/usr/lib/ruby/vendor_ruby/ffi/struct_layout_builder.rb is in ruby-ffi 1.9.10debian-1+b2.
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# Copyright (C) 2008-2010 Wayne Meissner
#
# This file is part of ruby-ffi.
#
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# * Neither the name of the Ruby FFI project nor the names of its contributors
# may be used to endorse or promote products derived from this software
# without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
module FFI
# Build a {StructLayout struct layout}.
class StructLayoutBuilder
attr_reader :size
attr_reader :alignment
def initialize
@size = 0
@alignment = 1
@min_alignment = 1
@packed = false
@union = false
@fields = Array.new
end
# Set size attribute with +size+ only if +size+ is greater than attribute value.
# @param [Numeric] size
def size=(size)
@size = size if size > @size
end
# Set alignment attribute with +align+ only if it is greater than attribute value.
# @param [Numeric] align
def alignment=(align)
@alignment = align if align > @alignment
@min_alignment = align
end
# Set union attribute.
# Set to +true+ to build a {Union} instead of a {Struct}.
# @param [Boolean] is_union
# @return [is_union]
def union=(is_union)
@union = is_union
end
# Building a {Union} or a {Struct} ?
#
# @return [Boolean]
#
def union?
@union
end
# Set packed attribute
# @overload packed=(packed) Set alignment and packed attributes to
# +packed+.
#
# @param [Fixnum] packed
#
# @return [packed]
# @overload packed=(packed) Set packed attribute.
# @param packed
#
# @return [0,1]
#
def packed=(packed)
if packed.is_a?(Fixnum)
@alignment = packed
@packed = packed
else
@packed = packed ? 1 : 0
end
end
# List of number types
NUMBER_TYPES = [
Type::INT8,
Type::UINT8,
Type::INT16,
Type::UINT16,
Type::INT32,
Type::UINT32,
Type::LONG,
Type::ULONG,
Type::INT64,
Type::UINT64,
Type::FLOAT32,
Type::FLOAT64,
Type::LONGDOUBLE,
Type::BOOL,
]
# @param [String, Symbol] name name of the field
# @param [Array, DataConverter, Struct, StructLayout::Field, Symbol, Type] type type of the field
# @param [Numeric, nil] offset
# @return [self]
# Add a field to the builder.
# @note Setting +offset+ to +nil+ or +-1+ is equivalent to +0+.
def add(name, type, offset = nil)
if offset.nil? || offset == -1
offset = @union ? 0 : align(@size, @packed ? [ @packed, type.alignment ].min : [ @min_alignment, type.alignment ].max)
end
#
# If a FFI::Type type was passed in as the field arg, try and convert to a StructLayout::Field instance
#
field = type.is_a?(StructLayout::Field) ? type : field_for_type(name, offset, type)
@fields << field
@alignment = [ @alignment, field.alignment ].max unless @packed
@size = [ @size, field.size + (@union ? 0 : field.offset) ].max
return self
end
# @param (see #add)
# @return (see #add)
# Same as {#add}.
# @see #add
def add_field(name, type, offset = nil)
add(name, type, offset)
end
# @param (see #add)
# @return (see #add)
# Add a struct as a field to the builder.
def add_struct(name, type, offset = nil)
add(name, Type::Struct.new(type), offset)
end
# @param name (see #add)
# @param type (see #add)
# @param [Numeric] count array length
# @param offset (see #add)
# @return (see #add)
# Add an array as a field to the builder.
def add_array(name, type, count, offset = nil)
add(name, Type::Array.new(type, count), offset)
end
# @return [StructLayout]
# Build and return the struct layout.
def build
# Add tail padding if the struct is not packed
size = @packed ? @size : align(@size, @alignment)
layout = StructLayout.new(@fields, size, @alignment)
layout.__union! if @union
layout
end
private
# @param [Numeric] offset
# @param [Numeric] align
# @return [Numeric]
def align(offset, align)
align + ((offset - 1) & ~(align - 1));
end
# @param (see #add)
# @return [StructLayout::Field]
def field_for_type(name, offset, type)
field_class = case
when type.is_a?(Type::Function)
StructLayout::Function
when type.is_a?(Type::Struct)
StructLayout::InnerStruct
when type.is_a?(Type::Array)
StructLayout::Array
when type.is_a?(FFI::Enum)
StructLayout::Enum
when NUMBER_TYPES.include?(type)
StructLayout::Number
when type == Type::POINTER
StructLayout::Pointer
when type == Type::STRING
StructLayout::String
when type.is_a?(Class) && type < StructLayout::Field
type
when type.is_a?(DataConverter)
return StructLayout::Mapped.new(name, offset, Type::Mapped.new(type), field_for_type(name, offset, type.native_type))
when type.is_a?(Type::Mapped)
return StructLayout::Mapped.new(name, offset, type, field_for_type(name, offset, type.native_type))
else
raise TypeError, "invalid struct field type #{type.inspect}"
end
field_class.new(name, offset, type)
end
end
end
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