1 files changed, 112 insertions, 0 deletions
diff --git a/lib/asn1kit/types/bit_string.rb b/lib/asn1kit/types/bit_string.rb
new file mode 100644
index 0000000..53426dd
--- /dev/null
+++ b/lib/asn1kit/types/bit_string.rb
@@ -0,0 +1,112 @@
+# coding: ASCII-8BIT
+
+class ASN1Kit::BitString < ASN1Kit::Type
+  asn1_tag :IMPLICIT, :UNIVERSAL, 3
+  asn1_alias "BIT STRING"
+
+  NAMED_BITS = {}
+  NAMED_BITS_INVERTED = {}
+
+  class << self
+    def [](*named_bits)
+      return self if named_bits.empty?
+      ret = Class.new(self)
+      hash = named_bits.to_h
+      hash_inverted = hash.invert
+      raise "duplicate name(s) in named bit list" if named_bits.size != hash.size
+      raise "duplicate value(s) in named bit list" if hash.size != hash_inverted.size
+      ret.const_set(:NAMED_BITS, hash)
+      ret.const_set(:NAMED_BITS_INVERTED, hash.invert)
+      ret
+    end
+
+    def named_bit(name)
+      self::NAMED_BITS[name]
+    end
+
+    def named_bits
+      self::NAMED_BITS.keys
+    end
+
+    private def inspect_inner
+      return nil if self::NAMED_BITS.empty?
+      nns = self::NAMED_BITS.map { |name, value|
+        "#{name}(#{value})"
+      }.join(", ")
+      "{ #{nns} }"
+    end
+
+    def new_with_names(*list)
+      if self::NAMED_BITS.empty?
+        raise TypeError, "BIT STRING without NamedBits defined cannot be " \
+          "instantiated by #from_names"
+      end
+      return new(String.new, 0) if list.empty?
+
+      bits = list.map { |name|
+        named_bit(name) or
+          raise ArgumentError, "invalid name: %p" % name
+      }
+      bit_length = bits.max + 1
+      str = "0".b * bit_length
+      bits.each { |pos| str[pos] = "1" }
+      new([str].pack("B*"), bit_length)
+    end
+  end
+
+  attr_reader :string, :bit_length
+
+  def initialize(str, bit_length)
+    if bit_length <= (str.bytesize - 1) * 8 || bit_length > str.bytesize * 8
+      raise ArgumentError, "invalid bit_length"
+    end
+    @string = str
+    @bit_length = bit_length
+  end
+
+  def set?(name_or_pos)
+    if name_or_pos.is_a?(String)
+      name_or_pos = self.class.named_bit(name_or_pos)
+    end
+    unless name_or_pos.is_a?(::Integer)
+      raise TypeError, "invalid argument type: %p" % name_or_pos
+    end
+    byte = @string.getbyte(name_or_pos / 8)
+    byte[7 - name_or_pos % 8] == 1
+  end
+
+  def to_der
+    byte_length = (bit_length / 8r).ceil
+    unused_bits = byte_length * 8 - bit_length
+    content = [unused_bits].pack("C") << @string
+    der_header(byte_length + 1) << content
+  end
+
+  def ==(other)
+    return false unless other.is_a?(ASN1Kit::BitString)
+    return false unless self.class::NAMED_BITS.equal?(other.class::NAMED_BITS)
+    value == other.value && bit_length == other.bit_length
+  end
+end
+
+module ASN1Kit::Internal::CompileBitString
+  refine ASN1Kit::BitString.singleton_class do
+    def _compile_fixup(state)
+      self::NAMED_BITS.transform_values! do |value|
+        if value.is_a?(ASN1Kit::Internal::UnresolvedValue)
+          vname = value.value.name
+          value = state.value_symbols[vname] ||
+            raise("unresolved value: %s" % vname)
+          if !value.is_a?(ASN1Kit::Integer)
+            raise ASN1Kit::ParseError, "DefinedValue in NamedBit resolved to non-integer: %s" % vname
+          end
+          if value.value < 0
+            raise ASN1Kit::ParseError, "DefinedValue in NamedBit resolved to negative integer: %s" % vname
+          end
+          value = value.value
+        end
+        value
+      end
+    end
+  end
+end