struct Reader [src]
Alias for std.Io.Reader
Fields
vtable: *const VTable
buffer: []u8
seek: usizeNumber of bytes which have been consumed from buffer.
end: usizeIn buffer before this are buffered bytes, after this is undefined.
Members
- allocRemaining (Function)
- allocRemainingAlignedSentinel (Function)
- appendRemaining (Function)
- appendRemainingAligned (Function)
- appendRemainingUnlimited (Function)
- buffered (Function)
- bufferedLen (Function)
- defaultDiscard (Function)
- defaultReadVec (Function)
- defaultRebase (Function)
- DelimiterError (Error Set)
- discard (Function)
- discardAll (Function)
- discardAll64 (Function)
- discardDelimiterExclusive (Function)
- discardDelimiterInclusive (Function)
- discardDelimiterLimit (Function)
- DiscardDelimiterLimitError (Error Set)
- discardRemaining (Function)
- discardShort (Function)
- ending (Constant)
- ending_instance (Constant)
- Error (Error Set)
- failing (Constant)
- fill (Function)
- fillMore (Function)
- fixed (Function)
- hashed (Function)
- Hashed (Type Function)
- limited (Function)
- Limited (struct)
- LimitedAllocError (Error Set)
- peek (Function)
- peekArray (Function)
- peekByte (Function)
- peekDelimiterExclusive (Function)
- peekDelimiterInclusive (Function)
- peekGreedy (Function)
- peekInt (Function)
- peekSentinel (Function)
- peekStruct (Function)
- peekStructPointer (Function)
- readAlloc (Function)
- ReadAllocError (Error Set)
- readSliceAll (Function)
- readSliceEndian (Function)
- readSliceEndianAlloc (Function)
- readSliceShort (Function)
- readVec (Function)
- readVecAll (Function)
- rebase (Function)
- RebaseError (Error Set)
- ShortError (Error Set)
- stream (Function)
- streamDelimiter (Function)
- streamDelimiterEnding (Function)
- streamDelimiterLimit (Function)
- StreamDelimiterLimitError (Error Set)
- StreamError (Error Set)
- streamExact (Function)
- streamExact64 (Function)
- streamExactPreserve (Function)
- streamRemaining (Function)
- StreamRemainingError (Error Set)
- take (Function)
- takeArray (Function)
- takeByte (Function)
- takeByteSigned (Function)
- takeDelimiter (Function)
- takeDelimiterExclusive (Function)
- takeDelimiterInclusive (Function)
- takeEnum (Function)
- TakeEnumError (Error Set)
- takeEnumNonexhaustive (Function)
- takeInt (Function)
- takeLeb128 (Function)
- TakeLeb128Error (Error Set)
- takeSentinel (Function)
- takeStruct (Function)
- takeStructPointer (Function)
- takeVarInt (Function)
- toss (Function)
- tossBuffered (Function)
- UnlimitedAllocError (Error Set)
- VTable (struct)
- writableVector (Function)
- writableVectorPosix (Function)
- writableVectorWsa (Function)
Source
const Reader = @This();
const builtin = @import("builtin");
const native_endian = builtin.target.cpu.arch.endian();
const std = @import("../std.zig");
const Writer = std.Io.Writer;
const Limit = std.Io.Limit;
const assert = std.debug.assert;
const testing = std.testing;
const Allocator = std.mem.Allocator;
const ArrayList = std.ArrayList;
pub const Limited = @import("Reader/Limited.zig");
vtable: *const VTable,
buffer: []u8,
/// Number of bytes which have been consumed from `buffer`.
seek: usize,
/// In `buffer` before this are buffered bytes, after this is `undefined`.
end: usize,
pub const VTable = struct {
/// Writes bytes from the internally tracked logical position to `w`.
///
/// Returns the number of bytes written, which will be at minimum `0` and
/// at most `limit`. The number returned, including zero, does not indicate
/// end of stream.
///
/// The reader's internal logical seek position moves forward in accordance
/// with the number of bytes returned from this function.
///
/// Implementations are encouraged to utilize mandatory minimum buffer
/// sizes combined with short reads (returning a value less than `limit`)
/// in order to minimize complexity.
///
/// Although this function is usually called when `buffer` is empty, it is
/// also called when it needs to be filled more due to the API user
/// requesting contiguous memory. In either case, the existing buffer data
/// should be ignored; new data written to `w`.
///
/// In addition to, or instead of writing to `w`, the implementation may
/// choose to store data in `buffer`, modifying `seek` and `end`
/// accordingly. Implementations are encouraged to take advantage of
/// this if it simplifies the logic.
stream: *const fn (r: *Reader, w: *Writer, limit: Limit) StreamError!usize,
/// Consumes bytes from the internally tracked stream position without
/// providing access to them.
///
/// Returns the number of bytes discarded, which will be at minimum `0` and
/// at most `limit`. The number of bytes returned, including zero, does not
/// indicate end of stream.
///
/// The reader's internal logical seek position moves forward in accordance
/// with the number of bytes returned from this function.
///
/// Implementations are encouraged to utilize mandatory minimum buffer
/// sizes combined with short reads (returning a value less than `limit`)
/// in order to minimize complexity.
///
/// The default implementation is is based on calling `stream`, borrowing
/// `buffer` to construct a temporary `Writer` and ignoring the written
/// data.
///
/// This function is only called when `buffer` is empty.
discard: *const fn (r: *Reader, limit: Limit) Error!usize = defaultDiscard,
/// Returns number of bytes written to `data`.
///
/// `data` must have nonzero length. `data[0]` may have zero length, in
/// which case the implementation must write to `Reader.buffer`.
///
/// `data` may not contain an alias to `Reader.buffer`.
///
/// `data` is mutable because the implementation may temporarily modify the
/// fields in order to handle partial reads. Implementations must restore
/// the original value before returning.
///
/// Implementations may ignore `data`, writing directly to `Reader.buffer`,
/// modifying `seek` and `end` accordingly, and returning 0 from this
/// function. Implementations are encouraged to take advantage of this if
/// it simplifies the logic.
///
/// The default implementation calls `stream` with either `data[0]` or
/// `Reader.buffer`, whichever is bigger.
readVec: *const fn (r: *Reader, data: [][]u8) Error!usize = defaultReadVec,
/// Ensures `capacity` data can be buffered without rebasing.
///
/// Asserts `capacity` is within buffer capacity, or that the stream ends
/// within `capacity` bytes.
///
/// Only called when `capacity` cannot be satisfied by unused capacity of
/// `buffer`.
///
/// The default implementation moves buffered data to the start of
/// `buffer`, setting `seek` to zero, and cannot fail.
rebase: *const fn (r: *Reader, capacity: usize) RebaseError!void = defaultRebase,
};
pub const StreamError = error{
/// See the `Reader` implementation for detailed diagnostics.
ReadFailed,
/// See the `Writer` implementation for detailed diagnostics.
WriteFailed,
/// End of stream indicated from the `Reader`. This error cannot originate
/// from the `Writer`.
EndOfStream,
};
pub const Error = error{
/// See the `Reader` implementation for detailed diagnostics.
ReadFailed,
EndOfStream,
};
pub const StreamRemainingError = error{
/// See the `Reader` implementation for detailed diagnostics.
ReadFailed,
/// See the `Writer` implementation for detailed diagnostics.
WriteFailed,
};
pub const ShortError = error{
/// See the `Reader` implementation for detailed diagnostics.
ReadFailed,
};
pub const RebaseError = error{
EndOfStream,
};
pub const failing: Reader = .{
.vtable = &.{
.stream = failingStream,
.discard = failingDiscard,
},
.buffer = &.{},
.seek = 0,
.end = 0,
};
/// This is generally safe to `@constCast` because it has an empty buffer, so
/// there is not really a way to accidentally attempt mutation of these fields.
pub const ending_instance: Reader = .fixed(&.{});
pub const ending: *Reader = @constCast(&ending_instance);
pub fn limited(r: *Reader, limit: Limit, buffer: []u8) Limited {
return .init(r, limit, buffer);
}
/// Constructs a `Reader` such that it will read from `buffer` and then end.
pub fn fixed(buffer: []const u8) Reader {
return .{
.vtable = &.{
.stream = endingStream,
.discard = endingDiscard,
.readVec = endingReadVec,
.rebase = endingRebase,
},
// This cast is safe because all potential writes to it will instead
// return `error.EndOfStream`.
.buffer = @constCast(buffer),
.end = buffer.len,
.seek = 0,
};
}
pub fn stream(r: *Reader, w: *Writer, limit: Limit) StreamError!usize {
const buffer = limit.slice(r.buffer[r.seek..r.end]);
if (buffer.len > 0) {
@branchHint(.likely);
const n = try w.write(buffer);
r.seek += n;
return n;
}
const n = try r.vtable.stream(r, w, limit);
assert(n <= @intFromEnum(limit));
return n;
}
pub fn discard(r: *Reader, limit: Limit) Error!usize {
const buffered_len = r.end - r.seek;
const remaining: Limit = if (limit.toInt()) |n| l: {
if (buffered_len >= n) {
r.seek += n;
return n;
}
break :l .limited(n - buffered_len);
} else .unlimited;
r.seek = r.end;
const n = try r.vtable.discard(r, remaining);
assert(n <= @intFromEnum(remaining));
return buffered_len + n;
}
pub fn defaultDiscard(r: *Reader, limit: Limit) Error!usize {
assert(r.seek == r.end);
r.seek = 0;
r.end = 0;
var d: Writer.Discarding = .init(r.buffer);
const n = r.stream(&d.writer, limit) catch |err| switch (err) {
error.WriteFailed => unreachable,
error.ReadFailed => return error.ReadFailed,
error.EndOfStream => return error.EndOfStream,
};
assert(n <= @intFromEnum(limit));
return n;
}
/// "Pump" exactly `n` bytes from the reader to the writer.
pub fn streamExact(r: *Reader, w: *Writer, n: usize) StreamError!void {
var remaining = n;
while (remaining != 0) remaining -= try r.stream(w, .limited(remaining));
}
/// "Pump" exactly `n` bytes from the reader to the writer.
pub fn streamExact64(r: *Reader, w: *Writer, n: u64) StreamError!void {
var remaining = n;
while (remaining != 0) remaining -= try r.stream(w, .limited64(remaining));
}
/// "Pump" exactly `n` bytes from the reader to the writer.
