class Racc::Grammar::PrecedenceDefinitionEnv

def higher
  if @prechigh_seen
    raise CompileError, "prechigh used twice"
  end
  @prechigh_seen = true
end

def initialize(g)
  @grammar = g
  @prechigh_seen = false
  @preclow_seen = false
  @reverse = false
end

def left(*syms)
  @grammar.declare_precedence :Left, syms.map {|s| @grammar.intern(s) }
end

def lower
  if @preclow_seen
    raise CompileError, "preclow used twice"
  end
  if @prechigh_seen
    @reverse = true
  end
  @preclow_seen = true
end

def nonassoc(*syms)
  @grammar.declare_precedence :Nonassoc, syms.map {|s| @grammar.intern(s)}
end

def right(*syms)
  @grammar.declare_precedence :Right, syms.map {|s| @grammar.intern(s) }
end