Module: FFI::DRY::ConstMap

Included in:

ConstFlagsMap

Defined in:

lib/ffi/dry.rb

Overview

ConstMap can be used to organize and lookup value to constant mappings and vice versa. Constants can be imported from a namespace based on a regular expression or other means.

Class Method Summary

• .included(klass) ⇒ Object

Instance Method Summary

• #[](arg) ⇒ Object

  A flexible name to value lookup.

• #list ⇒ Object

  Generates a hash of all the constant names mapped to value.

• #slurp_constants(nspace, prefix) ⇒ Object

  When called from a module definition or class method, this method imports all the constants from # namespace ‘nspace’ that start with into the local namespace as constants named with whatever follows the prefix.

Class Method Details

.included(klass) ⇒ Object

# File 'lib/ffi/dry.rb', line 315

def self.included(klass)
  klass.extend(ConstMap)
end

Instance Method Details

#[](arg) ⇒ Object

A flexible name to value lookup.

Parameters:

• arg (String, Symbol, Integer) —

  Use a Symbol or String as a name to lookup its value. Use an Integer to lookup the corresponding name.

# File 'lib/ffi/dry.rb', line 325

def [](arg)
  if arg.is_a? Integer
    list.invert[arg]
  elsif arg.is_a? String or arg.is_a? Symbol
    list[arg.to_s.upcase]
  end
end

#list ⇒ Object

Generates a hash of all the constant names mapped to value. Usually, it’s a good idea to override this like so to cache results in derived modules:

def list; @@list ||= super() ; end

# File 'lib/ffi/dry.rb', line 339

def list
  constants.inject({}){|h,c| h.merge! c => const_get(c) }
end

#slurp_constants(nspace, prefix) ⇒ Object

When called from a module definition or class method, this method imports all the constants from # namespace ‘nspace’ that start with into the local namespace as constants named with whatever follows the prefix. Only constant names that match [A-Z]+ are imported, the rest are ignored.

This method also yields the (short) constant name and value to a block if one is provided. The block works like […].select {|c,v| … } in that the value is not mapped if the block returns nil or false.

# File 'lib/ffi/dry.rb', line 352

def slurp_constants(nspace, prefix)
  nspace.constants.grep(/^(#{prefix}([A-Z][A-Z0-9_]+))$/) do
    c = $2
    v = nspace.const_get($1)
    next if block_given? and not yield(c,v)
    const_set c, v
  end
end