class Sass::Tree::Visitors::Base
The abstract base class for Sass
visitors. Visitors
should extend this class, then implement ‘visit_*` methods for each node they care about (e.g. `visit_rule` for {RuleNode} or `visit_for` for {ForNode}). These methods take the node in question as argument. They may `yield` to visit the child nodes of the current node.
Note: due to the unusual nature of {Sass::Tree::IfNode}, special care must be taken to ensure that it is properly handled. In particular, there is no built-in scaffolding for dealing with the return value of ‘@else` nodes.
@abstract
Public Class Methods
Runs the visitor on a tree.
@param root [Tree::Node] The root node of the Sass
tree. @return [Object] The return value of {#visit} for the root node.
# File lib/sass/tree/visitors/base.rb, line 23 def self.visit(root) new.send(:visit, root) end
Protected Class Methods
Returns the name of a node as used in the ‘visit_*` method.
@param [Tree::Node] node The node. @return [String] The name.
# File lib/sass/tree/visitors/base.rb, line 59 def self.node_name(node) Sass::Util.deprecated(self, "Call node.class.node_name instead.") node.class.node_name end
Protected Instance Methods
Runs the visitor on the given node. This can be overridden by subclasses that need to do something for each node.
@param node [Tree::Node] The node to visit. @return [Object] The return value of the ‘visit_*` method for this node.
# File lib/sass/tree/visitors/base.rb, line 34 def visit(node) if respond_to?(node.class.visit_method, true) send(node.class.visit_method, node) {visit_children(node)} else visit_children(node) end end
Visit the child nodes for a given node. This can be overridden by subclasses that need to do something with the child nodes’ return values.
This method is run when ‘visit_*` methods `yield`, and its return value is returned from the `yield`.
@param parent [Tree::Node] The parent node of the children to visit. @return [Array<Object>] The return values of the ‘visit_*` methods for the children.
# File lib/sass/tree/visitors/base.rb, line 51 def visit_children(parent) parent.children.map {|c| visit(c)} end
‘yield`s, then runs the visitor on the `@else` clause if the node has one. This exists to ensure that the contents of the `@else` clause get visited.
# File lib/sass/tree/visitors/base.rb, line 66 def visit_if(node) yield visit(node.else) if node.else node end