Lib/fontTools/ttLib/tables/otBase.py

from DefaultTable import DefaultTable
import otData
import struct
from types import TupleType


class BaseTTXConverter(DefaultTable):
	
	"""Generic base class for TTX table converters. Functions as an adapter
	between the TTX (ttLib actually) table model and the model we use for
	OpenType tables, which is neccesarily subtly different."""
	
	def decompile(self, data, font):
		import otTables
		reader = OTTableReader(data, self.tableTag)
		tableClass = getattr(otTables, self.tableTag)
		self.table = tableClass()
		self.table.decompile(reader, font)
	
	def compile(self, font):
		writer = OTTableWriter(self.tableTag)
		self.table.compile(writer, font)
		return writer.getData()
	
	def toXML(self, writer, font):
		self.table.toXML2(writer, font)
	
	def fromXML(self, (name, attrs, content), font):
		import otTables
		if not hasattr(self, "table"):
			tableClass = getattr(otTables, self.tableTag)
			self.table = tableClass()
		self.table.fromXML((name, attrs, content), font)


class OTTableReader:
	
	"""Helper class to retrieve data from an OpenType table."""
	
	def __init__(self, data, tableType, offset=0, valueFormat=None, cachingStats=None):
		self.data = data
		self.offset = offset
		self.pos = offset
		self.tableType = tableType
		if valueFormat is None:
			valueFormat = (ValueRecordFactory(), ValueRecordFactory())
		self.valueFormat = valueFormat
		self.cachingStats = cachingStats
	
	def getSubReader(self, offset):
		offset = self.offset + offset
		if self.cachingStats is not None:
			try:
				self.cachingStats[offset] = self.cachingStats[offset] + 1
			except KeyError:
				self.cachingStats[offset] = 1
		
		subReader = self.__class__(self.data, self.tableType, offset,
			self.valueFormat, self.cachingStats)
		return subReader
	
	def readUShort(self):
		pos = self.pos
		newpos = pos + 2
		value, = struct.unpack(">H", self.data[pos:newpos])
		self.pos = newpos
		return value
	
	def readShort(self):
		pos = self.pos
		newpos = pos + 2
		value, = struct.unpack(">h", self.data[pos:newpos])
		self.pos = newpos
		return value
	
	def readLong(self):
		pos = self.pos
		newpos = pos + 4
		value, = struct.unpack(">l", self.data[pos:newpos])
		self.pos = newpos
		return value
	
	def readTag(self):
		pos = self.pos
		newpos = pos + 4
		value = self.data[pos:newpos]
		assert len(value) == 4
		self.pos = newpos
		return value
	
	def readStruct(self, format, size=None):
		if size is None:
			size = struct.calcsize(format)
		else:
			assert size == struct.calcsize(format)
		pos = self.pos
		newpos = pos + size
		values = struct.unpack(format, self.data[pos:newpos])
		self.pos = newpos
		return values
	
	def setValueFormat(self, format, which):
		self.valueFormat[which].setFormat(format)
	
	def readValueRecord(self, font, which):
		return self.valueFormat[which].readValueRecord(self, font)


class OTTableWriter:
	
	"""Helper class to gather and assemble data for OpenType tables."""
	
	def __init__(self, tableType, valueFormat=None):
		self.items = []
		self.tableType = tableType
		if valueFormat is None:
			valueFormat = ValueRecordFactory(), ValueRecordFactory()
		self.valueFormat = valueFormat
	
	def getSubWriter(self):
		return self.__class__(self.tableType, self.valueFormat)
	
	def getData(self):
		items = list(self.items)
		offset = 0
		for item in items:
			if hasattr(item, "getData") or hasattr(item, "getCount"):
				offset = offset + 2  # sizeof(UShort)
			else:
				offset = offset + len(item)
		subTables = []
		cache = {}
		for i in range(len(items)):
			item = items[i]
			if hasattr(item, "getData"):
				subTableData = item.getData()
				if cache.has_key(subTableData):
					items[i] = packUShort(cache[subTableData])
				else:
					items[i] = packUShort(offset)
					subTables.append(subTableData)
					cache[subTableData] = offset
					offset = offset + len(subTableData)
			elif hasattr(item, "getCount"):
				items[i] = item.getCount()
		return "".join(items + subTables)
	
	def writeUShort(self, value):
		assert 0 <= value < 0x10000
		self.items.append(struct.pack(">H", value))
	
	def writeShort(self, value):
		self.items.append(struct.pack(">h", value))
	
	def writeLong(self, value):
		self.items.append(struct.pack(">l", value))
	
	def writeTag(self, tag):
		assert len(tag) == 4
		self.items.append(tag)
	
	def writeSubTable(self, subWriter):
		self.items.append(subWriter)
	
	def writeCountReference(self, table, name):
		self.items.append(CountReference(table, name))
	
	def writeStruct(self, format, values):
		data = apply(struct.pack, (format,) + values)
		self.items.append(data)
	
	def setValueFormat(self, format, which):
		self.valueFormat[which].setFormat(format)
	
