Parent

Object

Dhaka::ProductionBuilder

Productions for specific grammar symbols are defined in the context of this class.

Public Class Methods

new(grammar, symbol) click to toggle source

symbol is the grammar symbol that productions are being defined for.

# File lib/dhaka/grammar/grammar.rb, line 10
def initialize(grammar, symbol)
  @grammar = grammar
  @symbol  = symbol
end

Public Instance Methods

method_missing(production_name, expansion, options = {}, &blk) click to toggle source

Creates a new production for symbol with an expansion of expansion. The options hash can include a directive :prec, the value of which is a grammar symbol name. The precedence of the production is then set to the precedence of the grammar symbol corresponding to that name.

See the arithmetic precedence grammar in the test suites for an example.

# File lib/dhaka/grammar/grammar.rb, line 20
def method_missing(production_name, expansion, options = {}, &blk)
  expansion_symbols = expansion.collect {|name| @grammar.symbols[name]}
  production_args   = [@symbol, expansion_symbols, production_name.to_s, blk, @grammar.production_index]
  if precedence_symbol_name = options[:prec] 
    production_args << @grammar.symbol_for_name(precedence_symbol_name).precedence
  end
  
  production = Production.new(*production_args)
  @grammar.production_index += 1
  
  @symbol.nullable = true if expansion_symbols.empty?
  @grammar.productions_by_symbol[production.symbol] << production
  raise "Duplicate production named #{production.name}" if @grammar.productions_by_name[production.name]
  @grammar.productions_by_name[production.name] = production
end

[Validate]

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