Class: Rley::ParseTreeVisitor
- Inherits:
-
Object
- Object
- Rley::ParseTreeVisitor
- Defined in:
- lib/rley/parse_tree_visitor.rb
Overview
A visitor class dedicated in the visit of a parse tree. It combines the Visitor and Observer patterns.
Instance Attribute Summary collapse
-
#ptree ⇒ Object
readonly
Link to the parse tree to visit.
-
#subscribers ⇒ Object
readonly
List of objects that subscribed to the visit event notification.
-
#traversal ⇒ Object
readonly
Indicates the kind of tree traversal to perform: :post_order, :pre-order.
Instance Method Summary collapse
-
#end_visit_nonterminal(aNonTerminalNode) ⇒ Object
Visit event.
-
#end_visit_ptree(aParseTree) ⇒ Object
Visit event.
-
#initialize(aParseTree, aTraversalStrategy = :post_order) ⇒ ParseTreeVisitor
constructor
Build a visitor for the given ptree.
-
#start ⇒ Object
The signal to begin the visit of the parse tree.
-
#start_visit_ptree(aParseTree) ⇒ Object
Visit event.
-
#subscribe(aSubscriber) ⇒ Object
Add a subscriber for the visit event notifications.
-
#unsubscribe(aSubscriber) ⇒ Object
Remove the given object from the subscription list.
-
#visit_nonterminal(aNonTerminalNode) ⇒ Object
Visit event.
-
#visit_terminal(aTerminalNode) ⇒ Object
Visit event.
Constructor Details
#initialize(aParseTree, aTraversalStrategy = :post_order) ⇒ ParseTreeVisitor
Build a visitor for the given ptree.
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# File 'lib/rley/parse_tree_visitor.rb', line 16 def initialize(aParseTree, aTraversalStrategy = :post_order) @ptree = aParseTree @subscribers = [] @traversal = aTraversalStrategy end |
Instance Attribute Details
#ptree ⇒ Object (readonly)
Link to the parse tree to visit
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# File 'lib/rley/parse_tree_visitor.rb', line 6 def ptree @ptree end |
#subscribers ⇒ Object (readonly)
List of objects that subscribed to the visit event notification.
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# File 'lib/rley/parse_tree_visitor.rb', line 9 def subscribers @subscribers end |
#traversal ⇒ Object (readonly)
Indicates the kind of tree traversal to perform: :post_order, :pre-order
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# File 'lib/rley/parse_tree_visitor.rb', line 12 def traversal @traversal end |
Instance Method Details
#end_visit_nonterminal(aNonTerminalNode) ⇒ Object
Visit event. The visitor has completed its visit of the given non-terminal node.
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# File 'lib/rley/parse_tree_visitor.rb', line 73 def end_visit_nonterminal(aNonTerminalNode) broadcast(:after_non_terminal, aNonTerminalNode) end |
#end_visit_ptree(aParseTree) ⇒ Object
Visit event. The visitor has completed the visit of the ptree.
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# File 'lib/rley/parse_tree_visitor.rb', line 79 def end_visit_ptree(aParseTree) broadcast(:after_ptree, aParseTree) end |
#start ⇒ Object
The signal to begin the visit of the parse tree.
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# File 'lib/rley/parse_tree_visitor.rb', line 36 def start() ptree.accept(self) end |
#start_visit_ptree(aParseTree) ⇒ Object
Visit event. The visitor is about to visit the ptree.
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# File 'lib/rley/parse_tree_visitor.rb', line 43 def start_visit_ptree(aParseTree) broadcast(:before_ptree, aParseTree) end |
#subscribe(aSubscriber) ⇒ Object
Add a subscriber for the visit event notifications.
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# File 'lib/rley/parse_tree_visitor.rb', line 24 def subscribe(aSubscriber) subscribers << aSubscriber end |
#unsubscribe(aSubscriber) ⇒ Object
Remove the given object from the subscription list. The object won't be notified of visit events.
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# File 'lib/rley/parse_tree_visitor.rb', line 31 def unsubscribe(aSubscriber) subscribers.delete_if { |entry| entry == aSubscriber } end |
#visit_nonterminal(aNonTerminalNode) ⇒ Object
Visit event. The visitor is about to visit the given non terminal node.
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# File 'lib/rley/parse_tree_visitor.rb', line 50 def visit_nonterminal(aNonTerminalNode) if @traversal == :post_order broadcast(:before_non_terminal, aNonTerminalNode) traverse_subnodes(aNonTerminalNode) else traverse_subnodes(aNonTerminalNode) broadcast(:before_non_terminal, aNonTerminalNode) end broadcast(:after_non_terminal, aNonTerminalNode) end |
#visit_terminal(aTerminalNode) ⇒ Object
Visit event. The visitor is visiting the given terminal node.
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# File 'lib/rley/parse_tree_visitor.rb', line 64 def visit_terminal(aTerminalNode) broadcast(:before_terminal, aTerminalNode) broadcast(:after_terminal, aTerminalNode) end |