diff options
| -rw-r--r-- | spec/util_array_spec.lua | 19 | ||||
| -rw-r--r-- | util/array.lua | 34 |
2 files changed, 53 insertions, 0 deletions
diff --git a/spec/util_array_spec.lua b/spec/util_array_spec.lua index 1d9da947..ff049d0e 100644 --- a/spec/util_array_spec.lua +++ b/spec/util_array_spec.lua @@ -148,6 +148,25 @@ describe("util.array", function () end); end); + describe("slice", function () + it("works", function () + local a = array({ "a", "b", "c" }); + assert.equal(array.slice(a, 1, 2), array{ "a", "b" }); + assert.equal(array.slice(a, 1, 3), array{ "a", "b", "c" }); + assert.equal(array.slice(a, 2, 3), array{ "b", "c" }); + assert.equal(array.slice(a, 2), array{ "b", "c" }); + assert.equal(array.slice(a, -4), array{ "a", "b", "c" }); + assert.equal(array.slice(a, -3), array{ "a", "b", "c" }); + assert.equal(array.slice(a, -2), array{ "b", "c" }); + assert.equal(array.slice(a, -1), array{ "c" }); + end); + + it("can mutate", function () + local a = array({ "a", "b", "c" }); + assert.equal(a:slice(-1), array{"c"}); + assert.equal(a, array{"c"}); + end); + end); end); -- TODO The various array.foo(array ina, array outa) functions diff --git a/util/array.lua b/util/array.lua index 6e5c8383..c33a5ef1 100644 --- a/util/array.lua +++ b/util/array.lua @@ -114,6 +114,40 @@ function array_base.filter(outa, ina, func) return outa; end +function array_base.slice(outa, ina, i, j) + if j == nil then + j = -1; + end + if j < 0 then + j = #ina + (j+1); + end + if i < 0 then + i = #ina + (i+1); + end + if i < 1 then + i = 1; + end + if j > #ina then + j = #ina; + end + if i > j then + for idx = 1, #outa do + outa[idx] = nil; + end + return outa; + end + + for idx = 1, 1+j-i do + outa[idx] = ina[i+(idx-1)]; + end + if ina == outa then + for idx = 2+j-i, #outa do + outa[idx] = nil; + end + end + return outa; +end + function array_base.sort(outa, ina, ...) if ina ~= outa then outa:append(ina); |