///
/// When draining `w`, ensures that at least `preserve_len` bytes remain
/// buffered.
///
/// Asserts `Writer.buffer` capacity exceeds `preserve_len`.
pub fn streamExactPreserve(r: *Reader, w: *Writer, preserve_len: usize, n: usize) StreamError!void {
if (w.end + n <= w.buffer.len) {
@branchHint(.likely);
return streamExact(r, w, n);
}
// If `n` is large, we can ignore `preserve_len` up to a point.
var remaining = n;
while (remaining > preserve_len) {
assert(remaining != 0);
remaining -= try r.stream(w, .limited(remaining - preserve_len));
if (w.end + remaining <= w.buffer.len) return streamExact(r, w, remaining);
}
// All the next bytes received must be preserved.
if (preserve_len < w.end) {
@memmove(w.buffer[0..preserve_len], w.buffer[w.end - preserve_len ..][0..preserve_len]);
w.end = preserve_len;
}
return streamExact(r, w, remaining);
}
/// "Pump" data from the reader to the writer, handling `error.EndOfStream` as
/// a success case.
///
/// Returns total number of bytes written to `w`.
pub fn streamRemaining(r: *Reader, w: *Writer) StreamRemainingError!usize {
var offset: usize = 0;
while (true) {
offset += r.stream(w, .unlimited) catch |err| switch (err) {
error.EndOfStream => return offset,
else => |e| return e,
};
}
}
/// Consumes the stream until the end, ignoring all the data, returning the
/// number of bytes discarded.
pub fn discardRemaining(r: *Reader) ShortError!usize {
var offset: usize = r.end - r.seek;
r.seek = r.end;
while (true) {
offset += r.vtable.discard(r, .unlimited) catch |err| switch (err) {
error.EndOfStream => return offset,
else => |e| return e,
};
}
}
pub const LimitedAllocError = Allocator.Error || ShortError || error{StreamTooLong};
/// Transfers all bytes from the current position to the end of the stream, up
/// to `limit`, returning them as a caller-owned allocated slice.
///
/// If `limit` would be exceeded, `error.StreamTooLong` is returned instead. In
/// such case, the next byte that would be read will be the first one to exceed
/// `limit`, and all preceeding bytes have been discarded.
///
/// See also:
/// * `appendRemaining`
pub fn allocRemaining(r: *Reader, gpa: Allocator, limit: Limit) LimitedAllocError![]u8 {
var buffer: ArrayList(u8) = .empty;
defer buffer.deinit(gpa);
try appendRemaining(r, gpa, &buffer, limit);
return buffer.toOwnedSlice(gpa);
}
pub fn allocRemainingAlignedSentinel(
r: *Reader,
gpa: Allocator,
limit: Limit,
comptime alignment: std.mem.Alignment,
comptime sentinel: ?u8,
) LimitedAllocError!(if (sentinel) |s| [:s]align(alignment.toByteUnits()) u8 else []align(alignment.toByteUnits()) u8) {
var buffer: std.array_list.Aligned(u8, alignment) = .empty;
defer buffer.deinit(gpa);
try appendRemainingAligned(r, gpa, alignment, &buffer, limit);
if (sentinel) |s| {
return buffer.toOwnedSliceSentinel(gpa, s);
} else {
return buffer.toOwnedSlice(gpa);
}
}
/// Transfers all bytes from the current position to the end of the stream, up
/// to `limit`, appending them to `list`.
///
/// If `limit` is reached or exceeded, `error.StreamTooLong` is returned
/// instead. In such case, the next byte that would be read will be the first
/// one to exceed `limit`, and all preceeding bytes have been appended to
/// `list`.
///
/// See also:
/// * `allocRemaining`
pub fn appendRemaining(
r: *Reader,
gpa: Allocator,
list: *ArrayList(u8),
limit: Limit,
) LimitedAllocError!void {
return appendRemainingAligned(r, gpa, .of(u8), list, limit);
}
/// Transfers all bytes from the current position to the end of the stream, up
/// to `limit`, appending them to `list`.
///
/// If `limit` is reached or exceeded, `error.StreamTooLong` is returned
/// instead. In such case, the next byte that would be read will be the first
/// one to exceed `limit`, and all preceeding bytes have been appended to
/// `list`.
///
/// See also:
/// * `appendRemaining`
/// * `allocRemainingAligned`
pub fn appendRemainingAligned(
r: *Reader,
gpa: Allocator,
comptime alignment: std.mem.Alignment,
list: *std.array_list.Aligned(u8, alignment),
limit: Limit,
) LimitedAllocError!void {
var a = std.Io.Writer.Allocating.fromArrayListAligned(gpa, alignment, list);
defer list.* = a.toArrayListAligned(alignment);
var remaining = limit;
while (remaining.nonzero()) {
const n = stream(r, &a.writer, remaining) catch |err| switch (err) {
error.EndOfStream => return,
error.WriteFailed => return error.OutOfMemory,
error.ReadFailed => return error.ReadFailed,
};
remaining = remaining.subtract(n).?;
}
return error.StreamTooLong;
}
pub const UnlimitedAllocError = Allocator.Error || ShortError;
pub fn appendRemainingUnlimited(r: *Reader, gpa: Allocator, list: *ArrayList(u8)) UnlimitedAllocError!void {
var a: std.Io.Writer.Allocating = .initOwnedSlice(gpa, list.allocatedSlice());
a.writer.end = list.items.len;
list.* = .empty;
defer {
list.* = .{
.items = a.writer.buffer[0..a.writer.end],
.capacity = a.writer.buffer.len,
};
}
_ = streamRemaining(r, &a.writer) catch |err| switch (err) {
error.WriteFailed => return error.OutOfMemory,
error.ReadFailed => return error.ReadFailed,
};
}
/// Writes bytes from the internally tracked stream position to `data`.
///
/// Returns the number of bytes written, which will be at minimum `0` and
/// at most the sum of each data slice length. The number of bytes read,
/// including zero, does not indicate end of stream.
///
/// The reader's internal logical seek position moves forward in accordance
/// with the number of bytes returned from this function.
pub fn readVec(r: *Reader, data: [][]u8) Error!usize {
var seek = r.seek;
for (data, 0..) |buf, i| {
const contents = r.buffer[seek..r.end];
const copy_len = @min(contents.len, buf.len);
@memcpy(buf[0..copy_len], contents[0..copy_len]);
seek += copy_len;
if (buf.len - copy_len == 0) continue;
// All of `buffer` has been copied to `data`.
const n = seek - r.seek;
r.seek = seek;
data[i] = buf[copy_len..];
defer data[i] = buf;
return n + (r.vtable.readVec(r, data[i..]) catch |err| switch (err) {
error.EndOfStream => if (n == 0) return error.EndOfStream else 0,
error.ReadFailed => return error.ReadFailed,
});
}
const n = seek - r.seek;
r.seek = seek;
return n;
}
/// Writes to `Reader.buffer` or `data`, whichever has larger capacity.
pub fn defaultReadVec(r: *Reader, data: [][]u8) Error!usize {
const first = data[0];
if (first.len >= r.buffer.len - r.end) {
var writer: Writer = .{
.buffer = first,
.end = 0,
.vtable = &.{ .drain = Writer.fixedDrain },
};
const limit: Limit = .limited(writer.buffer.len - writer.end);
return r.vtable.stream(r, &writer, limit) catch |err| switch (err) {
error.WriteFailed => unreachable,
else => |e| return e,
};
}
var writer: Writer = .{
.buffer = r.buffer,
.end = r.end,
.vtable = &.{ .drain = Writer.fixedDrain },
};
const limit: Limit = .limited(writer.buffer.len - writer.end);
r.end += r.vtable.stream(r, &writer, limit) catch |err| switch (err) {
error.WriteFailed => unreachable,
else => |e| return e,
};
return 0;
}
pub fn buffered(r: *Reader) []u8 {
return r.buffer[r.seek..r.end];
}
pub fn bufferedLen(r: *const Reader) usize {
return r.end - r.seek;
}
pub fn hashed(r: *Reader, hasher: anytype, buffer: []u8) Hashed(@TypeOf(hasher)) {
return .init(r, hasher, buffer);
}
pub fn readVecAll(r: *Reader, data: [][]u8) Error!void {
var index: usize = 0;
var truncate: usize = 0;
while (index < data.len) {
{
const untruncated = data[index];
data[index] = untruncated[truncate..];
defer data[index] = untruncated;
truncate += try r.readVec(data[index..]);
}
while (index < data.len and truncate >= data[index].len) {
truncate -= data[index].len;
index += 1;
}
}
}
/// Returns the next `len` bytes from the stream, filling the buffer as
/// necessary.
