Software / code / prosody
Diff
spec/util_dbuffer_spec.lua @ 10973:39991e40d1dc
util.dbuffer: dynamic string buffer
Similar to util.ringbuffer (and shares almost identical API). Differences:
- size limit is optional and dynamic
- does not allocate a fixed buffer of max_size bytes
- focus on simply storing references to existing string objects where possible,
avoiding unnecessary allocations
- references are still stored in a ring buffer to enable use as a fast FIFO
Optional second parameter to new() provides the number of ring buffer segments. On
Lua 5.2 on my laptop, a segment is ~19 bytes. If the ring buffer fills up, the next
write will compact all strings into a single item.
| author | Matthew Wild <mwild1@gmail.com> |
|---|---|
| date | Fri, 26 Jun 2020 16:41:31 +0100 |
| child | 10977:29b9b679bdbc |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/spec/util_dbuffer_spec.lua Fri Jun 26 16:41:31 2020 +0100 @@ -0,0 +1,95 @@ +local dbuffer = require "util.dbuffer"; +describe("util.dbuffer", function () + describe("#new", function () + it("has a constructor", function () + assert.Function(dbuffer.new); + end); + it("can be created", function () + assert.truthy(dbuffer.new()); + end); + it("won't create an empty buffer", function () + assert.falsy(dbuffer.new(0)); + end); + it("won't create a negatively sized buffer", function () + assert.falsy(dbuffer.new(-1)); + end); + end); + describe(":write", function () + local b = dbuffer.new(); + it("works", function () + assert.truthy(b:write("hi")); + end); + end); + + describe(":discard", function () + local b = dbuffer.new(); + it("works", function () + assert.truthy(b:write("hello world")); + assert.truthy(b:discard(6)); + assert.equal(5, #b); + assert.equal("world", b:read(5)); + end); + end); + + describe(":sub", function () + -- Helper function to compare buffer:sub() with string:sub() + local s = "hello world"; + local function test_sub(b, x, y) + 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 = dbuffer.new(); + assert.truthy(b:write("hello world")); + assert.equals("hello", b:sub(1, 5)); + end); + + it("supports optional end parameter", function () + local b = dbuffer.new(); + assert.truthy(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 = dbuffer.new(11); + assert.truthy(b:write(s)); + 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 s = "hello world" + local function test_byte(b, x, y) + 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 = dbuffer.new(11); + assert.truthy(b:write(s)); + 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); + + it("works with characters > 127", function () + local b = dbuffer.new(); + b:write(string.char(0, 140)); + local r = { b:byte(1, 2) }; + assert.same({ 0, 140 }, r); + end); + end); +end);
