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zig/lib/std/mem.zig
Vexu 06c08e5219
std.mem.zeroes use std.mem.set instead of @memset 
stage1 comptime is not smart enough to remeber the size of the casted
item which leads to out of bounds errors.
2020-07-16 17:05:14 +03:00

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const std = @import("std.zig");
const debug = std.debug;
const assert = debug.assert;
const math = std.math;
const builtin = @import("builtin");
const mem = @This();
const meta = std.meta;
const trait = meta.trait;
const testing = std.testing;
// https://github.com/ziglang/zig/issues/2564
pub const page_size = switch (builtin.arch) {
.wasm32, .wasm64 => 64 * 1024,
else => 4 * 1024,
};
pub const Allocator = struct {
pub const Error = error{OutOfMemory};
/// Attempt to allocate at least `len` bytes aligned to `ptr_align`.
///
/// If `len_align` is `0`, then the length returned MUST be exactly `len` bytes,
/// otherwise, the length must be aligned to `len_align`.
///
/// `len` must be greater than or equal to `len_align` and must be aligned by `len_align`.
allocFn: fn (self: *Allocator, len: usize, ptr_align: u29, len_align: u29) Error![]u8,
/// Attempt to expand or shrink memory in place. `buf.len` must equal the most recent
/// length returned by `allocFn` or `resizeFn`.
///
/// Passing a `new_len` of 0 frees and invalidates the buffer such that it can no
/// longer be passed to `resizeFn`.
///
/// error.OutOfMemory can only be returned if `new_len` is greater than `buf.len`.
/// If `buf` cannot be expanded to accomodate `new_len`, then the allocation MUST be
/// unmodified and error.OutOfMemory MUST be returned.
///
/// If `len_align` is `0`, then the length returned MUST be exactly `len` bytes,
/// otherwise, the length must be aligned to `len_align`.
///
/// `new_len` must be greater than or equal to `len_align` and must be aligned by `len_align`.
resizeFn: fn (self: *Allocator, buf: []u8, new_len: usize, len_align: u29) Error!usize,
pub fn callAllocFn(self: *Allocator, new_len: usize, alignment: u29, len_align: u29) Error![]u8 {
return self.allocFn(self, new_len, alignment, len_align);
}
pub fn callResizeFn(self: *Allocator, buf: []u8, new_len: usize, len_align: u29) Error!usize {
return self.resizeFn(self, buf, new_len, len_align);
}
/// Set to resizeFn if in-place resize is not supported.
pub fn noResize(self: *Allocator, buf: []u8, new_len: usize, len_align: u29) Error!usize {
if (new_len > buf.len)
return error.OutOfMemory;
return new_len;
}
/// Call `resizeFn`, but caller guarantees that `new_len` <= `buf.len` meaning
/// error.OutOfMemory should be impossible.
pub fn shrinkBytes(self: *Allocator, buf: []u8, new_len: usize, len_align: u29) usize {
assert(new_len <= buf.len);
return self.callResizeFn(buf, new_len, len_align) catch unreachable;
}
/// Realloc is used to modify the size or alignment of an existing allocation,
/// as well as to provide the allocator with an opportunity to move an allocation
/// to a better location.
/// When the size/alignment is greater than the previous allocation, this function
/// returns `error.OutOfMemory` when the requested new allocation could not be granted.
/// When the size/alignment is less than or equal to the previous allocation,
/// this function returns `error.OutOfMemory` when the allocator decides the client
/// would be better off keeping the extra alignment/size. Clients will call
/// `callResizeFn` when they require the allocator to track a new alignment/size,
/// and so this function should only return success when the allocator considers
/// the reallocation desirable from the allocator's perspective.
/// As an example, `std.ArrayList` tracks a "capacity", and therefore can handle
/// reallocation failure, even when `new_n` <= `old_mem.len`. A `FixedBufferAllocator`
/// would always return `error.OutOfMemory` for `reallocFn` when the size/alignment
/// is less than or equal to the old allocation, because it cannot reclaim the memory,
/// and thus the `std.ArrayList` would be better off retaining its capacity.
/// When `reallocFn` returns,
/// `return_value[0..min(old_mem.len, new_byte_count)]` must be the same
/// as `old_mem` was when `reallocFn` is called. The bytes of
/// `return_value[old_mem.len..]` have undefined values.
/// The returned slice must have its pointer aligned at least to `new_alignment` bytes.
fn reallocBytes(
self: *Allocator,
/// Guaranteed to be the same as what was returned from most recent call to
/// `allocFn` or `resizeFn`.
/// If `old_mem.len == 0` then this is a new allocation and `new_byte_count`
/// is guaranteed to be >= 1.
old_mem: []u8,
/// If `old_mem.len == 0` then this is `undefined`, otherwise:
/// Guaranteed to be the same as what was passed to `allocFn`.
/// Guaranteed to be >= 1.
/// Guaranteed to be a power of 2.
old_alignment: u29,
/// If `new_byte_count` is 0 then this is a free and it is guaranteed that
/// `old_mem.len != 0`.
new_byte_count: usize,
/// Guaranteed to be >= 1.
/// Guaranteed to be a power of 2.
/// Returned slice's pointer must have this alignment.
new_alignment: u29,
/// 0 indicates the length of the slice returned MUST match `new_byte_count` exactly
/// non-zero means the length of the returned slice must be aligned by `len_align`
/// `new_len` must be aligned by `len_align`
len_align: u29,
) Error![]u8 {
if (old_mem.len == 0) {
const new_mem = try self.callAllocFn(new_byte_count, new_alignment, len_align);
@memset(new_mem.ptr, undefined, new_byte_count);
return new_mem;
}
if (isAligned(@ptrToInt(old_mem.ptr), new_alignment)) {
if (new_byte_count <= old_mem.len) {
const shrunk_len = self.shrinkBytes(old_mem, new_byte_count, len_align);
return old_mem.ptr[0..shrunk_len];
}
if (self.callResizeFn(old_mem, new_byte_count, len_align)) |resized_len| {
assert(resized_len >= new_byte_count);
@memset(old_mem.ptr + new_byte_count, undefined, resized_len - new_byte_count);
return old_mem.ptr[0..resized_len];
} else |_| {}
}
if (new_byte_count <= old_mem.len and new_alignment <= old_alignment) {
return error.OutOfMemory;
}
return self.moveBytes(old_mem, new_byte_count, new_alignment, len_align);
}
/// Move the given memory to a new location in the given allocator to accomodate a new
/// size and alignment.
fn moveBytes(self: *Allocator, old_mem: []u8, new_len: usize, new_alignment: u29, len_align: u29) Error![]u8 {
assert(old_mem.len > 0);
assert(new_len > 0);
const new_mem = try self.callAllocFn(new_len, new_alignment, len_align);
@memcpy(new_mem.ptr, old_mem.ptr, std.math.min(new_len, old_mem.len));
// DISABLED TO AVOID BUGS IN TRANSLATE C
// use './zig build test-translate-c' to reproduce, some of the symbols in the
// generated C code will be a sequence of 0xaa (the undefined value), meaning
// it is printing data that has been freed
//@memset(old_mem.ptr, undefined, old_mem.len);
_ = self.shrinkBytes(old_mem, 0, 0);
return new_mem;
}
/// Returns a pointer to undefined memory.
/// Call `destroy` with the result to free the memory.
pub fn create(self: *Allocator, comptime T: type) Error!*T {
if (@sizeOf(T) == 0) return &(T{});
const slice = try self.alloc(T, 1);
return &slice[0];
}
/// `ptr` should be the return value of `create`, or otherwise
/// have the same address and alignment property.
pub fn destroy(self: *Allocator, ptr: anytype) void {
const T = @TypeOf(ptr).Child;
if (@sizeOf(T) == 0) return;
const non_const_ptr = @intToPtr([*]u8, @ptrToInt(ptr));
_ = self.shrinkBytes(non_const_ptr[0..@sizeOf(T)], 0, 0);
}
/// Allocates an array of `n` items of type `T` and sets all the
/// items to `undefined`. Depending on the Allocator
/// implementation, it may be required to call `free` once the
/// memory is no longer needed, to avoid a resource leak. If the
/// `Allocator` implementation is unknown, then correct code will
/// call `free` when done.
///
/// For allocating a single item, see `create`.
pub fn alloc(self: *Allocator, comptime T: type, n: usize) Error![]T {
return self.alignedAlloc(T, null, n);
}
pub fn allocWithOptions(
self: *Allocator,
comptime Elem: type,
n: usize,
/// null means naturally aligned
comptime optional_alignment: ?u29,
comptime optional_sentinel: ?Elem,
) Error!AllocWithOptionsPayload(Elem, optional_alignment, optional_sentinel) {
if (optional_sentinel) |sentinel| {
const ptr = try self.alignedAlloc(Elem, optional_alignment, n + 1);
ptr[n] = sentinel;
return ptr[0..n :sentinel];
} else {
return self.alignedAlloc(Elem, optional_alignment, n);
}
}
fn AllocWithOptionsPayload(comptime Elem: type, comptime alignment: ?u29, comptime sentinel: ?Elem) type {
if (sentinel) |s| {
return [:s]align(alignment orelse @alignOf(Elem)) Elem;
} else {
return []align(alignment orelse @alignOf(Elem)) Elem;
}
}
/// Allocates an array of `n + 1` items of type `T` and sets the first `n`
/// items to `undefined` and the last item to `sentinel`. Depending on the
/// Allocator implementation, it may be required to call `free` once the
/// memory is no longer needed, to avoid a resource leak. If the
/// `Allocator` implementation is unknown, then correct code will
/// call `free` when done.
///
/// For allocating a single item, see `create`.
///
/// Deprecated; use `allocWithOptions`.
pub fn allocSentinel(self: *Allocator, comptime Elem: type, n: usize, comptime sentinel: Elem) Error![:sentinel]Elem {
return self.allocWithOptions(Elem, n, null, sentinel);
}
/// Deprecated: use `allocAdvanced`
pub fn alignedAlloc(
self: *Allocator,
comptime T: type,
/// null means naturally aligned
comptime alignment: ?u29,
n: usize,
) Error![]align(alignment orelse @alignOf(T)) T {
return self.allocAdvanced(T, alignment, n, .exact);
}
const Exact = enum { exact, at_least };
pub fn allocAdvanced(
self: *Allocator,
comptime T: type,
/// null means naturally aligned
comptime alignment: ?u29,
n: usize,
exact: Exact,
) Error![]align(alignment orelse @alignOf(T)) T {
const a = if (alignment) |a| blk: {
if (a == @alignOf(T)) return allocAdvanced(self, T, null, n, exact);
break :blk a;
} else @alignOf(T);
if (n == 0) {
return @as([*]align(a) T, undefined)[0..0];
}
const byte_count = math.mul(usize, @sizeOf(T), n) catch return Error.OutOfMemory;
// TODO The `if (alignment == null)` blocks are workarounds for zig not being able to
// access certain type information about T without creating a circular dependency in async
// functions that heap-allocate their own frame with @Frame(func).
const sizeOfT = if (alignment == null) @intCast(u29, @divExact(byte_count, n)) else @sizeOf(T);
const byte_slice = try self.callAllocFn(byte_count, a, if (exact == .exact) @as(u29, 0) else sizeOfT);
switch (exact) {
.exact => assert(byte_slice.len == byte_count),
.at_least => assert(byte_slice.len >= byte_count),
}
@memset(byte_slice.ptr, undefined, byte_slice.len);
if (alignment == null) {
// This if block is a workaround (see comment above)
return @intToPtr([*]T, @ptrToInt(byte_slice.ptr))[0..@divExact(byte_slice.len, @sizeOf(T))];
} else {
return mem.bytesAsSlice(T, @alignCast(a, byte_slice));
}
}
/// This function requests a new byte size for an existing allocation,
/// which can be larger, smaller, or the same size as the old memory
/// allocation.
