feat: Remove the drain function from stream context

Allow decouping the function from a shared stream context.

BREAKING CHANGE: Do not pass the drain function to new_compress_stream_context and new_decompress_stream_context. Pass it to each call of compress_chunk, compress_chunk_at, compress_end, decompress_chunk and decompress_chunk_at.

README.md

@@ -183,36 +183,39 @@ If you want to compress or decompress large data, or if the data comes chunk aft
 cctx := zstd.new_compress_context()!
 defer { cctx.free() }
 cctx.set_param(zstd.CompressParam.checksum_flag, 1)!
+mut sctx := zstd.new_compress_stream_context()
 
 mut dst := []u8{cap: zstd.compress_bound(src.len)}
 mut dst_ref := &dst
-
 drain := fn [dst_ref] (buf &u8, len int) ! {
   unsafe { dst_ref.push_many(buf, len) }
 }
-mut sctx := new_compress_stream_context(drain)
 
-cctx.compress_chunk(mut sctx, src, false)!
+cctx.compress_chunk(mut sctx, src, false, drain)!
 ...
-unsafe { cctx.compress_chunk(mut sctx, data, len, true)! }
+unsafe { cctx.compress_chunk(mut sctx, data, len, true, drain)! }
 ...
 cctx.compress_end(mut sctx)!
 ```
 
 #### Compression
 
 ```v
-new_compress_stream_context(drain fn (buf &u8, len int) !) &StreamContext
-(c &CompressContext) compress_chunk(mut sctx StreamContext, src []u8, last bool) !
-(c &CompressContext) compress_chunk_at(mut sctx StreamContext, src &u8, src_len int, last bool) !
+new_compress_stream_context() &StreamContext
+(c &CompressContext) compress_chunk(
+  mut sctx StreamContext, src []u8, last bool, drain fn (buf &u8, len int) !) !
+(c &CompressContext) compress_chunk_at(
+  mut sctx StreamContext, src &u8, src_len int, last bool, drain fn (buf &u8, len int) !) !
 ```
 
 #### Decompression
 