	def writeValueRecord(self, value, font, which):
		return self.valueFormat[which].writeValueRecord(self, font, value)


class CountReference:
	"""A reference to a Count value, not a count of a reference."""
	def __init__(self, table, name):
		self.table = table
		self.name = name
	def getCount(self):
		return packUShort(self.table[self.name])


def packUShort(value):
	assert 0 <= value < 0x10000
	return struct.pack(">H", value)



class TableStack:
	"""A stack of table dicts, working as a stack of namespaces so we can
	retrieve values from (and store values to) tables higher up the stack."""
	def __init__(self):
		self.stack = []
	def push(self, table):
		self.stack.insert(0, table)
	def pop(self):
		self.stack.pop(0)
	def getTop(self):
		return self.stack[0]
	def getValue(self, name):
		return self.__findTable(name)[name]
	def storeValue(self, name, value):
		table = self.__findTable(name)
		if table[name] is None:
			table[name] = value
		else:
			assert table[name] == value, (table[name], value)
	def __findTable(self, name):
		for table in self.stack:
			if table.has_key(name):
				return table
		raise KeyError, name


class BaseTable:
	
	"""Generic base class for all OpenType (sub)tables."""
	
	def getConverters(self):
		return self.converters
	
	def getConverterByName(self, name):
		return self.convertersByName[name]
	
	def decompile(self, reader, font, tableStack=None):
		if tableStack is None:
			tableStack = TableStack()
		table = {}
		self.__rawTable = table  # for debugging
		tableStack.push(table)
		for conv in self.getConverters():
			if conv.name == "SubTable":
				conv = conv.getConverter(reader.tableType,
						table["LookupType"])
			if conv.repeat:
				l = []
				for i in range(tableStack.getValue(conv.repeat) + conv.repeatOffset):
					l.append(conv.read(reader, font, tableStack))
				table[conv.name] = l
			else:
				table[conv.name] = conv.read(reader, font, tableStack)
		tableStack.pop()
		self.postRead(table, font)
		del self.__rawTable  # succeeded, get rid of debugging info
	
	def compile(self, writer, font, tableStack=None):
		if tableStack is None:
			tableStack = TableStack()
		table = self.preWrite(font)
		tableStack.push(table)
		for conv in self.getConverters():
			value = table.get(conv.name)
			if conv.repeat:
				if value is None:
					value = []
				tableStack.storeValue(conv.repeat, len(value) - conv.repeatOffset)
				for item in value:
					conv.write(writer, font, tableStack, item)
			elif conv.isCount:
				# Special-case Count values.
				# Assumption: a Count field will *always* precede
				# the actual array.
				# We need a default value, as it may be set later by a nested
				# table. TableStack.storeValue() will then find it here.
				table[conv.name] = None
				# We add a reference: by the time the data is assembled
				# the Count value will be filled in.
				writer.writeCountReference(table, conv.name)
			else:
				conv.write(writer, font, tableStack, value)
		tableStack.pop()
	
	def postRead(self, table, font):
		self.__dict__.update(table)
	
	def preWrite(self, font):
		return self.__dict__.copy()
	
	def toXML(self, xmlWriter, font, attrs=None):
		tableName = self.__class__.__name__
		if attrs is None:
			attrs = []
		if hasattr(self, "Format"):
			attrs = attrs + [("Format", self.Format)]
		xmlWriter.begintag(tableName, attrs)
		xmlWriter.newline()
		self.toXML2(xmlWriter, font)
		xmlWriter.endtag(tableName)
		xmlWriter.newline()
	
	def toXML2(self, xmlWriter, font):
		# Simpler variant of toXML, *only* for the top level tables (like GPOS, GSUB).
		# This is because in TTX our parent writes our main tag, and in otBase.py we
		# do it ourselves. I think I'm getting schizophrenic...
		for conv in self.getConverters():
			value = getattr(self, conv.name)
			if conv.repeat:
				for i in range(len(value)):
					item = value[i]
					conv.xmlWrite(xmlWriter, font, item, conv.name,
							[("index", i)])
			else:
				conv.xmlWrite(xmlWriter, font, value, conv.name, [])
	
	def fromXML(self, (name, attrs, content), font):
		try:
			conv = self.getConverterByName(name)
		except KeyError:
##			print self, name, attrs, content
			raise    # XXX on KeyError, raise nice error
		value = conv.xmlRead(attrs, content, font)
		if conv.repeat:
			try:
				seq = getattr(self, conv.name)
			except AttributeError:
				seq = []
				setattr(self, conv.name, seq)
			seq.append(value)
		else:
			setattr(self, conv.name, value)
	
	def __cmp__(self, other):
		# this is only for debugging, so it's ok to barf
		# when 'other' has no __dict__ or __class__
		rv = cmp(self.__class__, other.__class__)
		if not rv:
			rv = cmp(self.__dict__, other.__dict__)
			return rv
		else:
			return rv


class FormatSwitchingBaseTable(BaseTable):
	
	"""Small specialization of BaseTable, for tables that have multiple
	formats, eg. CoverageFormat1 vs. CoverageFormat2."""
	