/// This function is preferred over `shrink`, because it can fail, even
/// when shrinking. This gives the allocator a chance to perform a
/// cheap shrink operation if possible, or otherwise return OutOfMemory,
/// indicating that the caller should keep their capacity, for example
/// in `std.ArrayList.shrink`.
/// If you need guaranteed success, call `shrink`.
/// If `new_n` is 0, this is the same as `free` and it always succeeds.
pub fn realloc(self: *Allocator, old_mem: anytype, new_n: usize) t: {
const Slice = @typeInfo(@TypeOf(old_mem)).Pointer;
break :t Error![]align(Slice.alignment) Slice.child;
} {
const old_alignment = @typeInfo(@TypeOf(old_mem)).Pointer.alignment;
return self.reallocAdvanced(old_mem, old_alignment, new_n, .exact);
}
pub fn reallocAtLeast(self: *Allocator, old_mem: anytype, new_n: usize) t: {
const Slice = @typeInfo(@TypeOf(old_mem)).Pointer;
break :t Error![]align(Slice.alignment) Slice.child;
} {
const old_alignment = @typeInfo(@TypeOf(old_mem)).Pointer.alignment;
return self.reallocAdvanced(old_mem, old_alignment, new_n, .at_least);
}
// Deprecated: use `reallocAdvanced`
pub fn alignedRealloc(
self: *Allocator,
old_mem: anytype,
comptime new_alignment: u29,
new_n: usize,
) Error![]align(new_alignment) @typeInfo(@TypeOf(old_mem)).Pointer.child {
return self.reallocAdvanced(old_mem, new_alignment, new_n, .exact);
}
/// This is the same as `realloc`, except caller may additionally request
/// a new alignment, which can be larger, smaller, or the same as the old
/// allocation.
pub fn reallocAdvanced(
self: *Allocator,
old_mem: anytype,
comptime new_alignment: u29,
new_n: usize,
exact: Exact,
) Error![]align(new_alignment) @typeInfo(@TypeOf(old_mem)).Pointer.child {
const Slice = @typeInfo(@TypeOf(old_mem)).Pointer;
const T = Slice.child;
if (old_mem.len == 0) {
return self.allocAdvanced(T, new_alignment, new_n, exact);
}
if (new_n == 0) {
self.free(old_mem);
return @as([*]align(new_alignment) T, undefined)[0..0];
}
const old_byte_slice = mem.sliceAsBytes(old_mem);
const byte_count = math.mul(usize, @sizeOf(T), new_n) catch return Error.OutOfMemory;
// Note: can't set shrunk memory to undefined as memory shouldn't be modified on realloc failure
const new_byte_slice = try self.reallocBytes(old_byte_slice, Slice.alignment, byte_count, new_alignment, if (exact == .exact) @as(u29, 0) else @sizeOf(T));
return mem.bytesAsSlice(T, @alignCast(new_alignment, new_byte_slice));
}
/// Prefer calling realloc to shrink if you can tolerate failure, such as
/// in an ArrayList data structure with a storage capacity.
/// Shrink always succeeds, and `new_n` must be <= `old_mem.len`.
/// Returned slice has same alignment as old_mem.
/// Shrinking to 0 is the same as calling `free`.
pub fn shrink(self: *Allocator, old_mem: anytype, new_n: usize) t: {
const Slice = @typeInfo(@TypeOf(old_mem)).Pointer;
break :t []align(Slice.alignment) Slice.child;
} {
const old_alignment = @typeInfo(@TypeOf(old_mem)).Pointer.alignment;
return self.alignedShrink(old_mem, old_alignment, new_n);
}
/// This is the same as `shrink`, except caller may additionally request
/// a new alignment, which must be smaller or the same as the old
/// allocation.
pub fn alignedShrink(
self: *Allocator,
old_mem: anytype,
comptime new_alignment: u29,
new_n: usize,
) []align(new_alignment) @typeInfo(@TypeOf(old_mem)).Pointer.child {
const Slice = @typeInfo(@TypeOf(old_mem)).Pointer;
const T = Slice.child;
if (new_n == old_mem.len)
return old_mem;
assert(new_n < old_mem.len);
assert(new_alignment <= Slice.alignment);
// Here we skip the overflow checking on the multiplication because
// new_n <= old_mem.len and the multiplication didn't overflow for that operation.
const byte_count = @sizeOf(T) * new_n;
const old_byte_slice = mem.sliceAsBytes(old_mem);
@memset(old_byte_slice.ptr + byte_count, undefined, old_byte_slice.len - byte_count);
_ = self.shrinkBytes(old_byte_slice, byte_count, 0);
return old_mem[0..new_n];
}
/// Free an array allocated with `alloc`. To free a single item,
/// see `destroy`.
pub fn free(self: *Allocator, memory: anytype) void {
const Slice = @typeInfo(@TypeOf(memory)).Pointer;
const bytes = mem.sliceAsBytes(memory);
const bytes_len = bytes.len + if (Slice.sentinel != null) @sizeOf(Slice.child) else 0;
if (bytes_len == 0) return;
const non_const_ptr = @intToPtr([*]u8, @ptrToInt(bytes.ptr));
@memset(non_const_ptr, undefined, bytes_len);
_ = self.shrinkBytes(non_const_ptr[0..bytes_len], 0, 0);
}
/// Copies `m` to newly allocated memory. Caller owns the memory.
pub fn dupe(allocator: *Allocator, comptime T: type, m: []const T) ![]T {
const new_buf = try allocator.alloc(T, m.len);
copy(T, new_buf, m);
return new_buf;
}
/// Copies `m` to newly allocated memory, with a null-terminated element. Caller owns the memory.
pub fn dupeZ(allocator: *Allocator, comptime T: type, m: []const T) ![:0]T {
const new_buf = try allocator.alloc(T, m.len + 1);
copy(T, new_buf, m);
new_buf[m.len] = 0;
return new_buf[0..m.len :0];
}
};
/// Detects and asserts if the std.mem.Allocator interface is violated by the caller
/// or the allocator.
pub fn ValidationAllocator(comptime T: type) type {
return struct {
const Self = @This();
allocator: Allocator,
underlying_allocator: T,
pub fn init(allocator: T) @This() {
return .{
.allocator = .{
.allocFn = alloc,
.resizeFn = resize,
},
.underlying_allocator = allocator,
};
}
fn getUnderlyingAllocatorPtr(self: *@This()) *Allocator {
if (T == *Allocator) return self.underlying_allocator;
if (*T == *Allocator) return &self.underlying_allocator;
return &self.underlying_allocator.allocator;
}
pub fn alloc(allocator: *Allocator, n: usize, ptr_align: u29, len_align: u29) Allocator.Error![]u8 {
assert(n > 0);
assert(mem.isValidAlign(ptr_align));
if (len_align != 0) {
assert(mem.isAlignedAnyAlign(n, len_align));
assert(n >= len_align);
}
const self = @fieldParentPtr(@This(), "allocator", allocator);
const result = try self.getUnderlyingAllocatorPtr().callAllocFn(n, ptr_align, len_align);
assert(mem.isAligned(@ptrToInt(result.ptr), ptr_align));
if (len_align == 0) {
assert(result.len == n);
} else {
assert(result.len >= n);
assert(mem.isAlignedAnyAlign(result.len, len_align));
}
return result;
}
pub fn resize(allocator: *Allocator, buf: []u8, new_len: usize, len_align: u29) Allocator.Error!usize {
assert(buf.len > 0);
if (len_align != 0) {
assert(mem.isAlignedAnyAlign(new_len, len_align));
assert(new_len >= len_align);
}
const self = @fieldParentPtr(@This(), "allocator", allocator);
const result = try self.getUnderlyingAllocatorPtr().callResizeFn(buf, new_len, len_align);
if (len_align == 0) {
assert(result == new_len);
} else {
assert(result >= new_len);
assert(mem.isAlignedAnyAlign(result, len_align));
}
return result;
}
pub usingnamespace if (T == *Allocator or !@hasDecl(T, "reset")) struct {} else struct {
pub fn reset(self: *Self) void {
self.underlying_allocator.reset();
}
};
};
}
pub fn validationWrap(allocator: anytype) ValidationAllocator(@TypeOf(allocator)) {
return ValidationAllocator(@TypeOf(allocator)).init(allocator);
}
/// An allocator helper function. Adjusts an allocation length satisfy `len_align`.
/// `full_len` should be the full capacity of the allocation which may be greater
/// than the `len` that was requsted. This function should only be used by allocators
/// that are unaffected by `len_align`.
pub fn alignAllocLen(full_len: usize, alloc_len: usize, len_align: u29) usize {
assert(alloc_len > 0);
assert(alloc_len >= len_align);
assert(full_len >= alloc_len);
if (len_align == 0)
return alloc_len;
const adjusted = alignBackwardAnyAlign(full_len, len_align);
assert(adjusted >= alloc_len);
return adjusted;
}
var failAllocator = Allocator{
.allocFn = failAllocatorAlloc,
.resizeFn = Allocator.noResize,
};
fn failAllocatorAlloc(self: *Allocator, n: usize, alignment: u29, len_align: u29) Allocator.Error![]u8 {
return error.OutOfMemory;
}
test "mem.Allocator basics" {
testing.expectError(error.OutOfMemory, failAllocator.alloc(u8, 1));
testing.expectError(error.OutOfMemory, failAllocator.allocSentinel(u8, 1, 0));
}
/// Copy all of source into dest at position 0.
/// dest.len must be >= source.len.
/// dest.ptr must be <= src.ptr.
pub fn copy(comptime T: type, dest: []T, source: []const T) void {
// TODO instead of manually doing this check for the whole array
// and turning off runtime safety, the compiler should detect loops like
// this and automatically omit safety checks for loops
@setRuntimeSafety(false);
assert(dest.len >= source.len);
for (source) |s, i|
dest[i] = s;
}
/// Copy all of source into dest at position 0.
/// dest.len must be >= source.len.