///
/// Invalidates previously returned values from `peek`.
///
/// Asserts that the `Reader` was initialized with a buffer capacity at
/// least as big as `len`.
///
/// If there are fewer than `len` bytes left in the stream, `error.EndOfStream`
/// is returned instead.
///
/// See also:
/// * `peek`
/// * `toss`
pub fn peek(r: *Reader, n: usize) Error![]u8 {
try r.fill(n);
return r.buffer[r.seek..][0..n];
}
/// Returns all the next buffered bytes, after filling the buffer to ensure it
/// contains at least `n` bytes.
///
/// Invalidates previously returned values from `peek` and `peekGreedy`.
///
/// Asserts that the `Reader` was initialized with a buffer capacity at
/// least as big as `n`.
///
/// If there are fewer than `n` bytes left in the stream, `error.EndOfStream`
/// is returned instead.
///
/// See also:
/// * `peek`
/// * `toss`
pub fn peekGreedy(r: *Reader, n: usize) Error![]u8 {
try r.fill(n);
return r.buffer[r.seek..r.end];
}
/// Skips the next `n` bytes from the stream, advancing the seek position. This
/// is typically and safely used after `peek`.
///
/// Asserts that the number of bytes buffered is at least as many as `n`.
///
/// The "tossed" memory remains alive until a "peek" operation occurs.
///
/// See also:
/// * `peek`.
/// * `discard`.
pub fn toss(r: *Reader, n: usize) void {
r.seek += n;
assert(r.seek <= r.end);
}
/// Equivalent to `toss(r.bufferedLen())`.
pub fn tossBuffered(r: *Reader) void {
r.seek = r.end;
}
/// Equivalent to `peek` followed by `toss`.
///
/// The data returned is invalidated by the next call to `take`, `peek`,
/// `fill`, and functions with those prefixes.
pub fn take(r: *Reader, n: usize) Error![]u8 {
const result = try r.peek(n);
r.toss(n);
return result;
}
/// Returns the next `n` bytes from the stream as an array, filling the buffer
/// as necessary and advancing the seek position `n` bytes.
///
/// Asserts that the `Reader` was initialized with a buffer capacity at
/// least as big as `n`.
///
/// If there are fewer than `n` bytes left in the stream, `error.EndOfStream`
/// is returned instead.
///
/// See also:
/// * `take`
pub fn takeArray(r: *Reader, comptime n: usize) Error!*[n]u8 {
return (try r.take(n))[0..n];
}
/// Returns the next `n` bytes from the stream as an array, filling the buffer
/// as necessary, without advancing the seek position.
///
/// Asserts that the `Reader` was initialized with a buffer capacity at
/// least as big as `n`.
///
/// If there are fewer than `n` bytes left in the stream, `error.EndOfStream`
/// is returned instead.
///
/// See also:
/// * `peek`
/// * `takeArray`
pub fn peekArray(r: *Reader, comptime n: usize) Error!*[n]u8 {
return (try r.peek(n))[0..n];
}
/// Skips the next `n` bytes from the stream, advancing the seek position.
///
/// Unlike `toss` which is infallible, in this function `n` can be any amount.
///
/// Returns `error.EndOfStream` if fewer than `n` bytes could be discarded.
///
/// See also:
/// * `toss`
/// * `discardRemaining`
/// * `discardShort`
/// * `discard`
pub fn discardAll(r: *Reader, n: usize) Error!void {
if ((try r.discardShort(n)) != n) return error.EndOfStream;
}
pub fn discardAll64(r: *Reader, n: u64) Error!void {
var remaining: u64 = n;
while (remaining > 0) {
const limited_remaining = std.math.cast(usize, remaining) orelse std.math.maxInt(usize);
try discardAll(r, limited_remaining);
remaining -= limited_remaining;
}
}
/// Skips the next `n` bytes from the stream, advancing the seek position.
///
/// Unlike `toss` which is infallible, in this function `n` can be any amount.
///
/// Returns the number of bytes discarded, which is less than `n` if and only
/// if the stream reached the end.
///
/// See also:
/// * `discardAll`
/// * `discardRemaining`
/// * `discard`
pub fn discardShort(r: *Reader, n: usize) ShortError!usize {
const proposed_seek = r.seek + n;
if (proposed_seek <= r.end) {
@branchHint(.likely);
r.seek = proposed_seek;
return n;
}
var remaining = n - (r.end - r.seek);
r.seek = r.end;
while (true) {
const discard_len = r.vtable.discard(r, .limited(remaining)) catch |err| switch (err) {
error.EndOfStream => return n - remaining,
error.ReadFailed => return error.ReadFailed,
};
remaining -= discard_len;
if (remaining == 0) return n;
}
}
/// Fill `buffer` with the next `buffer.len` bytes from the stream, advancing
/// the seek position.
///
/// Invalidates previously returned values from `peek`.
///
/// If the provided buffer cannot be filled completely, `error.EndOfStream` is
/// returned instead.
///
/// See also:
/// * `peek`
/// * `readSliceShort`
pub fn readSliceAll(r: *Reader, buffer: []u8) Error!void {
const n = try readSliceShort(r, buffer);
if (n != buffer.len) return error.EndOfStream;
}
/// Fill `buffer` with the next `buffer.len` bytes from the stream, advancing
/// the seek position.
///
/// Invalidates previously returned values from `peek`.
///
/// Returns the number of bytes read, which is less than `buffer.len` if and
/// only if the stream reached the end.
///
/// See also:
/// * `readSliceAll`
pub fn readSliceShort(r: *Reader, buffer: []u8) ShortError!usize {
const contents = r.buffer[r.seek..r.end];
const copy_len = @min(buffer.len, contents.len);
@memcpy(buffer[0..copy_len], contents[0..copy_len]);
r.seek += copy_len;
if (buffer.len - copy_len == 0) {
@branchHint(.likely);
return buffer.len;
}
var i: usize = copy_len;
var data: [1][]u8 = undefined;
while (true) {
data[0] = buffer[i..];
i += readVec(r, &data) catch |err| switch (err) {
error.EndOfStream => return i,
error.ReadFailed => return error.ReadFailed,
};
if (buffer.len - i == 0) return buffer.len;
}
}
/// Fill `buffer` with the next `buffer.len` bytes from the stream, advancing
/// the seek position.
///
/// Invalidates previously returned values from `peek`.
///
/// If the provided buffer cannot be filled completely, `error.EndOfStream` is
/// returned instead.
///
/// The function is inline to avoid the dead code in case `endian` is
/// comptime-known and matches host endianness.
///
/// See also:
/// * `readSliceAll`
/// * `readSliceEndianAlloc`
pub inline fn readSliceEndian(
r: *Reader,
comptime Elem: type,
buffer: []Elem,
endian: std.builtin.Endian,
) Error!void {
try readSliceAll(r, @ptrCast(buffer));
if (native_endian != endian) for (buffer) |*elem| std.mem.byteSwapAllFields(Elem, elem);
}
pub const ReadAllocError = Error || Allocator.Error;
/// The function is inline to avoid the dead code in case `endian` is
/// comptime-known and matches host endianness.
pub inline fn readSliceEndianAlloc(
r: *Reader,
allocator: Allocator,
comptime Elem: type,
len: usize,
endian: std.builtin.Endian,
) ReadAllocError![]Elem {
const dest = try allocator.alloc(Elem, len);
errdefer allocator.free(dest);
try readSliceAll(r, @ptrCast(dest));
if (native_endian != endian) for (dest) |*elem| std.mem.byteSwapAllFields(Elem, elem);
return dest;
}
/// Shortcut for calling `readSliceAll` with a buffer provided by `allocator`.
pub fn readAlloc(r: *Reader, allocator: Allocator, len: usize) ReadAllocError![]u8 {
const dest = try allocator.alloc(u8, len);
errdefer allocator.free(dest);
try readSliceAll(r, dest);
return dest;
}
pub const DelimiterError = error{
/// See the `Reader` implementation for detailed diagnostics.
ReadFailed,
/// For "inclusive" functions, stream ended before the delimiter was found.
/// For "exclusive" functions, stream ended and there are no more bytes to
/// return.
EndOfStream,
/// The delimiter was not found within a number of bytes matching the
/// capacity of the `Reader`.
StreamTooLong,
};
/// Returns a slice of the next bytes of buffered data from the stream until
/// `sentinel` is found, advancing the seek position.
///
/// Returned slice has a sentinel.
///
/// Invalidates previously returned values from `peek`.
///
/// See also:
/// * `peekSentinel`
/// * `takeDelimiterExclusive`
/// * `takeDelimiterInclusive`
pub fn takeSentinel(r: *Reader, comptime sentinel: u8) DelimiterError![:sentinel]u8 {
const result = try r.peekSentinel(sentinel);
r.toss(result.len + 1);
return result;
}
/// Returns a slice of the next bytes of buffered data from the stream until
/// `sentinel` is found, without advancing the seek position.
///
/// Returned slice has a sentinel; end of stream does not count as a delimiter.
///
/// Invalidates previously returned values from `peek`.
