Module: JSI::Util

Included in:
JSI
Defined in:
lib/jsi/util.rb

Constant Summary collapse

NOOP =

a proc which does nothing

-> (*_) { }

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.ycomb ⇒ Object

this is the Y-combinator, which allows anonymous recursive functions. for a simple example, to define a recursive function to return the length of an array:

length = ycomb do |len| proc{|list| list == [] ? 0 : 1 + len.call(list[1..-1]) } end

see https://secure.wikimedia.org/wikipedia/en/wiki/Fixed_point_combinator#Y_combinator and chapter 9 of the little schemer, available as the sample chapter at http://www.ccs.neu.edu/home/matthias/BTLS/



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# File 'lib/jsi/util.rb', line 86

def ycomb
  proc { |f| f.call(f) }.call(proc { |f| yield proc { |*x| f.call(f).call(*x) } })
end

Instance Method Details

#deep_stringify_symbol_keys(object) ⇒ Object 



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# File 'lib/jsi/util.rb', line 38

def deep_stringify_symbol_keys(object)
  if object.respond_to?(:to_hash)
    JSI::Typelike.modified_copy(object) do |hash|
      changed = false
      out = {}
      (hash.respond_to?(:each) ? hash : hash.to_hash).each do |k, v|
        if k.is_a?(Symbol)
          changed = true
          k = k.to_s
        end
        out_k = deep_stringify_symbol_keys(k)
        out_v = deep_stringify_symbol_keys(v)
        changed = true if out_k.object_id != k.object_id
        changed = true if out_v.object_id != v.object_id
        out[out_k] = out_v
      end
      changed ? out : hash
    end
  elsif object.respond_to?(:to_ary)
    JSI::Typelike.modified_copy(object) do |ary|
      changed = false
      out = (ary.respond_to?(:each) ? ary : ary.to_ary).map do |e|
        out_e = deep_stringify_symbol_keys(e)
        changed = true if out_e.object_id != e.object_id
        out_e
      end
      changed ? out : ary
    end
  else
    object
  end
end

#object_group_str(object_group_text) ⇒ String

Parameters:

  • object_group_text (Array<String>)

Returns:

  • (String) 


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# File 'lib/jsi/util.rb', line 73

def object_group_str(object_group_text)
  object_group_text.compact.map { |t| " #{t}" }.join('')
end

#stringify_symbol_keys(hash) ⇒ same class as the param `hash`, or Hash if the former cannot be done

returns a version of the given hash, in which any symbol keys are converted to strings. behavior on collisions is undefined (but in the future could take a block like ActiveSupport::HashWithIndifferentAccess#update)

at the moment it is undefined whether the returned hash is the same instance as the hash param. if hash is already a hash which contains no symbol keys, this method MAY return that same instance. use #dup on the return if you need to ensure it is not the same instance as the argument instance.

Parameters:

  • hash (#to_hash) —

    the hash from which to convert symbol keys to strings

Returns:

  • (same class as the param `hash`, or Hash if the former cannot be done) —

    a hash(-like) instance containing no symbol keys



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# File 'lib/jsi/util.rb', line 20

def stringify_symbol_keys(hash)
  unless hash.respond_to?(:to_hash)
    raise(ArgumentError, "expected argument to be a hash; got #{hash.class.inspect}: #{hash.pretty_inspect.chomp}")
  end
  JSI::Typelike.modified_copy(hash) do |hash_|
    changed = false
    out = {}
    hash_.each do |k, v|
      if k.is_a?(Symbol)
        changed = true
        k = k.to_s
      end
      out[k] = v
    end
    changed ? out : hash_
  end
end