# jashkenas/coffeescript

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 # Comprehensions # -------------- # * Array Comprehensions # * Range Comprehensions # * Object Comprehensions # * Implicit Destructuring Assignment # * Comprehensions with Nonstandard Step # TODO: refactor comprehension tests test "Basic array comprehensions.", -> nums = (n * n for n in [1, 2, 3] when n & 1) results = (n * 2 for n in nums) ok results.join(',') is '2,18' test "Basic object comprehensions.", -> obj = {one: 1, two: 2, three: 3} names = (prop + '!' for prop of obj) odds = (prop + '!' for prop, value of obj when value & 1) ok names.join(' ') is "one! two! three!" ok odds.join(' ') is "one! three!" test "Basic range comprehensions.", -> nums = (i * 3 for i in [1..3]) negs = (x for x in [-20..-5*2]) negs = negs[0..2] result = nums.concat(negs).join(', ') ok result is '3, 6, 9, -20, -19, -18' test "With range comprehensions, you can loop in steps.", -> results = (x for x in [0...15] by 5) ok results.join(' ') is '0 5 10' results = (x for x in [0..100] by 10) ok results.join(' ') is '0 10 20 30 40 50 60 70 80 90 100' test "And can loop downwards, with a negative step.", -> results = (x for x in [5..1]) ok results.join(' ') is '5 4 3 2 1' ok results.join(' ') is [(10-5)..(-2+3)].join(' ') results = (x for x in [10..1]) ok results.join(' ') is [10..1].join(' ') results = (x for x in [10...0] by -2) ok results.join(' ') is [10, 8, 6, 4, 2].join(' ') test "Range comprehension gymnastics.", -> eq "#{i for i in [5..1]}", '5,4,3,2,1' eq "#{i for i in [5..-5] by -5}", '5,0,-5' a = 6 b = 0 c = -2 eq "#{i for i in [a..b]}", '6,5,4,3,2,1,0' eq "#{i for i in [a..b] by c}", '6,4,2,0' test "Multiline array comprehension with filter.", -> evens = for num in [1, 2, 3, 4, 5, 6] when not (num & 1) num *= -1 num -= 2 num * -1 eq evens + '', '4,6,8' test "The in operator still works, standalone.", -> ok 2 of evens test "all isn't reserved.", -> all = 1 test "Ensure that the closure wrapper preserves local variables.", -> obj = {} for method in ['one', 'two', 'three'] then do (method) -> obj[method] = -> "I'm " + method ok obj.one() is "I'm one" ok obj.two() is "I'm two" ok obj.three() is "I'm three" test "Index values at the end of a loop.", -> i = 0 for i in [1..3] -> 'func' break if false ok i is 4 test "Ensure that local variables are closed over for range comprehensions.", -> funcs = for i in [1..3] do (i) -> -> -i eq (func() for func in funcs).join(' '), '-1 -2 -3' ok i is 4 test "Even when referenced in the filter.", -> list = ['one', 'two', 'three'] methods = for num, i in list when num isnt 'two' and i isnt 1 do (num, i) -> -> num + ' ' + i ok methods.length is 2 ok methods[0]() is 'one 0' ok methods[1]() is 'three 2' test "Even a convoluted one.", -> funcs = [] for i in [1..3] do (i) -> x = i * 2 ((z)-> funcs.push -> z + ' ' + i )(x) ok (func() for func in funcs).join(', ') is '2 1, 4 2, 6 3' funcs = [] results = for i in [1..3] do (i) -> z = (x * 3 for x in [1..i]) ((a, b, c) -> [a, b, c].join(' ')).apply this, z ok results.join(', ') is '3 , 3 6 , 3 6 9' test "Naked ranges are expanded into arrays.", -> array = [0..10] ok(num % 2 is 0 for num in array by 2) test "Nested shared scopes.", -> foo = -> for i in [0..7] do (i) -> for