aether/reflection.zig
2025-06-04 21:59:32 -05:00

516 lines
18 KiB
Zig

const std = @import("std");
const mem = std.mem;
const Language = @import("language.zig");
const Tokenizer = @import("tokenizer.zig");
const assert = std.debug.assert;
const Self = @This();
pub const Error = error{TypeError};
language: *Language,
tokenizer: *Tokenizer,
pub fn parse(self: *Self, allocator: mem.Allocator) !usize {
return self.language.parse(allocator, self.tokenizer);
}
pub fn init(allocator: mem.Allocator, text: []const u8) !Self {
const self = Self{
.language = try allocator.create(Language),
.tokenizer = try allocator.create(Tokenizer),
};
self.language.* = .init;
self.tokenizer.* = try .init(allocator, text);
return self;
}
pub fn deinit(self: *Self, allocator: mem.Allocator) void {
self.language.deinit(allocator);
self.tokenizer.deinit(allocator);
allocator.destroy(self.language);
allocator.destroy(self.tokenizer);
}
/// needs an index but useful otherwise
/// root starting from idx
pub fn reflectT(self: *Self, comptime T: type, allocator: mem.Allocator, idx: usize) !T {
const Schema = @typeInfo(T);
if (std.meta.hasFn(T, "toJson")) {
return T.toJson(self, allocator, idx);
}
switch (self.language.index.get(idx)) {
.null => {
if (Schema == .null or Schema == .optional) return null;
},
.bool => |b| switch (Schema) {
.bool => return b,
.@"union" => |unionInfo| inline for (unionInfo.fields) |field| {
var r: T = undefined;
r = @unionInit(T, field.name, b);
return r;
},
else => unreachable,
},
.number => |number| switch (Schema) {
.int, .comptime_int => return @intCast(number.int),
.float, .comptime_float => return switch (number) {
.float => @floatCast(number.float),
.int => @floatFromInt(number.int),
},
.@"enum" => |enumInfo| {
const int: enumInfo.tag_type = @intCast(number.int);
return @enumFromInt(int);
},
.@"struct" => |structInfo| switch (structInfo.layout) {
.@"packed" => {
const int: structInfo.backing_integer.? = @intCast(number.int);
return @bitCast(int);
},
else => unreachable, // may only cast packed structs
},
.@"union" => |unionInfo| {
inline for (unionInfo.fields) |field| switch (@typeInfo(field.type)) {
.int, .comptime_int => return @unionInit(T, field.name, @intCast(number.int)),
.float, .comptime_float => return @unionInit(T, field.name, @floatCast(number.float)),
else => {},
};
return error.TypeError;
},
else => unreachable,
},
.string => |string| switch (Schema) {
.@"enum" => |enumInfo| {
const strslice = string.slice(&self.language.strings);
inline for (enumInfo.fields) |field| if (mem.eql(u8, field.name, strslice)) {
return std.meta.stringToEnum(T, strslice) orelse error.TypeError;
};
},
.@"union" => |unionInfo| inline for (unionInfo.fields) |field| {
if (field.type == []const u8) {
var r: T = undefined;
const strslice = string.slice(&self.language.strings);
r = @unionInit(T, field.name, strslice);
return r;
}
},
.array => |arrayInfo| {
assert(arrayInfo.child == u8);
const strslice = string.slice(&self.language.strings);
assert(arrayInfo.len == strslice.len - 1);
var r: T = undefined;
for (strslice, 0..) |char, i| r[i] = char;
return r;
},
.pointer => |ptrInfo| switch (ptrInfo.size) {
.slice => {
assert(ptrInfo.child == u8);
const strslice = string.slice(&self.language.strings);
var arraylist: std.ArrayList(u8) = .init(allocator);
try arraylist.ensureUnusedCapacity(strslice.len);
for (strslice) |char| if (char != 0x00)
arraylist.appendAssumeCapacity(char);
if (ptrInfo.sentinel_ptr) |some| {
const sentinel = @as(*align(1) const ptrInfo.child, @ptrCast(some)).*;
return try arraylist.toOwnedSliceSentinel(sentinel);
}
if (ptrInfo.is_const) {
arraylist.deinit();
return strslice;
} else {
arraylist.deinit();
const slice = try allocator.dupe(u8, strslice);
return @as(T, slice);
}
return try arraylist.toOwnedSlice();
},
.many => {
assert(ptrInfo.child == u8);
const strslice = string.slice(&self.language.strings);
var arraylist: std.ArrayList(u8) = .init(allocator);
try arraylist.ensureUnusedCapacity(strslice.len);
for (strslice) |char|
arraylist.appendAssumeCapacity(char);
if (ptrInfo.sentinel_ptr) |some| {
return arraylist.toOwnedSliceSentinel(blk: {
const sentinel: *align(1) const ptrInfo.child = @ptrCast(some);
break :blk sentinel.*;
});
}
return arraylist.toOwnedSlice();
},
else => unreachable,
},
else => unreachable,
},
