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const std = @import("std");
fn Args(params: []const std.builtin.Type.Fn.Param) type {
var argTypes: [params.len]type = undefined;
for (params, 0..) |p, i| {
argTypes[i] = p.type.?;
}
return @Tuple(&argTypes);
}
fn Val(comptime T: type) type {
const ti = @typeInfo(T).@"struct";
const fieldCount = ti.fields.len + ti.decls.len + 1;
var names: [fieldCount][]const u8 = undefined;
var types: [fieldCount]type = undefined;
var attrs: [fieldCount]std.builtin.Type.StructField.Attributes = undefined;
inline for (ti.fields, 0..) |field, idx| {
if (field.is_comptime)
@compileError("implement skipping comptime fields");
const fi = @typeInfo(field.type);
switch (fi) {
.@"struct" => {
names[idx] = field.name;
const NT = Val(field.type);
types[idx] = NT;
attrs[idx] = .{
.default_value_ptr = &NT{},
};
},
else => {
names[idx] = field.name;
const NT = struct {
pub fn get(self: *@This()) field.type {
std.debug.print("getting {s}\n", .{field.name});
const parent = self.valuePtr();
return @field(parent.value, field.name);
}
pub fn set(self: *@This(), value: field.type) void {
std.debug.print("setting {s}\n", .{field.name});
const parent = self.valuePtr();
@field(parent.value, field.name) = value;
}
fn valuePtr(self: *@This()) *align(@alignOf(@This())) Val(T) {
const parent: *align(@alignOf(@This())) Val(T) = @fieldParentPtr(field.name, self);
return parent;
}
};
types[idx] = NT;
attrs[idx] = .{
.default_value_ptr = &NT{},
};
},
}
}
inline for (ti.decls, 0..) |decl, idx| {
names[ti.fields.len + idx] = decl.name;
const fi = @typeInfo(@TypeOf(@field(T, decl.name))).@"fn";
const NT = struct {
pub fn call(self: @This(), args: Args(fi.params)) (fi.return_type orelse void) {
_ = self;
std.debug.print("calling {s}\n", .{decl.name});
@call(.auto, @field(T, decl.name), args);
std.debug.print("done calling {s}\n", .{decl.name});
}
};
types[ti.fields.len + idx] = NT;
attrs[ti.fields.len + idx] = .{ .default_value_ptr = &NT{} };
}
names[fieldCount - 1] = "value";
types[fieldCount - 1] = T;
attrs[fieldCount - 1] = .{
.@"comptime" = false,
.@"align" = @alignOf(T),
.default_value_ptr = &T{},
};
return @Struct(.auto, null, &names, &types, &attrs);
}
pub fn main() !void {
var a = Val(struct {
i: i32 = 123,
j: i32 = 456,
s: struct {
i: i32 = 789,
} = .{},
pub fn b() void {
std.debug.print("B!\n", .{});
}
pub fn c(self: @This()) void {
std.debug.print("C! ({})\n", .{self});
}
pub fn d(self: @This(), i: i32) void {
self.i += i;
std.debug.print("D! ({})\n", .{self});
}
}){};
std.debug.print("[{}] {}\n{}\n", .{ @TypeOf(a), a, a.value });
// a.b.call(.{});
// a.c.call(.{a});
// a.c.call(.{a, 5});
std.debug.print("{}\n", .{a.i.get()});
std.debug.print("{}\n", .{a.j.get()});
a.j.set(9);
std.debug.print("{}\n", .{a.j.get()});
std.debug.print("{}\n", .{a.s.i.get()});
}
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