#
# Copyright (c) 2008 Martin Decky
# 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.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
#
"""
Convert descriptive structure definitions to structure object
"""

import struct

class Struct:
	def size(self):
		return struct.calcsize(self._format_)
	
	def pack(self):
		list = []
		for variable in self._list_:
			list.append(self.__dict__[variable])
		
		return struct.pack(self._format_, *list)

def create(definition):
	"Create structure object"
	
	tokens = definition.split(None)
	
	# Initial byte order tag
	format = {
		"little:":  lambda: "<",
		"big:":     lambda: ">",
		"network:": lambda: "!"
	}[tokens[0]]()
	inst = Struct()
	list = []
	
	# Member tags
	comment = False
	variable = False
	for token in tokens[1:]:
		if (comment):
			if (token == "*/"):
				comment = False
			continue
		
		if (variable):
			inst.__dict__[token] = None
			list.append(token)
			variable = False
			continue
		
		if (token == "/*"):
			comment = True
		elif (token[0:8] == "padding["):
			size = token[8:].split("]")[0]
			format += "%dx" % int(size)
		elif (token[0:5] == "char["):
			size = token[5:].split("]")[0]
			format += "%ds" % int(size)
			variable = True
		else:
			format += {
				"uint8_t":  lambda: "B",
				"uint16_t": lambda: "H",
				"uint32_t": lambda: "L",
				"uint64_t": lambda: "Q",
				
				"int8_t":   lambda: "b",
				"int16_t":  lambda: "h",
				"int32_t":  lambda: "l",
				"int64_t":  lambda: "q"
			}[token]()
			variable = True
	
	inst.__dict__['_format_'] = format
	inst.__dict__['_list_'] = list
	return inst