X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=scripts%2Fextgen.py;h=f5df83f21588ab0cbb71f94d8a94a8d05023af7a;hb=137b642f43f175a98a45b95de5b0735c5c487a2e;hp=d6727123d97cb842a5836ea1b7d2f4a901396962;hpb=6afbace895a7bbcf216ab8e48280ea0303ab5892;p=libs%2Fgl.git

diff --git a/scripts/extgen.py b/scripts/extgen.py
index d6727123..f5df83f2 100755
--- a/scripts/extgen.py
+++ b/scripts/extgen.py
@@ -1,169 +1,700 @@
 #!/usr/bin/python
 
 import sys
+import os
+import xml.dom
+import xml.dom.minidom
+import itertools
+import re
 
-if len(sys.argv)<2:
-	print """Usage:
-  extgen.py <extension> [<version>] [<secondary> ...]"
-
-Reads gl.spec and generates files to use <extension>.  Any promoted functions
-are exposed with their promoted names.  If <secondary> extensions are given,
-any promoted functions from those are pulled in as well.  <version> can be
-given to override the version where <extension> was promoted to core."""
-	sys.exit(0)
-
-ext = sys.argv[1]
-exttype = ext.split('_')[0]
-secondary = sys.argv[2:]
-ver = None
-if secondary and secondary[0][0].isdigit():
-	ver = secondary.pop(0)
-bp_ext = None
-
-class Function:
-	def __init__(self, name):
+class Version:
+	def __init__(self, *args):
+		if len(args)==0:
+			self.major = 0
+			self.minor = 0
+		elif len(args)==2:
+			self.major = args[0]
+			self.minor = args[1]
+		else:
+			raise TypeError, "__init__() takes zero or two arguments (%d given)"%len(args)
+
+	def __str__(self):
+		return "%d.%d"%(self.major, self.minor)
+
+	def __repr__(self):
+		return "Version(%d, %d)"%(self.major, self.minor)
+
+	def as_define(self):
+		return "VERSION_%d_%d"%(self.major, self.minor)
+
+	def __lt__(self, other):
+		if other is None:
+			return False
+
+		if self.major!=other.major:
+			return self.major<other.major
+		return self.minor<other.minor
+
+	def __gt__(self, other):
+		if other is None:
+			return True
+
+		if self.major!=other.major:
+			return self.major>other.major
+		return self.minor>other.minor
+
+
+class Thing:
+	FUNCTION = 1
+	ENUM = 2
+
+	class ApiSupport:
+		def __init__(self):
+			self.core_version = None
+			self.deprecated_version = None
+			self.extensions = []
+			self.sources = []
+
+	def __init__(self, name, kind):
 		self.name = name
-		self.version = None
-		self.category = None
-		self.vectorequiv = None
+		self.kind = kind
 		self.aliases = []
-		self.extfunc = None
-
-funcs = {}
-cur_func = None
-
-def parse_file(fn):
-	for line in open(fn):
-		if line[0]=='#' or line.find(':')>=0:
-			continue
-		elif line[0]=='\t':
-			if cur_func:
-				parts = line.split()
-				if parts[0]=="category":
-					cur_func.category = parts[1]
-				elif parts[0]=="vectorequiv":
-					cur_func.vectorequiv = parts[1]
-				elif parts[0]=="alias":
-					cur_func.aliases.append(parts[1])
-				elif parts[0]=="version":
-					cur_func.version = parts[1]
-				elif parts[0]=="delete":
-					del funcs[cur_func.name]
-					cur_func = None
+		self.api_support = {}
+
+	def get_or_create_api_support(self, api):
+		supp = self.api_support.get(api)
+		if not supp:
+			supp = Thing.ApiSupport()
+			self.api_support[api] = supp