/// dest.ptr must be >= src.ptr.
pub fn copyBackwards(comptime T: type, dest: []T, source: []const T) void {
// TODO instead of manually doing this check for the whole array
// and turning off runtime safety, the compiler should detect loops like
// this and automatically omit safety checks for loops
@setRuntimeSafety(false);
assert(dest.len >= source.len);
var i = source.len;
while (i > 0) {
i -= 1;
dest[i] = source[i];
}
}
/// Sets all elements of `dest` to `value`.
pub fn set(comptime T: type, dest: []T, value: T) void {
for (dest) |*d|
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 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 => {
return @as(T, 0);
},
.Enum, .EnumLiteral => {
return @intToEnum(T, 0);
},
.Void => {
return {};
},
.Bool => {
return false;
},
.Optional, .Null => {
return null;
},
.Struct => |struct_info| {
if (@sizeOf(T) == 0) return T{};
if (comptime meta.containerLayout(T) == .Extern) {
var item: T = undefined;
set(u8, asBytes(&item), 0);
return item;
} else {
var structure: T = undefined;
inline for (struct_info.fields) |field| {
@field(structure, field.name) = zeroes(@TypeOf(@field(structure, field.name)));
}
return structure;
}
},
.Pointer => |ptr_info| {
switch (ptr_info.size) {
.Slice => {
return &[_]ptr_info.child{};
},
.C => {
return null;
},
.One, .Many => {
@compileError("Can't set a non nullable pointer to zero.");
},
}
},
.Array => |info| {
if (info.sentinel) |sentinel| {
return [_:sentinel]info.child{zeroes(info.child)} ** info.len;
}
return [_]info.child{zeroes(info.child)} ** info.len;
},
.Vector => |info| {
return @splat(info.len, zeroes(info.child));
},
.ErrorUnion,
.ErrorSet,
.Union,
.Fn,
.BoundFn,
.Type,
.NoReturn,
.Undefined,
.Opaque,
.Frame,
.AnyFrame,
=> {
@compileError("Can't set a " ++ @typeName(T) ++ " to zero.");
},
}
}
test "mem.zeroes" {
const C_struct = extern struct {
x: u32,
y: u32,
};
var a = zeroes(C_struct);
a.y += 10;
testing.expect(a.x == 0);
testing.expect(a.y == 10);
const ZigStruct = struct {
integral_types: struct {
integer_0: i0,
integer_8: i8,
integer_16: i16,
integer_32: i32,
integer_64: i64,
integer_128: i128,
unsigned_0: u0,
unsigned_8: u8,
unsigned_16: u16,
unsigned_32: u32,
unsigned_64: u64,
unsigned_128: u128,
float_32: f32,
float_64: f64,
},
pointers: struct {
optional: ?*u8,
c_pointer: [*c]u8,
slice: []u8,
},
array: [2]u32,
vector_u32: meta.Vector(2, u32),
vector_f32: meta.Vector(2, f32),
vector_bool: meta.Vector(2, bool),
optional_int: ?u8,
empty: void,
sentinel: [3:0]u8,
};
const b = zeroes(ZigStruct);
testing.expectEqual(@as(i8, 0), b.integral_types.integer_0);
testing.expectEqual(@as(i8, 0), b.integral_types.integer_8);
testing.expectEqual(@as(i16, 0), b.integral_types.integer_16);
testing.expectEqual(@as(i32, 0), b.integral_types.integer_32);
testing.expectEqual(@as(i64, 0), b.integral_types.integer_64);
testing.expectEqual(@as(i128, 0), b.integral_types.integer_128);
testing.expectEqual(@as(u8, 0), b.integral_types.unsigned_0);
testing.expectEqual(@as(u8, 0), b.integral_types.unsigned_8);
testing.expectEqual(@as(u16, 0), b.integral_types.unsigned_16);
testing.expectEqual(@as(u32, 0), b.integral_types.unsigned_32);
testing.expectEqual(@as(u64, 0), b.integral_types.unsigned_64);
testing.expectEqual(@as(u128, 0), b.integral_types.unsigned_128);
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);
}
testing.expectEqual(@splat(2, @as(u32, 0)), b.vector_u32);
testing.expectEqual(@splat(2, @as(f32, 0.0)), b.vector_f32);
testing.expectEqual(@splat(2, @as(bool, false)), b.vector_bool);
testing.expectEqual(@as(?u8, null), b.optional_int);
for (b.sentinel) |e| {
testing.expectEqual(@as(u8, 0), e);
}
}
/// Sets a slice to zeroes.
/// Prevents the store from being optimized out.
pub fn secureZero(comptime T: type, s: []T) void {
// NOTE: We do not use a volatile slice cast here since LLVM cannot
// see that it can be replaced by a memset.
const ptr = @ptrCast([*]volatile u8, s.ptr);
const length = s.len * @sizeOf(T);
@memset(ptr, 0, length);
}
test "mem.secureZero" {
var a = [_]u8{0xfe} ** 8;
var b = [_]u8{0xfe} ** 8;
set(u8, a[0..], 0);
secureZero(u8, b[0..]);
testing.expectEqualSlices(u8, a[0..], b[0..]);
}
/// Initializes all fields of the struct with their default value, or zero values if no default value is present.
/// If the field is present in the provided initial values, it will have that value instead.
/// Structs are initialized recursively.
pub fn zeroInit(comptime T: type, init: anytype) T {
comptime const Init = @TypeOf(init);
switch (@typeInfo(T)) {
.Struct => |struct_info| {
switch (@typeInfo(Init)) {
.Struct => |init_info| {
var value = std.mem.zeroes(T);
// typeInfo won't tell us if this is a tuple
if (comptime eql(u8, init_info.fields[0].name, "0")) {
inline for (init_info.fields) |field, i| {
@field(value, struct_info.fields[i].name) = @field(init, field.name);
}
return value;
}
inline for (init_info.fields) |field| {
if (!@hasField(T, field.name)) {
@compileError("Encountered an initializer for `" ++ field.name ++ "`, but it is not a field of " ++ @typeName(T));
}
}
inline for (struct_info.fields) |field| {
if (@hasField(Init, field.name)) {
switch (@typeInfo(field.field_type)) {
.Struct => {
@field(value, field.name) = zeroInit(field.field_type, @field(init, field.name));
},
else => {
@field(value, field.name) = @field(init, field.name);
},
}
} else if (field.default_value) |default_value| {
@field(value, field.name) = default_value;
}
}
return value;
},
else => {
@compileError("The initializer must be a struct");
},
}
},
else => {
@compileError("Can't default init a " ++ @typeName(T));
},
}
}
test "zeroInit" {
const I = struct {
d: f64,
};
const S = struct {
a: u32,
b: ?bool,
c: I,
e: [3]u8,
f: i64 = -1,
};
const s = zeroInit(S, .{
.a = 42,
});
testing.expectEqual(S{
.a = 42,
.b = null,
.c = .{
.d = 0,
},
.e = [3]u8{ 0, 0, 0 },
.f = -1,
}, s);
const Color = struct {
r: u8,
g: u8,
b: u8,
a: u8,
};
const c = zeroInit(Color, .{255, 255});
testing.expectEqual(Color{
.r = 255,
.g = 255,
.b = 0,
.a = 0,
}, c);
}
/// Compares two slices of numbers lexicographically. O(n).
pub fn order(comptime T: type, lhs: []const T, rhs: []const T) math.Order {
const n = math.min(lhs.len, rhs.len);
var i: usize = 0;
while (i < n) : (i += 1) {
switch (math.order(lhs[i], rhs[i])) {
.eq => continue,
.lt => return .lt,
.gt => return .gt,
}
}
return math.order(lhs.len, rhs.len);
}
test "order" {
testing.expect(order(u8, "abcd", "bee") == .lt);
testing.expect(order(u8, "abc", "abc") == .eq);
testing.expect(order(u8, "abc", "abc0") == .lt);
testing.expect(order(u8, "", "") == .eq);
testing.expect(order(u8, "", "a") == .lt);
}
/// Returns true if lhs < rhs, false otherwise
pub fn lessThan(comptime T: type, lhs: []const T, rhs: []const T) bool {
return order(T, lhs, rhs) == .lt;
}
test "mem.lessThan" {
testing.expect(lessThan(u8, "abcd", "bee"));
testing.expect(!lessThan(u8, "abc", "abc"));
testing.expect(lessThan(u8, "abc", "abc0"));
testing.expect(!lessThan(u8, "", ""));
testing.expect(lessThan(u8, "", "a"));
}
/// Compares two slices and returns whether they are equal.
pub fn eql(comptime T: type, a: []const T, b: []const T) bool {
if (a.len != b.len) return false;
if (a.ptr == b.ptr) return true;
for (a) |item, index| {
if (b[index] != item) return false;
}
return true;
}
/// Compares two slices and returns the index of the first inequality.
/// Returns null if the slices are equal.
pub fn indexOfDiff(comptime T: type, a: []const T, b: []const T) ?usize {
const shortest = math.min(a.len, b.len);
if (a.ptr == b.ptr)
return if (a.len == b.len) null else shortest;
var index: usize = 0;
while (index < shortest) : (index += 1) if (a[index] != b[index]) return index;
return if (a.len == b.len) null else shortest;
}
test "indexOfDiff" {
testing.expectEqual(indexOfDiff(u8, "one", "one"), null);
testing.expectEqual(indexOfDiff(u8, "one two", "one"), 3);
testing.expectEqual(indexOfDiff(u8, "one", "one two"), 3);
testing.expectEqual(indexOfDiff(u8, "one twx", "one two"), 6);
testing.expectEqual(indexOfDiff(u8, "xne", "one"), 0);
}
pub const toSliceConst = @compileError("deprecated; use std.mem.spanZ");
pub const toSlice = @compileError("deprecated; use std.mem.spanZ");
/// Takes a pointer to an array, a sentinel-terminated pointer, or a slice, and
/// returns a slice. If there is a sentinel on the input type, there will be a
/// sentinel on the output type. The constness of the output type matches
/// the constness of the input type. `[*c]` pointers are assumed to be 0-terminated,
/// and assumed to not allow null.
pub fn Span(comptime T: type) type {
switch (@typeInfo(T)) {
.Optional => |optional_info| {
return ?Span(optional_info.child);
},
.Pointer => |ptr_info| {
var new_ptr_info = ptr_info;
switch (ptr_info.size) {
.One => switch (@typeInfo(ptr_info.child)) {
.Array => |info| {
new_ptr_info.child = info.child;
new_ptr_info.sentinel = info.sentinel;
},
else => @compileError("invalid type given to std.mem.Span"),
},
.C => {
new_ptr_info.sentinel = 0;
new_ptr_info.is_allowzero = false;
},
.Many, .Slice => {},
}
new_ptr_info.size = .Slice;
return @Type(std.builtin.TypeInfo{ .Pointer = new_ptr_info });
},
else => @compileError("invalid type given to std.mem.Span"),
}
}
test "Span" {
testing.expect(Span(*[5]u16) == []u16);
testing.expect(Span(?*[5]u16) == ?[]u16);
testing.expect(Span(*const [5]u16) == []const u16);
testing.expect(Span(?*const [5]u16) == ?[]const u16);
testing.expect(Span([]u16) == []u16);
testing.expect(Span(?[]u16) == ?[]u16);
testing.expect(Span([]const u8) == []const u8);
testing.expect(Span(?[]const u8) == ?[]const u8);
testing.expect(Span([:1]u16) == [:1]u16);
testing.expect(Span(?[:1]u16) == ?[:1]u16);
testing.expect(Span([:1]const u8) == [:1]const u8);
testing.expect(Span(?[:1]const u8) == ?[:1]const u8);
testing.expect(Span([*:1]u16) == [:1]u16);
testing.expect(Span(?[*:1]u16) == ?[:1]u16);
testing.expect(Span([*:1]const u8) == [:1]const u8);
testing.expect(Span(?[*:1]const u8) == ?[:1]const u8);
testing.expect(Span([*c]u16) == [:0]u16);
testing.expect(Span(?[*c]u16) == ?[:0]u16);
testing.expect(Span([*c]const u8) == [:0]const u8);
testing.expect(Span(?[*c]const u8) == ?[:0]const u8);
}
/// Takes a pointer to an array, a sentinel-terminated pointer, or a slice, and
/// returns a slice. If there is a sentinel on the input type, there will be a
/// sentinel on the output type. The constness of the output type matches
/// the constness of the input type.