///
/// See also:
/// * `takeSentinel`
/// * `peekDelimiterExclusive`
/// * `peekDelimiterInclusive`
pub fn peekSentinel(r: *Reader, comptime sentinel: u8) DelimiterError![:sentinel]u8 {
const result = try r.peekDelimiterInclusive(sentinel);
return result[0 .. result.len - 1 :sentinel];
}
/// Returns a slice of the next bytes of buffered data from the stream until
/// `delimiter` is found, advancing the seek position.
///
/// Returned slice includes the delimiter as the last byte.
///
/// Invalidates previously returned values from `peek`.
///
/// See also:
/// * `takeSentinel`
/// * `takeDelimiterExclusive`
/// * `peekDelimiterInclusive`
pub fn takeDelimiterInclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
const result = try r.peekDelimiterInclusive(delimiter);
r.toss(result.len);
return result;
}
/// Returns a slice of the next bytes of buffered data from the stream until
/// `delimiter` is found, without advancing the seek position.
///
/// Returned slice includes the delimiter as the last byte.
///
/// Invalidates previously returned values from `peek`.
///
/// See also:
/// * `peekSentinel`
/// * `peekDelimiterExclusive`
/// * `takeDelimiterInclusive`
pub fn peekDelimiterInclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
const buffer = r.buffer[0..r.end];
const seek = r.seek;
if (std.mem.indexOfScalarPos(u8, buffer, seek, delimiter)) |end| {
@branchHint(.likely);
return buffer[seek .. end + 1];
}
// TODO take a parameter for max search length rather than relying on buffer capacity
try rebase(r, r.buffer.len);
while (r.buffer.len - r.end != 0) {
const end_cap = r.buffer[r.end..];
var writer: Writer = .fixed(end_cap);
const n = r.vtable.stream(r, &writer, .limited(end_cap.len)) catch |err| switch (err) {
error.WriteFailed => unreachable,
else => |e| return e,
};
r.end += n;
if (std.mem.indexOfScalarPos(u8, end_cap[0..n], 0, delimiter)) |end| {
return r.buffer[0 .. r.end - n + end + 1];
}
}
return error.StreamTooLong;
}
/// Returns a slice of the next bytes of buffered data from the stream until
/// `delimiter` is found, advancing the seek position up to the delimiter.
///
/// Returned slice excludes the delimiter. End-of-stream is treated equivalent
/// to a delimiter, unless it would result in a length 0 return value, in which
/// case `error.EndOfStream` is returned instead.
///
/// If the delimiter is not found within a number of bytes matching the
/// capacity of this `Reader`, `error.StreamTooLong` is returned. In
/// such case, the stream state is unmodified as if this function was never
/// called.
///
/// Invalidates previously returned values from `peek`.
///
/// See also:
/// * `takeDelimiterInclusive`
/// * `peekDelimiterExclusive`
pub fn takeDelimiterExclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
const result = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
error.EndOfStream => {
const remaining = r.buffer[r.seek..r.end];
if (remaining.len == 0) return error.EndOfStream;
r.toss(remaining.len);
return remaining;
},
else => |e| return e,
};
r.toss(result.len);
return result[0 .. result.len - 1];
}
/// Returns a slice of the next bytes of buffered data from the stream until
/// `delimiter` is found, advancing the seek position past the delimiter.
///
/// Returned slice excludes the delimiter. End-of-stream is treated equivalent
/// to a delimiter, unless it would result in a length 0 return value, in which
/// case `null` is returned instead.
///
/// If the delimiter is not found within a number of bytes matching the
/// capacity of this `Reader`, `error.StreamTooLong` is returned. In
/// such case, the stream state is unmodified as if this function was never
/// called.
///
/// Invalidates previously returned values from `peek`.
///
/// See also:
/// * `takeDelimiterInclusive`
/// * `takeDelimiterExclusive`
pub fn takeDelimiter(r: *Reader, delimiter: u8) error{ ReadFailed, StreamTooLong }!?[]u8 {
const result = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
error.EndOfStream => {
const remaining = r.buffer[r.seek..r.end];
if (remaining.len == 0) return null;
r.toss(remaining.len);
return remaining;
},
else => |e| return e,
};
r.toss(result.len + 1);
return result[0 .. result.len - 1];
}
/// Returns a slice of the next bytes of buffered data from the stream until
/// `delimiter` is found, without advancing the seek position.
///
/// Returned slice excludes the delimiter. End-of-stream is treated equivalent
/// to a delimiter, unless it would result in a length 0 return value, in which
/// case `error.EndOfStream` is returned instead.
///
/// If the delimiter is not found within a number of bytes matching the
/// capacity of this `Reader`, `error.StreamTooLong` is returned. In
/// such case, the stream state is unmodified as if this function was never
/// called.
///
/// Invalidates previously returned values from `peek`.
///
/// See also:
/// * `peekDelimiterInclusive`
/// * `takeDelimiterExclusive`
pub fn peekDelimiterExclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
const result = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
error.EndOfStream => {
const remaining = r.buffer[r.seek..r.end];
if (remaining.len == 0) return error.EndOfStream;
return remaining;
},
else => |e| return e,
};
return result[0 .. result.len - 1];
}
/// Appends to `w` contents by reading from the stream until `delimiter` is
/// found. Does not write the delimiter itself.
///
/// Does not discard the delimiter from the `Reader`.
///
/// Returns number of bytes streamed, which may be zero, or error.EndOfStream
/// if the delimiter was not found.
///
/// Asserts buffer capacity of at least one. This function performs better with
/// larger buffers.
///
/// See also:
/// * `streamDelimiterEnding`
/// * `streamDelimiterLimit`
pub fn streamDelimiter(r: *Reader, w: *Writer, delimiter: u8) StreamError!usize {
const n = streamDelimiterLimit(r, w, delimiter, .unlimited) catch |err| switch (err) {
error.StreamTooLong => unreachable, // unlimited is passed
else => |e| return e,
};
if (r.seek == r.end) return error.EndOfStream;
return n;
}
/// Appends to `w` contents by reading from the stream until `delimiter` is found.
/// Does not write the delimiter itself.
///
/// Returns number of bytes streamed, which may be zero. If the stream reaches
/// the end, the reader buffer will be empty when this function returns.
/// Otherwise, it will have at least one byte buffered, starting with the
/// delimiter.
///
/// Asserts buffer capacity of at least one. This function performs better with
/// larger buffers.
///
/// See also:
/// * `streamDelimiter`
/// * `streamDelimiterLimit`
pub fn streamDelimiterEnding(
r: *Reader,
w: *Writer,
delimiter: u8,
) StreamRemainingError!usize {
return streamDelimiterLimit(r, w, delimiter, .unlimited) catch |err| switch (err) {
error.StreamTooLong => unreachable, // unlimited is passed
else => |e| return e,
};
}
pub const StreamDelimiterLimitError = error{
ReadFailed,
WriteFailed,
/// The delimiter was not found within the limit.
StreamTooLong,
};
/// Appends to `w` contents by reading from the stream until `delimiter` is found.
/// Does not write the delimiter itself.
///
/// Does not discard the delimiter from the `Reader`.
///
/// Returns number of bytes streamed, which may be zero. End of stream can be
/// detected by checking if the next byte in the stream is the delimiter.
///
/// Asserts buffer capacity of at least one. This function performs better with
/// larger buffers.
pub fn streamDelimiterLimit(
r: *Reader,
w: *Writer,
delimiter: u8,
limit: Limit,
) StreamDelimiterLimitError!usize {
var remaining = @intFromEnum(limit);
while (remaining != 0) {
const available = Limit.limited(remaining).slice(r.peekGreedy(1) catch |err| switch (err) {
error.ReadFailed => return error.ReadFailed,
error.EndOfStream => return @intFromEnum(limit) - remaining,
});
if (std.mem.indexOfScalar(u8, available, delimiter)) |delimiter_index| {
try w.writeAll(available[0..delimiter_index]);
r.toss(delimiter_index);
remaining -= delimiter_index;
return @intFromEnum(limit) - remaining;
}
try w.writeAll(available);
r.toss(available.len);
remaining -= available.len;
}
return error.StreamTooLong;
}
/// Reads from the stream until specified byte is found, discarding all data,
/// including the delimiter.
///
/// Returns number of bytes discarded, or `error.EndOfStream` if the delimiter
/// is not found.
///
/// See also:
/// * `discardDelimiterExclusive`
/// * `discardDelimiterLimit`
pub fn discardDelimiterInclusive(r: *Reader, delimiter: u8) Error!usize {
const n = discardDelimiterLimit(r, delimiter, .unlimited) catch |err| switch (err) {
error.StreamTooLong => unreachable, // unlimited is passed
else => |e| return e,
};
if (r.seek == r.end) return error.EndOfStream;
assert(r.buffer[r.seek] == delimiter);
toss(r, 1);
return n + 1;
}
/// Reads from the stream until specified byte is found, discarding all data,
/// excluding the delimiter.
///
/// Returns the number of bytes discarded.
///
/// Succeeds if stream ends before delimiter found. End of stream can be
/// detected by checking if the delimiter is buffered.
///
/// See also:
/// * `discardDelimiterInclusive`
/// * `discardDelimiterLimit`
pub fn discardDelimiterExclusive(r: *Reader, delimiter: u8) ShortError!usize {
return discardDelimiterLimit(r, delimiter, .unlimited) catch |err| switch (err) {
error.StreamTooLong => unreachable, // unlimited is passed
else => |e| return e,
};
}
pub const DiscardDelimiterLimitError = error{
ReadFailed,
/// The delimiter was not found within the limit.