+		return supp
+
+
+class Function(Thing):
+	def __init__(self, name):
+		Thing.__init__(self, name, Thing.FUNCTION)
+		self.return_type = "void"
+		self.params = []
+
+
+r_bitmask = re.compile("_BIT[0-9]*(_|$)")
+
+class Enum(Thing):
+	def __init__(self, name):
+		Thing.__init__(self, name, Thing.ENUM)
+		self.value = 0
+		self.bitmask = bool(r_bitmask.search(self.name))
+
+
+class Extension:
+	def __init__(self, name, api):
+		self.name = name
+		underscore = name.find('_')
+		self.ext_type = name[0:underscore]
+		self.base_name = name[underscore+1:]
+		self.api = api
+		self.things = {}
+		self.preference = 0
+		if self.ext_type=="EXT":
+			self.preference = 1
+		elif self.ext_type=="ARB" or self.ext_type=="OES":
+			self.preference = 2
+		self.backport = False
+
+
+class Api:
+	def __init__(self, name):
+		self.name = name
+		self.latest_version = None
+		self.core_things = {}
+		self.extensions = {}
+
+
+def get_nested_elements(elem, path):
+	childElements = [c for c in elem.childNodes if c.nodeType==xml.dom.Node.ELEMENT_NODE]
+	if '/' in path:
+		head, tail = path.split('/', 1)
+		result = []
+		for c in childElements:
+			if c.tagName==head:
+				result += get_nested_elements(c, tail)
+		return result
+	else:
+		return [c for c in childElements if c.tagName==path]
+
+def get_first_child(elem, tag):
+	for c in elem.childNodes:
+		if c.nodeType==xml.dom.Node.ELEMENT_NODE and c.tagName==tag:
+			return c
+	return None
+
+def get_text_contents(node):
+	result = ""
+	for c in node.childNodes:
+		if c.nodeType==xml.dom.Node.TEXT_NODE or c.nodeType==xml.dom.Node.CDATA_SECTION_NODE:
+			result += c.data
 		else:
-			paren = line.find('(')
-			if paren>0:
-				name = line[:paren]
-				if name in funcs:
-					cur_func = funcs[name]
-				else:
-					cur_func = Function(name)
-					funcs[name] = cur_func
-
-parse_file("gl.spec")
-parse_file("gl.spec.fixes")
-
-for f in funcs.itervalues():
-	if f.category==ext or f.category in secondary:
-		if not f.aliases and f.vectorequiv:
-			for g in funcs.itervalues():
-				if g!=f and g.vectorequiv==f.vectorequiv and f.name.startswith(g.name):
-					f.aliases.append(g.name)
+			result += get_text_contents(c)
+	return result
+
+def get_or_create(map, name, type, *args):
+	obj = map.get(name)
+	if not obj:
+		obj = type(name, *args)
+		map[name] = obj
+	return obj
+
+
+class GlXmlParser:
+	def __init__(self, host_api_name, target_ext_name):
+		self.host_api_name = host_api_name
+		self.target_ext_name = target_ext_name
+		self.apis = {}
+		self.things = {}
+
+	def parse_command(self, cmd):
+		proto = get_first_child(cmd, "proto")
+		name = get_text_contents(get_first_child(proto, "name"))
+		func = get_or_create(self.things, name, Function)
+
+		aliases = get_nested_elements(cmd, "alias")
+		func.aliases = [a.getAttribute("name") for a in aliases]
+
+		ptype = get_first_child(proto, "ptype")
+		if ptype:
+			func.return_type = get_text_contents(ptype)
+		else:
+			for c in proto.childNodes:
+				if c.nodeType==xml.dom.Node.TEXT_NODE and c.data.strip():
+					func.return_type = c.data.strip()
 					break
 
