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Processed review comments. Updated documentation, used the typinfo for field access, generate compile error on allowzero and set C poitners to null

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This commit is contained in:
Bas van den Berg 2020-02-24 22:15:04 +01:00
parent 195195d238
commit f7aa4f5280
1 changed files with 20 additions and 16 deletions
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24
lib/std/mem.zig
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@ -276,8 +276,12 @@ pub fn set(comptime T: type, dest: []T, value: T) void {
d.* = value;
}
/// Generally, Zig users are encouraged to explicitly initialize all fields of a struct explicitly rather than using this function.
/// However, it is recognized that there are sometimes use cases for initializing all fields to a "zero" value. For example, when
/// interfacing with a C API where this practice is more common and relied upon. If you are performing code review and see this
/// function used, examine closely - it may be a code smell.
/// Zero initializes the type.
/// This can be used to zero initialize a C-struct.
/// This can be used to zero initialize a any type for which it makes sense. Structs will be initialized recursively.
pub fn zeroes(comptime T: type) T {
switch (@typeInfo(T)) {
.ComptimeInt, .Int, .ComptimeFloat, .Float => {
@ -295,7 +299,7 @@ pub fn zeroes(comptime T: type) T {
.Optional, .Null => {
return null;
},
.Struct => {
.Struct => |struct_info| {
if (@sizeOf(T) == 0) return T{};
if (comptime meta.containerLayout(T) == .Extern) {
var item: T = undefined;
@ -303,26 +307,24 @@ pub fn zeroes(comptime T: type) T {
return item;
} else {
var structure: T = undefined;
comptime var field_i = 0;
inline while (field_i < @memberCount(T)) : (field_i += 1) {
@field(structure, @memberName(T, field_i)) = zeroes(@TypeOf(@field(structure, @memberName(T, field_i))));
inline for (struct_info.fields) |field| {
@field(structure, field.name) = zeroes(@TypeOf(@field(structure, field.name)));
}
return structure;
}
},
.Pointer => |ptr_info| {
if (ptr_info.is_allowzero) {
return null;
} else {
switch (ptr_info.size) {
.Slice => {
return &[_]ptr_info.child{};
},
.One, .Many, .C => {
.C => {
return null;
},
.One, .Many => {
@compileError("Can't set a non nullable pointer to zero.");
},
}
}
},
.Array => |info| {
var array: T = undefined;
@ -372,6 +374,7 @@ test "mem.zeroes" {
const Pointers = struct {
optional: ?*u8,
c_pointer: [*c]u8,
slice: []u8,
};
pointers: Pointers,
@ -397,6 +400,7 @@ test "mem.zeroes" {
testing.expectEqual(@as(f32, 0), b.integral_types.float_32);
testing.expectEqual(@as(f64, 0), b.integral_types.float_64);
testing.expectEqual(@as(?*u8, null), b.pointers.optional);
testing.expectEqual(@as([*c]u8, null), b.pointers.c_pointer);
testing.expectEqual(@as([]u8, &[_]u8{}), b.pointers.slice);
for (b.array) |e| {
testing.expectEqual(@as(u32, 0), e);