StreamTooLong,
};
/// Reads from the stream until specified byte is found, discarding all data,
/// excluding the delimiter.
///
/// Returns the number of bytes discarded.
///
/// Succeeds if stream ends before delimiter found. End of stream can be
/// detected by checking if the delimiter is buffered.
pub fn discardDelimiterLimit(r: *Reader, delimiter: u8, limit: Limit) DiscardDelimiterLimitError!usize {
var remaining = @intFromEnum(limit);
while (remaining != 0) {
const available = Limit.limited(remaining).slice(r.peekGreedy(1) catch |err| switch (err) {
error.ReadFailed => return error.ReadFailed,
error.EndOfStream => return @intFromEnum(limit) - remaining,
});
if (std.mem.indexOfScalar(u8, available, delimiter)) |delimiter_index| {
r.toss(delimiter_index);
remaining -= delimiter_index;
return @intFromEnum(limit) - remaining;
}
r.toss(available.len);
remaining -= available.len;
}
return error.StreamTooLong;
}
/// Fills the buffer such that it contains at least `n` bytes, without
/// advancing the seek position.
///
/// Returns `error.EndOfStream` if and only if there are fewer than `n` bytes
/// remaining.
///
/// If the end of stream is not encountered, asserts buffer capacity is at
/// least `n`.
pub fn fill(r: *Reader, n: usize) Error!void {
if (r.seek + n <= r.end) {
@branchHint(.likely);
return;
}
return fillUnbuffered(r, n);
}
/// This internal function is separated from `fill` to encourage optimizers to inline `fill`, hence
/// propagating its `@branchHint` to usage sites. If these functions are combined, `fill` is large
/// enough that LLVM is reluctant to inline it, forcing usages of APIs like `takeInt` to go through
/// an expensive runtime function call just to figure out that the data is, in fact, already in the
/// buffer.
///
/// Missing this optimization can result in wall-clock time for the most affected benchmarks
/// increasing by a factor of 5 or more.
fn fillUnbuffered(r: *Reader, n: usize) Error!void {
try rebase(r, n);
var bufs: [1][]u8 = .{""};
while (r.end < r.seek + n) _ = try r.vtable.readVec(r, &bufs);
}
/// Without advancing the seek position, does exactly one underlying read, filling the buffer as
/// much as possible. This may result in zero bytes added to the buffer, which is not an end of
/// stream condition. End of stream is communicated via returning `error.EndOfStream`.
///
/// Asserts buffer capacity is at least 1.
pub fn fillMore(r: *Reader) Error!void {
try rebase(r, r.end - r.seek + 1);
var bufs: [1][]u8 = .{""};
_ = try r.vtable.readVec(r, &bufs);
}
/// Returns the next byte from the stream or returns `error.EndOfStream`.
///
/// Does not advance the seek position.
///
/// Asserts the buffer capacity is nonzero.
pub fn peekByte(r: *Reader) Error!u8 {
const buffer = r.buffer[0..r.end];
const seek = r.seek;
if (seek < buffer.len) {
@branchHint(.likely);
return buffer[seek];
}
try fill(r, 1);
return r.buffer[r.seek];
}
/// Reads 1 byte from the stream or returns `error.EndOfStream`.
///
/// Asserts the buffer capacity is nonzero.
pub fn takeByte(r: *Reader) Error!u8 {
const result = try peekByte(r);
r.seek += 1;
return result;
}
/// Same as `takeByte` except the returned byte is signed.
pub fn takeByteSigned(r: *Reader) Error!i8 {
return @bitCast(try r.takeByte());
}
/// Asserts the buffer was initialized with a capacity at least `@bitSizeOf(T) / 8`.
pub inline fn takeInt(r: *Reader, comptime T: type, endian: std.builtin.Endian) Error!T {
const n = @divExact(@typeInfo(T).int.bits, 8);
return std.mem.readInt(T, try r.takeArray(n), endian);
}
/// Asserts the buffer was initialized with a capacity at least `@bitSizeOf(T) / 8`.
pub inline fn peekInt(r: *Reader, comptime T: type, endian: std.builtin.Endian) Error!T {
const n = @divExact(@typeInfo(T).int.bits, 8);
return std.mem.readInt(T, try r.peekArray(n), endian);
}
/// Asserts the buffer was initialized with a capacity at least `n`.
pub fn takeVarInt(r: *Reader, comptime Int: type, endian: std.builtin.Endian, n: usize) Error!Int {
assert(n <= @sizeOf(Int));
return std.mem.readVarInt(Int, try r.take(n), endian);
}
/// Obtains an unaligned pointer to the beginning of the stream, reinterpreted
/// as a pointer to the provided type, advancing the seek position.
///
/// Asserts the buffer was initialized with a capacity at least `@sizeOf(T)`.
///
/// See also:
/// * `peekStructPointer`
/// * `takeStruct`
pub fn takeStructPointer(r: *Reader, comptime T: type) Error!*align(1) T {
// Only extern and packed structs have defined in-memory layout.
comptime assert(@typeInfo(T).@"struct".layout != .auto);
return @ptrCast(try r.takeArray(@sizeOf(T)));
}
/// Obtains an unaligned pointer to the beginning of the stream, reinterpreted
/// as a pointer to the provided type, without advancing the seek position.
///
/// Asserts the buffer was initialized with a capacity at least `@sizeOf(T)`.
///
/// See also:
/// * `takeStructPointer`
/// * `peekStruct`
pub fn peekStructPointer(r: *Reader, comptime T: type) Error!*align(1) T {
// Only extern and packed structs have defined in-memory layout.
comptime assert(@typeInfo(T).@"struct".layout != .auto);
return @ptrCast(try r.peekArray(@sizeOf(T)));
}
/// Asserts the buffer was initialized with a capacity at least `@sizeOf(T)`.
///
/// This function is inline to avoid referencing `std.mem.byteSwapAllFields`
/// when `endian` is comptime-known and matches the host endianness.
///
/// See also:
/// * `takeStructPointer`
/// * `peekStruct`
pub inline fn takeStruct(r: *Reader, comptime T: type, endian: std.builtin.Endian) Error!T {
switch (@typeInfo(T)) {
.@"struct" => |info| switch (info.layout) {
.auto => @compileError("ill-defined memory layout"),
.@"extern" => {
var res = (try r.takeStructPointer(T)).*;
if (native_endian != endian) std.mem.byteSwapAllFields(T, &res);
return res;
},
.@"packed" => {
return @bitCast(try takeInt(r, info.backing_integer.?, endian));
},
},
else => @compileError("not a struct"),
}
}
/// Asserts the buffer was initialized with a capacity at least `@sizeOf(T)`.
///
/// This function is inline to avoid referencing `std.mem.byteSwapAllFields`
/// when `endian` is comptime-known and matches the host endianness.
///
/// See also:
/// * `takeStruct`
/// * `peekStructPointer`
pub inline fn peekStruct(r: *Reader, comptime T: type, endian: std.builtin.Endian) Error!T {
switch (@typeInfo(T)) {
.@"struct" => |info| switch (info.layout) {
.auto => @compileError("ill-defined memory layout"),
.@"extern" => {
var res = (try r.peekStructPointer(T)).*;
if (native_endian != endian) std.mem.byteSwapAllFields(T, &res);
return res;
},
.@"packed" => {
return @bitCast(try peekInt(r, info.backing_integer.?, endian));
},
},
else => @compileError("not a struct"),
}
}
pub const TakeEnumError = Error || error{InvalidEnumTag};
/// Reads an integer with the same size as the given enum's tag type. If the
/// integer matches an enum tag, casts the integer to the enum tag and returns
/// it. Otherwise, returns `error.InvalidEnumTag`.
///
/// Asserts the buffer was initialized with a capacity at least `@sizeOf(Enum)`.
pub fn takeEnum(r: *Reader, comptime Enum: type, endian: std.builtin.Endian) TakeEnumError!Enum {
const Tag = @typeInfo(Enum).@"enum".tag_type;
const int = try r.takeInt(Tag, endian);
return std.meta.intToEnum(Enum, int);
}
/// Reads an integer with the same size as the given nonexhaustive enum's tag type.
