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module BinData
# Raised when #lookup fails.
class UnRegisteredTypeError < StandardError; end
# This registry contains a register of name -> class mappings.
#
# Numerics (integers and floating point numbers) have an endian property as
# part of their name (e.g. int32be, float_le).
#
# Classes can be looked up based on their full name or an abbreviated +name+
# with +hints+.
#
# There are two hints supported, :endian and :search_prefix.
#
# #lookup("int32", { endian: :big }) will return Int32Be.
#
# #lookup("my_type", { search_prefix: :ns }) will return NsMyType.
#
# Names are stored in under_score_style, not camelCase.
class Registry
def initialize
@registry = {}
end
def register(name, class_to_register)
return if name.nil? || class_to_register.nil?
formatted_name = underscore_name(name)
warn_if_name_is_already_registered(formatted_name, class_to_register)
@registry[formatted_name] = class_to_register
end
def unregister(name)
@registry.delete(underscore_name(name))
end
def lookup(name, hints = {})
search_names(name, hints).each do |search|
register_dynamic_class(search)
if @registry.has_key?(search)
return @registry[search]
end
end
# give the user a hint if the endian keyword is missing
search_names(name, hints.merge(endian: :big)).each do |search|
register_dynamic_class(search)
if @registry.has_key?(search)
raise(UnRegisteredTypeError, "#{name}, do you need to specify endian?")
end
end
raise(UnRegisteredTypeError, name)
end
# Convert CamelCase +name+ to underscore style.
def underscore_name(name)
name
.to_s
.sub(/.*::/, "")
.gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
.gsub(/([a-z\d])([A-Z])/, '\1_\2')
.tr('-', '_')
.downcase
end
#---------------
private
def search_names(name, hints)
base = underscore_name(name)
searches = []
search_prefix = [""] + Array(hints[:search_prefix])
search_prefix.each do |prefix|
nwp = name_with_prefix(base, prefix)
nwe = name_with_endian(nwp, hints[:endian])
searches << nwp
searches << nwe if nwe
end
searches
end
def name_with_prefix(name, prefix)
prefix = prefix.to_s.chomp('_')
if prefix == ""
name
else
"#{prefix}_#{name}"
end
end
def name_with_endian(name, endian)
return nil if endian.nil?
suffix = (endian == :little) ? 'le' : 'be'
if /^u?int\d+$/.match?(name)
name + suffix
else
name + '_' + suffix
end
end
def register_dynamic_class(name)
if /^u?int\d+(le|be)$/.match?(name) || /^s?bit\d+(le)?$/.match?(name)
class_name = name.gsub(/(?:^|_)(.)/) { $1.upcase }
begin
# call const_get for side effect of creating class
BinData.const_get(class_name)
rescue NameError
end
end
end
def warn_if_name_is_already_registered(name, class_to_register)
prev_class = @registry[name]
if prev_class && prev_class != class_to_register
Kernel.warn "warning: replacing registered class #{prev_class} " \
"with #{class_to_register}"
end
end
end
# A singleton registry of all registered classes.
RegisteredClasses = Registry.new
end
|