///
/// When there is both a sentinel and an array length or slice length, the
/// length value is used instead of the sentinel.
pub fn span(ptr: anytype) Span(@TypeOf(ptr)) {
if (@typeInfo(@TypeOf(ptr)) == .Optional) {
if (ptr) |non_null| {
return span(non_null);
} else {
return null;
}
}
const Result = Span(@TypeOf(ptr));
const l = len(ptr);
if (@typeInfo(Result).Pointer.sentinel) |s| {
return ptr[0..l :s];
} else {
return ptr[0..l];
}
}
test "span" {
var array: [5]u16 = [_]u16{ 1, 2, 3, 4, 5 };
const ptr = @as([*:3]u16, array[0..2 :3]);
testing.expect(eql(u16, span(ptr), &[_]u16{ 1, 2 }));
testing.expect(eql(u16, span(&array), &[_]u16{ 1, 2, 3, 4, 5 }));
testing.expectEqual(@as(?[:0]u16, null), span(@as(?[*:0]u16, null)));
}
/// Same as `span`, except when there is both a sentinel and an array
/// length or slice length, scans the memory for the sentinel value
/// rather than using the length.
pub fn spanZ(ptr: anytype) Span(@TypeOf(ptr)) {
if (@typeInfo(@TypeOf(ptr)) == .Optional) {
if (ptr) |non_null| {
return spanZ(non_null);
} else {
return null;
}
}
const Result = Span(@TypeOf(ptr));
const l = lenZ(ptr);
if (@typeInfo(Result).Pointer.sentinel) |s| {
return ptr[0..l :s];
} else {
return ptr[0..l];
}
}
test "spanZ" {
var array: [5]u16 = [_]u16{ 1, 2, 3, 4, 5 };
const ptr = @as([*:3]u16, array[0..2 :3]);
testing.expect(eql(u16, spanZ(ptr), &[_]u16{ 1, 2 }));
testing.expect(eql(u16, spanZ(&array), &[_]u16{ 1, 2, 3, 4, 5 }));
testing.expectEqual(@as(?[:0]u16, null), spanZ(@as(?[*:0]u16, null)));
}
/// Takes a pointer to an array, an array, a vector, a sentinel-terminated pointer,
/// or a slice, and returns the length.
/// In the case of a sentinel-terminated array, it uses the array length.
/// For C pointers it assumes it is a pointer-to-many with a 0 sentinel.
pub fn len(value: anytype) usize {
return switch (@typeInfo(@TypeOf(value))) {
.Array => |info| info.len,
.Vector => |info| info.len,
.Pointer => |info| switch (info.size) {
.One => switch (@typeInfo(info.child)) {
.Array => value.len,
else => @compileError("invalid type given to std.mem.len"),
},
.Many => if (info.sentinel) |sentinel|
indexOfSentinel(info.child, sentinel, value)
else
@compileError("length of pointer with no sentinel"),
.C => indexOfSentinel(info.child, 0, value),
.Slice => value.len,
},
else => @compileError("invalid type given to std.mem.len"),
};
}
test "len" {
testing.expect(len("aoeu") == 4);
{
var array: [5]u16 = [_]u16{ 1, 2, 3, 4, 5 };
testing.expect(len(&array) == 5);
testing.expect(len(array[0..3]) == 3);
array[2] = 0;
const ptr = @as([*:0]u16, array[0..2 :0]);
testing.expect(len(ptr) == 2);
}
{
var array: [5:0]u16 = [_:0]u16{ 1, 2, 3, 4, 5 };
testing.expect(len(&array) == 5);
array[2] = 0;
testing.expect(len(&array) == 5);
}
{
const vector: meta.Vector(2, u32) = [2]u32{ 1, 2 };
testing.expect(len(vector) == 2);
}
}
/// Takes a pointer to an array, an array, a sentinel-terminated pointer,
/// or a slice, and returns the length.
/// In the case of a sentinel-terminated array, it scans the array
/// for a sentinel and uses that for the length, rather than using the array length.
/// For C pointers it assumes it is a pointer-to-many with a 0 sentinel.
pub fn lenZ(ptr: anytype) usize {
return switch (@typeInfo(@TypeOf(ptr))) {
.Array => |info| if (info.sentinel) |sentinel|
indexOfSentinel(info.child, sentinel, &ptr)
else
info.len,
.Pointer => |info| switch (info.size) {
.One => switch (@typeInfo(info.child)) {
.Array => |x| if (x.sentinel) |sentinel|
indexOfSentinel(x.child, sentinel, ptr)
else
ptr.len,
else => @compileError("invalid type given to std.mem.lenZ"),
},
.Many => if (info.sentinel) |sentinel|
indexOfSentinel(info.child, sentinel, ptr)
else
@compileError("length of pointer with no sentinel"),
.C => indexOfSentinel(info.child, 0, ptr),
.Slice => if (info.sentinel) |sentinel|
indexOfSentinel(info.child, sentinel, ptr.ptr)
else
ptr.len,
},
else => @compileError("invalid type given to std.mem.lenZ"),
};
}
test "lenZ" {
testing.expect(lenZ("aoeu") == 4);
{
var array: [5]u16 = [_]u16{ 1, 2, 3, 4, 5 };
testing.expect(lenZ(&array) == 5);
testing.expect(lenZ(array[0..3]) == 3);
array[2] = 0;
const ptr = @as([*:0]u16, array[0..2 :0]);
testing.expect(lenZ(ptr) == 2);
}
{
var array: [5:0]u16 = [_:0]u16{ 1, 2, 3, 4, 5 };
testing.expect(lenZ(&array) == 5);
array[2] = 0;
testing.expect(lenZ(&array) == 2);
}
}
pub fn indexOfSentinel(comptime Elem: type, comptime sentinel: Elem, ptr: [*:sentinel]const Elem) usize {
var i: usize = 0;
while (ptr[i] != sentinel) {
i += 1;
}
return i;
}
/// Returns true if all elements in a slice are equal to the scalar value provided
pub fn allEqual(comptime T: type, slice: []const T, scalar: T) bool {
for (slice) |item| {
if (item != scalar) return false;
}
return true;
}
/// Deprecated, use `Allocator.dupe`.
pub fn dupe(allocator: *Allocator, comptime T: type, m: []const T) ![]T {
return allocator.dupe(T, m);
}
/// Deprecated, use `Allocator.dupeZ`.
pub fn dupeZ(allocator: *Allocator, comptime T: type, m: []const T) ![:0]T {
return allocator.dupeZ(T, m);
}
/// Remove values from the beginning of a slice.
pub fn trimLeft(comptime T: type, slice: []const T, values_to_strip: []const T) []const T {
var begin: usize = 0;
while (begin < slice.len and indexOfScalar(T, values_to_strip, slice[begin]) != null) : (begin += 1) {}
return slice[begin..];
}
/// Remove values from the end of a slice.
pub fn trimRight(comptime T: type, slice: []const T, values_to_strip: []const T) []const T {
var end: usize = slice.len;
while (end > 0 and indexOfScalar(T, values_to_strip, slice[end - 1]) != null) : (end -= 1) {}
return slice[0..end];
}
/// Remove values from the beginning and end of a slice.
pub fn trim(comptime T: type, slice: []const T, values_to_strip: []const T) []const T {
var begin: usize = 0;
var end: usize = slice.len;
while (begin < end and indexOfScalar(T, values_to_strip, slice[begin]) != null) : (begin += 1) {}
while (end > begin and indexOfScalar(T, values_to_strip, slice[end - 1]) != null) : (end -= 1) {}
return slice[begin..end];
}
test "mem.trim" {
testing.expectEqualSlices(u8, "foo\n ", trimLeft(u8, " foo\n ", " \n"));
testing.expectEqualSlices(u8, " foo", trimRight(u8, " foo\n ", " \n"));
testing.expectEqualSlices(u8, "foo", trim(u8, " foo\n ", " \n"));
testing.expectEqualSlices(u8, "foo", trim(u8, "foo", " \n"));
}
/// Linear search for the index of a scalar value inside a slice.
pub fn indexOfScalar(comptime T: type, slice: []const T, value: T) ?usize {
return indexOfScalarPos(T, slice, 0, value);
}
/// Linear search for the last index of a scalar value inside a slice.
pub fn lastIndexOfScalar(comptime T: type, slice: []const T, value: T) ?usize {
var i: usize = slice.len;
while (i != 0) {
i -= 1;
if (slice[i] == value) return i;
}
return null;
}
pub fn indexOfScalarPos(comptime T: type, slice: []const T, start_index: usize, value: T) ?usize {
var i: usize = start_index;
while (i < slice.len) : (i += 1) {
if (slice[i] == value) return i;
}
return null;
}
pub fn indexOfAny(comptime T: type, slice: []const T, values: []const T) ?usize {
return indexOfAnyPos(T, slice, 0, values);
}
pub fn lastIndexOfAny(comptime T: type, slice: []const T, values: []const T) ?usize {
var i: usize = slice.len;
while (i != 0) {
i -= 1;
for (values) |value| {
if (slice[i] == value) return i;
}
}
return null;
}
pub fn indexOfAnyPos(comptime T: type, slice: []const T, start_index: usize, values: []const T) ?usize {
var i: usize = start_index;
while (i < slice.len) : (i += 1) {
for (values) |value| {
if (slice[i] == value) return i;
}
}
return null;
}
pub fn indexOf(comptime T: type, haystack: []const T, needle: []const T) ?usize {
return indexOfPos(T, haystack, 0, needle);
}
/// Find the index in a slice of a sub-slice, searching from the end backwards.
/// To start looking at a different index, slice the haystack first.
/// TODO is there even a better algorithm for this?
pub fn lastIndexOf(comptime T: type, haystack: []const T, needle: []const T) ?usize {
if (needle.len > haystack.len) return null;
var i: usize = haystack.len - needle.len;
while (true) : (i -= 1) {
if (mem.eql(T, haystack[i .. i + needle.len], needle)) return i;
if (i == 0) return null;
}
}
// TODO boyer-moore algorithm
pub fn indexOfPos(comptime T: type, haystack: []const T, start_index: usize, needle: []const T) ?usize {
if (needle.len > haystack.len) return null;
var i: usize = start_index;
const end = haystack.len - needle.len;
while (i <= end) : (i += 1) {
if (eql(T, haystack[i .. i + needle.len], needle)) return i;
}
return null;
}
test "mem.indexOf" {
testing.expect(indexOf(u8, "one two three four", "four").? == 14);
testing.expect(lastIndexOf(u8, "one two three two four", "two").? == 14);
testing.expect(indexOf(u8, "one two three four", "gour") == null);
testing.expect(lastIndexOf(u8, "one two three four", "gour") == null);
testing.expect(indexOf(u8, "foo", "foo").? == 0);
testing.expect(lastIndexOf(u8, "foo", "foo").? == 0);
testing.expect(indexOf(u8, "foo", "fool") == null);
testing.expect(lastIndexOf(u8, "foo", "lfoo") == null);
testing.expect(lastIndexOf(u8, "foo", "fool") == null);
testing.expect(indexOf(u8, "foo foo", "foo").? == 0);
testing.expect(lastIndexOf(u8, "foo foo", "foo").? == 4);
testing.expect(lastIndexOfAny(u8, "boo, cat", "abo").? == 6);
testing.expect(lastIndexOfScalar(u8, "boo", 'o').? == 2);
}
/// Reads an integer from memory with size equal to bytes.len.
