New top-level Context wrapper

context.go

@@ -0,0 +1,15 @@
+package liquid
+
+type context struct {
+	bindings map[string]interface{}
+}
+
+// NewContext creates a new context from a variable binding map.
+func NewContext(bindings map[string]interface{}) Context {
+	return &context{bindings}
+}
+
+// Bindings is in the Render interface.
+func (c *context) Bindings() map[string]interface{} {
+	return c.bindings
+}

engine.go

@@ -47,17 +47,17 @@ func (e engine) ParseTemplate(text []byte) (Template, error) {
 }
 
 // ParseAndRender is in the Engine interface.
-func (e engine) ParseAndRender(text []byte, bindings map[string]interface{}) ([]byte, error) {
+func (e engine) ParseAndRender(text []byte, c Context) ([]byte, error) {
 	t, err := e.ParseTemplate(text)
 	if err != nil {
 		return nil, err
 	}
-	return t.Render(bindings)
+	return t.Render(c)
 }
 
 // ParseAndRenderString is in the Engine interface.
-func (e engine) ParseAndRenderString(text string, bindings map[string]interface{}) (string, error) {
-	b, err := e.ParseAndRender([]byte(text), bindings)
+func (e engine) ParseAndRenderString(text string, c Context) (string, error) {
+	b, err := e.ParseAndRender([]byte(text), c)
 	if err != nil {
 		return "", err
 	}

interface.go

@@ -28,15 +28,34 @@ type Engine interface {
 	DefineTag(string, TagDefinition)
 	DefineStartTag(string, func(io.Writer, chunks.RenderContext) error)
 
-	ParseTemplate(b []byte) (Template, error)
+	ParseTemplate([]byte) (Template, error)
 	// ParseAndRender parses and then renders the template.
-	ParseAndRender(b []byte, bindings map[string]interface{}) ([]byte, error)
+	ParseAndRender([]byte, Context) ([]byte, error)
 	// ParseAndRenderString is a convenience wrapper for ParseAndRender, that has string input and output.
-	ParseAndRenderString(s string, bindings map[string]interface{}) (string, error)
+	ParseAndRenderString(string, Context) (string, error)
+}
+
+// Template renders a template according to scope.
+//
+// Bindings is a map of liquid variable names to objects.
+type Template interface {
+	// Render executes the template with the specified bindings.
+	Render(Context) ([]byte, error)
+	// RenderString is a convenience wrapper for Render, that has string input and output.
+	RenderString(Context) (string, error)
+}
+
+// Context supplies variable bindings and other information to a
+// Render.
+//
+// In the future, it will hold methods to get and set the current
+// filename.
+type Context interface {
+	Bindings() map[string]interface{}
 }
 
 // Renderer is the type of a function that is evaluated within a context and writes to output.
-type Renderer func(io.Writer, chunks.Context) error
+// type Renderer func(io.Writer, chunks.Context) error
 
 // TagDefinition is the type of a function that parses the argument string "args" from a tag "{% tagname args %}",
 // and returns a renderer.

liquid_test.go

@@ -16,19 +16,19 @@ var liquidTests = []struct{ in, expected string }{
 	{`{{ "upper" | upcase }}`, "UPPER"},
 }
 
-var liquidTestScope = map[string]interface{}{
+var testContext = NewContext(map[string]interface{}{
 	"x":  123,
 	"ar": []string{"first", "second", "third"},
 	"page": map[string]interface{}{
 		"title": "Introduction",
 	},
-}
+})
 
 func TestLiquid(t *testing.T) {
 	engine := NewEngine()
 	for i, test := range liquidTests {
 		t.Run(fmt.Sprint(i+1), func(t *testing.T) {
-			out, err := engine.ParseAndRenderString(test.in, liquidTestScope)
+			out, err := engine.ParseAndRenderString(test.in, testContext)
 			require.NoErrorf(t, err, test.in)
 			require.Equalf(t, test.expected, out, test.in)
 		})
@@ -43,7 +43,8 @@ func Example() {
 			"title": "Introduction",
 		},
 	}
-	out, err := engine.ParseAndRenderString(template, bindings)
+	context := NewContext(bindings)
+	out, err := engine.ParseAndRenderString(template, context)
 	if err != nil {
 		log.Fatalln(err)
 	}

template.go

@@ -6,25 +6,15 @@ import (
 	"github.com/osteele/liquid/chunks"
 )
 
-// Template renders a template according to scope.
-//
-// Bindings is a map of liquid variable names to objects.
-type Template interface {
-	// Render executes the template with the specified bindings.
-	Render(bindings map[string]interface{}) ([]byte, error)
-	// RenderString is a convenience wrapper for Render, that has string input and output.
-	RenderString(bindings map[string]interface{}) (string, error)
-}
-
 type template struct {
 	ast      chunks.ASTNode
 	settings chunks.Settings
 }
 
 // Render executes the template within the bindings environment.
-func (t *template) Render(bindings map[string]interface{}) ([]byte, error) {
+func (t *template) Render(c Context) ([]byte, error) {
 	buf := new(bytes.Buffer)
-	err := t.ast.Render(buf, chunks.NewContext(bindings, t.settings))
+	err := t.ast.Render(buf, chunks.NewContext(c.Bindings(), t.settings))
 	if err != nil {
 		return nil, err
 	}
@@ -32,8 +22,8 @@ func (t *template) Render(bindings map[string]interface{}) ([]byte, error) {
 }
 
 // RenderString is a convenience wrapper for Render, that has string input and output.
-func (t *template) RenderString(bindings map[string]interface{}) (string, error) {
-	b, err := t.Render(bindings)
+func (t *template) RenderString(c Context) (string, error) {
+	b, err := t.Render(c)
 	if err != nil {
 		return "", err
 	}