diff --git a/generator/generator.zig b/generator/generator.zig
new file mode 100644
index 0000000..7bd7ec0
--- /dev/null
+++ b/generator/generator.zig
@@ -0,0 +1,174 @@
+const std = @import("std");
+const reg = @import("registry.zig");
+const xml = @import("xml.zig");
+const parseXml = @import("registry/parse.zig").parseXml;
+const Allocator = std.mem.Allocator;
+const FeatureLevel = reg.FeatureLevel;
+
+fn cmpFeatureLevels(a: FeatureLevel, b: FeatureLevel) std.math.Order {
+    if (a.major > b.major) {
+        return .gt;
+    } if (a.major < b.major) {
+        return .lt;
+    }
+
+    if (a.minor > b.minor) {
+        return .gt;
+    } else if (a.minor < b.minor) {
+        return .lt;
+    }
+
+    return .eq;
+}
+
+const DeclarationResolver = struct {
+    const DeclarationSet = std.StringHashMap(void);
+    const EnumExtensionMap = std.StringHashMap(std.ArrayList(reg.Enum.Field));
+
+    allocator: *Allocator,
+    reg_arena: *Allocator,
+    registry: *reg.Registry,
+    declarations: DeclarationSet,
+    enum_extensions: EnumExtensionMap,
+
+    fn init(allocator: *Allocator, reg_arena: *Allocator, registry: *reg.Registry) DeclarationResolver {
+        return .{
+            .allocator = allocator,
+            .reg_arena = reg_arena,
+            .registry = registry,
+            .declarations = DeclarationSet.init(allocator),
+            .enum_extensions = EnumExtensionMap.init(allocator),
+        };
+    }
+
+    fn deinit(self: DeclarationResolver) void {
+        var it = self.enum_extensions.iterator();
+        while (it.next()) |kv| {
+            kv.value.deinit();
+        }
+
+        self.enum_extensions.deinit();
+        self.declarations.deinit();
+    }
+
+    fn putEnumExtension(self: *DeclarationResolver, enum_name: []const u8, field: reg.Enum.Field) !void {
+        const res = try self.enum_extensions.getOrPut(enum_name);
+        if (!res.found_existing) {
+            res.kv.value = std.ArrayList(reg.Enum.Field).init(self.allocator);
+        }
+
+        try res.kv.value.append(field);
+    }
+
+    fn addRequire(self: *DeclarationResolver, req: reg.Require) !void {
+        for (req.types) |type_name| {
+            _ = try self.declarations.put(type_name, {});
+        }
+
+        for (req.commands) |command| {
+            _ = try self.declarations.put(command, {});
+        }
+
+        for (req.extends) |enum_ext| {
+            try self.putEnumExtension(enum_ext.extends, enum_ext.field);
+        }
+    }
+
+    fn mergeEnumFields(self: *DeclarationResolver, name: []const u8, base_enum: *reg.Enum) !void {
+        // If there are no extensions for this enum, assume its valid.
+        const extensions = self.enum_extensions.get(name) orelse return;
+
+        // Todo: cache this in DeclarationResolver
+        var field_map = std.StringHashMap(reg.Enum.Value).init(self.allocator);
+        defer field_map.deinit();
+
+        for (base_enum.fields) |field| {
+            _ = try field_map.put(field.name, field.value);
+        }
+
+        // Assume that if a field name clobbers, the value is the same
+        for (extensions.value.items) |field| {
+            _ = try field_map.put(field.name, field.value);
+        }
