Work on deserialization refactor
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2 changed files with 378 additions and 0 deletions
376
src/util/deserialize.zig
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376
src/util/deserialize.zig
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@ -0,0 +1,376 @@
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const std = @import("std");
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const util = @import("./lib.zig");
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const FieldRef = []const []const u8;
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const QueryStringOptions = struct {
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fn isScalar(comptime T: type) bool {
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if (comptime std.meta.trait.is(.Optional)(T) and isScalar(std.meta.Child(T))) return true;
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if (comptime std.meta.trait.isZigString(T)) return true;
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if (comptime std.meta.trait.isIntegral(T)) return true;
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if (comptime std.meta.trait.isFloat(T)) return true;
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if (comptime std.meta.trait.is(.Enum)(T)) return true;
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if (comptime std.meta.trait.is(.EnumLiteral)(T)) return true;
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if (comptime std.meta.trait.hasFn("parse")(T)) return true;
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if (T == bool) return true;
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return false;
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}
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const embed_unions = true;
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const ParsedField = ?[]const u8;
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fn deserializeScalar(comptime T: type, maybe_value: ParsedField) !T {
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const is_optional = comptime std.meta.trait.is(.Optional)(T);
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if (maybe_value) |value| {
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const Eff = if (is_optional) std.meta.Child(T) else T;
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// Treat all empty values as nulls if possible
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if (value.len == 0 and is_optional) return null;
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// TODO:
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//const decoded = try decodeString(alloc, value);
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const decoded = value;
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if (comptime std.meta.trait.isZigString(Eff)) return decoded;
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// TOOD:
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//defer alloc.free(decoded);
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if (comptime std.meta.trait.isIntegral(Eff)) return try std.fmt.parseInt(Eff, decoded, 0);
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if (comptime std.meta.trait.isFloat(Eff)) return try std.fmt.parseFloat(Eff, decoded);
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if (comptime std.meta.trait.is(.Enum)(Eff)) {
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//_ = std.ascii.lowerString(decoded, decoded);
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return std.meta.stringToEnum(Eff, decoded) orelse return error.InvalidEnumValue;
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}
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if (Eff == bool) {
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//_ = std.ascii.lowerString(decoded, decoded);
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return bool_map.get(decoded) orelse return error.InvalidBool;
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}
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if (comptime std.meta.trait.hasFn("parse")(Eff)) return try Eff.parse(decoded);
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@compileError("Invalid type " ++ @typeName(T));
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} else {
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// Parameter is present, but no associated value
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return if (is_optional)
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null
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else if (T == bool)
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true
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else
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error.MissingValue;
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}
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}
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};
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const FormDataField = struct {
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filename: ?[]const u8 = null,
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charset: ?[]const u8 = null,
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value: []const u8,
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};
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const FormFile = struct {
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filename: []const u8,
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value: []const u8,
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};
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const FormDataOptions = struct {
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const embed_unions = true;
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fn isScalar(comptime T: type) bool {
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if (comptime std.meta.trait.is(.Optional)(T) and isScalar(std.meta.Child(T))) return true;
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if (comptime std.meta.trait.isZigString(T)) return true;
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if (comptime std.meta.trait.isIntegral(T)) return true;
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if (comptime std.meta.trait.isFloat(T)) return true;
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if (comptime std.meta.trait.is(.Enum)(T)) return true;
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if (comptime std.meta.trait.is(.EnumLiteral)(T)) return true;
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if (comptime std.meta.trait.hasFn("parse")(T)) return true;
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if (T == bool) return true;
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return false;
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}
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const ParsedField = FormDataField;
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fn deserializeScalar(comptime T: type, field: FormDataField) !T {
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// TODO: allocation??