///
/// Asserts the buffer was initialized with a capacity at least `@sizeOf(Enum)`.
pub fn takeEnumNonexhaustive(r: *Reader, comptime Enum: type, endian: std.builtin.Endian) Error!Enum {
const info = @typeInfo(Enum).@"enum";
comptime assert(!info.is_exhaustive);
comptime assert(@bitSizeOf(info.tag_type) == @sizeOf(info.tag_type) * 8);
return takeEnum(r, Enum, endian) catch |err| switch (err) {
error.InvalidEnumTag => unreachable,
else => |e| return e,
};
}
pub const TakeLeb128Error = Error || error{Overflow};
/// Read a single LEB128 value as type T, or `error.Overflow` if the value cannot fit.
pub fn takeLeb128(r: *Reader, comptime Result: type) TakeLeb128Error!Result {
const result_info = @typeInfo(Result).int;
return std.math.cast(Result, try r.takeMultipleOf7Leb128(@Type(.{ .int = .{
.signedness = result_info.signedness,
.bits = std.mem.alignForwardAnyAlign(u16, result_info.bits, 7),
} }))) orelse error.Overflow;
}
fn takeMultipleOf7Leb128(r: *Reader, comptime Result: type) TakeLeb128Error!Result {
const result_info = @typeInfo(Result).int;
comptime assert(result_info.bits % 7 == 0);
var remaining_bits: std.math.Log2IntCeil(Result) = result_info.bits;
const UnsignedResult = @Type(.{ .int = .{
.signedness = .unsigned,
.bits = result_info.bits,
} });
var result: UnsignedResult = 0;
var fits = true;
while (true) {
const buffer: []const packed struct(u8) { bits: u7, more: bool } = @ptrCast(try r.peekGreedy(1));
for (buffer, 1..) |byte, len| {
if (remaining_bits > 0) {
result = @shlExact(@as(UnsignedResult, byte.bits), result_info.bits - 7) |
if (result_info.bits > 7) @shrExact(result, 7) else 0;
remaining_bits -= 7;
} else if (fits) fits = switch (result_info.signedness) {
.signed => @as(i7, @bitCast(byte.bits)) ==
@as(i7, @truncate(@as(Result, @bitCast(result)) >> (result_info.bits - 1))),
.unsigned => byte.bits == 0,
};
if (byte.more) continue;
r.toss(len);
return if (fits) @as(Result, @bitCast(result)) >> remaining_bits else error.Overflow;
}
r.toss(buffer.len);
}
}
/// Ensures `capacity` data can be buffered without rebasing.
pub fn rebase(r: *Reader, capacity: usize) RebaseError!void {
if (r.buffer.len - r.seek >= capacity) {
@branchHint(.likely);
return;
}
return r.vtable.rebase(r, capacity);
}
pub fn defaultRebase(r: *Reader, capacity: usize) RebaseError!void {
assert(r.buffer.len - r.seek < capacity);
const data = r.buffer[r.seek..r.end];
@memmove(r.buffer[0..data.len], data);
r.seek = 0;
r.end = data.len;
assert(r.buffer.len - r.seek >= capacity);
}
test fixed {
var r: Reader = .fixed("a\x02");
try testing.expect((try r.takeByte()) == 'a');
try testing.expect((try r.takeEnum(enum(u8) {
a = 0,
b = 99,
c = 2,
d = 3,
}, builtin.cpu.arch.endian())) == .c);
try testing.expectError(error.EndOfStream, r.takeByte());
}
test peek {
var r: Reader = .fixed("abc");
try testing.expectEqualStrings("ab", try r.peek(2));
try testing.expectEqualStrings("a", try r.peek(1));
}
test peekGreedy {
var r: Reader = .fixed("abc");
try testing.expectEqualStrings("abc", try r.peekGreedy(1));
}
test toss {
var r: Reader = .fixed("abc");
r.toss(1);
try testing.expectEqualStrings("bc", r.buffered());
}
test take {
var r: Reader = .fixed("abc");
try testing.expectEqualStrings("ab", try r.take(2));
try testing.expectEqualStrings("c", try r.take(1));
}
test takeArray {
var r: Reader = .fixed("abc");
try testing.expectEqualStrings("ab", try r.takeArray(2));
try testing.expectEqualStrings("c", try r.takeArray(1));
}
test peekArray {
var r: Reader = .fixed("abc");
try testing.expectEqualStrings("ab", try r.peekArray(2));
try testing.expectEqualStrings("a", try r.peekArray(1));
}
test discardAll {
var r: Reader = .fixed("foobar");
try r.discardAll(3);
try testing.expectEqualStrings("bar", try r.take(3));
try r.discardAll(0);
try testing.expectError(error.EndOfStream, r.discardAll(1));
}
test discardRemaining {
var r: Reader = .fixed("foobar");
r.toss(1);
try testing.expectEqual(5, try r.discardRemaining());
try testing.expectEqual(0, try r.discardRemaining());
}
test stream {
var out_buffer: [10]u8 = undefined;
var r: Reader = .fixed("foobar");
var w: Writer = .fixed(&out_buffer);
// Short streams are possible with this function but not with fixed.
try testing.expectEqual(2, try r.stream(&w, .limited(2)));
try testing.expectEqualStrings("fo", w.buffered());
try testing.expectEqual(4, try r.stream(&w, .unlimited));
try testing.expectEqualStrings("foobar", w.buffered());
}
test takeSentinel {
var r: Reader = .fixed("ab\nc");
try testing.expectEqualStrings("ab", try r.takeSentinel('\n'));
try testing.expectError(error.EndOfStream, r.takeSentinel('\n'));
try testing.expectEqualStrings("c", try r.peek(1));
}
test peekSentinel {
var r: Reader = .fixed("ab\nc");
try testing.expectEqualStrings("ab", try r.peekSentinel('\n'));
try testing.expectEqualStrings("ab", try r.peekSentinel('\n'));
}
test takeDelimiterInclusive {
var r: Reader = .fixed("ab\nc");
try testing.expectEqualStrings("ab\n", try r.takeDelimiterInclusive('\n'));
try testing.expectError(error.EndOfStream, r.takeDelimiterInclusive('\n'));
}
test peekDelimiterInclusive {
var r: Reader = .fixed("ab\nc");
try testing.expectEqualStrings("ab\n", try r.peekDelimiterInclusive('\n'));
try testing.expectEqualStrings("ab\n", try r.peekDelimiterInclusive('\n'));
r.toss(3);
try testing.expectError(error.EndOfStream, r.peekDelimiterInclusive('\n'));
}
test takeDelimiterExclusive {
var r: Reader = .fixed("ab\nc");
try testing.expectEqualStrings("ab", try r.takeDelimiterExclusive('\n'));
try testing.expectEqualStrings("c", try r.takeDelimiterExclusive('\n'));
try testing.expectError(error.EndOfStream, r.takeDelimiterExclusive('\n'));
}
test peekDelimiterExclusive {
var r: Reader = .fixed("ab\nc");
try testing.expectEqualStrings("ab", try r.peekDelimiterExclusive('\n'));
try testing.expectEqualStrings("ab", try r.peekDelimiterExclusive('\n'));
r.toss(3);
try testing.expectEqualStrings("c", try r.peekDelimiterExclusive('\n'));
try testing.expectEqualStrings("c", try r.peekDelimiterExclusive('\n'));
}
test streamDelimiter {
var out_buffer: [10]u8 = undefined;
var r: Reader = .fixed("foo\nbars");
var w: Writer = .fixed(&out_buffer);
try testing.expectEqual(3, try r.streamDelimiter(&w, '\n'));
try testing.expectEqualStrings("foo", w.buffered());
try testing.expectEqual(0, try r.streamDelimiter(&w, '\n'));
r.toss(1);
try testing.expectError(error.EndOfStream, r.streamDelimiter(&w, '\n'));
}
test streamDelimiterEnding {
var out_buffer: [10]u8 = undefined;
var r: Reader = .fixed("foo\nbars");
var w: Writer = .fixed(&out_buffer);
try testing.expectEqual(3, try r.streamDelimiterEnding(&w, '\n'));
try testing.expectEqualStrings("foo", w.buffered());
r.toss(1);
try testing.expectEqual(4, try r.streamDelimiterEnding(&w, '\n'));
try testing.expectEqualStrings("foobars", w.buffered());
try testing.expectEqual(0, try r.streamDelimiterEnding(&w, '\n'));
try testing.expectEqual(0, try r.streamDelimiterEnding(&w, '\n'));
}
test streamDelimiterLimit {
var out_buffer: [10]u8 = undefined;
var r: Reader = .fixed("foo\nbars");
var w: Writer = .fixed(&out_buffer);
try testing.expectError(error.StreamTooLong, r.streamDelimiterLimit(&w, '\n', .limited(2)));
try testing.expectEqual(1, try r.streamDelimiterLimit(&w, '\n', .limited(3)));
try testing.expectEqualStrings("\n", try r.take(1));
try testing.expectEqual(4, try r.streamDelimiterLimit(&w, '\n', .unlimited));
try testing.expectEqualStrings("foobars", w.buffered());
}
test discardDelimiterExclusive {
var r: Reader = .fixed("foob\nar");
try testing.expectEqual(4, try r.discardDelimiterExclusive('\n'));
try testing.expectEqualStrings("\n", try r.take(1));
try testing.expectEqual(2, try r.discardDelimiterExclusive('\n'));
try testing.expectEqual(0, try r.discardDelimiterExclusive('\n'));
}