 ```v
-new_decompress_stream_context(drain fn (buf &u8, len int) !) &StreamContext
-(d &DecompressContext) decompress_chunk(mut sctx StreamContext, src []u8, last bool) !
-(d &DecompressContext) decompress_chunk_at(mut sctx StreamContext, src &u8, src_len int, last bool) !
+new_decompress_stream_context() &StreamContext
+(d &DecompressContext) decompress_chunk(
+  mut sctx StreamContext, src []u8, last bool, drain fn (buf &u8, len int) !) !
+(d &DecompressContext) decompress_chunk_at(
+  mut sctx StreamContext, src &u8, src_len int, last bool, drain fn (buf &u8, len int) !) !
 ```
 
 ### Errors

src/compress_stream.v

@@ -5,21 +5,17 @@ const (
 	compress_stream_in_size  = int(C.ZSTD_CStreamInSize())
 )
 
-pub fn new_compress_stream_context(drain fn (buf &u8, len int) !) &StreamContext {
-	dst := []u8{len: zstd.compress_stream_out_size}
-	output := &C.ZSTD_outBuffer{dst.data, usize(zstd.compress_stream_out_size), 0}
-	src := []u8{len: zstd.compress_stream_in_size}
-	input := &C.ZSTD_inBuffer{src.data, 0, 0}
-	return &StreamContext{drain, output, input}
+pub fn new_compress_stream_context() &StreamContext {
+	return new_stream_context(zstd.compress_stream_out_size, zstd.compress_stream_in_size)
 }
 
 [inline]
-pub fn (c &CompressContext) compress_chunk(mut sctx StreamContext, src []u8, last bool) ! {
-	unsafe { c.compress_chunk_at(mut sctx, src.data, src.len, last)! }
+pub fn (c &CompressContext) compress_chunk(mut sctx StreamContext, src []u8, last bool, drain fn (buf &u8, len int) !) ! {
+	unsafe { c.compress_chunk_at(mut sctx, src.data, src.len, last, drain)! }
 }
 
 [unsafe]
-pub fn (c &CompressContext) compress_chunk_at(mut sctx StreamContext, src &u8, src_len int, last bool) ! {
+pub fn (c &CompressContext) compress_chunk_at(mut sctx StreamContext, src &u8, src_len int, last bool, drain fn (buf &u8, len int) !) ! {
 	mut res := usize(0)
 	mut pos := 0
 	mut rest_len := src_len
@@ -40,19 +36,18 @@ pub fn (c &CompressContext) compress_chunk_at(mut sctx StreamContext, src &u8, s
 		}
 		res = C.ZSTD_compressStream2(c.cctx, sctx.output, sctx.input, end_op)
 		check_error(res)!
-		drain_buffer(mut sctx)!
+		drain_buffer(mut sctx, drain)!
 		pos += max_len
 	}
 	if last && (res != 0 || sctx.input.pos != sctx.input.size) {
 		return error('unfinished compression')
 	}
 }
 
-pub fn (c &CompressContext) compress_end(mut sctx StreamContext) ! {
+pub fn (c &CompressContext) compress_end(mut sctx StreamContext, drain fn (buf &u8, len int) !) ! {
 	mut res := C.ZSTD_compressStream2(c.cctx, sctx.output, sctx.input, C.ZSTD_e_end)
 	check_error(res)!
 	if sctx.output.pos > 0 {
-		sctx.drain(sctx.output.dst, int(sctx.output.pos))!
-		sctx.output.pos = 0
+		drain_buffer(mut sctx, drain)!
 	}
 }

src/compress_stream_test.v

@@ -12,8 +12,8 @@ fn decompress_stream_test(src []u8) ![]u8 {
 	drain := fn [dst_ref] (buf &u8, len int) ! {
 		unsafe { dst_ref.push_many(buf, len) }
 	}
-	mut sctx := new_decompress_stream_context(drain)
-	dctx.decompress_chunk(mut sctx, src, true)!
+	mut sctx := new_decompress_stream_context()
+	dctx.decompress_chunk(mut sctx, src, true, drain)!
 
 	return dst
 }
@@ -33,8 +33,8 @@ fn test_compress_one() {
 	drain := fn [dst_ref] (buf &u8, len int) ! {
 		unsafe { dst_ref.push_many(buf, len) }
 	}
-	mut sctx := new_compress_stream_context(drain)
-	cctx.compress_chunk(mut sctx, src, true)!
+	mut sctx := new_compress_stream_context()
+	cctx.compress_chunk(mut sctx, src, true, drain)!
 	cctx.reset(ResetDir.session_and_parameters)
 
 	assert dst == [u8(40), u8(181), u8(47), u8(253), u8(36), u8(85), u8(61), u8(2), u8(0), u8(18),
@@ -66,11 +66,12 @@ fn test_compress_two() {
 	drain := fn [dst_ref] (buf &u8, len int) ! {
 		unsafe { dst_ref.push_many(buf, len) }
 	}
-	mut sctx := new_compress_stream_context(drain)