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if (T == FormFile) {
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return FormFile{
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.filename = field.filename orelse "untitled",
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.data = field.value,
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};
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}
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const decoded = field.value;
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if (comptime std.meta.trait.isZigString(T)) return decoded;
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// TOOD:
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//defer alloc.free(decoded);
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if (comptime std.meta.trait.isIntegral(T)) return try std.fmt.parseInt(T, decoded, 0);
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if (comptime std.meta.trait.isFloat(T)) return try std.fmt.parseFloat(T, decoded);
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if (comptime std.meta.trait.is(.Enum)(T)) {
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//_ = std.ascii.lowerString(decoded, decoded);
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return std.meta.stringToEnum(T, decoded) orelse return error.InvalidEnumValue;
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}
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if (T == bool) {
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//_ = std.ascii.lowerString(decoded, decoded);
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return bool_map.get(decoded) orelse return error.InvalidBool;
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}
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if (comptime std.meta.trait.hasFn("parse")(T)) return try T.parse(decoded);
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@compileError("Invalid type " ++ @typeName(T));
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}
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};
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fn getRecursiveFieldList(comptime T: type, comptime prefix: FieldRef, comptime options: SerializationOptions) []const FieldRef {
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comptime {
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if (std.meta.trait.is(.Union)(T) and prefix.len == 0 and options.embed_unions) {
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@compileError("Cannot embed a union into nothing");
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}
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if (options.isScalar(T)) return &.{prefix};
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if (std.meta.trait.is(.Optional)(T)) return getRecursiveFieldList(std.meta.Child(T), prefix, options);
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const eff_prefix: FieldRef = if (std.meta.trait.is(.Union)(T) and options.embed_unions)
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prefix[0 .. prefix.len - 1]
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else
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prefix;
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var fields: []const FieldRef = &.{};
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for (std.meta.fields(T)) |f| {
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const new_prefix = eff_prefix ++ &[_][]const u8{f.name};
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const F = f.field_type;
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fields = fields ++ getRecursiveFieldList(F, new_prefix, options);
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}
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return fields;
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}
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}
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const SerializationOptions = struct {
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embed_unions: bool = true,
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isScalar: fn (type) bool = QueryStringOptions.isScalar,
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};
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fn Intermediary(comptime Result: type, comptime From: type, comptime options: SerializationOptions) type {
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const field_refs = getRecursiveFieldList(Result, &.{}, options);
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var fields: [field_refs.len]std.builtin.Type.StructField = undefined;
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for (field_refs) |ref, i| {
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//@compileLog(i, ref, util.comptimeJoin(".", ref));
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fields[i] = .{
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.name = util.comptimeJoin(".", ref),
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.field_type = ?From,
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.default_value = &@as(?From, null),
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.is_comptime = false,
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.alignment = @alignOf(?From),
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};
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}
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return @Type(.{ .Struct = .{
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.layout = .Auto,
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.fields = &fields,
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.decls = &.{},
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.is_tuple = false,
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} });
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}
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pub fn Deserializer(comptime Result: type, comptime From: type) type {
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return DeserializerContext(Result, From, struct {
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const options = SerializationOptions{};
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const deserializeScalar = QueryStringOptions.deserializeScalar;
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const isScalar = QueryStringOptions.isScalar;
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});
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}
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fn DeserializerContext(comptime Result: type, comptime From: type, comptime Context: type) type {
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return struct {
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const Data = Intermediary(Result, From, Context.options);
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data: Data = .{},
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context: Context = .{},
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pub fn setSerializedField(self: *@This(), key: []const u8, value: From) !void {
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const field = std.meta.stringToEnum(std.meta.FieldEnum(Data), key);
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inline for (comptime std.meta.fieldNames(Data)) |field_name| {
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@setEvalBranchQuota(10000);
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const f = comptime std.meta.stringToEnum(std.meta.FieldEnum(Data), field_name);
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if (field == f) {
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@field(self.data, field_name) = value;
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return;
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}
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}
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return error.UnknownField;
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}
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pub fn finish(self: *@This()) !Result {
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return (try self.deserialize(Result, &.{})).?;
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}
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fn getSerializedField(self: *@This(), comptime field_ref: FieldRef) ?From {
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//inline for (comptime std.meta.fieldNames(Data)) |f| @compileLog(f.ptr);
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return @field(self.data, util.comptimeJoin(".", field_ref));
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}
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fn deserialize(self: *@This(), comptime T: type, comptime field_ref: FieldRef) !?T {
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if (comptime Context.isScalar(T)) {
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return try Context.deserializeScalar(T, self.getSerializedField(field_ref) orelse return null);
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}
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switch (@typeInfo(T)) {
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// At most one of any union field can be active at a time, and it is embedded
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// in its parent container
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.Union => |info| {
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var result: ?T = null;
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// TODO: errdefer cleanup
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const union_ref: FieldRef = if (Context.options.embed_unions) field_ref[0 .. field_ref.len - 1] else field_ref;
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inline for (info.fields) |field| {
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const F = field.field_type;
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const new_field_ref = union_ref ++ &[_][]const u8{field.name};
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const maybe_value = try self.deserialize(F, new_field_ref);
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if (maybe_value) |value| {
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// TODO: errdefer cleanup
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if (result != null) return error.DuplicateUnionField;
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result = @unionInit(T, field.name, value);