-		for a in f.aliases:
-			if a in funcs:
-				funcs[a].extfunc = f
+		params = get_nested_elements(cmd, "param")
+		func.params = map(get_text_contents, params)
 
-def is_relevant(f):
-	if f.category==ext and not f.aliases:
-		return True
-	if f.extfunc:
-		e = f.extfunc
-		if e.category==ext or e.category in secondary:
-			return True
-	return False
+	def parse_enum(self, en):
+		name = en.getAttribute("name")
+		enum = get_or_create(self.things, name, Enum)
 
-funcs = [f for f in funcs.itervalues() if is_relevant(f)]
-funcs.sort(key=(lambda f: f.name))
+		enum.value = int(en.getAttribute("value"), 16)
+
+	def parse_feature(self, feat):
+		api_name = feat.getAttribute("api")
+		if not api_name:
+			api_name = self.host_api_name
+		api = get_or_create(self.apis, api_name, Api)
+
+		version = feat.getAttribute("number")
+		if version:
+			version = Version(*map(int, version.split('.')))
+		else:
+			version = None
 
-for f in funcs:
-	if f.extfunc:
-		if not ver:
-			ver = f.version
-		if not f.category.startswith("VERSION_"):
-			bp_ext = f.category
-	if not f.extfunc and not f.name.endswith(exttype):
-		bp_ext = f.category
+		requires = get_nested_elements(feat, "require")
+		for req in requires:
+			commands = get_nested_elements(req, "command")
+			enums = get_nested_elements(req, "enum")
+			for t in itertools.chain(commands, enums):
+				name = t.getAttribute("name")
+				thing = self.things.get(name)
+				if thing:
+					supp = thing.get_or_create_api_support(api.name)
+					if not supp.core_version or version<supp.core_version:
+						supp.core_version = version
+					api.core_things[thing.name] = thing
+
+		removes = get_nested_elements(feat, "remove")
+		for rem in removes:
+			profile = rem.getAttribute("profile")
+			commands = get_nested_elements(rem, "command")
+			enums = get_nested_elements(rem, "enum")
+
+			for t in itertools.chain(commands, enums):
+				name = t.getAttribute("name")
+				thing = self.things.get(name)
+				if thing:
+					if profile!="core":
+						if thing.name in api.core_things:
+							del api.core_things[thing.name]
+						for s in thing.api_support.itervalues():
+							for e in s.extensions:
+								del e.things[thing.name]
+					else:
+						supp = thing.get_or_create_api_support(api.name)
+						supp.deprecated_version = version
+
+	def parse_extension(self, ext):
+		ext_things_by_api = {}
+		requires = get_nested_elements(ext, "require")
+		for req in requires:
+			api = req.getAttribute("api")
+			ext_things = ext_things_by_api.setdefault(api, [])
+
+			commands = get_nested_elements(req, "command")
+			enums = get_nested_elements(req, "enum")
+			for t in itertools.chain(commands, enums):
+				name = t.getAttribute("name")
+				thing = self.things.get(name)
+				if thing:
+					ext_things.append(thing)
+
+		ext_name = ext.getAttribute("name")
+		if ext_name.startswith("GL_"):
+			ext_name = ext_name[3:]
+
+		common_things = ext_things_by_api.get("", [])
+		supported = ext.getAttribute("supported").split('|')
+		for s in supported:
+			api = self.apis.get(s)
+			if not api:
+				continue
+
+			ext = get_or_create(api.extensions, ext_name, Extension, api)
+			api_things = ext_things_by_api.get(s, [])
+			for t in itertools.chain(common_things, api_things):
+				ext.things[t.name] = t
+				t.get_or_create_api_support(api.name).extensions.append(ext)
+
+	def parse_file(self, fn):
+		doc = xml.dom.minidom.parse(fn)
+		root = doc.documentElement
+
+		commands = get_nested_elements(root, "commands/command")
+		for cmd in commands:
+			self.parse_command(cmd)
+
+		enums = get_nested_elements(root, "enums/enum")
+		for en in enums:
+			self.parse_enum(en)
+
+		features = get_nested_elements(root, "feature")
+		for feat in features:
+			self.parse_feature(feat)
+
+		extensions = get_nested_elements(root, "extensions/extension")
+		for ext in extensions:
+			self.parse_extension(ext)
+
+	def check_backport_extensions(self, api):
+		for e in api.extensions.itervalues():
+			e.backport = True
+			for t in e.things.itervalues():
+				if t.name.endswith(e.ext_type):
+					e.backport = False
+					break
 
-if ver:
-	ver = map(int, ver.split('.'))
+	def resolve_enum_aliases(self, api):
+		core_enums = filter((lambda t: t.kind==Thing.ENUM), api.core_things.itervalues())
+		core_enums_by_value = dict((e.value, None) for e in core_enums)
 
-out = file(ext.lower()+".h", "w")
-out.write("#ifndef MSP_GL_%s_\n"%ext.upper())
-out.write("#define MSP_GL_%s_\n"%ext.upper())
+		for e in api.extensions.itervalues():
+			ext_enums = filter((lambda t: t.kind==Thing.ENUM), e.things.itervalues())
+			enum_suffix = "_"+e.ext_type
+			for n in ext_enums:
+				if n.api_support[api.name].core_version:
+					continue
 