+
+        const new_fields = try self.reg_arena.alloc(reg.Enum.Field, field_map.count());
+
+        var it = field_map.iterator();
+        for (new_fields) |*field| {
+            const kv = it.next().?;
+            field.* = .{
+                .name = kv.key,
+                .value = kv.value,
+            };
+        }
+
+        // Existing base_enum.fields was allocatued by `self.reg_arena`, so
+        // it gets cleaned up whenever that is deinited.
+        base_enum.fields = new_fields;
+    }
+
+    fn resolve(self: *DeclarationResolver) !void {
+        for (self.registry.features) |feature| {
+            for (feature.requires) |req| {
+                try self.addRequire(req);
+            }
+        }
+
+        for (self.registry.extensions) |ext| {
+            for (ext.requires) |req| {
+                try self.addRequire(req);
+            }
+        }
+
+        // Merge all the enum fields.
+        // Assume that all keys of enum_extensions appear in `self.registry.decls`
+        for (self.registry.decls) |*decl| {
+            if (decl.decl_type == .enumeration) {
+                try self.mergeEnumFields(decl.name, &decl.decl_type.enumeration);
+            }
+        }
+
+        // Swap-remove all declarations that are not required.
+        // Some declarations may exist in `self.declarations` that do not exit in
+        // `self.registry.decls`, these are mostly macros and other stuff not parsed.
+        var i: usize = 0;
+        var count = self.registry.decls.len;
+        while (i < count) {
+            const decl = self.registry.decls[i];
+            if (self.declarations.contains(decl.name)) {
+                i += 1;
+            } else {
+                count -= 1;
+                self.registry.decls[i] = self.registry.decls[count];
+            }
+        }
+
+        self.registry.decls = self.reg_arena.shrink(self.registry.decls, count);
+    }
+};
+
+pub const Generator = struct {
+    gpa: *Allocator,
+    registry_arena: std.heap.ArenaAllocator,
+    registry: reg.Registry,
+
+    pub fn init(allocator: *Allocator, spec: *xml.Element) !Generator {
+        const result = try parseXml(allocator, spec);
+        return Generator{
+            .gpa = allocator,
+            .registry_arena = result.arena,
+            .registry = result.registry,
+        };
+    }
+
+    pub fn deinit(self: Generator) void {
+        self.registry_arena.deinit();
+    }
+
+    // Solve registry.declarations according to registry.extensions and registry.features
+    pub fn resolveDeclarations(self: *Generator) !void {
+        var resolver = DeclarationResolver.init(self.gpa, &self.registry_arena.allocator, &self.registry);
+        defer resolver.deinit();
+        try resolver.resolve();
+    }
+};
diff --git a/generator/main.zig b/generator/main.zig
index bbae7f2..20d5f39 100644
--- a/generator/main.zig
+++ b/generator/main.zig
@@ -1,9 +1,11 @@
 const std = @import("std");
 const xml = @import("xml.zig");
 const parseXml = @import("registry/parse.zig").parseXml;
-const registry = @import("registry.zig");
+const reg = @import("registry.zig");
+const vkgen = @import("generator.zig");
+const Allocator = std.mem.Allocator;
 