/// T specifies the return type, which must be large enough to store
/// the result.
pub fn readVarInt(comptime ReturnType: type, bytes: []const u8, endian: builtin.Endian) ReturnType {
var result: ReturnType = 0;
switch (endian) {
.Big => {
for (bytes) |b| {
result = (result << 8) | b;
}
},
.Little => {
const ShiftType = math.Log2Int(ReturnType);
for (bytes) |b, index| {
result = result | (@as(ReturnType, b) << @intCast(ShiftType, index * 8));
}
},
}
return result;
}
/// Reads an integer from memory with bit count specified by T.
/// The bit count of T must be evenly divisible by 8.
/// This function cannot fail and cannot cause undefined behavior.
/// Assumes the endianness of memory is native. This means the function can
/// simply pointer cast memory.
pub fn readIntNative(comptime T: type, bytes: *const [@divExact(T.bit_count, 8)]u8) T {
return @ptrCast(*align(1) const T, bytes).*;
}
/// Reads an integer from memory with bit count specified by T.
/// The bit count of T must be evenly divisible by 8.
/// This function cannot fail and cannot cause undefined behavior.
/// Assumes the endianness of memory is foreign, so it must byte-swap.
pub fn readIntForeign(comptime T: type, bytes: *const [@divExact(T.bit_count, 8)]u8) T {
return @byteSwap(T, readIntNative(T, bytes));
}
pub const readIntLittle = switch (builtin.endian) {
.Little => readIntNative,
.Big => readIntForeign,
};
pub const readIntBig = switch (builtin.endian) {
.Little => readIntForeign,
.Big => readIntNative,
};
/// Asserts that bytes.len >= T.bit_count / 8. Reads the integer starting from index 0
/// and ignores extra bytes.
/// The bit count of T must be evenly divisible by 8.
/// Assumes the endianness of memory is native. This means the function can
/// simply pointer cast memory.
pub fn readIntSliceNative(comptime T: type, bytes: []const u8) T {
const n = @divExact(T.bit_count, 8);
assert(bytes.len >= n);
return readIntNative(T, bytes[0..n]);
}
/// Asserts that bytes.len >= T.bit_count / 8. Reads the integer starting from index 0
/// and ignores extra bytes.
/// The bit count of T must be evenly divisible by 8.
/// Assumes the endianness of memory is foreign, so it must byte-swap.
pub fn readIntSliceForeign(comptime T: type, bytes: []const u8) T {
return @byteSwap(T, readIntSliceNative(T, bytes));
}
pub const readIntSliceLittle = switch (builtin.endian) {
.Little => readIntSliceNative,
.Big => readIntSliceForeign,
};
pub const readIntSliceBig = switch (builtin.endian) {
.Little => readIntSliceForeign,
.Big => readIntSliceNative,
};
/// Reads an integer from memory with bit count specified by T.
/// The bit count of T must be evenly divisible by 8.
/// This function cannot fail and cannot cause undefined behavior.
pub fn readInt(comptime T: type, bytes: *const [@divExact(T.bit_count, 8)]u8, endian: builtin.Endian) T {
if (endian == builtin.endian) {
return readIntNative(T, bytes);
} else {
return readIntForeign(T, bytes);
}
}
/// Asserts that bytes.len >= T.bit_count / 8. Reads the integer starting from index 0
/// and ignores extra bytes.
/// The bit count of T must be evenly divisible by 8.
pub fn readIntSlice(comptime T: type, bytes: []const u8, endian: builtin.Endian) T {
const n = @divExact(T.bit_count, 8);
assert(bytes.len >= n);
return readInt(T, bytes[0..n], endian);
}
test "comptime read/write int" {
comptime {
var bytes: [2]u8 = undefined;
writeIntLittle(u16, &bytes, 0x1234);
const result = readIntBig(u16, &bytes);
testing.expect(result == 0x3412);
}
comptime {
var bytes: [2]u8 = undefined;
writeIntBig(u16, &bytes, 0x1234);
const result = readIntLittle(u16, &bytes);
testing.expect(result == 0x3412);
}
}
test "readIntBig and readIntLittle" {
testing.expect(readIntSliceBig(u0, &[_]u8{}) == 0x0);
testing.expect(readIntSliceLittle(u0, &[_]u8{}) == 0x0);
testing.expect(readIntSliceBig(u8, &[_]u8{0x32}) == 0x32);
testing.expect(readIntSliceLittle(u8, &[_]u8{0x12}) == 0x12);
testing.expect(readIntSliceBig(u16, &[_]u8{ 0x12, 0x34 }) == 0x1234);
testing.expect(readIntSliceLittle(u16, &[_]u8{ 0x12, 0x34 }) == 0x3412);
testing.expect(readIntSliceBig(u72, &[_]u8{ 0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x24 }) == 0x123456789abcdef024);
testing.expect(readIntSliceLittle(u72, &[_]u8{ 0xec, 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe }) == 0xfedcba9876543210ec);
testing.expect(readIntSliceBig(i8, &[_]u8{0xff}) == -1);
testing.expect(readIntSliceLittle(i8, &[_]u8{0xfe}) == -2);
testing.expect(readIntSliceBig(i16, &[_]u8{ 0xff, 0xfd }) == -3);
testing.expect(readIntSliceLittle(i16, &[_]u8{ 0xfc, 0xff }) == -4);
}
/// Writes an integer to memory, storing it in twos-complement.
/// This function always succeeds, has defined behavior for all inputs, and
/// accepts any integer bit width.
/// This function stores in native endian, which means it is implemented as a simple
/// memory store.
pub fn writeIntNative(comptime T: type, buf: *[(T.bit_count + 7) / 8]u8, value: T) void {
@ptrCast(*align(1) T, buf).* = value;
}
/// Writes an integer to memory, storing it in twos-complement.
/// This function always succeeds, has defined behavior for all inputs, but
/// the integer bit width must be divisible by 8.
/// This function stores in foreign endian, which means it does a @byteSwap first.
pub fn writeIntForeign(comptime T: type, buf: *[@divExact(T.bit_count, 8)]u8, value: T) void {
writeIntNative(T, buf, @byteSwap(T, value));
}
pub const writeIntLittle = switch (builtin.endian) {
.Little => writeIntNative,
.Big => writeIntForeign,
};
pub const writeIntBig = switch (builtin.endian) {
.Little => writeIntForeign,
.Big => writeIntNative,
};
/// Writes an integer to memory, storing it in twos-complement.
/// This function always succeeds, has defined behavior for all inputs, but
/// the integer bit width must be divisible by 8.
pub fn writeInt(comptime T: type, buffer: *[@divExact(T.bit_count, 8)]u8, value: T, endian: builtin.Endian) void {
if (endian == builtin.endian) {
return writeIntNative(T, buffer, value);
} else {
return writeIntForeign(T, buffer, value);
}
}
/// Writes a twos-complement little-endian integer to memory.
/// Asserts that buf.len >= T.bit_count / 8.
/// The bit count of T must be divisible by 8.
/// Any extra bytes in buffer after writing the integer are set to zero. To
/// avoid the branch to check for extra buffer bytes, use writeIntLittle
/// instead.
pub fn writeIntSliceLittle(comptime T: type, buffer: []u8, value: T) void {
assert(buffer.len >= @divExact(T.bit_count, 8));
if (T.bit_count == 0)
return set(u8, buffer, 0);
// TODO I want to call writeIntLittle here but comptime eval facilities aren't good enough
const uint = std.meta.Int(false, T.bit_count);
var bits = @truncate(uint, value);
for (buffer) |*b| {
b.* = @truncate(u8, bits);
bits >>= 8;
}
}
/// Writes a twos-complement big-endian integer to memory.
/// Asserts that buffer.len >= T.bit_count / 8.
/// The bit count of T must be divisible by 8.
/// Any extra bytes in buffer before writing the integer are set to zero. To
/// avoid the branch to check for extra buffer bytes, use writeIntBig instead.
pub fn writeIntSliceBig(comptime T: type, buffer: []u8, value: T) void {
assert(buffer.len >= @divExact(T.bit_count, 8));
if (T.bit_count == 0)
return set(u8, buffer, 0);
// TODO I want to call writeIntBig here but comptime eval facilities aren't good enough
const uint = std.meta.Int(false, T.bit_count);
var bits = @truncate(uint, value);
var index: usize = buffer.len;
while (index != 0) {
index -= 1;
buffer[index] = @truncate(u8, bits);
bits >>= 8;
}
}
pub const writeIntSliceNative = switch (builtin.endian) {
.Little => writeIntSliceLittle,
.Big => writeIntSliceBig,
};
pub const writeIntSliceForeign = switch (builtin.endian) {
.Little => writeIntSliceBig,
.Big => writeIntSliceLittle,
};
/// Writes a twos-complement integer to memory, with the specified endianness.
/// Asserts that buf.len >= T.bit_count / 8.
/// The bit count of T must be evenly divisible by 8.
/// Any extra bytes in buffer not part of the integer are set to zero, with
/// respect to endianness. To avoid the branch to check for extra buffer bytes,
/// use writeInt instead.
pub fn writeIntSlice(comptime T: type, buffer: []u8, value: T, endian: builtin.Endian) void {
comptime assert(T.bit_count % 8 == 0);
return switch (endian) {
.Little => writeIntSliceLittle(T, buffer, value),
.Big => writeIntSliceBig(T, buffer, value),
};
}
test "writeIntBig and writeIntLittle" {
var buf0: [0]u8 = undefined;
var buf1: [1]u8 = undefined;
var buf2: [2]u8 = undefined;
var buf9: [9]u8 = undefined;
writeIntBig(u0, &buf0, 0x0);
testing.expect(eql(u8, buf0[0..], &[_]u8{}));
writeIntLittle(u0, &buf0, 0x0);
testing.expect(eql(u8, buf0[0..], &[_]u8{}));
writeIntBig(u8, &buf1, 0x12);
testing.expect(eql(u8, buf1[0..], &[_]u8{0x12}));
writeIntLittle(u8, &buf1, 0x34);
testing.expect(eql(u8, buf1[0..], &[_]u8{0x34}));
writeIntBig(u16, &buf2, 0x1234);
testing.expect(eql(u8, buf2[0..], &[_]u8{ 0x12, 0x34 }));
writeIntLittle(u16, &buf2, 0x5678);
testing.expect(eql(u8, buf2[0..], &[_]u8{ 0x78, 0x56 }));
writeIntBig(u72, &buf9, 0x123456789abcdef024);
testing.expect(eql(u8, buf9[0..], &[_]u8{ 0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0xf0, 0x24 }));
writeIntLittle(u72, &buf9, 0xfedcba9876543210ec);
testing.expect(eql(u8, buf9[0..], &[_]u8{ 0xec, 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe }));
writeIntBig(i8, &buf1, -1);
testing.expect(eql(u8, buf1[0..], &[_]u8{0xff}));
writeIntLittle(i8, &buf1, -2);
testing.expect(eql(u8, buf1[0..], &[_]u8{0xfe}));
writeIntBig(i16, &buf2, -3);
testing.expect(eql(u8, buf2[0..], &[_]u8{ 0xff, 0xfd }));
writeIntLittle(i16, &buf2, -4);
testing.expect(eql(u8, buf2[0..], &[_]u8{ 0xfc, 0xff }));
}
/// Returns an iterator that iterates over the slices of `buffer` that are not
/// any of the bytes in `delimiter_bytes`.