-out.write("""
-#include "extension.h"
-#include "gl.h"
-#include <GL/glext.h>
+				name = n.name
+				if name.endswith(enum_suffix):
+					name = name[:-len(enum_suffix)]
+				ce = api.core_things.get(name)
+				if not ce and n.value in core_enums_by_value:
+					if core_enums_by_value[n.value] is None:
+						core_enums_by_value[n.value] = filter((lambda e: e.value==n.value), core_enums)
+					for c in core_enums_by_value[n.value]:
+						if c.bitmask==n.bitmask:
+							ce = c
+							break
+				if ce and ce.value==n.value and ce.name not in n.aliases:
+					n.aliases.append(ce.name)
+
+	def resolve_sources(self, api):
+		for e in api.extensions.itervalues():
+			for t in e.things.itervalues():
+				for a in t.aliases:
+					# There are a few cases where a vendor function is aliased to
+					# an EXT or ARB function but those are rare and not relevant for
+					# our use
+					alias = api.core_things.get(a)
+					if alias:
+						sources = alias.api_support[api.name].sources
+						if t not in sources:
+							sources.append(t)
+
+	def sort_extensions(self):
+		for a in self.apis.itervalues():
+			e = a.extensions.get(self.target_ext_name)
+			if e:
+				e.preference = 3
+		for t in self.things.itervalues():
+			for s in t.api_support.itervalues():
+				s.extensions.sort(key=(lambda e: e.preference), reverse=True)
+
+	def finalize(self):
+		for a in self.apis.itervalues():
+			self.check_backport_extensions(a)
+			self.resolve_enum_aliases(a)
+			self.resolve_sources(a)
+		self.sort_extensions()
+
+
+def detect_core_version(host_api, things):
+	candidates = {}
+	for t in things:
+		supp = t.api_support.get(host_api.name)
+		if supp and supp.core_version:
+			candidates[supp.core_version] = candidates.get(supp.core_version, 0)+1
+
+	if candidates:
+		candidates = list((v, k) for k, v in candidates.items())
+		if len(candidates)>1:
+			candidates.sort(reverse=True)
+			if candidates[1][0]+1>=candidates[0][0]:
+				print "Warning: multiple likely core version candidates: %s %s"%(candidates[0][1], candidates[1][1])
+		return candidates[0][1]
+
+def detect_deprecated_version(host_api, things):
+	min_version = None
+	for t in things:
+		supp = t.api_support.get(host_api.name)
+		if supp and supp.deprecated_version:
+			if min_version is None:
+				min_version = supp.deprecated_version
+			else:
+				min_version = min(min_version, supp.deprecated_version)
+		else:
+			return None
+
+	return min_version
+
+def detect_backport_extension(host_api, target_ext, things):
+	candidates = []
+	for t in things:
+		supp = t.api_support.get(host_api.name)
+		if supp and supp.core_version:
+			for e in supp.extensions:
+				if e.backport and e not in candidates:
+					candidates.append(e)
+
+	if len(candidates)>1:
+		print "Warning: multiple backport extension candidates: %s"%(" ".join(e.name for e in candidates))
+
+	for e in candidates:
+		if e.base_name==target_ext.base_name:
+			return e
+
+	if len(candidates)==1:
+		print "Warning: potential backport extension has mismatched name: %s"%candidates[0].name
+
+def collect_extensions(thing, api, exts):
+	supp = thing.api_support.get(api)
+	if not supp:
+		return
+
+	for e in supp.extensions:
+		if not e.backport and e not in exts:
+			exts.append(e)
+
+	for s in supp.sources:
+		collect_extensions(s, api, exts)
+
+def detect_source_extension(host_api, target_ext, things):
+	if target_ext.name in host_api.extensions:
+		return target_ext
+
+	things_by_ext = {}
+	for t in things:
+		exts = []
+		collect_extensions(t, host_api.name, exts)
+		for e in exts:
+			things_by_ext.setdefault(e, []).append(t)
+
+	largest_ext = None
+	largest_count = 0
+	for e, t in things_by_ext.iteritems():
+		count = len(t)
+		if count>largest_count:
+			largest_ext = e
+			largest_count = count
+
+	return largest_ext
+
+
+class SourceGenerator:
+	def __init__(self, host_api, target_ext, things):
+		self.host_api = host_api
+		self.api_prefix = "GL"
+		if self.host_api.name=="gles2":
+			self.api_prefix = "GL_ES"
+		self.target_ext = target_ext
+		self.funcs = filter((lambda t: t.kind==Thing.FUNCTION), things)
+		self.funcs.sort(key=(lambda f: f.name))
+		self.func_typedefs = dict((f.name, "FPtr_"+f.name) for f in self.funcs)
+		self.enums = filter((lambda t: t.kind==Thing.ENUM), things)
+		self.enums.sort(key=(lambda e: e.value))
+		self.core_version = detect_core_version(host_api, things)
+		self.deprecated_version = detect_deprecated_version(host_api, things)
+		self.backport_ext = detect_backport_extension(host_api, target_ext, things);
+		self.source_ext = detect_source_extension(host_api, target_ext, things)
+
+	def write_header_intro(self, out):
+		out.write("#ifndef MSP_GL_%s_\n"%self.target_ext.name.upper())
+		out.write("#define MSP_GL_%s_\n"%self.target_ext.name.upper())
+
+		out.write("""
+#include <msp/gl/extension.h>
+#include <msp/gl/gl.h>
 