-fn renderType(type_info: registry.TypeInfo) void {
+fn renderType(type_info: reg.TypeInfo) void {
     switch (type_info) {
         .container => |c| {
             if (c.is_union) {
@@ -45,12 +47,12 @@ fn renderType(type_info: registry.TypeInfo) void {
     }
 }
 
-fn dumpRegistry(reg: registry.Registry) void {
-    for (reg.tags) |tag| {
+fn dumpRegistry(registry: reg.Registry) void {
+    for (registry.tags) |tag| {
         std.debug.warn("tag: name = {}, author = {}\n", .{tag.name, tag.author});
     }
 
-    for (reg.api_constants) |api_constant| {
+    for (registry.api_constants) |api_constant| {
         std.debug.warn("constant: name = {}, ", .{api_constant.name});
         switch (api_constant.value) {
             .expr => |expr| std.debug.warn("expr = {}\n", .{expr}),
@@ -58,35 +60,80 @@ fn dumpRegistry(reg: registry.Registry) void {
         }
     }
 
-    for (reg.decls) |decl| {
+    for (registry.decls) |decl| {
         std.debug.warn("decl: name = {}; ", .{decl.name});
         renderType(decl.decl_type);
         std.debug.warn("\n", .{});
     }
 }
 
+const ProfilingAllocator = struct {
+    allocator: Allocator,
+    parent_allocator: *Allocator,
+    max_usage: usize,
+    current_usage: usize,
+
+    fn init(parent_allocator: *Allocator) ProfilingAllocator {
+        return ProfilingAllocator{
+            .allocator = Allocator{
+                .reallocFn = realloc,
+                .shrinkFn = shrink,
+            },
+            .parent_allocator = parent_allocator,
+            .max_usage = 0,
+            .current_usage = 0,
+        };
+    }
+
+    fn realloc(allocator: *Allocator, old_mem: []u8, old_align: u29, new_size: usize, new_align: u29) ![]u8 {
+        const self = @fieldParentPtr(ProfilingAllocator, "allocator", allocator);
+        self.current_usage = self.current_usage - old_mem.len + new_size;
+        if (self.current_usage > self.max_usage) {
+            self.max_usage = self.current_usage;
+        }
+
+        return self.parent_allocator.reallocFn(self.parent_allocator, old_mem, old_align, new_size, new_align);
+    }
+
+    fn shrink(allocator: *Allocator, old_mem: []u8, old_align: u29, new_size: usize, new_align: u29) []u8 {
+        const self = @fieldParentPtr(ProfilingAllocator, "allocator", allocator);
+        return self.parent_allocator.shrinkFn(self.parent_allocator, old_mem, old_align, new_size, new_align);
+    }
+};
+
 pub fn main() !void {
-    // if (std.os.argv.len <= 1) {
-    //     std.debug.warn("Usage: vulkan-zig-gen <path-to-vk.xml>\n", .{});
-    //     return;
-    // }
+    if (std.os.argv.len <= 1) {
+        std.debug.warn("Usage: vulkan-zig-gen <path-to-vk.xml>\n", .{});
+        return;
+    }
+
+    var prof_alloc = ProfilingAllocator.init(std.heap.page_allocator);
+    const allocator = &prof_alloc.allocator;
 
     const file = try std.fs.cwd().openFileZ(std.os.argv[1], .{});
     defer file.close();
 
     const size = try file.seekableStream().getEndPos();
-    const source = try std.heap.page_allocator.alloc(u8, size);
-    defer std.heap.page_allocator.free(source);
+    const source = try allocator.alloc(u8, size);
+    defer allocator.free(source);
 
     _ = try file.inStream().read(source);
 
-    const spec = try xml.parse(std.heap.page_allocator, source);
+    const spec = try xml.parse(allocator, source);
     defer spec.deinit();
 
-    const result = try parseXml(std.heap.page_allocator, spec.root);
-    defer result.deinit();
+    // const result = try parseXml(std.heap.page_allocator, spec.root);
+    // defer result.deinit();
 
-    dumpRegistry(result.registry);
+    // dumpRegistry(result.registry);
+
+    var gen = try vkgen.Generator.init(allocator, spec.root);
+    defer gen.deinit();
+
+    try gen.resolveDeclarations();
+
+    std.debug.warn("Total declarations: {}\n", .{gen.registry.decls.len});
+    std.debug.warn("Total memory usage: {} KiB\n", .{@divTrunc(prof_alloc.max_usage, 1024)});
 }
 
 test "main" {
diff --git a/generator/registry/parse.zig b/generator/registry/parse.zig
index d19b688..a3a2a8c 100644
--- a/generator/registry/parse.zig
+++ b/generator/registry/parse.zig
@@ -579,7 +579,7 @@ fn parseRequire(allocator: *Allocator, require: *xml.Element, extnumber: ?u31) !
     };
 
     return registry.Require{
-        .extends = extends,
+        .extends = allocator.shrink(extends, i_extends),
         .types = types,
         .commands = commands,
         .required_feature_level = required_feature_level,
@@ -594,10 +594,15 @@ fn parseExtensions(allocator: *Allocator, root: *xml.Element) ![]registry.Extens
     var i: usize = 0;
     var it = extensions_elem.findChildrenByTag("extension");
     while (it.next()) |extension| {
-        if (try parseExtension(allocator, extension)) |ext| {
-            extensions[i] = ext;
-            i += 1;
+        // Some extensions (in particular 94) are disabled, so just skip them
+        if (extension.getAttribute("supported")) |supported| {
+            if (mem.eql(u8, supported, "disabled")) {
+                continue;
+            }
         }
+
+        extensions[i] = try parseExtension(allocator, extension);
+        i += 1;
     }
 
     return allocator.shrink(extensions, i);
@@ -619,12 +624,7 @@ fn findExtVersion(extension: *xml.Element) !u32 {
     return error.InvalidRegistry;
 }
 