.array => |slice| switch (Schema) {
.@"struct" => |structInfo| {
if (structInfo.is_tuple) {
assert(structInfo.fields.len == slice.len);
var r: T = undefined;
inline for (structInfo.fields, 0..slice.len) |field, i| {
if (field.is_comptime)
@panic(@typeName(T) ++ "." ++ field.name ++ " may not be a comptime field");
@field(r, field.name) = try self.reflectT(field.type, allocator, slice.tip + i);
}
return r;
}
unreachable; // may only reflect tuples
},
.array => |arrayInfo| {
assert(slice.len == arrayInfo.len);
var r: T = undefined;
for (0..slice.len) |i|
r[i] = try self.reflectT(arrayInfo.child, allocator, slice.tip + i);
return r;
},
.pointer => |ptrInfo| switch (ptrInfo.size) {
.slice => {
var r: T = try allocator.alloc(ptrInfo.child, slice.len);
if (ptrInfo.sentinel_ptr) |some| {
r[slice.len - 1] = blk: {
const sentinel: *align(1) const ptrInfo.child = @ptrCast(some);
break :blk sentinel.*;
};
}
for (0..slice.len) |i| {
// weird hack to populate the string
const rptr = @constCast(r);
rptr[i] = try self.reflectT(ptrInfo.child, allocator, slice.tip + i);
}
return r;
},
else => unreachable,
},
else => unreachable,
},
.object => |object| switch (Schema) {
.@"struct" => |structInfo| {
if (structInfo.is_tuple) return error.TypeError;
var tip = object.tip;
var map: std.StringArrayHashMapUnmanaged(usize) = .empty;
try map.ensureTotalCapacity(allocator, object.len);
defer map.deinit(allocator);
for (0..object.len) |_| if (self.language.property_map.get(tip)) |pen| {
const key = pen.tip.slice(&self.language.properties);
map.putAssumeCapacity(key, tip);
tip += self.language.skipSlots(tip);
};
var r: T = undefined;
inline for (structInfo.fields) |field| {
if (field.is_comptime)
@panic(@typeName(T) ++ "." ++ field.name ++ " may not be a comptime field");
if (map.get(field.name)) |next_i| {
@field(r, field.name) = try self.reflectT(field.type, allocator, next_i);
} else switch (@typeInfo(field.type)) {
.optional => @field(r, field.name) = null,
else => @panic("Unknown property: " ++ field.name),
}
}
return r;
},
else => unreachable,
},
}
unreachable;
}
test reflectT {
const allocator = std.testing.allocator;
const text =
\\{
\\ "age": 15,
\\ "name": "Yuzu",
\\ "admin": true,
\\ "flags": 0,
\\ "union": ":D",
\\ "enum": "world",
\\ "many": [1,2,3],
\\ "tuple": [1, 2]
\\}
;
var self = try allocator.create(Self);
self.* = try init(allocator, text);
defer allocator.destroy(self);
defer self.deinit(allocator);
const idx: usize = try self.parse(allocator);
const UserFlags = packed struct {
is_cool: bool = false,
is_friendly: bool = false,
};
const UserSchema = struct {
age: f64,
name: []const u8,
admin: bool,
flags: UserFlags,
@"union": union { hi: bool, bye: f64, n128: []const u8 },
@"enum": enum { hello, world },
many: []const u8,
tuple: struct { u64, u64 },
};
const root = try self.reflectT(UserSchema, allocator, idx);
std.debug.print("hello? {s}\n", .{@tagName(root.@"enum")});
std.debug.print("friend? {s}\n", .{root.@"union".n128});
std.debug.print("many: {any}\n", .{root.many});
std.debug.print("tuple: {any}\n", .{root.tuple});
allocator.free(root.many);
}
pub const Options = struct {
max_buffer_size: usize = 4096,
ruleset: Ruleset = .{},
indent: u8 = 0,
};
pub const Ruleset = packed struct {
/// print 'packed struct' as a number
allow_bitfields: bool = false,
/// print 'enum' as a number
allow_data_cast: bool = false,
/// ignore comments
allow_comments: bool = false,
/// whether to print '*T' as int
allow_derefptrs: bool = false,
/// prettify the output
pretty: bool = false,
pub const Pedantic = Ruleset{};
pub const Chill = Ruleset{
.allow_bitfields = true,
.allow_data_cast = true,
.allow_comments = true,
.allow_derefptrs = true,
};
};
pub fn prettyStringify(raw: anytype, comptime options: Options) ![]const u8 {
return stringify(raw, comptime blk: {
var opts = options;
opts.ruleset.pretty = true;
break :blk opts;
});
}
pub fn stringify(raw: anytype, comptime options: Options) ![]const u8 {
if (options.indent > 0 and !options.ruleset.pretty)
@compileError("Indentation is only allowed when pretty is enabled");
var buf: [options.max_buffer_size]u8 = undefined;
var fba: std.heap.FixedBufferAllocator = .init(&buf);
const allocator = fba.allocator();
if (std.meta.hasFn(@TypeOf(raw), "stringify")) {
// If the type has a custom stringify function, use it.
