// walkChild only executes a subset of nodes, intended to be used on child templates.
func (s *state) walkChild(node parse.Node) error {
s.enter(node)
defer s.leave(node)
switch node := node.(type) {
case *parse.BodyNode:
for _, c := range node.Children() {
err := s.walkChild(c)
if err != nil {
return err
}
}
case *parse.UseNode:
return s.walkUseNode(node)
}
return nil
}
// Method walk is the main entry-point into template execution.
func (s *state) walk(node parse.Node) error {
s.enter(node)
defer s.leave(node)
switch node := node.(type) {
case *parse.ModuleNode:
if p := node.Parent(); p != nil {
tplName, err := s.evalExpr(p.TemplateRef())
if err != nil {
return err
}
tree, err := s.load(CoerceString(tplName))
if err != nil {
return err
}
s.blocks = append(s.blocks, tree.Blocks())
err = s.walkChild(node.BodyNode)
if err != nil {
return err
}
return s.walk(tree.Root())
}
return s.walk(node.BodyNode)
case *parse.BodyNode:
for _, c := range node.Children() {
err := s.walk(c)
if err != nil {
return err
}
}
case *parse.TextNode:
io.WriteString(s.out, node.Text())
case *parse.PrintNode:
v, err := s.evalExpr(node.Expr())
if err != nil {
return err
}
io.WriteString(s.out, CoerceString(v))
case *parse.BlockNode:
name := node.Name()
if block := s.getBlock(name); block != nil {
return s.walk(block.Body())
}
// TODO: It seems this should never occur.
return errors.New("Unable to locate block " + name)
case *parse.IfNode:
v, err := s.evalExpr(node.Cond())
if err != nil {
return err
}
if CoerceBool(v) {
s.walk(node.Body())
} else {
s.walk(node.Else())
}
case *parse.IncludeNode:
tpl, ctx, err := s.walkIncludeNode(node)
if err != nil {
return err
}
err = execute(tpl, s.out, ctx, s.env)
if err != nil {
return err
}
case *parse.EmbedNode:
tpl, ctx, err := s.walkIncludeNode(node.IncludeNode)
if err != nil {
return err
}
// TODO: We duplicate most of the "execute" function here.
si := newState(s.out, ctx, s.env)
tree, err := s.load(tpl)
if err != nil {
return err
}
si.blocks = append(s.blocks, node.Blocks(), tree.Blocks())
err = si.walk(tree.Root())
if err != nil {
return err
}
case *parse.UseNode:
return s.walkUseNode(node)
case *parse.ForNode:
return s.walkForNode(node)
default:
return errors.New("Unknown node " + node.String())
}
return nil
}