Add bin and edit workflow

bin/gems/ttfunk-1.8.0/lib/ttfunk/encoded_string.rb

@@ -0,0 +1,151 @@
+# frozen_string_literal: true
+
+require 'stringio'
+require_relative 'placeholder'
+
+module TTFunk
+  # Risen when the final encoded string was requested but there were some
+  # unresolved placeholders in it.
+  class UnresolvedPlaceholderError < StandardError
+  end
+
+  # Risen when a placeholder is added to an Encoded String but it already
+  # contains a placeholder with the same name.
+  class DuplicatePlaceholderError < StandardError
+  end
+
+  # Encoded string takes care of placeholders in binary strings. Placeholders
+  # are used when bytes need to be placed in the stream before their value is
+  # known.
+  #
+  # @api private
+  class EncodedString
+    # @yieldparam [self]
+    def initialize
+      yield(self) if block_given?
+    end
+
+    # Append to string.
+    #
+    # @param obj [String, Placeholder, EncodedString]
+    # @return [self]
+    def <<(obj)
+      case obj
+      when String
+        io << obj
+      when Placeholder
+        add_placeholder(obj)
+        io << ("\0" * obj.length)
+      when self.class
+        # adjust placeholders to be relative to the entire encoded string
+        obj.placeholders.each_pair do |_, placeholder|
+          add_placeholder(placeholder.dup, placeholder.position + io.length)
+        end
+
+        io << obj.unresolved_string
+      end
+
+      self
+    end
+
+    # Append multiple objects.
+    #
+    # @param objs [Array<String, Placeholder, EncodedString>]
+    # @return [self]
+    def concat(*objs)
+      objs.each do |obj|
+        self << obj
+      end
+      self
+    end
+
+    # Append padding to align string to the specified word width.
+    #
+    # @param width [Integer]
+    # @return [self]
+    def align!(width = 4)
+      if (length % width).positive?
+        self << ("\0" * (width - (length % width)))
+      end
+
+      self
+    end
+
+    # Length of this string.
+    #
+    # @return [Integer]
+    def length
+      io.length
+    end
+
+    # Raw string.
+    #
+    # @return [String]
+    # @raise [UnresolvedPlaceholderError] if there are any unresolved
+    #   placeholders left.
+    def string
+      unless placeholders.empty?
+        raise UnresolvedPlaceholderError,
+          "string contains #{placeholders.size} unresolved placeholder(s)"
+      end
+
+      io.string
+    end
+
+    # Raw bytes.
+    #
+    # @return [Array<Integer>]
+    # @raise [UnresolvedPlaceholderError] if there are any unresolved
+    #   placeholders left.
+    def bytes
+      string.bytes
+    end
+
+    # Unresolved raw string.
+    #
+    # @return [String]
+    def unresolved_string
+      io.string
+    end
+
+    # Resolve placeholder.
+    #
+    # @param name [Symbol]
+    # @param value [String]
+    # @return [void]
+    def resolve_placeholder(name, value)
+      last_pos = io.pos
+
+      if (placeholder = placeholders[name])
+        io.seek(placeholder.position)
+        io.write(value[0..placeholder.length])
+        placeholders.delete(name)
+      end
+    ensure
+      io.seek(last_pos)
+    end
+
+    # Plaholders
+    #
+    # @return [Hash{Symbol => Plaholder}]
+    def placeholders
+      @placeholders ||= {}
+    end
+
+    private
+
+    def add_placeholder(new_placeholder, pos = io.pos)
+      if placeholders.include?(new_placeholder.name)
+        raise DuplicatePlaceholderError,
+          "placeholder #{new_placeholder.name} already exists"
+      end
+
+      new_placeholder.position = pos
+      placeholders[new_placeholder.name] = new_placeholder
+    end
+
+    def io
+      @io ||= StringIO.new(''.b).binmode
+    end
+  end
+end