feat: add OffsetDateTime, nesting limits and uniform Marshaler dispatch

Assisted-by: DeepSeek V4.1 Flash

interpres_test.go

@@ -4,6 +4,7 @@
 package interpres
 
 import (
+	"errors"
 	"math"
 	"strings"
 	"testing"
@@ -192,7 +193,7 @@ clock = 07:32:00
 	if err != nil {
 		t.Fatalf("parse: %v", err)
 	}
-	if off, ok := tree["offset"].(time.Time); !ok || off.Year() != 1979 || off.Hour() != 7 {
+	if off, ok := tree["offset"].(OffsetDateTime); !ok || off.Year() != 1979 || off.Hour() != 7 {
 		t.Errorf("offset = %#v (%T)", tree["offset"], tree["offset"])
 	}
 	if ldt, ok := tree["local"].(LocalDateTime); !ok || ldt.Year() != 1979 || ldt.Hour() != 7 {
@@ -211,11 +212,11 @@ func TestDateTimeFormats(t *testing.T) {
 	if err != nil {
 		t.Fatalf("parse: %v", err)
 	}
-	if _, ok := tree["a"].(time.Time); !ok {
-		t.Errorf("a is %T, want time.Time", tree["a"])
+	if _, ok := tree["a"].(OffsetDateTime); !ok {
+		t.Errorf("a is %T, want OffsetDateTime", tree["a"])
 	}
-	if _, ok := tree["b"].(time.Time); !ok {
-		t.Errorf("b is %T, want time.Time", tree["b"])
+	if _, ok := tree["b"].(OffsetDateTime); !ok {
+		t.Errorf("b is %T, want OffsetDateTime", tree["b"])
 	}
 	if _, ok := tree["c"].(LocalDateTime); !ok {
 		t.Errorf("c is %T, want LocalDateTime", tree["c"])
@@ -419,11 +420,11 @@ func TestParseAcceptsOffsetBounds(t *testing.T) {
 	if err != nil {
 		t.Fatalf("parse: %v", err)
 	}
-	a := tree["a"].(time.Time)
+	a := tree["a"].(OffsetDateTime)
 	if _, offset := a.Zone(); offset != 23*3600+59*60 {
 		t.Fatalf("a offset = %d, want %d", offset, 23*3600+59*60)
 	}
-	b := tree["b"].(time.Time)
+	b := tree["b"].(OffsetDateTime)
 	if _, offset := b.Zone(); offset != -(23*3600 + 59*60) {
 		t.Fatalf("b offset = %d", offset)
 	}
@@ -619,10 +620,10 @@ odt2 = 1979-05-27 07:32-07:00
 	if got := tree["dt"].(LocalDateTime).String(); got != "1979-05-27T07:32" {
 		t.Errorf("dt = %q, want %q", got, "1979-05-27T07:32")
 	}
-	if got := tree["odt1"].(time.Time).Format(time.RFC3339Nano); got != "1979-05-27T07:32:00Z" {
+	if got := tree["odt1"].(OffsetDateTime).Format(time.RFC3339Nano); got != "1979-05-27T07:32:00Z" {
 		t.Errorf("odt1 = %q", got)
 	}
-	if got := tree["odt2"].(time.Time).Format(time.RFC3339Nano); got != "1979-05-27T07:32:00-07:00" {
+	if got := tree["odt2"].(OffsetDateTime).Format(time.RFC3339Nano); got != "1979-05-27T07:32:00-07:00" {
 		t.Errorf("odt2 = %q", got)
 	}
 	// The fraction still requires the seconds it belongs to.
@@ -703,3 +704,25 @@ func TestParseAcceptsMultilineInlineTables(t *testing.T) {
 		}
 	}
 }
+
+func TestParseNestingLimit(t *testing.T) {
+	// The parser is a recursive descent, so a document that nests without bound
+	// is rejected instead of exhausting the stack.
+	deep := func(n int) []byte {
+		return []byte("v = " + strings.Repeat("[", n) + strings.Repeat("]", n) + "\n")
+	}
+	if _, err := Parse(deep(100)); err != nil {
+		t.Fatalf("a document well inside the limit: %v", err)
+	}
+	_, err := Parse(deep(maxNestingDepth + 1))
+	if err == nil {
+		t.Fatal("expected a nesting error")
+	}
+	var se *SyntaxError
+	if !errors.As(err, &se) {
+		t.Fatalf("expected a *SyntaxError, got %T: %v", err, err)
+	}
+	if !strings.Contains(se.Msg, "nesting") {
+		t.Errorf("Msg = %q, want it to name the nesting limit", se.Msg)
+	}
+}