-fn parseExtension(allocator: *Allocator, extension: *xml.Element) !?registry.Extension {
-    // Some extensions (in particular 94) are disabled, so just skip them
-    if (extension.getAttribute("supported")) |supported| {
-        if (mem.eql(u8, supported, "disabled")) return null;
-    }
-
+fn parseExtension(allocator: *Allocator, extension: *xml.Element) !registry.Extension {
     const name = extension.getAttribute("name") orelse return error.InvalidRegistry;
     const platform = extension.getAttribute("platform");
     const version = try findExtVersion(extension);
diff --git a/generator/render.zig b/generator/render.zig
index 5d0fe33..4e45d62 100644
--- a/generator/render.zig
+++ b/generator/render.zig
@@ -1,515 +1,3 @@
 const std = @import("std");
-const ast = std.zig.ast;
-const mem = std.mem;
-const Allocator = mem.Allocator;
-const reg = @import("registry.zig");
-const Registry = reg.Registry;
-
-const base_indent = " " ** 4;
-
-const ForeignType = struct {
-    name: []const u8,
-    expr: []const u8
-};
-
-const foreign_types = [_]ForeignType{
-    .{.name = "Display", .expr = "@Type(.Opaque)"},
-    .{.name = "VisualID", .expr = @typeName(c_uint)},
-    .{.name = "Window", .expr = @typeName(c_ulong)},
-    .{.name = "RROutput", .expr = @typeName(c_ulong)},
-    .{.name = "wl_display", .expr = "@Type(.Opaque)"},
-    .{.name = "wl_surface", .expr = "@Type(.Opaque)"},
-    .{.name = "HINSTANCE", .expr = "u32; //std.os.HINSTANCE"},
-    .{.name = "HWND", .expr = "*@Type(.Opaque)"},
-    .{.name = "HMONITOR", .expr = "*@Type(.Opaque)"},
-    .{.name = "HANDLE", .expr = "u32; //std.os.HANDLE"},
-    .{.name = "SECURITY_ATTRIBUTES", .expr = "u32; //std.os.SECURITY_ATTRIBUTES"},
-    .{.name = "DWORD", .expr = "u32; //std.os.DWORD"},
-    .{.name = "LPCWSTR", .expr = "u32; //std.os.LPCWSTR"},
-    .{.name = "xcb_connection_t", .expr = "@Type(.Opaque)"},
-    .{.name = "xcb_visualid_t", .expr = @typeName(u32)},
-    .{.name = "xcb_window_t", .expr = @typeName(u32)},
-    .{.name = "zx_handle_t", .expr = @typeName(u32)},
-    .{.name = "GgpStreamDescriptor", .expr = @typeName(u32)}, // TODO: Remove GGP-related code
-    .{.name = "GgpFrameToken", .expr = @typeName(u32)},
-    .{.name = "ANativeWindow", .expr = "@Type(.Opaque)"},
-    .{.name = "AHardwareBuffer", .expr = "@Type(.Opaque)"},
-    .{.name = "CAMetalLayer", .expr = "@Type(.Opaque)"},
-};
-
-const foreign_types_namespace = "foreign";
-
-const BuiltinType = struct {
-    c_name: []const u8,
-    zig_name: []const u8
-};
-
-const builtin_types = [_]BuiltinType{
-    .{.c_name = "void", .zig_name = @typeName(void)},
-    .{.c_name = "char", .zig_name = @typeName(u8)},
-    .{.c_name = "float", .zig_name = @typeName(f32)},
-    .{.c_name = "double", .zig_name = @typeName(f64)},
-    .{.c_name = "uint8_t", .zig_name = @typeName(u8)},
-    .{.c_name = "uint16_t", .zig_name = @typeName(u16)},
-    .{.c_name = "uint32_t", .zig_name = @typeName(u32)},
-    .{.c_name = "uint64_t", .zig_name = @typeName(u64)},
-    .{.c_name = "int32_t", .zig_name = @typeName(i32)},
-    .{.c_name = "int64_t", .zig_name = @typeName(i64)},
-    .{.c_name = "size_t", .zig_name = @typeName(usize)},
-    .{.c_name = "int", .zig_name = @typeName(c_int)},
-};
-
-pub fn render(out: var, registry: *Registry) !void {
-    try out.writeAll("const std = @import(\"std\");\n");
-    try renderApiConstants(out, registry);
-    try renderForeignTypes(out);
-    try out.writeAll("\n");
-    try renderDeclarations(out, registry);
-    try renderTest(out);
-}
-
-fn trimNamespace(name: []const u8) []const u8 {
-    const prefixes = [_][]const u8{"VK_", "vk", "Vk", "PFN_vk"};
-    for (prefixes) |prefix| {
-        if (mem.startsWith(u8, name, prefix)) {
