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fix BufferedInStream not reading delayed input

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This commit is contained in:
sjdh02 2019-01-25 03:02:06 +00:00
parent c3c92ca8b1
commit fd61a084e4
1 changed files with 56 additions and 14 deletions
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70
std/io.zig
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@ -343,23 +343,24 @@ pub fn BufferedInStreamCustom(comptime buffer_size: usize, comptime Error: type)
const amt_buffered = self.end_index - self.start_index;
if (amt_buffered == 0) {
assert(self.end_index <= buffer_size);
if (self.end_index == buffer_size) {
// we can read more data from the unbuffered stream
if (dest_space < buffer_size) {
self.start_index = 0;
self.end_index = try self.unbuffered_in_stream.read(self.buffer[0..]);
} else {
// asking for so much data that buffering is actually less efficient.
// forward the request directly to the unbuffered stream
const amt_read = try self.unbuffered_in_stream.read(dest[dest_index..]);
return dest_index + amt_read;
}
} else {
// reading from the unbuffered stream returned less than we asked for
// so we cannot read any more data.
// Make sure the last read actually gave us some data
if (self.end_index == 0) {
// reading from the unbuffered stream returned nothing
// so we have nothing left to read.
return dest_index;
}
// we can read more data from the unbuffered stream
if (dest_space < buffer_size) {
self.start_index = 0;
self.end_index = try self.unbuffered_in_stream.read(self.buffer[0..]);
} else {
// asking for so much data that buffering is actually less efficient.
// forward the request directly to the unbuffered stream
const amt_read = try self.unbuffered_in_stream.read(dest[dest_index..]);
return dest_index + amt_read;
}
}
const copy_amount = math.min(dest_space, amt_buffered);
const copy_end_index = self.start_index + copy_amount;
mem.copy(u8, dest[dest_index..], self.buffer[self.start_index..copy_end_index]);
@ -370,6 +371,46 @@ pub fn BufferedInStreamCustom(comptime buffer_size: usize, comptime Error: type)
};
}
test "io.BufferedInStream" {
const OneByteReadInStream = struct {
const Error = error{NoError};
const Stream = InStream(Error);
stream: Stream,
str: []const u8,
curr: usize,
fn init(str: []const u8) @This() {
return @This(){
.stream = Stream{ .readFn = readFn },
.str = str,
.curr = 0,
};
}
fn readFn(in_stream: *Stream, dest: []u8) Error!usize {
const self = @fieldParentPtr(@This(), "stream", in_stream);
if (self.str.len <= self.curr or dest.len == 0)
return 0;
dest[0] = self.str[self.curr];
self.curr += 1;
return 1;
}
};
var buf: [100]u8 = undefined;
const allocator = &std.heap.FixedBufferAllocator.init(buf[0..]).allocator;
const str = "This is a test";
var one_byte_stream = OneByteReadInStream.init(str);
var buf_in_stream = BufferedInStream(OneByteReadInStream.Error).init(&one_byte_stream.stream);
const stream = &buf_in_stream.stream;
const res = try stream.readAllAlloc(allocator, str.len + 1);
debug.assertOrPanic(mem.eql(u8, str, res));
}
/// Creates a stream which supports 'un-reading' data, so that it can be read again.
/// This makes look-ahead style parsing much easier.
pub fn PeekStream(comptime buffer_size: usize, comptime InStreamError: type) type {
@ -1411,3 +1452,4 @@ test "import io tests" {
_ = @import("io_test.zig");
}
}