zig/lib/std/meta/trait.zig
2019-12-11 02:08:33 -05:00

349 lines
9.8 KiB
Zig

const std = @import("../std.zig");
const builtin = @import("builtin");
const mem = std.mem;
const debug = std.debug;
const testing = std.testing;
const warn = debug.warn;
const meta = @import("../meta.zig");
//This is necessary if we want to return generic functions directly because of how the
// the type erasure works. see: #1375
fn traitFnWorkaround(comptime T: type) bool {
return false;
}
pub const TraitFn = @TypeOf(traitFnWorkaround);
//////Trait generators
//Need TraitList because compiler can't do varargs at comptime yet
pub const TraitList = []const TraitFn;
pub fn multiTrait(comptime traits: TraitList) TraitFn {
const Closure = struct {
pub fn trait(comptime T: type) bool {
inline for (traits) |t|
if (!t(T)) return false;
return true;
}
};
return Closure.trait;
}
test "std.meta.trait.multiTrait" {
const Vector2 = struct {
const MyType = @This();
x: u8,
y: u8,
pub fn add(self: MyType, other: MyType) MyType {
return MyType{
.x = self.x + other.x,
.y = self.y + other.y,
};
}
};
const isVector = multiTrait(&[_]TraitFn{
hasFn("add"),
hasField("x"),
hasField("y"),
});
testing.expect(isVector(Vector2));
testing.expect(!isVector(u8));
}
pub fn hasFn(comptime name: []const u8) TraitFn {
const Closure = struct {
pub fn trait(comptime T: type) bool {
if (!comptime isContainer(T)) return false;
if (!comptime @hasDecl(T, name)) return false;
const DeclType = @TypeOf(@field(T, name));
const decl_type_id = @typeId(DeclType);
return decl_type_id == builtin.TypeId.Fn;
}
};
return Closure.trait;
}
test "std.meta.trait.hasFn" {
const TestStruct = struct {
pub fn useless() void {}
};
testing.expect(hasFn("useless")(TestStruct));
testing.expect(!hasFn("append")(TestStruct));
testing.expect(!hasFn("useless")(u8));
}
pub fn hasField(comptime name: []const u8) TraitFn {
const Closure = struct {
pub fn trait(comptime T: type) bool {
const info = @typeInfo(T);
const fields = switch (info) {
builtin.TypeId.Struct => |s| s.fields,
builtin.TypeId.Union => |u| u.fields,
builtin.TypeId.Enum => |e| e.fields,
else => return false,
};
inline for (fields) |field| {
if (mem.eql(u8, field.name, name)) return true;
}
return false;
}
};
return Closure.trait;
}
test "std.meta.trait.hasField" {
const TestStruct = struct {
value: u32,
};
testing.expect(hasField("value")(TestStruct));
testing.expect(!hasField("value")(*TestStruct));
testing.expect(!hasField("x")(TestStruct));
testing.expect(!hasField("x")(**TestStruct));
testing.expect(!hasField("value")(u8));
}
pub fn is(comptime id: builtin.TypeId) TraitFn {
const Closure = struct {
pub fn trait(comptime T: type) bool {
return id == @typeId(T);
}
};
return Closure.trait;
}
test "std.meta.trait.is" {
testing.expect(is(builtin.TypeId.Int)(u8));
testing.expect(!is(builtin.TypeId.Int)(f32));
testing.expect(is(builtin.TypeId.Pointer)(*u8));
testing.expect(is(builtin.TypeId.Void)(void));
testing.expect(!is(builtin.TypeId.Optional)(anyerror));
}
pub fn isPtrTo(comptime id: builtin.TypeId) TraitFn {
const Closure = struct {
pub fn trait(comptime T: type) bool {
if (!comptime isSingleItemPtr(T)) return false;
return id == @typeId(meta.Child(T));
}
};
return Closure.trait;
}
test "std.meta.trait.isPtrTo" {
testing.expect(!isPtrTo(builtin.TypeId.Struct)(struct {}));
testing.expect(isPtrTo(builtin.TypeId.Struct)(*struct {}));
testing.expect(!isPtrTo(builtin.TypeId.Struct)(**struct {}));
}
///////////Strait trait Fns
//@TODO:
// Somewhat limited since we can't apply this logic to normal variables, fields, or
// Fns yet. Should be isExternType?
