util.ringbuffer: Add :sub() and :byte() methods equivalent to the string methods

1 files changed, 58 insertions, 0 deletions

diff --git a/spec/util_ringbuffer_spec.lua b/spec/util_ringbuffer_spec.lua
index 9512bfd4..72656899 100644
--- a/spec/util_ringbuffer_spec.lua
+++ b/spec/util_ringbuffer_spec.lua
@@ -24,4 +24,62 @@ describe("util.ringbuffer", function ()
 			assert.truthy(b:write("hi"));
 		end);
 	end);
+	describe(":sub", function ()
+		-- Helper function to compare buffer:sub() with string:sub()
+		local function test_sub(b, x, y)
+			local s = b:read(#b, true);
+			local string_result, buffer_result = s:sub(x, y), b:sub(x, y);
+			assert.equals(string_result, buffer_result, ("buffer:sub(%d, %s) does not match string:sub()"):format(x, y and ("%d"):format(y) or "nil"));
+		end
+
+		it("works", function ()
+			local b = rb.new();
+			b:write("hello world");
+			assert.equals("hello", b:sub(1, 5));
+		end);
+
+		it("supports optional end parameter", function ()
+			local b = rb.new();
+			b:write("hello world");
+			assert.equals("hello world", b:sub(1));
+			assert.equals("world", b:sub(-5));
+		end);
+
+		it("is equivalent to string:sub", function ()
+			local b = rb.new(6);
+			b:write("foobar");
+			b:read(3);
+			b:write("foo");
+			for i = -13, 13 do
+				for j = -13, 13 do
+					test_sub(b, i, j);
+				end
+			end
+		end);
+	end);
+
+	describe(":byte", function ()
+		-- Helper function to compare buffer:byte() with string:byte()
+		local function test_byte(b, x, y)
+			local s = b:read(#b, true);
+			local string_result, buffer_result = {s:byte(x, y)}, {b:byte(x, y)};
+			assert.same(string_result, buffer_result, ("buffer:byte(%d, %s) does not match string:byte()"):format(x, y and ("%d"):format(y) or "nil"));
+		end
+
+		it("is equivalent to string:byte", function ()
+			local b = rb.new(6);
+			b:write("foobar");
+			b:read(3);
+			b:write("foo");
+			test_byte(b, 1);
+			test_byte(b, 3);
+			test_byte(b, -1);
+			test_byte(b, -3);
+			for i = -13, 13 do
+				for j = -13, 13 do
+					test_byte(b, i, j);
+				end
+			end
+		end);
+	end);
 end);