+	mut sctx := new_compress_stream_context()
 	unsafe {
-		cctx.compress_chunk_at(mut sctx, src.data, half, false)!
-		cctx.compress_chunk_at(mut sctx, &u8(src.data) + half, src.len - half, true)!
+		cctx.compress_chunk_at(mut sctx, src.data, half, false, drain)!
+		cctx.compress_chunk_at(mut sctx, &u8(src.data) + half, src.len - half, true, drain)!
 	}
+	sctx.reset()
 	assert dst == [u8(40), u8(181), u8(47), u8(253), u8(4), u8(88), u8(21), u8(2), u8(0), u8(82),
 		u8(133), u8(15), u8(19), u8(176), u8(23), u8(115), u8(208), u8(167), u8(37), u8(249), u8(38),
 		u8(211), u8(179), u8(108), u8(78), u8(82), u8(3), u8(236), u8(193), u8(25), u8(243), u8(136),
@@ -100,12 +101,13 @@ fn test_compress_with_end() {
 	drain := fn [dst_ref] (buf &u8, len int) ! {
 		unsafe { dst_ref.push_many(buf, len) }
 	}
-	mut sctx := new_compress_stream_context(drain)
+	mut sctx := new_compress_stream_context()
 	unsafe {
-		cctx.compress_chunk_at(mut sctx, src.data, half, false)!
-		cctx.compress_chunk_at(mut sctx, &u8(src.data) + half, src.len - half, false)!
+		cctx.compress_chunk_at(mut sctx, src.data, half, false, drain)!
+		cctx.compress_chunk_at(mut sctx, &u8(src.data) + half, src.len - half, false,
+			drain)!
 	}
-	cctx.compress_end(mut sctx)!
+	cctx.compress_end(mut sctx, drain)!
 
 	assert dst == [u8(40), u8(181), u8(47), u8(253), u8(4), u8(88), u8(21), u8(2), u8(0), u8(82),
 		u8(133), u8(15), u8(19), u8(176), u8(23), u8(115), u8(208), u8(167), u8(37), u8(249), u8(38),

src/decompress_stream.v

@@ -5,21 +5,17 @@ const (
 	decompress_stream_in_size  = int(C.ZSTD_DStreamInSize())
 )
 
-pub fn new_decompress_stream_context(drain fn (buf &u8, len int) !) &StreamContext {
-	dst := []u8{len: zstd.decompress_stream_out_size}
-	output := &C.ZSTD_outBuffer{dst.data, usize(zstd.decompress_stream_out_size), 0}
-	src := []u8{len: zstd.decompress_stream_in_size}
-	input := &C.ZSTD_inBuffer{src.data, 0, 0}
-	return &StreamContext{drain, output, input}
+pub fn new_decompress_stream_context() &StreamContext {
+	return new_stream_context(zstd.decompress_stream_out_size, zstd.decompress_stream_in_size)
 }
 
 [inline]
-pub fn (d &DecompressContext) decompress_chunk(mut sctx StreamContext, src []u8, last bool) ! {
-	unsafe { d.decompress_chunk_at(mut sctx, src.data, src.len, last)! }
+pub fn (d &DecompressContext) decompress_chunk(mut sctx StreamContext, src []u8, last bool, drain fn (buf &u8, len int) !) ! {
+	unsafe { d.decompress_chunk_at(mut sctx, src.data, src.len, last, drain)! }
 }
 
 [unsafe]
-pub fn (d &DecompressContext) decompress_chunk_at(mut sctx StreamContext, src &u8, src_len int, last bool) ! {
+pub fn (d &DecompressContext) decompress_chunk_at(mut sctx StreamContext, src &u8, src_len int, last bool, drain fn (buf &u8, len int) !) ! {
 	mut res := usize(0)
 	mut pos := 0
 	mut rest_len := src_len
@@ -35,7 +31,7 @@ pub fn (d &DecompressContext) decompress_chunk_at(mut sctx StreamContext, src &u
 		sctx.input.size += usize(len)
 		res = C.ZSTD_decompressStream(d.dctx, sctx.output, sctx.input)
 		check_error(res)!
-		drain_buffer(mut sctx)!
+		drain_buffer(mut sctx, drain)!
 		pos += max_len
 	}
 	if last && (res != 0 || sctx.input.pos != sctx.input.size) {

src/decompress_stream_test.v

@@ -13,8 +13,8 @@ fn compress_stream_test(src []u8) ![]u8 {
 	drain := fn [dst_ref] (buf &u8, len int) ! {
 		unsafe { dst_ref.push_many(buf, len) }
 	}
-	mut sctx := new_compress_stream_context(drain)
-	cctx.compress_chunk(mut sctx, src, true)!
+	mut sctx := new_compress_stream_context()
+	cctx.compress_chunk(mut sctx, src, true, drain)!
 
 	return dst
 }
@@ -42,8 +42,8 @@ fn test_decompress_one() {
 	drain := fn [dst_ref] (buf &u8, len int) ! {
 		unsafe { dst_ref.push_many(buf, len) }
 	}
-	mut sctx := new_decompress_stream_context(drain)
-	dctx.decompress_chunk(mut sctx, src, true)!
