Add support for read_until(limit:).

lib/io/stream/generic.rb

@@ -86,9 +86,11 @@ def readpartial(size = nil)
 		end
 
 		# Efficiently read data from the stream until encountering pattern.
-		# @param pattern [String] The pattern to match.
-		# @return [String] The contents of the stream up until the pattern, which is consumed but not returned.
-		def read_until(pattern, offset = 0, chomp: true)
+		# @parameter pattern [String] The pattern to match.
+		# @parameter offset [Integer] The offset to start searching from.
+		# @parameter limit [Integer] The maximum number of bytes to read, including the pattern (even if chomped).
+		# @returns [String | Nil] The contents of the stream up until the pattern, which is consumed but not returned.
+		def read_until(pattern, offset = 0, limit: nil, chomp: true)
 			# We don't want to split on the pattern, so we subtract the size of the pattern.
 			split_offset = pattern.bytesize - 1
 
@@ -97,9 +99,12 @@ def read_until(pattern, offset = 0, chomp: true)
 
 				offset = 0 if offset < 0
 
-				return unless fill_read_buffer
+				return nil if limit and offset >= limit
+				return nil unless fill_read_buffer
 			end
 
+			return nil if limit and index >= limit
+
 			@read_buffer.freeze
 			matched = @read_buffer.byteslice(0, index+(chomp ? 0 : pattern.bytesize))
 			@read_buffer = @read_buffer.byteslice(index+pattern.bytesize, @read_buffer.bytesize)

test/io/stream/buffered.rb

@@ -154,7 +154,17 @@
 			expect(client.read_until("\n")).to be == "world"
 			expect(client.read_until("\n")).to be_nil
 		end
-
+
+		it "can read with a limit" do
+			server.write("hello\nworld\n")
+			server.close
+
+			expect(client.read_until("\n", limit: 4)).to be_nil
+			expect(client.read_until("\n", limit: 5)).to be_nil
+			expect(client.read_until("\n", limit: 6)).to be == "hello"
+			expect(client.read_until("\n", limit: nil)).to be == "world"
+		end
+
 		with "with 1-byte block size" do
 			it "can read a line with a multi-byte pattern" do
 				server.write("hello\nworld\n")