apple", "green"),
+					owl.NewDirective("Grape", "purple"),
+					owl.NewDirective("pear"),
+				},
+				Leaf: true,
+			},
+		},
+	))
+}
+
+func TestWithDirectiveRunOrder_runtime(t *testing.T) {
+	ns, tracker := createNsForTracking()
+	resolver, err := owl.New(User{}, owl.WithNamespace(ns))
+	assert.NoError(t, err)
+
+	form := &User{
+		Name:     "Ggicci",
+		Gender:   "male",
+		Birthday: "1991-11-10",
+	}
+
+	err = resolver.Scan(form, owl.WithDirectiveRunOrder(func(d1, d2 *owl.Directive) bool {
+		return d1.Name == "default" // makes default directive run first
+	}))
+	assert.NoError(t, err)
+
+	expected := ExecutedDataList{
+		{owl.NewDirective("form", "name"), "Ggicci"},
+
+		// The order of directives below is different from the order in the struct.
+		// Because we set the directive run order with WithDirectiveRunOrder when calling Scan.
+		// Now the default directive will run first, then the form directive.
+		{owl.NewDirective("default", "unknown"), "male"},
+		{owl.NewDirective("form", "gender"), "male"},
+
+		{owl.NewDirective("form", "birthday"), "1991-11-10"},
+	}
+	assert.Equal(t, expected, tracker.Executed)
+}
+
 func TestTreeDebugLayout(t *testing.T) {
 	var (
 		tree *owl.Resolver