move generator/ to src/

A long time ago there was the idea to use src/ for something else,
but that is no longer relevant. Its nice to switch to a more
conventional repo layout.

src/main.zig

@@ -0,0 +1,129 @@
+const std = @import("std");
+const generator = @import("vulkan/generator.zig");
+
+fn invalidUsage(prog_name: []const u8, comptime fmt: []const u8, args: anytype) noreturn {
+    std.log.err(fmt, args);
+    std.log.err("see {s} --help for usage", .{prog_name});
+    std.process.exit(1);
+}
+
+pub fn main() void {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+    const allocator = arena.allocator();
+
+    var args = std.process.argsWithAllocator(allocator) catch |err| switch (err) {
+        error.OutOfMemory => @panic("OOM"),
+    };
+    const prog_name = args.next() orelse "vulkan-zig-generator";
+
+    var maybe_xml_path: ?[]const u8 = null;
+    var maybe_out_path: ?[]const u8 = null;
+    var api = generator.Api.vulkan;
+
+    while (args.next()) |arg| {
+        if (std.mem.eql(u8, arg, "--help") or std.mem.eql(u8, arg, "-h")) {
+            @setEvalBranchQuota(2000);
+            std.io.getStdOut().writer().print(
+                \\Utility to generate a Zig binding from the Vulkan XML API registry.
+                \\
+                \\The most recent Vulkan XML API registry can be obtained from
+                \\https://github.com/KhronosGroup/Vulkan-Docs/blob/master/xml/vk.xml,
+                \\and the most recent LunarG Vulkan SDK version can be found at
+                \\$VULKAN_SDK/x86_64/share/vulkan/registry/vk.xml.
+                \\
+                \\Usage: {s} [options] <spec xml path> <output zig source>
+                \\Options:
+                \\-h --help        show this message and exit.
+                \\-a --api <api>   Generate API for 'vulkan' or 'vulkansc'. Defaults to 'vulkan'.
+                \\
+            ,
+                .{prog_name},
+            ) catch |err| {
+                std.log.err("failed to write to stdout: {s}", .{@errorName(err)});
+                std.process.exit(1);
+            };
+            return;
+        } else if (std.mem.eql(u8, arg, "-a") or std.mem.eql(u8, arg, "--api")) {
+            const api_str = args.next() orelse {
+                invalidUsage(prog_name, "{s} expects argument <api>", .{arg});
+            };
+            api = std.meta.stringToEnum(generator.Api, api_str) orelse {
+                invalidUsage(prog_name, "invalid api '{s}'", .{api_str});
+            };
+        } else if (maybe_xml_path == null) {
+            maybe_xml_path = arg;
+        } else if (maybe_out_path == null) {
+            maybe_out_path = arg;
+        } else {
+            invalidUsage(prog_name, "superficial argument '{s}'", .{arg});
+        }
+    }
+
+    const xml_path = maybe_xml_path orelse {
+        invalidUsage(prog_name, "missing required argument <spec xml path>", .{});
+    };
+
+    const out_path = maybe_out_path orelse {
+        invalidUsage(prog_name, "missing required argument <output zig source>", .{});
+    };
+
+    const cwd = std.fs.cwd();
+    const xml_src = cwd.readFileAlloc(allocator, xml_path, std.math.maxInt(usize)) catch |err| {
+        std.log.err("failed to open input file '{s}' ({s})", .{ xml_path, @errorName(err) });
+        std.process.exit(1);
+    };
+
+    var out_buffer = std.ArrayList(u8).init(allocator);
+    generator.generate(allocator, api, xml_src, out_buffer.writer()) catch |err| switch (err) {
+        error.InvalidXml => {
+            std.log.err("invalid vulkan registry - invalid xml", .{});
+            std.log.err("please check that the correct vk.xml file is passed", .{});
+            std.process.exit(1);
+        },
+        error.InvalidRegistry => {
+            std.log.err("invalid vulkan registry - registry is valid xml but contents are invalid", .{});
+            std.log.err("please check that the correct vk.xml file is passed", .{});
+            std.process.exit(1);
+        },
+        error.UnhandledBitfieldStruct => {
+            std.log.err("unhandled struct with bit fields detected in vk.xml", .{});
+            std.log.err("this is a bug in vulkan-zig", .{});
+            std.log.err("please make a bug report at https://github.com/Snektron/vulkan-zig/issues/", .{});
+            std.process.exit(1);
+        },
+        error.OutOfMemory => @panic("oom"),
+    };
+
+    out_buffer.append(0) catch @panic("oom");
+
+    const src = out_buffer.items[0 .. out_buffer.items.len - 1 :0];
+    const tree = std.zig.Ast.parse(allocator, src, .zig) catch |err| switch (err) {
+        error.OutOfMemory => @panic("oom"),
+    };
+
+    if (tree.errors.len > 0) {
+        std.log.err("generated invalid zig code", .{});
+        std.log.err("this is a bug in vulkan-zig", .{});
+        std.log.err("please make a bug report at https://github.com/Snektron/vulkan-zig/issues/", .{});
+
+        std.process.exit(1);
+    }
+
+    const formatted = tree.render(allocator) catch |err| switch (err) {
+        error.OutOfMemory => @panic("oom"),
+    };
+    defer allocator.free(formatted);
+
+    if (std.fs.path.dirname(out_path)) |dir| {
+        cwd.makePath(dir) catch |err| {
+            std.log.err("failed to create output directory '{s}' ({s})", .{ dir, @errorName(err) });
+            std.process.exit(1);
+        };
+    }
+
+    cwd.writeFile(out_path, formatted) catch |err| {
+        std.log.err("failed to write to output file '{s}' ({s})", .{ out_path, @errorName(err) });
+        std.process.exit(1);
+    };
+}