-            return name[prefix.len..];
-        }
-    }
-
-    unreachable;
-}
-
-fn getAuthorTag(registry: *Registry, name: []const u8) ?[]const u8 {
-    var it = registry.tags.iterator(0);
-    while (it.next()) |tag| {
-        if (mem.endsWith(u8, name, tag.name)) {
-            return tag;
-        }
-    }
-
-    return null;
-}
-
-fn trimTag(registry: *Registry, name: []const u8) []const u8 {
-    const tag = getAuthorTag(name) orelse return name;
-    return mem.trimRight(u8, name[0 .. name.len - tag.name.len], "_");
-}
-
-// Lifted from src-self-hosted/translate_c.zig
-fn isValidZigIdentifier(name: []const u8) bool {
-    for (name) |c, i| {
-        switch (c) {
-            '_', 'a'...'z', 'A'...'Z' => {},
-            '0' ... '9' => if (i == 0) return false,
-            else => return false
-        }
-    }
-
-    return true;
-}
-
-// Lifted from src-self-hosted/translate_c.zig
-fn isZigReservedIdentifier(name: []const u8) bool {
-    if (name.len > 1 and (name[0] == 'u' or name[0] == 'i')) {
-        for (name[1..]) |c| {
-            switch (c) {
-                '0'...'9' => {},
-                else => return false,
-            }
-        }
-        return true;
-    }
-
-    // void is invalid in c so it doesn't need to be checked.
-    const reserved_names = [_][]const u8 {
-        "comptime_float", "comptime_int", "bool", "isize",
-        "usize", "f16", "f32", "f64", "f128", "c_longdouble",
-        "noreturn", "type", "anyerror", "c_short", "c_ushort",
-        "c_int", "c_uint", "c_long", "c_ulong", "c_longlong", "c_ulonglong"
-    };
-
-    for (reserved_names) |reserved| {
-        if (mem.eql(u8, reserved, name)) {
-            return true;
-        }
-    }
-
-    return false;
-}
-
-fn writeIdentifier(out: var, name: []const u8) !void {
-    if (!isValidZigIdentifier(name) or isZigReservedIdentifier(name) or std.zig.Token.getKeyword(name) != null) {
-        try out.print("@\"{}\"", .{name});
-    } else {
-        try out.writeAll(name);
-    }
-}
-
-const Identifier = struct {
-    name: []const u8,
-
-    fn init(name: []const u8) Identifier {
-        return .{.name = name};
-    }
-
-    fn needEscape(self: Identifier) bool {
-        return !isValidZigIdentifier(self.name)
-            or isZigReservedIdentifier(self.name)
-            or std.zig.Token.getKeyword(self.name) != null;
-    }
-
-    pub fn format(
-        self: Identifier,
-        fmt: []const u8,
-        options: std.fmt.FormatOptions,
-        out_stream: var
-    ) @TypeOf(out_stream).Error!void {
-        if (self.needEscape()){
-            try out_stream.print("@\"{}\"", .{self.name});
-        } else {
-            try out_stream.writeAll(self.name);
-        }
-    }
-};
-
-fn writeConstAssignmemt(out: var, name: []const u8) !void {
-    try out.print("pub const {} = ", .{Identifier.init(name)});
-}
-
-fn eqlIgnoreCase(lhs: []const u8, rhs: []const u8) bool {
-    if (lhs.len != rhs.len) {
-        return false;
-    }
-
-    for (lhs) |c, i| {
-        if (std.ascii.toLower(c) != std.ascii.toLower(rhs[i])) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
-fn renderTypeInfo(out: var, registry: *Registry, type_info: reg.TypeInfo) !void {
-    // If the type is a `void*`, it needs to be translated to `*c_void`.
-    // If its not a pointer, its a return type, so `void` should be emitted.
-    const is_void_ptr = mem.eql(u8, type_info.name, "void") and type_info.pointers.len > 0;
-
-    if (type_info.array_size) |array_size| {
-        try out.print("[{}]", .{trimNamespace(array_size)});
-    }
-
-    for (type_info.pointers) |ptr| {
-        // Apparently Vulkan optional-ness information is not correct, so every pointer
