Class: ActionDispatch::Journey::GTG::Builder
- Inherits:
-
Object
- Object
- ActionDispatch::Journey::GTG::Builder
- Defined in:
- lib/action_dispatch/journey/gtg/builder.rb
Overview
:nodoc:
Constant Summary collapse
Instance Attribute Summary collapse
-
#ast ⇒ Object
readonly
Returns the value of attribute ast.
-
#endpoints ⇒ Object
readonly
Returns the value of attribute endpoints.
-
#root ⇒ Object
readonly
Returns the value of attribute root.
Instance Method Summary collapse
- #firstpos(node) ⇒ Object
-
#initialize(root) ⇒ Builder
constructor
A new instance of Builder.
- #lastpos(node) ⇒ Object
- #nullable?(node) ⇒ Boolean
- #transition_table ⇒ Object
Constructor Details
#initialize(root) ⇒ Builder
Returns a new instance of Builder.
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# File 'lib/action_dispatch/journey/gtg/builder.rb', line 13 def initialize(root) @root = root @ast = Nodes::Cat.new root, DUMMY_END_NODE @followpos = build_followpos end |
Instance Attribute Details
#ast ⇒ Object (readonly)
Returns the value of attribute ast.
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# File 'lib/action_dispatch/journey/gtg/builder.rb', line 11 def ast @ast end |
#endpoints ⇒ Object (readonly)
Returns the value of attribute endpoints.
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# File 'lib/action_dispatch/journey/gtg/builder.rb', line 11 def endpoints @endpoints end |
#root ⇒ Object (readonly)
Returns the value of attribute root.
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# File 'lib/action_dispatch/journey/gtg/builder.rb', line 11 def root @root end |
Instance Method Details
#firstpos(node) ⇒ Object
[View source]
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# File 'lib/action_dispatch/journey/gtg/builder.rb', line 86 def firstpos(node) case node when Nodes::Star firstpos(node.left) when Nodes::Cat if nullable?(node.left) firstpos(node.left) | firstpos(node.right) else firstpos(node.left) end when Nodes::Or node.children.flat_map { |c| firstpos(c) }.tap(&:uniq!) when Nodes::Unary firstpos(node.left) when Nodes::Terminal nullable?(node) ? [] : [node] else raise ArgumentError, "unknown firstpos: %s" % node.class.name end end |
#lastpos(node) ⇒ Object
[View source]
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# File 'lib/action_dispatch/journey/gtg/builder.rb', line 107 def lastpos(node) case node when Nodes::Star lastpos(node.left) when Nodes::Or node.children.flat_map { |c| lastpos(c) }.tap(&:uniq!) when Nodes::Cat if nullable?(node.right) lastpos(node.left) | lastpos(node.right) else lastpos(node.right) end when Nodes::Terminal nullable?(node) ? [] : [node] when Nodes::Unary lastpos(node.left) else raise ArgumentError, "unknown lastpos: %s" % node.class.name end end |
#nullable?(node) ⇒ Boolean
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# File 'lib/action_dispatch/journey/gtg/builder.rb', line 64 def nullable?(node) case node when Nodes::Group true when Nodes::Star # the default star regex is /(.+)/ which is NOT nullable # but since different constraints can be provided we must # actually check if this is the case or not. node.regexp.match?("") when Nodes::Or node.children.any? { |c| nullable?(c) } when Nodes::Cat nullable?(node.left) && nullable?(node.right) when Nodes::Terminal !node.left when Nodes::Unary nullable?(node.left) else raise ArgumentError, "unknown nullable: %s" % node.class.name end end |
#transition_table ⇒ Object
[View source]
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# File 'lib/action_dispatch/journey/gtg/builder.rb', line 19 def transition_table dtrans = TransitionTable.new marked = {}.compare_by_identity state_id = Hash.new { |h, k| h[k] = h.length }.compare_by_identity dstates = [firstpos(root)] until dstates.empty? s = dstates.shift next if marked[s] marked[s] = true # mark s s.group_by { |state| symbol(state) }.each do |sym, ps| u = ps.flat_map { |l| @followpos[l] }.uniq next if u.empty? from = state_id[s] if u.all? { |pos| pos == DUMMY_END_NODE } to = state_id[Object.new] dtrans[from, to] = sym dtrans.add_accepting(to) ps.each { |state| dtrans.add_memo(to, state.memo) } else to = state_id[u] dtrans[from, to] = sym if u.include?(DUMMY_END_NODE) ps.each do |state| if @followpos[state].include?(DUMMY_END_NODE) dtrans.add_memo(to, state.memo) end end dtrans.add_accepting(to) end end dstates << u end end dtrans end |