Class: FFI::Generators::Structures

Inherits:
Object
  • Object
show all
Defined in:
lib/ffi2/generators/structures.rb

Overview

Generates an FFI Struct layout.

Given the @@@ portion in:

module Zlib::ZStream < FFI::Struct
  @@@
  name "struct z_stream_s"
  include "zlib.h"

  field :next_in,   :pointer
  field :avail_in,  :uint
  field :total_in,  :ulong

  # ...
  @@@
end

Structures will create the layout:

layout :next_in, :pointer, 0,
       :avail_in, :uint, 4,
       :total_in, :ulong, 8,
       # ...

StructGenerator does its best to pad the layout it produces to preserve line numbers. Place the struct definition as close to the top of the file for best results.

Defined Under Namespace

Classes: Field

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name) ⇒ Structures

Returns a new instance of Structures.



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# File 'lib/ffi2/generators/structures.rb', line 68

def initialize(name)
  @name = name
  @struct_name = nil
  @includes = []
  @include_dirs = []
  @fields = []
  @found = false
  @size = nil
  @platform = Platform.new

  if block_given? then
    yield self
    calculate
  end
end

Instance Attribute Details

#fields ⇒ Object (readonly)

Returns the value of attribute fields.



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# File 'lib/ffi2/generators/structures.rb', line 66

def fields
  @fields
end

#size ⇒ Object

Returns the value of attribute size.



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# File 'lib/ffi2/generators/structures.rb', line 65

def size
  @size
end

Instance Method Details

#calculate ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 122

def calculate
  raise "struct name not set" if @struct_name.nil?

  output = BodyGuard.new(self, @struct_name, @platform).perform.split "\n"

  sizeof = output.shift
  unless @size
    m = /\s*sizeof\([^)]+\) (\d+)/.match sizeof
    @size = m[1]
  end

  line_no = 0
  output.each do |line|
    md = line.match(/.+ (\d+) (\d+)/)
    @fields[line_no].offset = md[1].to_i
    @fields[line_no].size   = md[2].to_i

    line_no += 1
  end

  @found = true
end

#field(name, type = nil) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 145

def field(name, type=nil)
  field = Field.new(name, type)
  @fields << field
  return field
end

#found? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ffi2/generators/structures.rb', line 151

def found?
  @found
end

#generate_layout ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 161

def generate_layout
  buf = ""

  @fields.each_with_index do |field, i|
    if buf.empty?
      buf << "layout :#{field.name}, :#{field.type}, #{field.offset}"
    else
      buf << "       :#{field.name}, :#{field.type}, #{field.offset}"
    end

    if i < @fields.length - 1
      buf << ",\n"
    end
  end

  buf
end

#get_field(name) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 179

def get_field(name)
  @fields.find { |f| name == f.name }
end

#include(i) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 183

def include(i)
  @includes << i
end

#include_dir(i) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 187

def include_dir(i)
  @include_dirs << i
end

#name(n) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 191

def name(n)
  @struct_name = n
end

#prepare(name, target) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 106

def prepare(name, target)
  @platform.compile(@include_dirs, name, target)
end

#prepare_failed ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 110

def prepare_failed
  "Compilation error generating struct #{@name} (#{@struct_name})"
end

#process(target) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 114

def process(target)
  target
end

#process_failed ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 118

def process_failed
  "Error generating struct #{@name} (#{@struct_name})"
end

#source(io) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 84

def source(io)
  io.puts "#include <stdio.h>"

  @includes.each do |inc|
    io.puts "#include <#{inc}>"
  end

  io.puts "#include <stddef.h>\n\n"
  io.puts "int main(int argc, char **argv)\n{"
  io.puts "  #{@struct_name} s;"
  io.puts %[  printf("sizeof(#{@struct_name}) %u\\n", (unsigned int) sizeof(#{@struct_name}));]

  @fields.each do |field|
    io.puts <<-EOF
    printf("#{field.name} %u %u\\n", (unsigned int) offsetof(#{@struct_name}, #{field.name}),
     (unsigned int) sizeof(s.#{field.name}));
  EOF
  end

  io.puts "\n  return 0;\n}"
end

#write_config(io) ⇒ Object 



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# File 'lib/ffi2/generators/structures.rb', line 155

def write_config(io)
  io.puts "rbx.platform.#{@name}.sizeof = #{@size}"

  @fields.each { |field| io.puts field.to_config(@name) }
end