-        // is considered optional
-        switch (ptr.size) {
-            .One => try out.writeAll("?*"),
-            .Many => if (is_void_ptr)
-                    try out.writeAll("?*")
-                else
-                    try out.writeAll("?[*]"),
-            .ZeroTerminated => try out.writeAll("?[*:0]")
-        }
-
-        if (ptr.is_const) {
-            try out.writeAll("const ");
-        }
-    }
-
-    if (is_void_ptr) {
-        try out.writeAll("c_void");
-        return;
-    }
-
-    // If the type is foreign, add the appropriate namespace specifier
-    for (foreign_types) |fty| {
-        if (mem.eql(u8, type_info.name, fty.name)) {
-            try out.print(foreign_types_namespace ++ ".{}", .{type_info.name});
-            return;
-        }
-    }
-
-    // Some types can be mapped directly to a built-in type
-    for (builtin_types) |bty| {
-        if (mem.eql(u8, type_info.name, bty.c_name)) {
-            try out.writeAll(bty.zig_name);
-            return;
-        }
-    }
-
-    // Make sure the type is defined by Vulkan otherwise
-    if (registry.findDefinitionByName(type_info.name)) |def| {
-        if (def.* == .FnPtr) {
-            try out.writeAll("PFN_");
-        }
-
-        try writeIdentifier(out, trimNamespace(type_info.name));
-    } else {
-        return error.InvalidType;
-    }
-}
-
-fn renderApiConstantExpr(out: var, constant_expr: []const u8) !void {
-    // omit enclosing parenthesis
-    const expr = if (constant_expr[0] == '(' and constant_expr[constant_expr.len - 1] == ')')
-        constant_expr[1 .. constant_expr.len - 1]
-    else
-        constant_expr;
-
-    var i: usize = 0;
-    while (i < expr.len) {
-        switch (expr[i]) {
-            '(', ')', '~' => try out.writeByte(expr[i]),
-            '-' => try out.writeAll(" - "),
-            'a'...'z', 'A'...'Z', '_' => {
-                var j = i;
-                while (j < expr.len) : (j += 1) {
-                    switch (expr[j]) {
-                        'a'...'z', 'A'...'Z', '_', '0'...'9' => {},
-                        else => break
-                    }
-                }
-
-                try writeIdentifier(out, trimNamespace(expr[i .. j]));
-                i = j;
-                continue;
-            },
-            '0'...'9' => {
-                var j = i;
-                while (j < expr.len) : (j += 1) {
-                    switch (expr[j]) {
-                        '0'...'9', '.' => {},
-                        else => break
-                    }
-                }
-
-                if (mem.startsWith(u8, expr[j..], "f")) {
-                    try out.print("@as(f32, {})", .{expr[i .. j]});
-                    j += "f".len;
-                } else if (mem.startsWith(u8, expr[j..], "ULL")) {
-                    try out.print("@as(u32, {})", .{expr[i .. j]});
-                    j += "ULL".len;
-                } else if (mem.startsWith(u8, expr[j..], "U")) {
-                    try out.print("@as(u64, {})", .{expr[i .. j]});
-                    j += "U".len;
-                } else {
-                    try out.writeAll(expr[i .. j]);
-                }
-
-                i = j;
-                continue;
-            },
-            ' ' => {},
-            else => return error.InvalidConstantExpr
-        }
-
-        i += 1;
-    }
-}
-
-fn renderApiConstants(out: var, registry: *Registry) !void {
-    var it = registry.api_constants.iterator(0);
-    while (it.next()) |constant| {
-        try writeConstAssignmemt(out, trimNamespace(constant.name));
-        try renderApiConstantExpr(out, constant.expr);
-        try out.writeAll(";\n");
-    }
-
-    try out.writeAll("\n");
-}
-