j in [0..7] do (j) -> -> i + j eq foo()[3][4](), 7 test "Scoped loop pattern matching.", -> a = [[0], [1]] funcs = [] for [v] in a do (v) -> funcs.push -> v eq funcs[0](), 0 eq funcs[1](), 1 test "Nested comprehensions.", -> multiLiner = for x in [3..5] for y in [3..5] [x, y] singleLiner = (([x, y] for y in [3..5]) for x in [3..5]) ok multiLiner.length is singleLiner.length ok 5 is multiLiner[2][2][1] ok 5 is singleLiner[2][2][1] test "Comprehensions within parentheses.", -> result = null store = (obj) -> result = obj store (x * 2 for x in [3, 2, 1]) ok result.join(' ') is '6 4 2' test "Closure-wrapped comprehensions that refer to the 'arguments' object.", -> expr = -> result = (item * item for item in arguments) ok expr(2, 4, 8).join(' ') is '4 16 64' test "Fast object comprehensions over all properties, including prototypal ones.", -> class Cat constructor: -> @name = 'Whiskers' breed: 'tabby' hair: 'cream' whiskers = new Cat own = (value for own key, value of whiskers) all = (value for key, value of whiskers) ok own.join(' ') is 'Whiskers' ok all.sort().join(' ') is 'Whiskers cream tabby' test "Optimized range comprehensions.", -> exxes = ('x' for [0...10]) ok exxes.join(' ') is 'x x x x x x x x x x' test "Loop variables should be able to reference outer variables", -> outer = 1 do -> null for outer in [1, 2, 3] eq outer, 3 test "Lenient on pure statements not trying to reach out of the closure", -> val = for i in [1] for j in [] then break i ok val[0] is i test "Comprehensions only wrap their last line in a closure, allowing other lines to have pure expressions in them.", -> func = -> for i in [1] break if i is 2 j for j in [1] ok func()[0][0] is 1 i = 6 odds = while i-- continue unless i & 1 i ok odds.join(', ') is '5, 3, 1' test "Issue #897: Ensure that plucked function variables aren't leaked.", -> facets = {} list = ['one', 'two'] (-> for entity in list facets[entity] = -> entity )() eq typeof entity, 'undefined' eq facets['two'](), 'two' test "Issue #905. Soaks as the for loop subject.", -> a = {b: {c: [1, 2, 3]}} for d in a.b?.c e = d eq e, 3 test "Issue #948. Capturing loop variables.", -> funcs = [] list = -> [1, 2, 3] for y in list() do (y) -> z = y funcs.push -> "y is #{y} and z is #{z}" eq funcs[1](), "y is 2 and z is 2" test "Cancel the comprehension if there's a jump inside the loop.", -> result = try for i in [0...10] continue if i < 5 i eq result, 10 test "Comprehensions over break.", -> arrayEq (break for [1..10]), [] test "Comprehensions over continue.", -> arrayEq (continue for [1..10]), [] test "Comprehensions over function literals.", -> a = 0 for f in [-> a = 1] do (f) -> do f eq a, 1 test "Comprehensions that mention arguments.", -> list = [arguments: 10] args = for f in list do (f) -> f.arguments eq args[0], 10 test "expression conversion under explicit returns", -> nonce = {} fn = -> return (nonce for x in [1,2,3]) arrayEq [nonce,nonce,nonce], fn() fn = -> return [nonce for x in [1,2,3]][0] arrayEq [nonce,nonce,nonce], fn() fn = -> return [(nonce for x in [1..3])][0] arrayEq [nonce,nonce,nonce], fn() test "implicit destructuring assignment in object of objects", -> a={}; b={}; c={} obj = { a: { d: a }, b: { d: b } c: { d: c } } result = ([y,z] for y, { d: z } of obj) arrayEq [['a',a],['b',b],['c',c]], result test "implicit destructuring assignment in array of objects", -> a={}; b={}; c={}; d={}; e={}; f={} arr = [ { a: a, b: { c: b } }, { a: c, b: { c: d } }, { a: e, b: { c: f } } ] result = ([y,z] for { a: y, b: { c: z } } in arr) arrayEq [[a,b],[c,d],[e,f]], result test "implicit destructuring assignment in array of arrays", -> a={}; b={}; c={}; d={}; e={}; f={} arr = [[a, [b]], [c, [d]], [e, [f]]] result = ([y,z] for [y, [z]] in arr) arrayEq [[a,b],[c,d],[e,f]], result test "issue #1124: don't assign a variable in two scopes", -> lista = [1, 2, 3, 4, 5] listb = (_i + 1 for _i in lista) arrayEq [2, 3, 4, 5, 6], listb test "#1326: `by` value is uncached", -> a = [0,1,2] fi = gi = hi = 0 f = -> ++fi g = -> ++gi h = -> ++hi forCompile = [] rangeCompileSimple = [] #exercises For.compile for v, i in a by f() forCompile.push i #exercises Range.compileSimple rangeCompileSimple = (i for i in [0..2] by g()) arrayEq a, forCompile arrayEq a, rangeCompileSimple #exercises Range.compile eq "#{i for i in [0..2] by h()}", '0,1,2' test "#1669: break/continue should skip the result only for that branch", -> ns = for n in [0..99] if n > 9 break else if n & 1 continue else n eq "#{ns}", '0,2,4,6,8' # `else undefined` is implied. ns = for n in [1..9] if n % 2 continue unless n % 5 n eq "#{ns}", "1,,3,,,7,,9" # Ditto. ns = for n in [1..9] switch when n % 2 continue unless n % 5 n eq "#{ns}", "1,,3,,,7,,9" test "#1850: inner `for` should not be expression-ized if `return`ing", -> eq '3,4,5', do -> for a in [1..9] then \ for b in [1..9] c = Math.sqrt a*a + b*b return String [a, b, c] unless c % 1 test "#1910: loop index should be mutable within a loop iteration and immutable between loop iterations", -> n = 1 iterations = 0 arr = [0..n] for v, k in arr ++iterations v = k = 5 eq 5, k eq 2, k eq 2, iterations iterations = 0 for v in [0..n] ++iterations eq 2, k eq 2, iterations arr = ([v, v + 1] for v in [0..5]) iterations = 0 for own [v0, v1], k in arr when v0 k += 3 ++iterations eq 6, k eq 5, iterations test "#2007: Return object literal from comprehension", -> y = for x in [1, 2] foo: "foo" + x eq 2, y.length eq "foo1", y[0].foo eq "foo2", y[1].foo x = 2 y = while x x: --x eq 2, y.length eq 1, y[0].x eq 0, y[1].x test "#2274: Allow @values as loop variables", -> obj = { item: null method: -> for @item in [1, 2, 3] null } eq obj.item, null obj.method() eq obj.item, 3 test "#2525, #1187, #1208, #1758, looping over an array forwards", -> list = [0, 1, 2, 3, 4] ident = (x) -> x arrayEq (i for i in list), list arrayEq (index for i, index in list), list arrayEq (i for i in list by 1), list arrayEq (i for i in list by ident 1), list arrayEq (i for i in list by ident(1) * 2), [0, 2, 4] arrayEq (index for i, index in list by ident(1) * 2), [0, 2, 4] test "#2525, #1187, #1208, #1758, looping over an array backwards", -> list = [0, 1, 2, 3, 4] backwards = [4, 3, 2, 1, 0] ident = (x) -> x arrayEq (i for i in list by -1), backwards arrayEq (index for i, index in list by -1), backwards arrayEq (i for i in list by ident -1), backwards arrayEq (i for i in list by ident(-1) * 2), [4, 2, 0] arrayEq (index for i, index in list by ident(-1) * 2), [4, 2, 0]
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