/// tokenize(" abc def ghi ", " ")
/// Will return slices for "abc", "def", "ghi", null, in that order.
/// If `buffer` is empty, the iterator will return null.
/// If `delimiter_bytes` does not exist in buffer,
/// the iterator will return `buffer`, null, in that order.
/// See also the related function `split`.
pub fn tokenize(buffer: []const u8, delimiter_bytes: []const u8) TokenIterator {
return TokenIterator{
.index = 0,
.buffer = buffer,
.delimiter_bytes = delimiter_bytes,
};
}
test "mem.tokenize" {
var it = tokenize(" abc def ghi ", " ");
testing.expect(eql(u8, it.next().?, "abc"));
testing.expect(eql(u8, it.next().?, "def"));
testing.expect(eql(u8, it.next().?, "ghi"));
testing.expect(it.next() == null);
it = tokenize("..\\bob", "\\");
testing.expect(eql(u8, it.next().?, ".."));
testing.expect(eql(u8, "..", "..\\bob"[0..it.index]));
testing.expect(eql(u8, it.next().?, "bob"));
testing.expect(it.next() == null);
it = tokenize("//a/b", "/");
testing.expect(eql(u8, it.next().?, "a"));
testing.expect(eql(u8, it.next().?, "b"));
testing.expect(eql(u8, "//a/b", "//a/b"[0..it.index]));
testing.expect(it.next() == null);
it = tokenize("|", "|");
testing.expect(it.next() == null);
it = tokenize("", "|");
testing.expect(it.next() == null);
it = tokenize("hello", "");
testing.expect(eql(u8, it.next().?, "hello"));
testing.expect(it.next() == null);
it = tokenize("hello", " ");
testing.expect(eql(u8, it.next().?, "hello"));
testing.expect(it.next() == null);
}
test "mem.tokenize (multibyte)" {
var it = tokenize("a|b,c/d e", " /,|");
testing.expect(eql(u8, it.next().?, "a"));
testing.expect(eql(u8, it.next().?, "b"));
testing.expect(eql(u8, it.next().?, "c"));
testing.expect(eql(u8, it.next().?, "d"));
testing.expect(eql(u8, it.next().?, "e"));
testing.expect(it.next() == null);
}
/// Returns an iterator that iterates over the slices of `buffer` that
/// are separated by bytes in `delimiter`.
/// split("abc|def||ghi", "|")
/// will return slices for "abc", "def", "", "ghi", null, in that order.
/// If `delimiter` does not exist in buffer,
/// the iterator will return `buffer`, null, in that order.
/// The delimiter length must not be zero.
/// See also the related function `tokenize`.
pub fn split(buffer: []const u8, delimiter: []const u8) SplitIterator {
assert(delimiter.len != 0);
return SplitIterator{
.index = 0,
.buffer = buffer,
.delimiter = delimiter,
};
}
pub const separate = @compileError("deprecated: renamed to split (behavior remains unchanged)");
test "mem.split" {
var it = split("abc|def||ghi", "|");
testing.expect(eql(u8, it.next().?, "abc"));
testing.expect(eql(u8, it.next().?, "def"));
testing.expect(eql(u8, it.next().?, ""));
testing.expect(eql(u8, it.next().?, "ghi"));
testing.expect(it.next() == null);
it = split("", "|");
testing.expect(eql(u8, it.next().?, ""));
testing.expect(it.next() == null);
it = split("|", "|");
testing.expect(eql(u8, it.next().?, ""));
testing.expect(eql(u8, it.next().?, ""));
testing.expect(it.next() == null);
it = split("hello", " ");
testing.expect(eql(u8, it.next().?, "hello"));
testing.expect(it.next() == null);
}
test "mem.split (multibyte)" {
var it = split("a, b ,, c, d, e", ", ");
testing.expect(eql(u8, it.next().?, "a"));
testing.expect(eql(u8, it.next().?, "b ,"));
testing.expect(eql(u8, it.next().?, "c"));
testing.expect(eql(u8, it.next().?, "d"));
testing.expect(eql(u8, it.next().?, "e"));
testing.expect(it.next() == null);
}
pub fn startsWith(comptime T: type, haystack: []const T, needle: []const T) bool {
return if (needle.len > haystack.len) false else eql(T, haystack[0..needle.len], needle);
}
test "mem.startsWith" {
testing.expect(startsWith(u8, "Bob", "Bo"));
testing.expect(!startsWith(u8, "Needle in haystack", "haystack"));
}
pub fn endsWith(comptime T: type, haystack: []const T, needle: []const T) bool {
return if (needle.len > haystack.len) false else eql(T, haystack[haystack.len - needle.len ..], needle);
}
test "mem.endsWith" {
testing.expect(endsWith(u8, "Needle in haystack", "haystack"));
testing.expect(!endsWith(u8, "Bob", "Bo"));
}
pub const TokenIterator = struct {
buffer: []const u8,
delimiter_bytes: []const u8,
index: usize,
/// Returns a slice of the next token, or null if tokenization is complete.
pub fn next(self: *TokenIterator) ?[]const u8 {
// move to beginning of token
while (self.index < self.buffer.len and self.isSplitByte(self.buffer[self.index])) : (self.index += 1) {}
const start = self.index;
if (start == self.buffer.len) {
return null;
}
// move to end of token
while (self.index < self.buffer.len and !self.isSplitByte(self.buffer[self.index])) : (self.index += 1) {}
const end = self.index;
return self.buffer[start..end];
}
/// Returns a slice of the remaining bytes. Does not affect iterator state.
pub fn rest(self: TokenIterator) []const u8 {
// move to beginning of token
var index: usize = self.index;
while (index < self.buffer.len and self.isSplitByte(self.buffer[index])) : (index += 1) {}
return self.buffer[index..];
}
fn isSplitByte(self: TokenIterator, byte: u8) bool {
for (self.delimiter_bytes) |delimiter_byte| {
if (byte == delimiter_byte) {
return true;
}
}
return false;
}
};
pub const SplitIterator = struct {
buffer: []const u8,
index: ?usize,
delimiter: []const u8,
/// Returns a slice of the next field, or null if splitting is complete.
pub fn next(self: *SplitIterator) ?[]const u8 {
const start = self.index orelse return null;
const end = if (indexOfPos(u8, self.buffer, start, self.delimiter)) |delim_start| blk: {
self.index = delim_start + self.delimiter.len;
break :blk delim_start;
} else blk: {
self.index = null;
break :blk self.buffer.len;
};
return self.buffer[start..end];
}
/// Returns a slice of the remaining bytes. Does not affect iterator state.
pub fn rest(self: SplitIterator) []const u8 {
const end = self.buffer.len;
const start = self.index orelse end;
return self.buffer[start..end];
}
};
/// Naively combines a series of slices with a separator.
/// Allocates memory for the result, which must be freed by the caller.
pub fn join(allocator: *Allocator, separator: []const u8, slices: []const []const u8) ![]u8 {
return joinMaybeZ(allocator, separator, slices, false);
}
/// Naively combines a series of slices with a separator and null terminator.
/// Allocates memory for the result, which must be freed by the caller.
pub fn joinZ(allocator: *Allocator, separator: []const u8, slices: []const []const u8) ![:0]u8 {
const out = try joinMaybeZ(allocator, separator, slices, true);
return out[0 .. out.len - 1 :0];
}
fn joinMaybeZ(allocator: *Allocator, separator: []const u8, slices: []const []const u8, zero: bool) ![]u8 {
if (slices.len == 0) return &[0]u8{};
const total_len = blk: {
var sum: usize = separator.len * (slices.len - 1);
for (slices) |slice| sum += slice.len;
if (zero) sum += 1;
break :blk sum;
};
const buf = try allocator.alloc(u8, total_len);
errdefer allocator.free(buf);
copy(u8, buf, slices[0]);
var buf_index: usize = slices[0].len;
for (slices[1..]) |slice| {
copy(u8, buf[buf_index..], separator);
buf_index += separator.len;
copy(u8, buf[buf_index..], slice);
buf_index += slice.len;
}
if (zero) buf[buf.len - 1] = 0;
// No need for shrink since buf is exactly the correct size.
return buf;
}
test "mem.join" {
{
const str = try join(testing.allocator, ",", &[_][]const u8{ "a", "b", "c" });
defer testing.allocator.free(str);
testing.expect(eql(u8, str, "a,b,c"));
}
{
const str = try join(testing.allocator, ",", &[_][]const u8{"a"});
defer testing.allocator.free(str);
testing.expect(eql(u8, str, "a"));
}
{
const str = try join(testing.allocator, ",", &[_][]const u8{ "a", "", "b", "", "c" });
defer testing.allocator.free(str);
testing.expect(eql(u8, str, "a,,b,,c"));
}
}
test "mem.joinZ" {
{
const str = try joinZ(testing.allocator, ",", &[_][]const u8{ "a", "b", "c" });
defer testing.allocator.free(str);
testing.expect(eql(u8, str, "a,b,c"));
testing.expectEqual(str[str.len], 0);
}
{
const str = try joinZ(testing.allocator, ",", &[_][]const u8{"a"});
defer testing.allocator.free(str);
testing.expect(eql(u8, str, "a"));
testing.expectEqual(str[str.len], 0);
}
{
const str = try joinZ(testing.allocator, ",", &[_][]const u8{ "a", "", "b", "", "c" });
defer testing.allocator.free(str);
testing.expect(eql(u8, str, "a,,b,,c"));
testing.expectEqual(str[str.len], 0);
}
}
/// Copies each T from slices into a new slice that exactly holds all the elements.
pub fn concat(allocator: *Allocator, comptime T: type, slices: []const []const T) ![]T {
if (slices.len == 0) return &[0]T{};
const total_len = blk: {
var sum: usize = 0;
for (slices) |slice| {
sum += slice.len;
}
break :blk sum;
};
const buf = try allocator.alloc(T, total_len);
errdefer allocator.free(buf);
var buf_index: usize = 0;
for (slices) |slice| {
copy(T, buf[buf_index..], slice);
buf_index += slice.len;
}
// No need for shrink since buf is exactly the correct size.
