Class: Win32::CaptureIE::FFI::StructureType

Inherits:
Type
  • Object
show all
Defined in:
lib/win32/capture_ie/ffi/struct.rb

Overview

:nodoc:

Constant Summary collapse

PACKING_ALIGN = 
4

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, size = nil) ⇒ StructureType

Returns a new instance of StructureType.



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 52

def initialize(name, size=nil)
  super(name)
  @ruby_class = nil
  @fields = []
  @size = size
end

Instance Attribute Details

#fields ⇒ Object (readonly)

Returns the value of attribute fields.



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 51

def fields
  @fields
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 51

def name
  @name
end

#ruby_class ⇒ Object (readonly)

Returns the value of attribute ruby_class.



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 51

def ruby_class
  @ruby_class
end

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 51

def size
  @size
end

Instance Method Details

#align!(r, offset) ⇒ Object 



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 97

def align!(r, offset)
  if offset < r.length
    raise "buffer over flow: expected offset #{offset}, but was #{r.length}"
  end
  if r.length < offset
    r << "\0" * (offset - r.length)
  end
end

#calc_offsets ⇒ Object 



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 59

def calc_offsets
  offset = 0
  @fields.each do |f|
    align = [f.type.size, PACKING_ALIGN].min
    offset = (offset.to_f / align).ceil * align
    size = f.size
    if f.offset.nil?
      f.offset = offset
      offset += size
    else
      offset = f.offset
      offset += size
    end
  end
end

#calc_size ⇒ Object 



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 75

def calc_size
  return @size if @size
  if @fields.empty?
    @size = 0
    return
  end
  align = [@fields.first.type.size, PACKING_ALIGN].min
  offset = @fields.last.offset + @fields.last.size
  @size = (offset.to_f / align).ceil * align
end

#define!(ns) ⇒ Object 



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 106

def define!(ns)
  calc_offsets
  calc_size
  define_ruby_class(ns)
end

#define_ruby_class(ns) ⇒ Object 



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 112

def define_ruby_class(ns)
  types = self
  name = @name
  clazz = Class.new
  clazz.instance_eval {
    types.fields.each {|f|
      attr_accessor f.name
    }
    define_method(:initialize) {|*args|
      types.fields.zip(args).each {|f,arg|
        instance_variable_set(f.var, arg || f.init)
      }
    }
    define_method(:pack) {
      types.pack(self)
    }
  }
  clazz.class_eval %Q{
    def names
      [#{types.fields.map{|f| ":#{f.name}"} * ','}]
    end
    def values
      [#{types.fields.map{|f| f.var} * ','}]
    end
  }
  (class <<clazz; self; end).instance_eval {
    define_method(:packed_size) {
      CStruct.sizeof(name)
    }
    define_method(:c_type) {
      CStruct.c_type(name)
    }
  }
  @ruby_class = clazz
  ns.const_set(@name, clazz)
end

#pack(value) ⇒ Object 



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# File 'lib/win32/capture_ie/ffi/struct.rb', line 86

def pack(value)
  packed = @fields.zip(value.values).map{|f,v| [f.offset, f.pack(v)] }
  r = ""
  packed.each do |offset,c|
    align!(r, offset)
    r << c
  end
  align!(r, size)
  r
end