return raw.stringify(options);
}
switch (@typeInfo(@TypeOf(raw))) {
.null => return "null",
.bool => return if (raw) "true" else "false",
.int, .comptime_int => return std.fmt.bufPrint(&buf, "{d}", .{raw}),
.float, .comptime_float => return std.fmt.bufPrint(&buf, "{d:.1}", .{raw}),
.optional => {
if (raw) |value| {
return stringify(value, options);
} else {
return "null";
}
},
.@"enum" => |enumInfo| {
if (options.ruleset.allow_data_cast) {
const i: enumInfo.tag_type = @intFromEnum(raw);
return std.fmt.bufPrint(&buf, "{d}", .{i});
}
return std.fmt.bufPrint(&buf, "{s}", .{@tagName(raw)});
},
.@"struct" => |structInfo| switch (structInfo.layout) {
.@"packed" => {
if (options.ruleset.allow_bitfields) {
const i: structInfo.backing_integer.? = @bitCast(raw);
return std.fmt.bufPrint(&buf, "{d}", .{i});
}
return error.TypeError;
},
.auto, .@"extern" => {
var string: std.ArrayListUnmanaged(u8) = .empty;
var writer = string.writer(allocator);
try writer.writeByte('{');
if (options.ruleset.pretty)
try writer.writeByte('\n');
inline for (structInfo.fields, 0..) |field, i| {
inline for (0..options.indent) |_|
try writer.writeByte(' ');
try writer.writeByte('"');
try writer.writeAll(field.name);
try writer.writeByte('"');
if (options.ruleset.pretty)
try writer.writeAll(": ")
else
try writer.writeByte(':');
const value = @field(raw, field.name);
const str = try stringify(value, options);
try writer.writeAll(str);
if (i < structInfo.fields.len - 1)
try writer.writeByte(',');
if (options.ruleset.pretty)
try writer.writeByte('\n');
}
try writer.writeByte('}');
return string.toOwnedSlice(allocator);
},
},
.array => |arrayInfo| {
var string: std.ArrayListUnmanaged(u8) = .empty;
var writer = string.writer(allocator);
try writer.writeByte('[');
for (0..arrayInfo.len) |i| {
if (i > 0) {
try writer.writeAll(',');
if (options.ruleset.pretty)
try writer.writeByte(' ');
}
const value = @field(raw, i);
const str = try stringify(value, options);
try writer.writeAll(str);
}
try writer.writeByte(']');
return string.toOwnedSlice();
},
.pointer => |ptrInfo| switch (ptrInfo.size) {
.one => {
if (options.ruleset.allow_derefptrs) {
return stringify(blk: {
const ptr: *align(ptrInfo.alignment) const ptrInfo.child = @ptrCast(raw);
break :blk ptr.*;
}, options);
}
return std.fmt.bufPrint(&buf, "{d}", .{@intFromPtr(raw)});
},
.slice => {
if (ptrInfo.child == u8) {
if (ptrInfo.is_const)
return std.fmt.bufPrint(&buf, "\"{s}\"", .{raw});
return std.fmt.bufPrint(&buf, "\"{b}\"", .{raw});
}
// it is a regular array
const string: std.ArrayListUnmanaged(u8) = .empty;
const writer = string.writer(allocator);
try writer.writeByte('[');
for (0..raw.len) |i| {
if (i > 0) {
try writer.writeAll(',');
if (options.ruleset.pretty)
try writer.writeByte(' ');
}
const value = raw[i];
const str = try stringify(value, options);
try writer.writeAll(str);
}
try writer.writeByte(']');
return string.toOwnedSlice();
},
else => return error.TypeError,
},
.@"union" => |unionInfo| {
if (unionInfo.tag_type) |tag| {
inline for (unionInfo.fields) |field| {
if (field.name == @tagName(tag)) {
const value = @field(raw, field.name);
if (@typeInfo(field.type) == .pointer and field.type == []const u8) {
// idk
return std.fmt.bufPrint(&buf, "\"{s}\"", .{value});
} else {
return stringify(value, options);
}
}
return error.TypeError;
}
unreachable;
}
unreachable; // union has no tag
},
else => |t| @compileError("Error on " ++ @tagName(t)),
}
}
test stringify {
const UserFlags = packed struct {
is_cool: bool = false,
is_friendly: bool = false,
};
const UserSchema = struct {
age: f64,
name: []const u8,
admin: bool,
flags: UserFlags,
@"union": union {
hi: bool,
bye: f64,
n128: []const u8,
pub fn stringify(_: anytype, comptime options: Options) ![]const u8 {
_ = options; // unused
return "anything here";
}
},
@"enum": enum { hello, world },
many: []const u8,
epicptr: *const u8,
};
const e: []const u8 = "epic pointer";
const user = UserSchema{
.age = 15.0,
.name = "Yuzu",
.admin = true,
.flags = UserFlags{ .is_cool = true, .is_friendly = false },
.@"union" = .{ .hi = true },
.@"enum" = .world,
.many = "hello",
.epicptr = @ptrCast(e[0..1]),
};
const options = Options{
.max_buffer_size = 1024,
.ruleset = Ruleset.Chill,
.indent = 2,
};
const str = try prettyStringify(user, options);
std.debug.print("Stringified user: {s}\n", .{str});
}