66 lines
2.0 KiB
Zig
66 lines
2.0 KiB
Zig
const std = @import("std");
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const compileError = @import("meta.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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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: [32]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 = 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 fn FnSignature(comptime func: anytype, comptime argsT: ?type) type {
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return FnSignatureX(func, ArgsTuple(@TypeOf(func), argsT));
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}
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fn FnSignatureX(comptime func: anytype, comptime argsT: type) type {
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return struct {
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pub const FuncT = @TypeOf(func);
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pub const ArgsT = argsT;
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pub const ReturnT = @TypeOf(@call(.auto, func, @as(ArgsT, undefined)));
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pub const ReturnPayloadT = switch (@typeInfo(ReturnT)) {
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.ErrorUnion => |u| u.payload,
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else => ReturnT,
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};
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pub const ReturnErrorSet: ?type = switch (@typeInfo(ReturnT)) {
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.ErrorUnion => |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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