	def getConverters(self):
		return self.converters[self.Format]
	
	def getConverterByName(self, name):
		return self.convertersByName[self.Format][name]
	
	def decompile(self, reader, font, tableStack=None):
		self.Format = reader.readUShort()
		assert self.Format <> 0, (self, reader.pos, len(reader.data))
		BaseTable.decompile(self, reader, font, tableStack)
	
	def compile(self, writer, font, tableStack=None):
		writer.writeUShort(self.Format)
		BaseTable.compile(self, writer, font, tableStack)


#
# Support for ValueRecords
#
# This data type is so different from all other OpenType data types that
# it requires quite a bit of code for itself. It even has special support
# in OTTableReader and OTTableWriter...
#

valueRecordFormat = [
#	Mask	 Name            isDevice  signed
	(0x0001, "XPlacement",   0,        1),
	(0x0002, "YPlacement",   0,        1),
	(0x0004, "XAdvance",     0,        1),
	(0x0008, "YAdvance",     0,        1),
	(0x0010, "XPlaDevice",   1,        0),
	(0x0020, "YPlaDevice",   1,        0),
	(0x0040, "XAdvDevice",   1,        0),
	(0x0080, "YAdvDevice",   1,        0),
# 	reserved:
	(0x0100, "Reserved1",    0,        0),
	(0x0200, "Reserved2",    0,        0),
	(0x0400, "Reserved3",    0,        0),
	(0x0800, "Reserved4",    0,        0),
	(0x1000, "Reserved5",    0,        0),
	(0x2000, "Reserved6",    0,        0),
	(0x4000, "Reserved7",    0,        0),
	(0x8000, "Reserved8",    0,        0),
]

def _buildDict():
	d = {}
	for mask, name, isDevice, signed in valueRecordFormat:
		d[name] = mask, isDevice, signed
	return d

valueRecordFormatDict = _buildDict()


class ValueRecordFactory:
	
	"""Given a format code, this object convert ValueRecords."""
	
	def setFormat(self, valueFormat):
		format = []
		for mask, name, isDevice, signed in valueRecordFormat:
			if valueFormat & mask:
				format.append((name, isDevice, signed))
		self.format = format
	
	def readValueRecord(self, reader, font):
		format = self.format
		if not format:
			return None
		valueRecord = ValueRecord()
		for name, isDevice, signed in format:
			if signed:
				value = reader.readShort()
			else:
				value = reader.readUShort()
			if isDevice:
				if value:
					import otTables
					subReader = reader.getSubReader(value)
					value = getattr(otTables, name)()
					value.decompile(subReader, font)
				else:
					value = None
			setattr(valueRecord, name, value)
		return valueRecord
	
	def writeValueRecord(self, writer, font, valueRecord):
		for name, isDevice, signed in self.format:
			value = getattr(valueRecord, name, 0)
			if isDevice:
				if value:
					subWriter = writer.getSubWriter()
					writer.writeSubTable(subWriter)
					value.compile(subWriter, font)
				else:
					writer.writeUShort(0)
			elif signed:
				writer.writeShort(value)
			else:
				writer.writeUShort(value)


class ValueRecord:
	
	# see ValueRecordFactory
	
	def getFormat(self):
		format = 0
		for name in self.__dict__.keys():
			format = format | valueRecordFormatDict[name][0]
		return format
	
	def toXML(self, xmlWriter, font, valueName, attrs=None):
		if attrs is None:
			simpleItems = []
		else:
			simpleItems = list(attrs)
		for mask, name, isDevice, format in valueRecordFormat[:4]:  # "simple" values
			if hasattr(self, name):
				simpleItems.append((name, getattr(self, name)))
		deviceItems = []
		for mask, name, isDevice, format in valueRecordFormat[4:8]:  # device records
			if hasattr(self, name):
				device = getattr(self, name)
				if device is not None:
					deviceItems.append((name, device))
		if deviceItems:
			xmlWriter.begintag(valueName, simpleItems)
			xmlWriter.newline()
			for name, deviceRecord in deviceItems:
				if deviceRecord is not None:
					deviceRecord.toXML(xmlWriter, font)
			xmlWriter.endtag(valueName)
			xmlWriter.newline()
		else:
			xmlWriter.simpletag(valueName, simpleItems)
			xmlWriter.newline()
	
	def fromXML(self, (name, attrs, content), font):
		import otTables
		for k, v in attrs.items():
			setattr(self, k, int(v))
		for element in content:
			if type(element) <> TupleType:
				continue
			name, attrs, content = element
			value = getattr(otTables, name)()
			for elem2 in content:
				if type(elem2) <> TupleType:
					continue
				value.fromXML(elem2, font)
			setattr(self, name, value)
	
	def __cmp__(self, other):
		# this is only for debugging, so it's ok to barf
		# when 'other' has no __dict__ or __class__
		rv = cmp(self.__class__, other.__class__)
		if not rv:
			rv = cmp(self.__dict__, other.__dict__)
			return rv
		else:
			return rv