parse

pub fn parse(args: ParseOptions) !Query {
    var dummy_diags: ParseOptions.Diagnostics = undefined;
    const diags = args.diagnostics orelse &dummy_diags;

    var result: Query = .{
        .dynamic_linker = if (args.dynamic_linker) |dynamic_linker| .init(dynamic_linker) else null,
    };

    var it = mem.splitScalar(u8, args.arch_os_abi, '-');
    const arch_name = it.first();
    const arch_is_native = mem.eql(u8, arch_name, "native");
    if (!arch_is_native) {
        result.cpu_arch = std.meta.stringToEnum(Target.Cpu.Arch, arch_name) orelse {
            diags.unknown_architecture_name = arch_name;
            return error.UnknownArchitecture;
        };
    }
    const arch = result.cpu_arch orelse builtin.cpu.arch;
    diags.arch = arch;

    if (it.next()) |os_text| {
        try parseOs(&result, diags, os_text);
    } else if (!arch_is_native) {
        return error.MissingOperatingSystem;
    }

    const opt_abi_text = it.next();
    if (opt_abi_text) |abi_text| {
        var abi_it = mem.splitScalar(u8, abi_text, '.');
        const abi = std.meta.stringToEnum(Target.Abi, abi_it.first()) orelse
            return error.UnknownApplicationBinaryInterface;
        result.abi = abi;
        diags.abi = abi;

        const abi_ver_text = abi_it.rest();
        if (abi_it.next() != null) {
            if (abi.isGnu()) {
                result.glibc_version = parseVersion(abi_ver_text) catch |err| switch (err) {
                    error.Overflow => return error.InvalidAbiVersion,
                    error.InvalidVersion => return error.InvalidAbiVersion,
                };
            } else if (abi.isAndroid()) {
                result.android_api_level = std.fmt.parseUnsigned(u32, abi_ver_text, 10) catch |err| switch (err) {
                    error.InvalidCharacter => return error.InvalidVersion,
                    error.Overflow => |e| return e,
                };
            } else {
                return error.InvalidAbiVersion;
            }
        }
    }

    if (it.next() != null) return error.UnexpectedExtraField;

    if (args.cpu_features) |cpu_features| {
        const all_features = arch.allFeaturesList();
        var index: usize = 0;
        while (index < cpu_features.len and
            cpu_features[index] != '+' and
            cpu_features[index] != '-')
        {
            index += 1;
        }
        const cpu_name = cpu_features[0..index];
        diags.cpu_name = cpu_name;

        const add_set = &result.cpu_features_add;
        const sub_set = &result.cpu_features_sub;
        if (mem.eql(u8, cpu_name, "native")) {
            result.cpu_model = .native;
        } else if (mem.eql(u8, cpu_name, "baseline")) {
            result.cpu_model = .baseline;
        } else {
            result.cpu_model = .{ .explicit = arch.parseCpuModel(cpu_name) orelse return error.UnknownCpuModel };
        }

        while (index < cpu_features.len) {
            const op = cpu_features[index];
            const set = switch (op) {
                '+' => add_set,
                '-' => sub_set,
                else => unreachable,
            };
            index += 1;
            const start = index;
            while (index < cpu_features.len and
                cpu_features[index] != '+' and
                cpu_features[index] != '-')
            {
                index += 1;
            }
            const feature_name = cpu_features[start..index];
            for (all_features, 0..) |feature, feat_index_usize| {
                const feat_index = @as(Target.Cpu.Feature.Set.Index, @intCast(feat_index_usize));
                if (mem.eql(u8, feature_name, feature.name)) {
                    set.addFeature(feat_index);
                    break;
                }
            } else {
                diags.unknown_feature_name = feature_name;
                return error.UnknownCpuFeature;
            }
        }
    }

    if (args.object_format) |ofmt_name| {
        result.ofmt = std.meta.stringToEnum(Target.ObjectFormat, ofmt_name) orelse
            return error.UnknownObjectFormat;
    }

    return result;
}