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7f748556a2
This returns the number of bits that two strings have in common. It is significantly more efficient than similar calculations in Lua.
85 lines
2.8 KiB
Lua
85 lines
2.8 KiB
Lua
local strbitop = require "util.strbitop";
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describe("util.strbitop", function ()
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describe("sand()", function ()
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it("works", function ()
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assert.equal(string.rep("Aa", 100), strbitop.sand(string.rep("a", 200), "Aa"));
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end);
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it("returns empty string if first argument is empty", function ()
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assert.equal("", strbitop.sand("", ""));
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assert.equal("", strbitop.sand("", "key"));
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end);
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it("returns initial string if key is empty", function ()
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assert.equal("hello", strbitop.sand("hello", ""));
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end);
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end);
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describe("sor()", function ()
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it("works", function ()
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assert.equal(string.rep("a", 200), strbitop.sor(string.rep("Aa", 100), "a"));
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end);
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it("returns empty string if first argument is empty", function ()
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assert.equal("", strbitop.sor("", ""));
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assert.equal("", strbitop.sor("", "key"));
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end);
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it("returns initial string if key is empty", function ()
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assert.equal("hello", strbitop.sor("hello", ""));
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end);
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end);
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describe("sxor()", function ()
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it("works", function ()
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assert.equal(string.rep("Aa", 100), strbitop.sxor(string.rep("a", 200), " \0"));
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end);
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it("returns empty string if first argument is empty", function ()
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assert.equal("", strbitop.sxor("", ""));
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assert.equal("", strbitop.sxor("", "key"));
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end);
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it("returns initial string if key is empty", function ()
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assert.equal("hello", strbitop.sxor("hello", ""));
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end);
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end);
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describe("common_prefix_bits()", function ()
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local function B(s)
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assert(#s%8==0, "Invalid test input: B(s): s should be a multiple of 8 bits in length");
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local byte = 0;
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local out_str = {};
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for i = 1, #s do
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local bit_ascii = s:byte(i);
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if bit_ascii == 49 then -- '1'
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byte = byte + 2^((7-(i-1))%8);
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elseif bit_ascii ~= 48 then
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error("Invalid test input: B(s): s should contain only '0' or '1' characters");
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end
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if (i-1)%8 == 7 then
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table.insert(out_str, string.char(byte));
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byte = 0;
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end
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end
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return table.concat(out_str);
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end
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local _cpb = strbitop.common_prefix_bits;
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local function test(a, b)
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local Ba, Bb = B(a), B(b);
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local ret1 = _cpb(Ba, Bb);
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local ret2 = _cpb(Bb, Ba);
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assert(ret1 == ret2, ("parameter order should not make a difference to the result (%s, %s) = %d, reversed = %d"):format(a, b, ret1, ret2));
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return ret1;
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end
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local hex = require "util.hex";
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it("works on single bytes", function ()
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assert.equal(0, test("00000000", "11111111"));
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assert.equal(1, test("10000000", "11111111"));
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assert.equal(0, test("01000000", "11111111"));
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assert.equal(0, test("01000000", "11111111"));
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assert.equal(8, test("11111111", "11111111"));
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end);
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it("works on multiple bytes", function ()
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for i = 0, 16 do
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assert.equal(i, test(string.rep("1", i)..string.rep("0", 16-i), "1111111111111111"));
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end
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end);
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end);
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end);
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