-fn renderForeignTypes(out: var) !void {
-    try writeConstAssignmemt(out, foreign_types_namespace);
-    try out.writeAll("struct {\n");
-
-    for (foreign_types) |fty| {
-        try out.writeAll(base_indent);
-        try writeConstAssignmemt(out, fty.name);
-        try out.print("{};\n", .{fty.expr});
-    }
-
-    try out.writeAll("};\n");
-}
-
-fn renderDeclarations(out: var, registry: *Registry) !void {
-    var it = registry.declarations.iterator(0);
-    while (it.next()) |decl| {
-        switch (decl.definition) {
-            .Struct => |*info| try renderContainer(out, registry, .Struct, decl.name, info),
-            .Union => |*info| try renderContainer(out, registry, .Union, decl.name, info),
-            .Enum => |*info| try renderEnum(out, decl.name, info),
-            .Bitmask => |*info| try renderBitmask(out, decl.name, info),
-            .Handle => |*info| try renderHandle(out, decl.name, info),
-            .FnPtr => |*info| try renderFnPtr(out, registry, decl.name, info),
-            .Command => |*info| try renderCommand(out, registry, decl.name, info),
-            .Alias => |alias| try renderAlias(out, registry, decl.name, alias),
-            .BaseType => |type_info| {
-                try writeConstAssignmemt(out, trimNamespace(decl.name));
-                try renderTypeInfo(out, registry, type_info);
-                try out.writeAll(";\n");
-            },
-
-        }
-    }
-}
-
-fn renderCommand(out: var, registry: *Registry, name: []const u8, info: *reg.CommandInfo) !void {
-    try out.writeAll("extern fn ");
-    try writeIdentifier(out, name);
-    try out.writeAll("(");
-
-    if (info.parameters.count() > 0) {
-        try out.writeAll("\n");
-        var it = info.parameters.iterator(0);
-        while (it.next()) |param| {
-            try out.writeAll(base_indent);
-            try writeIdentifier(out, param.name);
-            try out.writeAll(": ");
-            try renderTypeInfo(out, registry, param.type_info);
-            try out.writeAll(",\n");
-        }
-    }
-
-    try out.writeAll(") callconv(.C) ");
-    try renderTypeInfo(out, registry, info.return_type_info);
-    try out.writeAll(";\n\n");
-
-    // var buf: [256]u8 = undefined;
-    // const trimmed = trimNamespace(name);
-    // mem.copy(u8, &buf, trimNamespace(name));
-    // buf[0] = std.ascii.toLower(buf[0]);
-
-    // try writeConstAssignmemt(out, buf[0 .. trimmed.len]);
-    // try writeIdentifier(out, name);
-    // try out.writeAll(";\n");
-}
-
-fn renderHandle(out: var, name: []const u8, info: *const reg.HandleInfo) !void {
-    try writeConstAssignmemt(out, trimNamespace(name));
-    // Todo: (non)-dispatchable
-    try out.writeAll("*@Type(.Opaque);\n");
-}
-
-fn renderBitmask(out: var, name: []const u8, info: *const reg.BitmaskInfo) !void {
-    try writeConstAssignmemt(out, trimNamespace(name));
-    try out.writeAll("Flags;\n");
-}
-
-fn shouldSkipEnum(enum_info: *reg.EnumInfo) bool {
-    // Skip empty declarations (which are unused bitflags)
-    return enum_info.variants.count() == 0;
-}
-
-fn renderEnum(out: var, name: []const u8, enum_info: *reg.EnumInfo) !void {
-    if (shouldSkipEnum(enum_info)) {
-        return;
-    }
-
-    const trimmed_name = trimNamespace(name);
-
-    try writeConstAssignmemt(out, trimmed_name);
-    try out.writeAll("extern enum {\n");
-
-    // Calculate the length of the enum namespace, by iterating through the segments
-    // of the variant (in screaming snake case) and comparing it to the name of the enum,
-    // until the two differ.
-    var prefix_len: usize = 0;
-    var snake_prefix_len: usize = 0;
-    var segment_it = mem.split(enum_info.variants.at(0).name, "_");
-    while (segment_it.next()) |segment| {
