diff options
| -rw-r--r-- | spec/util_ringbuffer_spec.lua | 58 | ||||
| -rw-r--r-- | util-src/ringbuffer.c | 103 |
2 files changed, 160 insertions, 1 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); diff --git a/util-src/ringbuffer.c b/util-src/ringbuffer.c index e15b66a6..07e1096f 100644 --- a/util-src/ringbuffer.c +++ b/util-src/ringbuffer.c @@ -2,7 +2,6 @@ #include <stdlib.h> #include <unistd.h> #include <string.h> -#include <stdio.h> #include <lua.h> #include <lauxlib.h> @@ -15,6 +14,55 @@ typedef struct { char buffer[]; } ringbuffer; +/* Translate absolute idx to a wrapped index within the buffer, + based on current read position */ +static int wrap_pos(const ringbuffer *b, const long idx, long *pos) { + if(idx > (long)b->blen) { + return 0; + } + if(idx + (long)b->rpos > (long)b->alen) { + *pos = idx - (b->alen - b->rpos); + } else { + *pos = b->rpos + idx; + } + return 1; +} + +static int calc_splice_positions(const ringbuffer *b, long start, long end, long *out_start, long *out_end) { + if(start < 0) { + start = 1 + start + b->blen; + } + if(start <= 0) { + start = 1; + } + + if(end < 0) { + end = 1 + end + b->blen; + } + + if(end > (long)b->blen) { + end = b->blen; + } + if(start < 1) { + start = 1; + } + + if(start > end) { + return 0; + } + + start = start - 1; + + if(!wrap_pos(b, start, out_start)) { + return 0; + } + if(!wrap_pos(b, end, out_end)) { + return 0; + } + + return 1; +} + static void writechar(ringbuffer *b, char c) { b->blen++; b->buffer[(b->wpos++) % b->alen] = c; @@ -178,6 +226,55 @@ static int rb_tostring(lua_State *L) { return 1; } +static int rb_sub(lua_State *L) { + ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); + + long start = luaL_checkinteger(L, 2); + long end = luaL_optinteger(L, 3, -1); + + long wrapped_start, wrapped_end; + if(!calc_splice_positions(b, start, end, &wrapped_start, &wrapped_end)) { + lua_pushstring(L, ""); + } else if(wrapped_end <= wrapped_start) { + lua_pushlstring(L, &b->buffer[wrapped_start], b->alen - wrapped_start); + lua_pushlstring(L, b->buffer, wrapped_end); + lua_concat(L, 2); + } else { + lua_pushlstring(L, &b->buffer[wrapped_start], (wrapped_end - wrapped_start)); + } + + return 1; +} + +static int rb_byte(lua_State *L) { + ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); + + long start = luaL_optinteger(L, 2, 1); + long end = luaL_optinteger(L, 3, start); + + long i; + + long wrapped_start, wrapped_end; + if(calc_splice_positions(b, start, end, &wrapped_start, &wrapped_end)) { + if(wrapped_end <= wrapped_start) { + for(i = wrapped_start; i < (long)b->alen; i++) { + lua_pushinteger(L, b->buffer[i]); + } + for(i = 0; i < wrapped_end; i++) { + lua_pushinteger(L, b->buffer[i]); + } + return wrapped_end + (b->alen - wrapped_start); + } else { + for(i = wrapped_start; i < wrapped_end; i++) { + lua_pushinteger(L, b->buffer[i]); + } + return wrapped_end - wrapped_start; + } + } + + return 0; +} + static int rb_length(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); lua_pushinteger(L, b->blen); @@ -239,6 +336,10 @@ int luaopen_util_ringbuffer(lua_State *L) { lua_setfield(L, -2, "size"); lua_pushcfunction(L, rb_length); lua_setfield(L, -2, "length"); + lua_pushcfunction(L, rb_sub); + lua_setfield(L, -2, "sub"); + lua_pushcfunction(L, rb_byte); + lua_setfield(L, -2, "byte"); lua_pushcfunction(L, rb_free); lua_setfield(L, -2, "free"); } |