79 lines
2.3 KiB
Zig
79 lines
2.3 KiB
Zig
const std = @import("std");
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const compileError = @import("debug.zig").compileError;
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pub fn ArgsTuple(comptime funcT: anytype, comptime ArgsT: ?type) type {
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const params = @typeInfo(funcT).@"fn".params;
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if (params.len == 0) {
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return @TypeOf(.{});
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}
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if (@typeInfo(funcT).@"fn".is_generic == false) {
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return std.meta.ArgsTuple(funcT);
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}
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const args = std.meta.fields(ArgsT orelse @compileError("generic function requires an explicit ArgsTuple"));
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var tuple_fields: [params.len]std.builtin.Type.StructField = undefined;
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if (params.len != args.len) {
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compileError("function {} expected {} args, got {}", .{ funcT, params.len, args.len });
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}
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inline for (params, args, 0..) |param, arg, i| {
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if (param.type == null) {
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tuple_fields[i] = arg;
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continue;
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}
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const T = param.type.?;
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var num_buf: [8]u8 = undefined;
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tuple_fields[i] = .{
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.name = blk: {
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const s = std.fmt.formatIntBuf(&num_buf, i, 10, .lower, .{});
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num_buf[s] = 0;
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break :blk num_buf[0..s :0];
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},
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.type = T,
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.default_value_ptr = null,
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.is_comptime = false,
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.alignment = if (@sizeOf(T) > 0) @alignOf(T) else 0,
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};
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}
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return @Type(.{
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.@"struct" = .{
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.is_tuple = true,
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.layout = .auto,
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.decls = &.{},
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.fields = &tuple_fields,
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},
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});
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}
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pub const Signature = struct {
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Func: type,
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FuncT: type,
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ArgsT: type,
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ReturnT: type,
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ReturnPayloadT: type,
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ReturnErrorSet: ?type,
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};
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pub fn FnSignature(comptime func: anytype, comptime argsT_: ?type) Signature {
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const argsT = ArgsTuple(@TypeOf(func), argsT_);
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const return_type = @TypeOf(@call(.auto, func, @as(argsT, undefined)));
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return Signature{
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.Func = struct {
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pub const Value = func;
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},
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.FuncT = @TypeOf(func),
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.ArgsT = argsT,
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.ReturnT = return_type,
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.ReturnPayloadT = switch (@typeInfo(return_type)) {
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.error_union => |u| u.payload,
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else => return_type,
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},
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.ReturnErrorSet = switch (@typeInfo(return_type)) {
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.error_union => |u| u.error_set,
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else => null,
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},
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};
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}
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