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Make Function closures only accept a pointer context

This commit is contained in:
kayomn 2022-11-02 11:27:10 +00:00
parent d49608f7bb
commit eb4a758251
2 changed files with 21 additions and 20 deletions
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10
src/core/io.zig
View File

@ -69,7 +69,7 @@ pub const Allocator = union (enum) {
/// Closure that captures a reference to readable resources like block devices, memory buffers,
/// network sockets, and more.
///
pub const Reader = meta.Function(@sizeOf(usize), []u8, usize);
pub const Reader = meta.Function([]u8, usize);
///
/// Returns a state machine for lazily computing all `Element` components of a given source input
@ -187,7 +187,7 @@ test "Spliterator of string literals" {
/// Closure that captures a reference to writable resources like block devices, memory buffers,
/// network sockets, and more.
///
pub const Writer = meta.Function(@sizeOf(usize), []const u8, usize);
pub const Writer = meta.Function([]const u8, usize);
///
/// Returns a sliced reference of the raw bytes in `pointer`.
@ -383,8 +383,10 @@ test "Data swapping" {
/// sent somewhere for whatever reason.
///
pub fn nullWriter() Writer {
return Writer.capture(@as(usize, 0), struct {
fn write(_: usize, buffer: []const u8) usize {
var dummy: usize = 0;
return Writer.capture(&dummy, struct {
fn write(_: *usize, buffer: []const u8) usize {
return buffer.len;
}
}.write);

31
src/core/meta.zig
View File

@ -13,10 +13,10 @@ pub fn FnReturn(comptime Fn: type) type {
/// Returns a single-input single-output closure type where `In` represents the input type, `Out`
/// represents the output type, and `captures_size` represents the size of the closure context.
///
pub fn Function(comptime captures_size: usize, comptime In: type, comptime Out: type) type {
pub fn Function(comptime In: type, comptime Out: type) type {
return struct {
callErased: fn (*anyopaque, In) Out,
context: [captures_size]u8,
context: *anyopaque,
///
/// Function type.
@ -27,37 +27,36 @@ pub fn Function(comptime captures_size: usize, comptime In: type, comptime Out:
/// Invokes `self` with `input`, producing a result according to the current context data.
///
pub fn call(self: *Self, input: In) Out {
return self.callErased(&self.context, input);
return self.callErased(self.context, input);
}
///
/// Creates a new [Self] by capturing the `captures` value as the context and `invoke` as
/// the as the behavior executed when [call] or [callErased] is called.
/// Creates a new [Self] by capturing the `context` value as the capture context and
/// `invoke` as the behavior executed when [call] or [callErased] is called.
///
/// The newly created [Self] is returned.
///
pub fn capture(captures: anytype, comptime invoke: fn (@TypeOf(captures), In) Out) Self {
const Captures = @TypeOf(captures);
pub fn capture(context: anytype, comptime invoke: fn (@TypeOf(context), In) Out) Self {
const Context = @TypeOf(context);
if (@sizeOf(Captures) > captures_size)
@compileError("`captures` exceeds the size limit of the capture context");
switch (@typeInfo(Context)) {
.Pointer => |info| if (info.size == .Slice)
@compileError("`context` cannot be a slice"),
const captures_align = @alignOf(Captures);
else => @compileError("`context` must be a pointer"),
}
var function = Self{
.context = undefined,
.context = @ptrCast(*anyopaque, context),
.callErased = struct {
fn callErased(erased: *anyopaque, input: In) Out {
return invoke(if (Captures == void) {} else @ptrCast(*Captures,
@alignCast(@alignOf(Captures), erased)).*, input);
return invoke(@ptrCast(*Context, @alignCast(
@alignOf(Context), erased)).*, input);
}
}.callErased,
};
if (Captures != void)
@ptrCast(*Captures, @alignCast(captures_align, &function.context)).* = captures;
return function;
}
};