return buf;
}
test "concat" {
{
const str = try concat(testing.allocator, u8, &[_][]const u8{ "abc", "def", "ghi" });
defer testing.allocator.free(str);
testing.expect(eql(u8, str, "abcdefghi"));
}
{
const str = try concat(testing.allocator, u32, &[_][]const u32{
&[_]u32{ 0, 1 },
&[_]u32{ 2, 3, 4 },
&[_]u32{},
&[_]u32{5},
});
defer testing.allocator.free(str);
testing.expect(eql(u32, str, &[_]u32{ 0, 1, 2, 3, 4, 5 }));
}
}
test "testStringEquality" {
testing.expect(eql(u8, "abcd", "abcd"));
testing.expect(!eql(u8, "abcdef", "abZdef"));
testing.expect(!eql(u8, "abcdefg", "abcdef"));
}
test "testReadInt" {
testReadIntImpl();
comptime testReadIntImpl();
}
fn testReadIntImpl() void {
{
const bytes = [_]u8{
0x12,
0x34,
0x56,
0x78,
};
testing.expect(readInt(u32, &bytes, builtin.Endian.Big) == 0x12345678);
testing.expect(readIntBig(u32, &bytes) == 0x12345678);
testing.expect(readIntBig(i32, &bytes) == 0x12345678);
testing.expect(readInt(u32, &bytes, builtin.Endian.Little) == 0x78563412);
testing.expect(readIntLittle(u32, &bytes) == 0x78563412);
testing.expect(readIntLittle(i32, &bytes) == 0x78563412);
}
{
const buf = [_]u8{
0x00,
0x00,
0x12,
0x34,
};
const answer = readInt(u32, &buf, builtin.Endian.Big);
testing.expect(answer == 0x00001234);
}
{
const buf = [_]u8{
0x12,
0x34,
0x00,
0x00,
};
const answer = readInt(u32, &buf, builtin.Endian.Little);
testing.expect(answer == 0x00003412);
}
{
const bytes = [_]u8{
0xff,
0xfe,
};
testing.expect(readIntBig(u16, &bytes) == 0xfffe);
testing.expect(readIntBig(i16, &bytes) == -0x0002);
testing.expect(readIntLittle(u16, &bytes) == 0xfeff);
testing.expect(readIntLittle(i16, &bytes) == -0x0101);
}
}
test "writeIntSlice" {
testWriteIntImpl();
comptime testWriteIntImpl();
}
fn testWriteIntImpl() void {
var bytes: [8]u8 = undefined;
writeIntSlice(u0, bytes[0..], 0, builtin.Endian.Big);
testing.expect(eql(u8, &bytes, &[_]u8{
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
}));
writeIntSlice(u0, bytes[0..], 0, builtin.Endian.Little);
testing.expect(eql(u8, &bytes, &[_]u8{
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
}));
writeIntSlice(u64, bytes[0..], 0x12345678CAFEBABE, builtin.Endian.Big);
testing.expect(eql(u8, &bytes, &[_]u8{
0x12,
0x34,
0x56,
0x78,
0xCA,
0xFE,
0xBA,
0xBE,
}));
writeIntSlice(u64, bytes[0..], 0xBEBAFECA78563412, builtin.Endian.Little);
testing.expect(eql(u8, &bytes, &[_]u8{
0x12,
0x34,
0x56,
0x78,
0xCA,
0xFE,
0xBA,
0xBE,
}));
writeIntSlice(u32, bytes[0..], 0x12345678, builtin.Endian.Big);
testing.expect(eql(u8, &bytes, &[_]u8{
0x00,
0x00,
0x00,
0x00,
0x12,
0x34,
0x56,
0x78,
}));
writeIntSlice(u32, bytes[0..], 0x78563412, builtin.Endian.Little);
testing.expect(eql(u8, &bytes, &[_]u8{
0x12,
0x34,
0x56,
0x78,
0x00,
0x00,
0x00,
0x00,
}));
writeIntSlice(u16, bytes[0..], 0x1234, builtin.Endian.Big);
testing.expect(eql(u8, &bytes, &[_]u8{
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x12,
0x34,
}));
writeIntSlice(u16, bytes[0..], 0x1234, builtin.Endian.Little);
testing.expect(eql(u8, &bytes, &[_]u8{
0x34,
0x12,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
}));
}
/// Returns the smallest number in a slice. O(n).
/// `slice` must not be empty.
pub fn min(comptime T: type, slice: []const T) T {
var best = slice[0];
for (slice[1..]) |item| {
best = math.min(best, item);
}
return best;
}
test "mem.min" {
testing.expect(min(u8, "abcdefg") == 'a');
}
/// Returns the largest number in a slice. O(n).
/// `slice` must not be empty.
pub fn max(comptime T: type, slice: []const T) T {
var best = slice[0];
for (slice[1..]) |item| {
best = math.max(best, item);
}
return best;
}
test "mem.max" {
testing.expect(max(u8, "abcdefg") == 'g');
}
pub fn swap(comptime T: type, a: *T, b: *T) void {
const tmp = a.*;
a.* = b.*;
b.* = tmp;
}
/// In-place order reversal of a slice
pub fn reverse(comptime T: type, items: []T) void {
var i: usize = 0;
const end = items.len / 2;
while (i < end) : (i += 1) {
swap(T, &items[i], &items[items.len - i - 1]);
}
}
test "reverse" {
var arr = [_]i32{ 5, 3, 1, 2, 4 };
reverse(i32, arr[0..]);
testing.expect(eql(i32, &arr, &[_]i32{ 4, 2, 1, 3, 5 }));
}
/// In-place rotation of the values in an array ([0 1 2 3] becomes [1 2 3 0] if we rotate by 1)
/// Assumes 0 <= amount <= items.len
pub fn rotate(comptime T: type, items: []T, amount: usize) void {
reverse(T, items[0..amount]);
reverse(T, items[amount..]);
reverse(T, items);
}
test "rotate" {
var arr = [_]i32{ 5, 3, 1, 2, 4 };
rotate(i32, arr[0..], 2);
testing.expect(eql(i32, &arr, &[_]i32{ 1, 2, 4, 5, 3 }));
}
/// Converts a little-endian integer to host endianness.
pub fn littleToNative(comptime T: type, x: T) T {
return switch (builtin.endian) {
.Little => x,
.Big => @byteSwap(T, x),
};
}
/// Converts a big-endian integer to host endianness.
pub fn bigToNative(comptime T: type, x: T) T {
return switch (builtin.endian) {
.Little => @byteSwap(T, x),
.Big => x,
};
}
/// Converts an integer from specified endianness to host endianness.
pub fn toNative(comptime T: type, x: T, endianness_of_x: builtin.Endian) T {
return switch (endianness_of_x) {
.Little => littleToNative(T, x),
.Big => bigToNative(T, x),
};
}
/// Converts an integer which has host endianness to the desired endianness.
pub fn nativeTo(comptime T: type, x: T, desired_endianness: builtin.Endian) T {
return switch (desired_endianness) {
.Little => nativeToLittle(T, x),
.Big => nativeToBig(T, x),
};
}
/// Converts an integer which has host endianness to little endian.
pub fn nativeToLittle(comptime T: type, x: T) T {
return switch (builtin.endian) {
.Little => x,
.Big => @byteSwap(T, x),
};
}
/// Converts an integer which has host endianness to big endian.
pub fn nativeToBig(comptime T: type, x: T) T {
return switch (builtin.endian) {
.Little => @byteSwap(T, x),
.Big => x,
};
}
fn AsBytesReturnType(comptime P: type) type {
if (!trait.isSingleItemPtr(P))
@compileError("expected single item pointer, passed " ++ @typeName(P));
const size = @sizeOf(meta.Child(P));
const alignment = meta.alignment(P);
if (alignment == 0) {
if (trait.isConstPtr(P))
return *const [size]u8;
return *[size]u8;
}
if (trait.isConstPtr(P))
return *align(alignment) const [size]u8;
return *align(alignment) [size]u8;
}
/// Given a pointer to a single item, returns a slice of the underlying bytes, preserving constness.
pub fn asBytes(ptr: anytype) AsBytesReturnType(@TypeOf(ptr)) {
const P = @TypeOf(ptr);
return @ptrCast(AsBytesReturnType(P), ptr);
}
test "asBytes" {
const deadbeef = @as(u32, 0xDEADBEEF);
const deadbeef_bytes = switch (builtin.endian) {
.Big => "\xDE\xAD\xBE\xEF",
.Little => "\xEF\xBE\xAD\xDE",
};
testing.expect(eql(u8, asBytes(&deadbeef), deadbeef_bytes));
var codeface = @as(u32, 0xC0DEFACE);
for (asBytes(&codeface).*) |*b|
b.* = 0;
testing.expect(codeface == 0);
const S = packed struct {
a: u8,
b: u8,
c: u8,
d: u8,
};
const inst = S{
.a = 0xBE,
.b = 0xEF,
.c = 0xDE,
.d = 0xA1,
};
testing.expect(eql(u8, asBytes(&inst), "\xBE\xEF\xDE\xA1"));
const ZST = struct {};
const zero = ZST{};
testing.expect(eql(u8, asBytes(&zero), ""));
}
/// Given any value, returns a copy of its bytes in an array.
pub fn toBytes(value: anytype) [@sizeOf(@TypeOf(value))]u8 {
return asBytes(&value).*;
}
test "toBytes" {
var my_bytes = toBytes(@as(u32, 0x12345678));
switch (builtin.endian) {
.Big => testing.expect(eql(u8, &my_bytes, "\x12\x34\x56\x78")),
.Little => testing.expect(eql(u8, &my_bytes, "\x78\x56\x34\x12")),
}
my_bytes[0] = '\x99';
switch (builtin.endian) {
.Big => testing.expect(eql(u8, &my_bytes, "\x99\x34\x56\x78")),
.Little => testing.expect(eql(u8, &my_bytes, "\x99\x56\x34\x12")),
}
}
fn BytesAsValueReturnType(comptime T: type, comptime B: type) type {
const size = @as(usize, @sizeOf(T));
if (comptime !trait.is(.Pointer)(B) or
(meta.Child(B) != [size]u8 and meta.Child(B) != [size:0]u8))
{
comptime var buf: [100]u8 = undefined;
@compileError(std.fmt.bufPrint(&buf, "expected *[{}]u8, passed " ++ @typeName(B), .{size}) catch unreachable);
}
const alignment = comptime meta.alignment(B);
return if (comptime trait.isConstPtr(B)) *align(alignment) const T else *align(alignment) T;
}
/// Given a pointer to an array of bytes, returns a pointer to a value of the specified type
/// backed by those bytes, preserving constness.
pub fn bytesAsValue(comptime T: type, bytes: anytype) BytesAsValueReturnType(T, @TypeOf(bytes)) {
return @ptrCast(BytesAsValueReturnType(T, @TypeOf(bytes)), bytes);
}
test "bytesAsValue" {
const deadbeef = @as(u32, 0xDEADBEEF);
const deadbeef_bytes = switch (builtin.endian) {
.Big => "\xDE\xAD\xBE\xEF",
.Little => "\xEF\xBE\xAD\xDE",
};
testing.expect(deadbeef == bytesAsValue(u32, deadbeef_bytes).*);
var codeface_bytes: [4]u8 = switch (builtin.endian) {
.Big => "\xC0\xDE\xFA\xCE",
.Little => "\xCE\xFA\xDE\xC0",
}.*;
var codeface = bytesAsValue(u32, &codeface_bytes);
testing.expect(codeface.* == 0xC0DEFACE);
codeface.* = 0;
for (codeface_bytes) |b|
testing.expect(b == 0);
const S = packed struct {
a: u8,
b: u8,
c: u8,
d: u8,
};
const inst = S{
.a = 0xBE,
.b = 0xEF,
.c = 0xDE,
.d = 0xA1,
};
const inst_bytes = "\xBE\xEF\xDE\xA1";
const inst2 = bytesAsValue(S, inst_bytes);
testing.expect(meta.eql(inst, inst2.*));
}
/// Given a pointer to an array of bytes, returns a value of the specified type backed by a
/// copy of those bytes.