pub fn isExtern(comptime T: type) bool {
const Extern = builtin.TypeInfo.ContainerLayout.Extern;
const info = @typeInfo(T);
return switch (info) {
builtin.TypeId.Struct => |s| s.layout == Extern,
builtin.TypeId.Union => |u| u.layout == Extern,
builtin.TypeId.Enum => |e| e.layout == Extern,
else => false,
};
}
test "std.meta.trait.isExtern" {
const TestExStruct = extern struct {};
const TestStruct = struct {};
testing.expect(isExtern(TestExStruct));
testing.expect(!isExtern(TestStruct));
testing.expect(!isExtern(u8));
}
pub fn isPacked(comptime T: type) bool {
const Packed = builtin.TypeInfo.ContainerLayout.Packed;
const info = @typeInfo(T);
return switch (info) {
builtin.TypeId.Struct => |s| s.layout == Packed,
builtin.TypeId.Union => |u| u.layout == Packed,
builtin.TypeId.Enum => |e| e.layout == Packed,
else => false,
};
}
test "std.meta.trait.isPacked" {
const TestPStruct = packed struct {};
const TestStruct = struct {};
testing.expect(isPacked(TestPStruct));
testing.expect(!isPacked(TestStruct));
testing.expect(!isPacked(u8));
}
pub fn isUnsignedInt(comptime T: type) bool {
return switch (@typeId(T)) {
builtin.TypeId.Int => !@typeInfo(T).Int.is_signed,
else => false,
};
}
test "isUnsignedInt" {
testing.expect(isUnsignedInt(u32) == true);
testing.expect(isUnsignedInt(comptime_int) == false);
testing.expect(isUnsignedInt(i64) == false);
testing.expect(isUnsignedInt(f64) == false);
}
pub fn isSignedInt(comptime T: type) bool {
return switch (@typeId(T)) {
builtin.TypeId.ComptimeInt => true,
builtin.TypeId.Int => @typeInfo(T).Int.is_signed,
else => false,
};
}
test "isSignedInt" {
testing.expect(isSignedInt(u32) == false);
testing.expect(isSignedInt(comptime_int) == true);
testing.expect(isSignedInt(i64) == true);
testing.expect(isSignedInt(f64) == false);
}
pub fn isSingleItemPtr(comptime T: type) bool {
if (comptime is(builtin.TypeId.Pointer)(T)) {
const info = @typeInfo(T);
return info.Pointer.size == builtin.TypeInfo.Pointer.Size.One;
}
return false;
}
test "std.meta.trait.isSingleItemPtr" {
const array = [_]u8{0} ** 10;
testing.expect(isSingleItemPtr(@TypeOf(&array[0])));
testing.expect(!isSingleItemPtr(@TypeOf(array)));
testing.expect(!isSingleItemPtr(@TypeOf(array[0..1])));
}
pub fn isManyItemPtr(comptime T: type) bool {
if (comptime is(builtin.TypeId.Pointer)(T)) {
const info = @typeInfo(T);
return info.Pointer.size == builtin.TypeInfo.Pointer.Size.Many;
}
return false;
}
test "std.meta.trait.isManyItemPtr" {
const array = [_]u8{0} ** 10;
const mip = @ptrCast([*]const u8, &array[0]);
testing.expect(isManyItemPtr(@TypeOf(mip)));
testing.expect(!isManyItemPtr(@TypeOf(array)));
testing.expect(!isManyItemPtr(@TypeOf(array[0..1])));
}
pub fn isSlice(comptime T: type) bool {
if (comptime is(builtin.TypeId.Pointer)(T)) {
const info = @typeInfo(T);
return info.Pointer.size == builtin.TypeInfo.Pointer.Size.Slice;
}
return false;
}
test "std.meta.trait.isSlice" {
const array = [_]u8{0} ** 10;
testing.expect(isSlice(@TypeOf(array[0..])));
testing.expect(!isSlice(@TypeOf(array)));
testing.expect(!isSlice(@TypeOf(&array[0])));
}
pub fn isIndexable(comptime T: type) bool {
if (comptime is(builtin.TypeId.Pointer)(T)) {
const info = @typeInfo(T);
if (info.Pointer.size == builtin.TypeInfo.Pointer.Size.One) {
if (comptime is(builtin.TypeId.Array)(meta.Child(T))) return true;
return false;
}
return true;
}
return comptime is(builtin.TypeId.Array)(T);
}
test "std.meta.trait.isIndexable" {
const array = [_]u8{0} ** 10;
const slice = array[0..];
testing.expect(isIndexable(@TypeOf(array)));
testing.expect(isIndexable(@TypeOf(&array)));
testing.expect(isIndexable(@TypeOf(slice)));
testing.expect(!isIndexable(meta.Child(@TypeOf(slice))));
}
pub fn isNumber(comptime T: type) bool {
return switch (@typeId(T)) {
builtin.TypeId.Int, builtin.TypeId.Float, builtin.TypeId.ComptimeInt, builtin.TypeId.ComptimeFloat => true,
else => false,
};
}
test "std.meta.trait.isNumber" {
const NotANumber = struct {
number: u8,
};
testing.expect(isNumber(u32));
testing.expect(isNumber(f32));
testing.expect(isNumber(u64));
testing.expect(isNumber(@TypeOf(102)));
testing.expect(isNumber(@TypeOf(102.123)));
testing.expect(!isNumber([]u8));
testing.expect(!isNumber(NotANumber));
}
pub fn isConstPtr(comptime T: type) bool {
if (!comptime is(builtin.TypeId.Pointer)(T)) return false;
const info = @typeInfo(T);
return info.Pointer.is_const;
}
test "std.meta.trait.isConstPtr" {
var t = @as(u8, 0);
const c = @as(u8, 0);
testing.expect(isConstPtr(*const @TypeOf(t)));
testing.expect(isConstPtr(@TypeOf(&c)));
testing.expect(!isConstPtr(*@TypeOf(t)));
testing.expect(!isConstPtr(@TypeOf(6)));
}
pub fn isContainer(comptime T: type) bool {
const info = @typeInfo(T);
return switch (info) {
builtin.TypeId.Struct => true,
builtin.TypeId.Union => true,
builtin.TypeId.Enum => true,
else => false,
};
}
test "std.meta.trait.isContainer" {
const TestStruct = struct {};
const TestUnion = union {
a: void,
};
const TestEnum = enum {
A,
B,
};
testing.expect(isContainer(TestStruct));
testing.expect(isContainer(TestUnion));
testing.expect(isContainer(TestEnum));
testing.expect(!isContainer(u8));
}