 namespace Msp {
 namespace GL {
+
 """)
 
-if funcs:
-	out.write("\n")
-for f in funcs:
-	out.write("extern PFNGL%sPROC gl%s;\n"%(f.name.upper(), f.name))
+	def write_enum_definitions(self, out):
+		enums_by_category = {}
+		for e in self.enums:
+			cat = None
+			supp = e.api_support.get(self.host_api.name)
+			if supp:
+				if supp.core_version:
+					cat = "%s_%s"%(self.api_prefix, supp.core_version.as_define())
+				elif supp.extensions:
+					cat = "GL_"+supp.extensions[0].name
+			enums_by_category.setdefault(cat, []).append(e)
+
+		for cat in sorted(enums_by_category.keys()):
+			if cat:
+				out.write("#ifndef %s\n"%cat)
+			for e in enums_by_category[cat]:
+				out.write("#define %s 0x%04X\n"%(e.name, e.value))
+			if cat:
+				out.write("#endif\n")
+			out.write("\n")
 
-out.write("\nextern Extension %s;\n"%ext)
+	def write_function_pointer_declarations(self, out):
+		for f in self.funcs:
+			typedef = self.func_typedefs[f.name]
+			out.write("typedef %s (APIENTRY *%s)(%s);\n"%(f.return_type, typedef, ", ".join(f.params)))
+			out.write("extern %s %s;\n"%(typedef, f.name))
+			out.write("\n")
 
-out.write("""
+	def write_header_outro(self, out):
+		out.write("""
 } // namespace GL
 } // namespace Msp
 
 #endif
 """)
 
-out = file(ext.lower()+".cpp", "w")
-out.write("#include \"%s.h\"\n"%ext.lower())
+	def write_source_intro(self, out):
+		out.write("#include \"%s.h\"\n"%self.target_ext.name.lower())
+		if self.funcs:
+			out.write("""
+#ifdef __APPLE__
+#define GET_PROC_ADDRESS(x) &::x
+#else
+#define GET_PROC_ADDRESS(x) get_proc_address(#x)
+#endif
 
-out.write("""
+#ifdef _WIN32
+#define GET_PROC_ADDRESS_1_1(x) &::x
+#else
+#define GET_PROC_ADDRESS_1_1(x) GET_PROC_ADDRESS(x)
+#endif
+""")
+		out.write("""
 namespace Msp {
 namespace GL {
+
 """)
 
