Zig 0.17.0-dev (Split by item)

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resize

Request to modify the size of an allocation.

It is guaranteed to not move the pointer, however the allocator implementation may refuse the resize request by returning false.

allocation may be an empty slice, in which case false is returned, unless new_len is also 0, in which case true is returned.

new_len may be zero, in which case the allocation is freed.

Allocator.resize

pub fn resize(self: Allocator, allocation: anytype, new_len: usize) bool

File

lib/std/mem/Allocator.zig:317

Code

pub fn resize(self: Allocator, allocation: anytype, new_len: usize) bool {
    const slice_info = @typeInfo(@TypeOf(allocation)).pointer;
    comptime assert(slice_info.size == .slice);
    const T = slice_info.child;
    if (new_len == 0) {
        self.free(allocation);
        return true;
    }
    if (allocation.len == 0) {
        return false;
    }
    const old_memory: []u8 = @ptrCast(@constCast(mem.absorbSentinel(allocation)));
    // I would like to use saturating multiplication here, but LLVM cannot lower it
    // on WebAssembly: https://github.com/ziglang/zig/issues/9660
    //const new_len_bytes = new_len *| @sizeOf(T);
    const new_len_bytes = math.mul(usize, @sizeOf(T), new_len) catch return false;
    return self.rawResize(
        old_memory,
        .fromByteUnits(slice_info.attrs.@"align" orelse @alignOf(T)),
        new_len_bytes,
        @returnAddress(),
    );
}