-        if (prefix_len + segment.len <= name.len and eqlIgnoreCase(segment, name[prefix_len .. prefix_len + segment.len])) {
-            prefix_len += segment.len;
-            snake_prefix_len += segment.len + 1; // Add one for the underscore
-        } else {
-            break;
-        }
-    }
-
-    var it = enum_info.variants.iterator(0);
-    while (it.next()) |variant| {
-        if (variant.value == .Alias) continue; // Skip aliases
-
-        try out.writeAll(base_indent);
-        try writeIdentifier(out, variant.name[snake_prefix_len ..]);
-
-        switch (variant.value) {
-            .Value => |value| try out.print(" = {},\n", .{value}),
-            .HexValue => |value| try out.print(" = 0x{X},\n", .{value}),
-            .Bitpos => |value| try out.print(" = 1 << {},\n", .{value}),
-            .Alias => unreachable
-        }
-    }
-
-    try out.writeAll("};\n");
-}
-
-fn renderAlias(out: var, registry: *Registry, name: []const u8, alias: []const u8) !void {
-    // An declaration may be aliased to a bit flag enum which has no members, in which case
-    // the alias also has to be skipped.
-    var def = registry.findDefinitionByName(alias).?;
-    while (def.* == .Alias) {
-        def = registry.findDefinitionByName(def.Alias).?;
-    }
-
-    if ((def.* == .Enum and shouldSkipEnum(&def.Enum)) or def.* == .Command) {
-        return;
-    }
-
-    try writeConstAssignmemt(out, trimNamespace(name));
-    try writeIdentifier(out, trimNamespace(alias));
-    try out.writeAll(";\n");
-}
-
-fn renderFnPtr(out: var, registry: *Registry, name: []const u8, info: *reg.CommandInfo) !void {
-    try out.writeAll("pub const PFN_");
-    try writeIdentifier(out, name);
-    try out.writeAll(" = ");
-
-    try out.writeAll("?fn(");
-
-    if (info.parameters.count() > 0) {
-        try out.writeAll("\n");
-        var it = info.parameters.iterator(0);
-        while (it.next()) |param| {
-            try out.writeAll(base_indent);
-            try writeIdentifier(out, param.name);
-            try out.writeAll(": ");
-            try renderTypeInfo(out, registry, param.type_info);
-            try out.writeAll(",\n");
-        }
-    }
-
-    try out.writeAll(") callconv(.C) ");
-    try renderTypeInfo(out, registry, info.return_type_info);
-    try out.writeAll(";\n");
-}
-
-fn renderContainer(out: var, registry: *Registry, kind: enum{Struct, Union}, name: []const u8, info: *reg.ContainerInfo) !void {
-    try writeConstAssignmemt(out, trimNamespace(name));
-
-    switch (kind) {
-        .Struct => try out.writeAll("extern struct {\n"),
-        .Union => try out.writeAll("extern union {\n")
-    }
-
-    var it = info.members.iterator(0);
-    while (it.next()) |member| {
-        try out.writeAll(base_indent);
-        try writeIdentifier(out, member.name);
-        try out.writeAll(": ");
-        try renderTypeInfo(out, registry, member.type_info);
-        try out.writeAll(",\n");
-    }
-
-    try out.writeAll("};\n");
-}
-
-fn renderTest(out: var) !void {
-    try out.writeAll(
-        \\test "Semantic analysis" {
-        \\    @setEvalBranchQuota(2000);
-        \\    std.meta.refAllDecls(@This());
-        \\}
-        \\
-    );
-}
+const registry = @import("registry.zig");
+const Allocator = std.mem.Allocator,
diff --git a/generator/xml.zig b/generator/xml.zig
index 2415e0c..96783c9 100644
--- a/generator/xml.zig
+++ b/generator/xml.zig
@@ -17,7 +17,7 @@ pub const Content = union(enum) {
 };
 
 pub const Element = struct {
-    pub const AttributeList = SegmentedList(*Attribute, 0);
+    pub const AttributeList = SegmentedList(*Attribute, 1);
     pub const ContentList = SegmentedList(Content, 0);
 
     tag: []const u8,