-if funcs:
-	out.write("\n")
-for f in funcs:
-	out.write("PFNGL%sPROC gl%s = 0;\n"%(f.name.upper(), f.name))
-
-out.write("\nExtension::SupportLevel init_%s()\n{\n"%ext.lower())
-if ver:
-	out.write("\tif(is_version_at_least(%d, %d)"%tuple(ver))
-	if bp_ext:
-		out.write(" || is_supported(\"GL_%s\")"%bp_ext)
-	out.write(")\n\t{\n")
-	for f in funcs:
-		out.write("\t\tgl%s = reinterpret_cast<PFNGL%sPROC>(get_proc_address(\"gl%s\"));\n"%(f.name, f.name.upper(), f.name))
-	out.write("\t\treturn Extension::CORE;\n")
-	out.write("\t}\n")
-if ext!=bp_ext:
-	out.write("\tif(is_supported(\"GL_%s\"))\n\t{\n"%(ext))
-	for f in funcs:
-		n = f.name
-		if f.extfunc:
-			n = f.extfunc.name
-		out.write("\t\tgl%s = reinterpret_cast<PFNGL%sPROC>(get_proc_address(\"gl%s\"));\n"%(f.name, f.name.upper(), n))
-	out.write("\t\treturn Extension::EXTENSION;\n")
-	out.write("\t}\n")
-out.write("\treturn Extension::UNSUPPORTED;\n")
-out.write("}\n")
-
-out.write("\nExtension %s(\"GL_%s\", init_%s);\n"%(ext, ext, ext.lower()))
-
-out.write("""
+	def write_function_pointer_definitions(self, out):
+		for f in self.funcs:
+			out.write("%s %s = 0;\n"%(self.func_typedefs[f.name], f.name))
+
+	def write_init_function(self, out):
+		out.write("\nExtension::SupportLevel init_%s()\n{\n"%self.target_ext.name.lower())
+		if self.core_version:
+			out.write("\tif(is_disabled(\"GL_%s\"))\n\t\treturn Extension::UNSUPPORTED;\n"%self.target_ext.name)
+			out.write("#if !defined(__APPLE__) || defined(%s_%s)\n"%(self.api_prefix, self.core_version.as_define()))
+			out.write("\tif(")
+			if self.backport_ext:
+				out.write("is_supported(\"GL_%s\") || "%self.backport_ext.name)
+			out.write("is_supported(%r"%self.core_version)
+			if self.deprecated_version:
+				out.write(", %r"%self.deprecated_version)
+			out.write("))\n\t{\n")
+			for f in self.funcs:
+				supp = f.api_support.get(self.host_api.name)
+				if supp:
+					gpa_suffix = ""
+					if supp.core_version is not None and supp.core_version<=Version(1, 1):
+						gpa_suffix = "_1_1"
+					out.write("\t\t%s = reinterpret_cast<%s>(GET_PROC_ADDRESS%s(%s));\n"%(f.name, self.func_typedefs[f.name], gpa_suffix, f.name))
+			out.write("\t\treturn Extension::CORE;\n")
+			out.write("\t}\n")
+			out.write("#endif\n")
+		if self.source_ext and self.source_ext!=self.backport_ext:
+			out.write("#if !defined(__APPLE__) || defined(GL_%s)\n"%self.target_ext.name)
+			out.write("\tif(is_supported(\"GL_%s\"))\n\t{\n"%(self.source_ext.name))
+			for f in self.funcs:
+				supp = f.api_support.get(self.host_api.name)
+				if supp and supp.sources:
+					src = None
+					for s in supp.sources:
+						if s.name.endswith(self.source_ext.ext_type):
+							src = s
+							break
+					if not src:
+						src = supp.sources[0]
+				else:
+					src = f
+
+				if self.host_api.name in src.api_support:
+					if not src.name.endswith(self.source_ext.ext_type):
+						print "Warning: %s does not match extension type %s"%(src.name, self.source_ext.ext_type)
+					out.write("\t\t%s = reinterpret_cast<%s>(GET_PROC_ADDRESS(%s));\n"%(f.name, self.func_typedefs[f.name], src.name))
+			out.write("\t\treturn Extension::EXTENSION;\n")
+			out.write("\t}\n")
+			out.write("#endif\n")
+		out.write("\treturn Extension::UNSUPPORTED;\n")
+		out.write("}\n")
+
+	def write_source_outro(self, out):
+		out.write("""
 } // namespace GL
 } // namespace Msp
 """)
+
+	def write_header(self, fn):
+		out = file(fn, "w")
+		self.write_header_intro(out)
+		self.write_enum_definitions(out)
+		self.write_function_pointer_declarations(out)
+		out.write("extern Extension %s;\n"%self.target_ext.name)
+		self.write_header_outro(out)