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}
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}
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return result;
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},
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.Struct => |info| {
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var result: T = undefined;
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var any_explicit = false;
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var any_missing = false;
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inline for (info.fields) |field| {
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const F = field.field_type;
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const new_field_ref = field_ref ++ &[_][]const u8{field.name};
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const maybe_value = try self.deserialize(F, new_field_ref);
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if (maybe_value) |v| {
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@field(result, field.name) = v;
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any_explicit = true;
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} else if (field.default_value) |ptr| {
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if (@sizeOf(F) != 0) {
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@field(result, field.name) = @ptrCast(*const F, @alignCast(field.alignment, ptr)).*;
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}
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} else {
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any_missing = true;
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std.debug.print("\nMissing field {s}\n", .{util.comptimeJoin(".", new_field_ref)});
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//return error.MissingStructField;
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}
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}
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if (any_missing) {
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return if (any_explicit) error.MissingStructField else null;
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}
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return result;
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},
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// Specifically non-scalar optionals
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.Optional => |info| return try self.deserialize(info.child, field_ref),
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else => @compileError("Unsupported type"),
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}
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}
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};
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}
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const bool_map = std.ComptimeStringMap(bool, .{
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.{ "true", true },
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.{ "t", true },
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.{ "yes", true },
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.{ "y", true },
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.{ "1", true },
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.{ "false", false },
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.{ "f", false },
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.{ "no", false },
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.{ "n", false },
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.{ "0", false },
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});
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test {
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const T = struct {
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foo: usize,
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bar: bool,
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};
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const TDefault = struct {
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foo: usize = 0,
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bar: bool = false,
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};
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_ = TDefault;
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{
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var ds = Deserializer(T, []const u8){};
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try ds.setSerializedField("foo", "123");
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try ds.setSerializedField("bar", "true");
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try std.testing.expectEqual(T{ .foo = 123, .bar = true }, try ds.finish());
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}
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{
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var ds = Deserializer(T, []const u8){};
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try ds.setSerializedField("foo", "123");
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try std.testing.expectError(error.MissingStructField, ds.finish());
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}
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//const int = Intermediary(T, QueryStringOptions){
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//.age = "123",
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//.@"sub_struct.foo" = "abc",
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//.@"sub_struct.bar" = "abc",
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//.@"foo_union" = "abc",
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//};
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//std.debug.print("{any}\n", .{int});
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//std.debug.print("{any}\n", .{deserialize(T, QueryStringOptions, &.{}, int)});
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//const int2 = Intermediary(T, FormDataOptions){
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//.age = .{ .value = "123" },
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//.@"sub_struct.foo" = .{ .value = "123" },
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//.@"sub_struct.bar" = .{ .value = "123" },
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////.@"foo_union" = .{
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//.value = "abc",
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//},
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//};
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//std.debug.print("{any}\n", .{int2});
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//
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// const T = struct {
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// age: usize,
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// sub_struct: ?struct {
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// x: union(enum) {
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// foo: []const u8,
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// bar: []const u8,
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// },
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// },
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// sub_union: union(enum) {
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// foo_union: []const u8,
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// bar_union: []const u8,
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// },
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// time: ?@import("./DateTime.zig"),
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// };
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// inline for (comptime getRecursiveFieldList(T, &.{}, .{})) |list| {
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// std.debug.print("{s}\n", .{util.comptimeJoin(".", list)});
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// }
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// // var ds = Deserializer(struct {
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// age: usize,
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// sub_struct: ?struct {
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// x: union(enum) {
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// foo: []const u8,
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// bar: []const u8,
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// },
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// },
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// sub_union: union(enum) {
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// foo_union: []const u8,
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// bar_union: []const u8,
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// },
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// time: ?@import("./DateTime.zig"),
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// }, []const u8){ .context = .{} };
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//try ds.setSerializedField("age", "123");
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//try ds.setSerializedField("foo_union", "123");
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//try ds.setSerializedField("sub_struct.foo", "123");
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//try ds.setSerializedField("sub_struct.bar", "123");
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//std.debug.print("{any}\n", .{try ds.finish()});
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}
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@ -8,6 +8,8 @@ pub const Url = @import("./Url.zig");
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pub const PathIter = iters.PathIter;
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pub const QueryIter = iters.QueryIter;
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pub const SqlStmtIter = iters.Separator(';');
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pub const deserialize = @import("./deserialize.zig");
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pub const Deserializer = deserialize.Deserializer;
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/// Joins an array of strings, prefixing every entry with `prefix`,
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/// and putting `separator` in between each pair
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