system/serenity
system/serenity
1
0
Fork 0
mirror of https://github.com/SerenityOS/serenity synced 2024-07-22 02:26:11 +00:00
Code Issues Actions 5 Packages Projects Releases Wiki Activity

AK: Add Stream::offset_of(ReadonlyBytes)

Browse source
This commit is contained in:
AnotherTest 2020-08-21 03:47:47 +04:30 committed by Andreas Kling
parent 67f7f6840d
commit 9cc996b1e5
1 changed files with 48 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

48
AK/Stream.h
View file

@ -29,6 +29,7 @@
#include <AK/ByteBuffer.h>
#include <AK/Concepts.h>
#include <AK/Forward.h>
#include <AK/MemMem.h>
#include <AK/Span.h>
#include <AK/StdLibExtras.h>
#include <AK/Vector.h>
@ -299,6 +300,53 @@ public:
return true;
}
Optional<size_t> offset_of(ReadonlyBytes value) const
{
if (value.size() > remaining())
return {};
// First, find which chunk we're in.
auto chunk_index = (m_read_offset - m_base_offset) / chunk_size;
auto last_written_chunk_index = (m_write_offset - m_base_offset) / chunk_size;
auto first_chunk_index = chunk_index;
auto last_written_chunk_offset = m_write_offset % chunk_size;
auto first_chunk_offset = m_read_offset % chunk_size;
size_t last_chunk_offset = 0;
auto found_value = false;
for (; chunk_index <= last_written_chunk_index; ++chunk_index) {
auto chunk_bytes = m_chunks[chunk_index].bytes();
size_t chunk_offset = 0;
if (chunk_index == last_written_chunk_index) {
chunk_bytes = chunk_bytes.slice(0, last_written_chunk_offset);
}
if (chunk_index == first_chunk_index) {
chunk_bytes = chunk_bytes.slice(first_chunk_offset);
chunk_offset = first_chunk_offset;
}
// See if 'value' is in this chunk,
auto position = AK::memmem(chunk_bytes.data(), chunk_bytes.size(), value.data(), value.size());
if (!position)
continue; // Not in this chunk either :(
// We found it!
found_value = true;
last_chunk_offset = (const u8*)position - chunk_bytes.data() + chunk_offset;
break;
}
if (found_value) {
if (first_chunk_index == chunk_index)
return last_chunk_offset - first_chunk_offset;
return (chunk_index - first_chunk_index) * chunk_size + last_chunk_offset - first_chunk_offset;
}
// No dice.
return {};
}
size_t read(Bytes bytes) override
{
size_t nread = 0;