pub fn bytesToValue(comptime T: type, bytes: anytype) T {
return bytesAsValue(T, bytes).*;
}
test "bytesToValue" {
const deadbeef_bytes = switch (builtin.endian) {
.Big => "\xDE\xAD\xBE\xEF",
.Little => "\xEF\xBE\xAD\xDE",
};
const deadbeef = bytesToValue(u32, deadbeef_bytes);
testing.expect(deadbeef == @as(u32, 0xDEADBEEF));
}
//TODO copy also is_volatile, etc. I tried to use @typeInfo, modify child type, use @Type, but ran into issues.
fn BytesAsSliceReturnType(comptime T: type, comptime bytesType: type) type {
if (!(trait.isSlice(bytesType) and meta.Child(bytesType) == u8) and !(trait.isPtrTo(.Array)(bytesType) and meta.Child(meta.Child(bytesType)) == u8)) {
@compileError("expected []u8 or *[_]u8, passed " ++ @typeName(bytesType));
}
if (trait.isPtrTo(.Array)(bytesType) and @typeInfo(meta.Child(bytesType)).Array.len % @sizeOf(T) != 0) {
@compileError("number of bytes in " ++ @typeName(bytesType) ++ " is not divisible by size of " ++ @typeName(T));
}
const alignment = meta.alignment(bytesType);
return if (trait.isConstPtr(bytesType)) []align(alignment) const T else []align(alignment) T;
}
pub fn bytesAsSlice(comptime T: type, bytes: anytype) BytesAsSliceReturnType(T, @TypeOf(bytes)) {
// let's not give an undefined pointer to @ptrCast
// it may be equal to zero and fail a null check
if (bytes.len == 0) {
return &[0]T{};
}
const Bytes = @TypeOf(bytes);
const alignment = comptime meta.alignment(Bytes);
const cast_target = if (comptime trait.isConstPtr(Bytes)) [*]align(alignment) const T else [*]align(alignment) T;
return @ptrCast(cast_target, bytes)[0..@divExact(bytes.len, @sizeOf(T))];
}
test "bytesAsSlice" {
{
const bytes = [_]u8{ 0xDE, 0xAD, 0xBE, 0xEF };
const slice = bytesAsSlice(u16, bytes[0..]);
testing.expect(slice.len == 2);
testing.expect(bigToNative(u16, slice[0]) == 0xDEAD);
testing.expect(bigToNative(u16, slice[1]) == 0xBEEF);
}
{
const bytes = [_]u8{ 0xDE, 0xAD, 0xBE, 0xEF };
var runtime_zero: usize = 0;
const slice = bytesAsSlice(u16, bytes[runtime_zero..]);
testing.expect(slice.len == 2);
testing.expect(bigToNative(u16, slice[0]) == 0xDEAD);
testing.expect(bigToNative(u16, slice[1]) == 0xBEEF);
}
}
test "bytesAsSlice keeps pointer alignment" {
{
var bytes = [_]u8{ 0x01, 0x02, 0x03, 0x04 };
const numbers = bytesAsSlice(u32, bytes[0..]);
comptime testing.expect(@TypeOf(numbers) == []align(@alignOf(@TypeOf(bytes))) u32);
}
{
var bytes = [_]u8{ 0x01, 0x02, 0x03, 0x04 };
var runtime_zero: usize = 0;
const numbers = bytesAsSlice(u32, bytes[runtime_zero..]);
comptime testing.expect(@TypeOf(numbers) == []align(@alignOf(@TypeOf(bytes))) u32);
}
}
test "bytesAsSlice on a packed struct" {
const F = packed struct {
a: u8,
};
var b = [1]u8{9};
var f = bytesAsSlice(F, &b);
testing.expect(f[0].a == 9);
}
test "bytesAsSlice with specified alignment" {
var bytes align(4) = [_]u8{
0x33,
0x33,
0x33,
0x33,
};
const slice: []u32 = std.mem.bytesAsSlice(u32, bytes[0..]);
testing.expect(slice[0] == 0x33333333);
}
//TODO copy also is_volatile, etc. I tried to use @typeInfo, modify child type, use @Type, but ran into issues.
fn SliceAsBytesReturnType(comptime sliceType: type) type {
if (!trait.isSlice(sliceType) and !trait.isPtrTo(.Array)(sliceType)) {
@compileError("expected []T or *[_]T, passed " ++ @typeName(sliceType));
}
const alignment = meta.alignment(sliceType);
return if (trait.isConstPtr(sliceType)) []align(alignment) const u8 else []align(alignment) u8;
}
pub fn sliceAsBytes(slice: anytype) SliceAsBytesReturnType(@TypeOf(slice)) {
const Slice = @TypeOf(slice);
// let's not give an undefined pointer to @ptrCast
// it may be equal to zero and fail a null check
if (slice.len == 0 and comptime meta.sentinel(Slice) == null) {
return &[0]u8{};
}
const alignment = comptime meta.alignment(Slice);
const cast_target = if (comptime trait.isConstPtr(Slice)) [*]align(alignment) const u8 else [*]align(alignment) u8;
return @ptrCast(cast_target, slice)[0 .. slice.len * @sizeOf(meta.Elem(Slice))];
}
test "sliceAsBytes" {
const bytes = [_]u16{ 0xDEAD, 0xBEEF };
const slice = sliceAsBytes(bytes[0..]);
testing.expect(slice.len == 4);
testing.expect(eql(u8, slice, switch (builtin.endian) {
.Big => "\xDE\xAD\xBE\xEF",
.Little => "\xAD\xDE\xEF\xBE",
}));
}
test "sliceAsBytes with sentinel slice" {
const empty_string: [:0]const u8 = "";
const bytes = sliceAsBytes(empty_string);
testing.expect(bytes.len == 0);
}
test "sliceAsBytes packed struct at runtime and comptime" {
const Foo = packed struct {
a: u4,
b: u4,
};
const S = struct {
fn doTheTest() void {
var foo: Foo = undefined;
var slice = sliceAsBytes(@as(*[1]Foo, &foo)[0..1]);
slice[0] = 0x13;
switch (builtin.endian) {
.Big => {
testing.expect(foo.a == 0x1);
testing.expect(foo.b == 0x3);
},
.Little => {
testing.expect(foo.a == 0x3);
testing.expect(foo.b == 0x1);
},
}
}
};
S.doTheTest();
comptime S.doTheTest();
}
test "sliceAsBytes and bytesAsSlice back" {
testing.expect(@sizeOf(i32) == 4);
var big_thing_array = [_]i32{ 1, 2, 3, 4 };
const big_thing_slice: []i32 = big_thing_array[0..];
const bytes = sliceAsBytes(big_thing_slice);
testing.expect(bytes.len == 4 * 4);
bytes[4] = 0;
bytes[5] = 0;
bytes[6] = 0;
bytes[7] = 0;
testing.expect(big_thing_slice[1] == 0);
const big_thing_again = bytesAsSlice(i32, bytes);
testing.expect(big_thing_again[2] == 3);
big_thing_again[2] = -1;
testing.expect(bytes[8] == math.maxInt(u8));
testing.expect(bytes[9] == math.maxInt(u8));
testing.expect(bytes[10] == math.maxInt(u8));
testing.expect(bytes[11] == math.maxInt(u8));
}
/// Round an address up to the nearest aligned address
/// The alignment must be a power of 2 and greater than 0.
pub fn alignForward(addr: usize, alignment: usize) usize {
return alignForwardGeneric(usize, addr, alignment);
}
/// Round an address up to the nearest aligned address
/// The alignment must be a power of 2 and greater than 0.
pub fn alignForwardGeneric(comptime T: type, addr: T, alignment: T) T {
return alignBackwardGeneric(T, addr + (alignment - 1), alignment);
}
test "alignForward" {
testing.expect(alignForward(1, 1) == 1);
testing.expect(alignForward(2, 1) == 2);
testing.expect(alignForward(1, 2) == 2);
testing.expect(alignForward(2, 2) == 2);
testing.expect(alignForward(3, 2) == 4);
testing.expect(alignForward(4, 2) == 4);
testing.expect(alignForward(7, 8) == 8);
testing.expect(alignForward(8, 8) == 8);
testing.expect(alignForward(9, 8) == 16);
testing.expect(alignForward(15, 8) == 16);
testing.expect(alignForward(16, 8) == 16);
testing.expect(alignForward(17, 8) == 24);
}
/// Round an address up to the previous aligned address
/// Unlike `alignBackward`, `alignment` can be any positive number, not just a power of 2.
pub fn alignBackwardAnyAlign(i: usize, alignment: usize) usize {
if (@popCount(usize, alignment) == 1)
return alignBackward(i, alignment);
assert(alignment != 0);
return i - @mod(i, alignment);
}
/// Round an address up to the previous aligned address
/// The alignment must be a power of 2 and greater than 0.
pub fn alignBackward(addr: usize, alignment: usize) usize {
return alignBackwardGeneric(usize, addr, alignment);
}
/// Round an address up to the previous aligned address
/// The alignment must be a power of 2 and greater than 0.
pub fn alignBackwardGeneric(comptime T: type, addr: T, alignment: T) T {
assert(@popCount(T, alignment) == 1);
// 000010000 // example alignment
// 000001111 // subtract 1
// 111110000 // binary not
return addr & ~(alignment - 1);
}
/// Returns whether `alignment` is a valid alignment, meaning it is
/// a positive power of 2.
pub fn isValidAlign(alignment: u29) bool {
return @popCount(u29, alignment) == 1;
}
pub fn isAlignedAnyAlign(i: usize, alignment: usize) bool {
if (@popCount(usize, alignment) == 1)
return isAligned(i, alignment);
assert(alignment != 0);
return 0 == @mod(i, alignment);
}
/// Given an address and an alignment, return true if the address is a multiple of the alignment
/// The alignment must be a power of 2 and greater than 0.
pub fn isAligned(addr: usize, alignment: usize) bool {
return isAlignedGeneric(u64, addr, alignment);
}
pub fn isAlignedGeneric(comptime T: type, addr: T, alignment: T) bool {
return alignBackwardGeneric(T, addr, alignment) == addr;
}
test "isAligned" {
testing.expect(isAligned(0, 4));
testing.expect(isAligned(1, 1));
testing.expect(isAligned(2, 1));
testing.expect(isAligned(2, 2));
testing.expect(!isAligned(2, 4));
testing.expect(isAligned(3, 1));
testing.expect(!isAligned(3, 2));
testing.expect(!isAligned(3, 4));
testing.expect(isAligned(4, 4));
testing.expect(isAligned(4, 2));
testing.expect(isAligned(4, 1));
testing.expect(!isAligned(4, 8));
testing.expect(!isAligned(4, 16));
}
test "freeing empty string with null-terminated sentinel" {
const empty_string = try dupeZ(testing.allocator, u8, "");
testing.allocator.free(empty_string);
}
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