+	mut sctx := new_decompress_stream_context()
+	dctx.decompress_chunk(mut sctx, src, true, drain)!
 	dctx.reset(ResetDir.session_and_parameters)
 
 	assert dst == 'A sentence with a length longer than a minimum content size to test zstd compression.'.bytes()
@@ -54,8 +54,6 @@ fn test_decompress_two() {
 	defer {
 		dctx.free()
 	}
-	dctx.set_param(DecompressParam.window_log_max, 27)!
-	assert dctx.get_param(DecompressParam.window_log_max)! == 27
 
 	src := [u8(40), u8(181), u8(47), u8(253), u8(36), u8(85), u8(61), u8(2), u8(0), u8(18), u8(133),
 		u8(15), u8(20), u8(176), u8(55), u8(7), u8(208), u8(167), u8(37), u8(249), u8(38), u8(165),
@@ -73,10 +71,11 @@ fn test_decompress_two() {
 	drain := fn [dst_ref] (buf &u8, len int) ! {
 		unsafe { dst_ref.push_many(buf, len) }
 	}
-	mut sctx := new_decompress_stream_context(drain)
+	mut sctx := new_decompress_stream_context()
 	unsafe {
-		dctx.decompress_chunk_at(mut sctx, src.data, half, false)!
-		dctx.decompress_chunk_at(mut sctx, &u8(src.data) + half, src.len - half, true)!
+		dctx.decompress_chunk_at(mut sctx, src.data, half, false, drain)!
+		dctx.decompress_chunk_at(mut sctx, &u8(src.data) + half, src.len - half, true,
+			drain)!
 	}
 	assert dst == 'A sentence with a length longer than a minimum content size to test zstd compression.'.bytes()
 	assert src == compress_stream_test(dst)!

src/stream_context.v

@@ -2,15 +2,28 @@ module zstd
 
 [noinit]
 pub struct StreamContext {
-	drain fn (buf &u8, len int) ! [required]
 mut:
 	output &C.ZSTD_outBuffer = unsafe { nil }
 	input  &C.ZSTD_inBuffer  = unsafe { nil }
 }
 
-fn drain_buffer(mut sctx StreamContext) ! {
+pub fn (mut s StreamContext) reset() {
+	s.output.pos = 0
+	s.input.size = 0
+	s.input.pos = 0
+}
+
+fn new_stream_context(out_len int, in_len int) &StreamContext {
+	dst := []u8{len: out_len}
+	output := &C.ZSTD_outBuffer{dst.data, usize(out_len), 0}
+	src := []u8{len: in_len}
+	input := &C.ZSTD_inBuffer{src.data, 0, 0}
+	return &StreamContext{output, input}
+}
+
+fn drain_buffer(mut sctx StreamContext, drain fn (buf &u8, len int) !) ! {
 	if sctx.output.pos > 0 {
-		sctx.drain(sctx.output.dst, int(sctx.output.pos))!
+		drain(sctx.output.dst, int(sctx.output.pos))!
 		sctx.output.pos = 0
 	}
 	if sctx.input.size > 0 {

src/stream_context_test.v

@@ -4,25 +4,25 @@ fn test_drain_empty_buffer() {
 	drain := fn (buf &u8, len int) ! {}
 	output := &C.ZSTD_outBuffer{unsafe { nil }, 0, 0}
 	input := &C.ZSTD_inBuffer{unsafe { nil }, 0, 0}
-	mut sctx := &StreamContext{drain, output, input}
-	drain_buffer(mut sctx)!
+	mut sctx := &StreamContext{output, input}
+	drain_buffer(mut sctx, drain)!
 }
 
 fn test_drain_output() {
 	drain := fn (buf &u8, len int) ! {}
 	output := &C.ZSTD_outBuffer{unsafe { nil }, 0, 1}
 	input := &C.ZSTD_inBuffer{unsafe { nil }, 0, 0}
-	mut sctx := &StreamContext{drain, output, input}
-	drain_buffer(mut sctx)!
+	mut sctx := &StreamContext{output, input}
+	drain_buffer(mut sctx, drain)!
 	assert output.pos == 0
 }
 
 fn test_drain_partially_consumed_input() {
 	drain := fn (buf &u8, len int) ! {}
 	output := &C.ZSTD_outBuffer{unsafe { nil }, 0, 0}
 	input := &C.ZSTD_inBuffer{unsafe { nil }, 1, 1}
-	mut sctx := &StreamContext{drain, output, input}
-	drain_buffer(mut sctx)!
+	mut sctx := &StreamContext{output, input}
+	drain_buffer(mut sctx, drain)!
 	assert input.size == 0
 	assert input.pos == 0
 }
@@ -32,8 +32,8 @@ fn test_drain_fully_consumed_input() {
 	output := &C.ZSTD_outBuffer{unsafe { nil }, 0, 0}
 	mut src := [u8(1), u8(2)]
 	input := &C.ZSTD_inBuffer{unsafe { src.data }, 2, 1}
-	mut sctx := &StreamContext{drain, output, input}
-	drain_buffer(mut sctx)!
+	mut sctx := &StreamContext{output, input}
+	drain_buffer(mut sctx, drain)!
 	assert input.size == 1
 	assert input.pos == 0
 	assert src[0] == u8(2)