test discardDelimiterInclusive {
var r: Reader = .fixed("foob\nar");
try testing.expectEqual(5, try r.discardDelimiterInclusive('\n'));
try testing.expectError(error.EndOfStream, r.discardDelimiterInclusive('\n'));
}
test discardDelimiterLimit {
var r: Reader = .fixed("foob\nar");
try testing.expectError(error.StreamTooLong, r.discardDelimiterLimit('\n', .limited(4)));
try testing.expectEqual(0, try r.discardDelimiterLimit('\n', .limited(2)));
try testing.expectEqualStrings("\n", try r.take(1));
try testing.expectEqual(2, try r.discardDelimiterLimit('\n', .unlimited));
try testing.expectEqual(0, try r.discardDelimiterLimit('\n', .unlimited));
}
test fill {
var r: Reader = .fixed("abc");
try r.fill(1);
try r.fill(3);
}
test takeByte {
var r: Reader = .fixed("ab");
try testing.expectEqual('a', try r.takeByte());
try testing.expectEqual('b', try r.takeByte());
try testing.expectError(error.EndOfStream, r.takeByte());
}
test takeByteSigned {
var r: Reader = .fixed(&.{ 255, 5 });
try testing.expectEqual(-1, try r.takeByteSigned());
try testing.expectEqual(5, try r.takeByteSigned());
try testing.expectError(error.EndOfStream, r.takeByteSigned());
}
test takeInt {
var r: Reader = .fixed(&.{ 0x12, 0x34, 0x56 });
try testing.expectEqual(0x1234, try r.takeInt(u16, .big));
try testing.expectError(error.EndOfStream, r.takeInt(u16, .little));
}
test takeVarInt {
var r: Reader = .fixed(&.{ 0x12, 0x34, 0x56 });
try testing.expectEqual(0x123456, try r.takeVarInt(u64, .big, 3));
try testing.expectError(error.EndOfStream, r.takeVarInt(u16, .little, 1));
}
test takeStructPointer {
var r: Reader = .fixed(&.{ 0x12, 0x00, 0x34, 0x56 });
const S = extern struct { a: u8, b: u16 };
switch (native_endian) {
.little => try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x5634 }), (try r.takeStructPointer(S)).*),
.big => try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x3456 }), (try r.takeStructPointer(S)).*),
}
try testing.expectError(error.EndOfStream, r.takeStructPointer(S));
}
test peekStructPointer {
var r: Reader = .fixed(&.{ 0x12, 0x00, 0x34, 0x56 });
const S = extern struct { a: u8, b: u16 };
switch (native_endian) {
.little => {
try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x5634 }), (try r.peekStructPointer(S)).*);
try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x5634 }), (try r.peekStructPointer(S)).*);
},
.big => {
try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x3456 }), (try r.peekStructPointer(S)).*);
try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x3456 }), (try r.peekStructPointer(S)).*);
},
}
}
test takeStruct {
var r: Reader = .fixed(&.{ 0x12, 0x00, 0x34, 0x56 });
const S = extern struct { a: u8, b: u16 };
try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x3456 }), try r.takeStruct(S, .big));
try testing.expectError(error.EndOfStream, r.takeStruct(S, .little));
}
test peekStruct {
var r: Reader = .fixed(&.{ 0x12, 0x00, 0x34, 0x56 });
const S = extern struct { a: u8, b: u16 };
try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x3456 }), try r.peekStruct(S, .big));
try testing.expectEqual(@as(S, .{ .a = 0x12, .b = 0x5634 }), try r.peekStruct(S, .little));
}
test takeEnum {
var r: Reader = .fixed(&.{ 2, 0, 1 });
const E1 = enum(u8) { a, b, c };
const E2 = enum(u16) { _ };
try testing.expectEqual(E1.c, try r.takeEnum(E1, .little));
try testing.expectEqual(@as(E2, @enumFromInt(0x0001)), try r.takeEnum(E2, .big));
}
test takeLeb128 {
var r: Reader = .fixed("\xc7\x9f\x7f\x80");
try testing.expectEqual(-12345, try r.takeLeb128(i64));
try testing.expectEqual(0x80, try r.peekByte());
try testing.expectError(error.EndOfStream, r.takeLeb128(i64));
}
test readSliceShort {
var r: Reader = .fixed("HelloFren");
var buf: [5]u8 = undefined;
try testing.expectEqual(5, try r.readSliceShort(&buf));
try testing.expectEqualStrings("Hello", buf[0..5]);
try testing.expectEqual(4, try r.readSliceShort(&buf));
try testing.expectEqualStrings("Fren", buf[0..4]);
try testing.expectEqual(0, try r.readSliceShort(&buf));
}
test "readSliceShort with smaller buffer than Reader" {
var reader_buf: [15]u8 = undefined;
const str = "This is a test";
var one_byte_stream: testing.Reader = .init(&reader_buf, &.{
.{ .buffer = str },
});
one_byte_stream.artificial_limit = .limited(1);
var buf: [14]u8 = undefined;
try testing.expectEqual(14, try one_byte_stream.interface.readSliceShort(&buf));
try testing.expectEqualStrings(str, &buf);
}
test readVec {
var r: Reader = .fixed(std.ascii.letters);
var flat_buffer: [52]u8 = undefined;
var bufs: [2][]u8 = .{
flat_buffer[0..26],
flat_buffer[26..],
};
// Short reads are possible with this function but not with fixed.
try testing.expectEqual(26 * 2, try r.readVec(&bufs));
try testing.expectEqualStrings(std.ascii.letters[0..26], bufs[0]);
try testing.expectEqualStrings(std.ascii.letters[26..], bufs[1]);
}
test "expected error.EndOfStream" {
// Unit test inspired by https://github.com/ziglang/zig/issues/17733
var buffer: [3]u8 = undefined;
var r: std.Io.Reader = .fixed(&buffer);
r.end = 0; // capacity 3, but empty
try std.testing.expectError(error.EndOfStream, r.takeEnum(enum(u8) { a, b }, .little));
try std.testing.expectError(error.EndOfStream, r.take(3));
}
test "readVec at end" {
var reader_buffer: [8]u8 = "abcd1234".*;
var reader: testing.Reader = .init(&reader_buffer, &.{});
reader.interface.end = reader_buffer.len;
var out: [16]u8 = undefined;
var vecs: [1][]u8 = .{&out};
try testing.expectEqual(8, try reader.interface.readVec(&vecs));
try testing.expectEqualStrings("abcd1234", vecs[0][0..8]);
}
fn endingStream(r: *Reader, w: *Writer, limit: Limit) StreamError!usize {
_ = r;
_ = w;
_ = limit;
return error.EndOfStream;
}
fn endingReadVec(r: *Reader, data: [][]u8) Error!usize {
_ = r;
_ = data;
return error.EndOfStream;
}
fn endingDiscard(r: *Reader, limit: Limit) Error!usize {
_ = r;
_ = limit;
return error.EndOfStream;
}
fn endingRebase(r: *Reader, capacity: usize) RebaseError!void {
_ = r;
_ = capacity;
return error.EndOfStream;
}
fn failingStream(r: *Reader, w: *Writer, limit: Limit) StreamError!usize {
_ = r;
_ = w;
_ = limit;
return error.ReadFailed;
}
fn failingDiscard(r: *Reader, limit: Limit) Error!usize {
_ = r;
_ = limit;
return error.ReadFailed;
}
test "readAlloc when the backing reader provides one byte at a time" {
const str = "This is a test";
var tiny_buffer: [1]u8 = undefined;
var one_byte_stream: testing.Reader = .init(&tiny_buffer, &.{
.{ .buffer = str },
});
one_byte_stream.artificial_limit = .limited(1);
const res = try one_byte_stream.interface.allocRemaining(std.testing.allocator, .unlimited);
defer std.testing.allocator.free(res);
try std.testing.expectEqualStrings(str, res);
}
test "takeDelimiterInclusive when it rebases" {
const written_line = "ABCDEFGHIJKLMNOPQRSTUVWXYZ\n";
var buffer: [128]u8 = undefined;
var tr: std.testing.Reader = .init(&buffer, &.{
.{ .buffer = written_line },
.{ .buffer = written_line },
.{ .buffer = written_line },
.{ .buffer = written_line },
.{ .buffer = written_line },
.{ .buffer = written_line },
});
const r = &tr.interface;
for (0..6) |_| {
try std.testing.expectEqualStrings(written_line, try r.takeDelimiterInclusive('\n'));
}
}
test "takeStruct and peekStruct packed" {
var r: Reader = .fixed(&.{ 0b11110000, 0b00110011 });
const S = packed struct(u16) { a: u2, b: u6, c: u7, d: u1 };
try testing.expectEqual(@as(S, .{
.a = 0b11,
.b = 0b001100,
.c = 0b1110000,
.d = 0b1,
}), try r.peekStruct(S, .big));
try testing.expectEqual(@as(S, .{
.a = 0b11,
.b = 0b001100,
.c = 0b1110000,
.d = 0b1,
}), try r.takeStruct(S, .big));
try testing.expectError(error.EndOfStream, r.takeStruct(S, .little));
}
/// Provides a `Reader` implementation by passing data from an underlying
/// reader through `Hasher.update`.
///
/// The underlying reader is best unbuffered.