+
+	def write_source(self, fn):
+		out = file(fn, "w")
+		self.write_source_intro(out)
+		self.write_function_pointer_definitions(out)
+		self.write_init_function(out)
+		ext_name = self.target_ext.name
+		out.write("\nExtension %s(\"GL_%s\", init_%s);\n"%(ext_name, ext_name, ext_name.lower()))
+		self.write_source_outro(out)
+
+
+class ExtensionParser:
+	def __init__(self, host_api):
+		self.host_api = host_api
+		self.target_ext = None
+		self.core_version = None
+		self.deprecated_version = None
+		self.secondary_exts = []
+		self.backport_ext = None
+		self.ignore_things = []
+
+	def parse(self, fn):
+		for line in open(fn):
+			line = line.strip()
+			if line.startswith("#"):
+				continue
+
+			parts = line.split()
+			keyword = parts[0]
+
+			if keyword=="extension":
+				self.target_ext = parts[1]
+			elif keyword=="core_version":
+				if parts[1]==self.host_api:
+					self.core_version = Version(*map(int, parts[2].split('.')))
+			elif keyword=="deprecated":
+				if parts[1]==self.host_api:
+					self.deprecated_version = Version(*map(int, parts[2].split('.')))
+			elif keyword=="secondary":
+				self.secondary_exts.append(parts[1])
+			elif keyword=="backport":
+				self.backport_ext = parts[1]
+			elif keyword=="ignore":
+				self.ignore_things.append(parts[1])
+
+
+def get_extension(api_map, ext_name):
+	main_api = api_map["gl"]
+	ext = main_api.extensions.get(ext_name)
+	if ext:
+		return ext
+
+	for a in api_map.itervalues():
+		ext = a.extensions.get(ext_name)
+		if ext:
+			return ext
+
+def collect_things(host_api, target_ext, secondary, ignore):
+	ext_things = [t for n, t in target_ext.things.iteritems() if n not in ignore]
+	core_things = target_ext.api.core_things
+
+	things = []
+	for t in ext_things:
+		found_in_core = False
+		for a in t.aliases:
+			if a in core_things:
+				things.append(core_things[a])
+				found_in_core = True
+		if not found_in_core:
+			things.append(t)
+
+	for s in secondary:
+		for t in s.things.itervalues():
+			for a in t.aliases:
+				if a in core_things and core_things[a] not in things:
+					things.append(core_things[a])
+
+	return things
+
+def main():
+	if len(sys.argv)<2:
+		print """Usage:
+  extgen.py [api] <extfile> [<outfile>]
+
+Reads gl.xml and generates C++ source files to use an OpenGL extension
+described in <extfile>.  If <outfile> is absent, the extension's lowercased
+name is used.  Anything after the last dot in <outfile> is removed and
+replaced with cpp and h."""
+		sys.exit(0)
+
+	host_api_name = "gl"
+
+	i = 1
+	if sys.argv[i].startswith("gl"):
+		host_api_name = sys.argv[i]
+		i += 1
+
+	ext_parser = ExtensionParser(host_api_name)
+	ext_parser.parse(sys.argv[i])
+	i += 1
+
+	if i<len(sys.argv):
+		out_base = os.path.splitext(sys.argv[i])[0]
+	else:
+		out_base = ext_parser.target_ext.lower()
+
+	xml_parser = GlXmlParser(host_api_name, ext_parser.target_ext)
+	xml_parser.parse_file("gl.xml")
+	xml_parser.parse_file("gl.fixes.xml")
+	xml_parser.finalize()
+
+	host_api = xml_parser.apis[host_api_name]
+	target_ext = get_extension(xml_parser.apis, ext_parser.target_ext)
+	secondary_exts = [get_extension(xml_parser.apis, s) for s in ext_parser.secondary_exts]
+	things = collect_things(host_api, target_ext, secondary_exts, ext_parser.ignore_things)
+
+	generator = SourceGenerator(host_api, target_ext, things)
+	if ext_parser.core_version:
+		generator.core_version = ext_parser.core_version
+	if ext_parser.deprecated_version:
+		generator.deprecated_version = ext_parser.deprecated_version
+	generator.write_header(out_base+".h")
+	generator.write_source(out_base+".cpp")
+
+if __name__=="__main__":
+	main()