feat: add UnregisterTag engine method

engine.go

@@ -173,3 +173,11 @@ func (e *Engine) ParseTemplateAndCache(source []byte, path string, line int) (*T
 func (e *Engine) SetAutoEscapeReplacer(replacer render.Replacer) {
 	e.cfg.SetAutoEscapeReplacer(replacer)
 }
+
+// UnregisterTag removes the named tag definition from the engine's configuration.
+// After calling UnregisterTag the tag will no longer be recognized by subsequent
+// parsing or rendering operations. The call is idempotent — unregistering a tag
+// that is not registered is a no-op.
+func (e *Engine) UnregisterTag(name string) {
+	e.cfg.UnregisterTag(name)
+}

engine_test.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/osteele/liquid/render"
 	"github.com/stretchr/testify/require"
 )
 
@@ -183,3 +184,19 @@ func Test_template_store(t *testing.T) {
 	out, _ := engine.ParseAndRenderString(string(template), params)
 	require.Equal(t, "Message Text: filename from: template.liquid.", out)
 }
+
+func TestEngine_UnregisterTag(t *testing.T) {
+	engine := NewEngine()
+	engine.RegisterTag("echo", func(c render.Context) (string, error) {
+		return c.TagArgs(), nil
+	})
+	source := `{% echo hello world %}`
+
+	_, err := engine.ParseAndRenderString(source, emptyBindings)
+	require.NoError(t, err)
+
+	engine.UnregisterTag("echo")
+
+	_, err = engine.ParseAndRenderString(source, emptyBindings)
+	require.Error(t, err)
+}

render/tags.go

@@ -18,3 +18,8 @@ func (c *Config) FindTagDefinition(name string) (TagCompiler, bool) {
 	td, ok := c.tags[name]
 	return td, ok
 }
+
+// UnregisterTag removes a tag definition.
+func (c *Config) UnregisterTag(name string) {
+	delete(c.tags, name)
+}