///
/// This implementation makes suboptimal buffering decisions due to being
/// generic. A better solution will involve creating a reader for each hash
/// function, where the discard buffer can be tailored to the hash
/// implementation details.
pub fn Hashed(comptime Hasher: type) type {
return struct {
in: *Reader,
hasher: Hasher,
reader: Reader,
pub fn init(in: *Reader, hasher: Hasher, buffer: []u8) @This() {
return .{
.in = in,
.hasher = hasher,
.reader = .{
.vtable = &.{
.stream = @This().stream,
.readVec = @This().readVec,
.discard = @This().discard,
},
.buffer = buffer,
.end = 0,
.seek = 0,
},
};
}
fn stream(r: *Reader, w: *Writer, limit: Limit) StreamError!usize {
const this: *@This() = @alignCast(@fieldParentPtr("reader", r));
const data = limit.slice(try w.writableSliceGreedy(1));
var vec: [1][]u8 = .{data};
const n = try this.in.readVec(&vec);
this.hasher.update(data[0..n]);
w.advance(n);
return n;
}
fn readVec(r: *Reader, data: [][]u8) Error!usize {
const this: *@This() = @alignCast(@fieldParentPtr("reader", r));
var vecs: [8][]u8 = undefined; // Arbitrarily chosen amount.
const dest_n, const data_size = try r.writableVector(&vecs, data);
const dest = vecs[0..dest_n];
const n = try this.in.readVec(dest);
var remaining: usize = n;
for (dest) |slice| {
if (remaining < slice.len) {
this.hasher.update(slice[0..remaining]);
remaining = 0;
break;
} else {
remaining -= slice.len;
this.hasher.update(slice);
}
}
assert(remaining == 0);
if (n > data_size) {
r.end += n - data_size;
return data_size;
}
return n;
}
fn discard(r: *Reader, limit: Limit) Error!usize {
const this: *@This() = @alignCast(@fieldParentPtr("reader", r));
const peeked = limit.slice(try this.in.peekGreedy(1));
this.hasher.update(peeked);
this.in.toss(peeked.len);
return peeked.len;
}
};
}
pub fn writableVectorPosix(r: *Reader, buffer: []std.posix.iovec, data: []const []u8) Error!struct { usize, usize } {
var i: usize = 0;
var n: usize = 0;
if (r.seek == r.end) {
for (data) |buf| {
if (buffer.len - i == 0) return .{ i, n };
if (buf.len != 0) {
buffer[i] = .{ .base = buf.ptr, .len = buf.len };
i += 1;
n += buf.len;
}
}
const buf = r.buffer;
if (buf.len != 0) {
r.seek = 0;
r.end = 0;
buffer[i] = .{ .base = buf.ptr, .len = buf.len };
i += 1;
}
} else {
const buf = r.buffer[r.end..];
buffer[i] = .{ .base = buf.ptr, .len = buf.len };
i += 1;
}
return .{ i, n };
}
pub fn writableVectorWsa(
r: *Reader,
buffer: []std.os.windows.ws2_32.WSABUF,
data: []const []u8,
) Error!struct { usize, usize } {
var i: usize = 0;
var n: usize = 0;
if (r.seek == r.end) {
for (data) |buf| {
if (buffer.len - i == 0) return .{ i, n };
if (buf.len == 0) continue;
if (std.math.cast(u32, buf.len)) |len| {
buffer[i] = .{ .buf = buf.ptr, .len = len };
i += 1;
n += len;
continue;
}
buffer[i] = .{ .buf = buf.ptr, .len = std.math.maxInt(u32) };
i += 1;
n += std.math.maxInt(u32);
return .{ i, n };
}
const buf = r.buffer;
if (buf.len != 0) {
r.seek = 0;
r.end = 0;
if (std.math.cast(u32, buf.len)) |len| {
buffer[i] = .{ .buf = buf.ptr, .len = len };
} else {
buffer[i] = .{ .buf = buf.ptr, .len = std.math.maxInt(u32) };
}
i += 1;
}
} else {
buffer[i] = .{
.buf = r.buffer.ptr + r.end,
.len = @min(std.math.maxInt(u32), r.buffer.len - r.end),
};
i += 1;
}
return .{ i, n };
}
pub fn writableVector(r: *Reader, buffer: [][]u8, data: []const []u8) Error!struct { usize, usize } {
var i: usize = 0;
var n: usize = 0;
if (r.seek == r.end) {
for (data) |buf| {
if (buffer.len - i == 0) return .{ i, n };
if (buf.len != 0) {
buffer[i] = buf;
i += 1;
n += buf.len;
}
}
if (r.buffer.len != 0) {
r.seek = 0;
r.end = 0;
buffer[i] = r.buffer;
i += 1;
}
} else {
buffer[i] = r.buffer[r.end..];
i += 1;
}
return .{ i, n };
}
test "deserialize signed LEB128" {
// Truncated
try testing.expectError(error.EndOfStream, testLeb128(i64, "\x80"));
// Overflow
try testing.expectError(error.Overflow, testLeb128(i8, "\x80\x80\x40"));
try testing.expectError(error.Overflow, testLeb128(i16, "\x80\x80\x80\x40"));
try testing.expectError(error.Overflow, testLeb128(i32, "\x80\x80\x80\x80\x40"));
try testing.expectError(error.Overflow, testLeb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x40"));
try testing.expectError(error.Overflow, testLeb128(i8, "\xff\x7e"));
try testing.expectError(error.Overflow, testLeb128(i32, "\x80\x80\x80\x80\x08"));
try testing.expectError(error.Overflow, testLeb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x01"));
// Decode SLEB128
try testing.expect((try testLeb128(i64, "\x00")) == 0);
try testing.expect((try testLeb128(i64, "\x01")) == 1);
try testing.expect((try testLeb128(i64, "\x3f")) == 63);
try testing.expect((try testLeb128(i64, "\x40")) == -64);
try testing.expect((try testLeb128(i64, "\x41")) == -63);
try testing.expect((try testLeb128(i64, "\x7f")) == -1);
try testing.expect((try testLeb128(i64, "\x80\x01")) == 128);
try testing.expect((try testLeb128(i64, "\x81\x01")) == 129);
try testing.expect((try testLeb128(i64, "\xff\x7e")) == -129);
try testing.expect((try testLeb128(i64, "\x80\x7f")) == -128);
try testing.expect((try testLeb128(i64, "\x81\x7f")) == -127);
try testing.expect((try testLeb128(i64, "\xc0\x00")) == 64);
try testing.expect((try testLeb128(i64, "\xc7\x9f\x7f")) == -12345);
try testing.expect((try testLeb128(i8, "\xff\x7f")) == -1);
try testing.expect((try testLeb128(i16, "\xff\xff\x7f")) == -1);
try testing.expect((try testLeb128(i32, "\xff\xff\xff\xff\x7f")) == -1);
try testing.expect((try testLeb128(i32, "\x80\x80\x80\x80\x78")) == -0x80000000);
try testing.expect((try testLeb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x7f")) == @as(i64, @bitCast(@as(u64, @intCast(0x8000000000000000)))));
try testing.expect((try testLeb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x40")) == -0x4000000000000000);
try testing.expect((try testLeb128(i64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x7f")) == -0x8000000000000000);
// Decode unnormalized SLEB128 with extra padding bytes.
try testing.expect((try testLeb128(i64, "\x80\x00")) == 0);
try testing.expect((try testLeb128(i64, "\x80\x80\x00")) == 0);
try testing.expect((try testLeb128(i64, "\xff\x00")) == 0x7f);
try testing.expect((try testLeb128(i64, "\xff\x80\x00")) == 0x7f);
try testing.expect((try testLeb128(i64, "\x80\x81\x00")) == 0x80);
try testing.expect((try testLeb128(i64, "\x80\x81\x80\x00")) == 0x80);
}
test "deserialize unsigned LEB128" {
// Truncated
try testing.expectError(error.EndOfStream, testLeb128(u64, "\x80"));
try testing.expectError(error.EndOfStream, testLeb128(u16, "\x80\x80\x84"));
try testing.expectError(error.EndOfStream, testLeb128(u32, "\x80\x80\x80\x80\x90"));
// Overflow
try testing.expectError(error.Overflow, testLeb128(u8, "\x80\x02"));
try testing.expectError(error.Overflow, testLeb128(u8, "\x80\x80\x40"));
try testing.expectError(error.Overflow, testLeb128(u16, "\x80\x80\x80\x40"));
try testing.expectError(error.Overflow, testLeb128(u32, "\x80\x80\x80\x80\x40"));
try testing.expectError(error.Overflow, testLeb128(u64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x40"));
// Decode ULEB128
try testing.expect((try testLeb128(u64, "\x00")) == 0);
try testing.expect((try testLeb128(u64, "\x01")) == 1);
try testing.expect((try testLeb128(u64, "\x3f")) == 63);
try testing.expect((try testLeb128(u64, "\x40")) == 64);
try testing.expect((try testLeb128(u64, "\x7f")) == 0x7f);
try testing.expect((try testLeb128(u64, "\x80\x01")) == 0x80);
try testing.expect((try testLeb128(u64, "\x81\x01")) == 0x81);
try testing.expect((try testLeb128(u64, "\x90\x01")) == 0x90);
try testing.expect((try testLeb128(u64, "\xff\x01")) == 0xff);
try testing.expect((try testLeb128(u64, "\x80\x02")) == 0x100);
try testing.expect((try testLeb128(u64, "\x81\x02")) == 0x101);
try testing.expect((try testLeb128(u64, "\x80\xc1\x80\x80\x10")) == 4294975616);
try testing.expect((try testLeb128(u64, "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x01")) == 0x8000000000000000);
// Decode ULEB128 with extra padding bytes
try testing.expect((try testLeb128(u64, "\x80\x00")) == 0);
try testing.expect((try testLeb128(u64, "\x80\x80\x00")) == 0);
try testing.expect((try testLeb128(u64, "\xff\x00")) == 0x7f);
try testing.expect((try testLeb128(u64, "\xff\x80\x00")) == 0x7f);
try testing.expect((try testLeb128(u64, "\x80\x81\x00")) == 0x80);
try testing.expect((try testLeb128(u64, "\x80\x81\x80\x00")) == 0x80);
}
fn testLeb128(comptime T: type, encoded: []const u8) !T {
var reader: std.Io.Reader = .fixed(encoded);
const result = try reader.takeLeb128(T);
try testing.expect(reader.seek == reader.end);
return result;
}
test {
_ = Limited;
}