class Dentaku::AST::StringFunctions::Mid

def self.max_param_count
  3
end

def self.min_param_count
  3
end

def initialize(*args)
  super
  @string, @offset, @length = *@args
end

def value(context = {})
  string = @string.value(context).to_s
  offset = Dentaku::AST::Function.numeric(@offset.value(context)).to_i
  negative_argument_failure('MID', 'offset') if offset < 0
  length = Dentaku::AST::Function.numeric(@length.value(context)).to_i
  negative_argument_failure('MID') if length < 0
  string[offset - 1, length].to_s
end