117 lines
2.3 KiB
CoffeeScript
117 lines
2.3 KiB
CoffeeScript
# Basic array comprehensions.
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nums: n * n for n in [1, 2, 3] when n % 2 isnt 0
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results: n * 2 for n in nums
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ok results.join(',') is '2,18'
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# Basic object comprehensions.
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obj: {one: 1, two: 2, three: 3}
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names: prop + '!' for prop of obj
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odds: prop + '!' for prop, value of obj when value % 2 isnt 0
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ok names.join(' ') is "one! two! three!"
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ok odds.join(' ') is "one! three!"
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# Basic range comprehensions.
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nums: i * 3 for i in [1..3]
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negs: x for x in [-20..-5*2]
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negs: negs[0..2]
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result: nums.concat(negs).join(', ')
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ok result is '3, 6, 9, -20, -19, -18'
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# Ensure that ranges are safe. This used to infinite loop:
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j = 5
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result: for j in [j..(j+3)]
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j
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ok result.join(' ') is '5 6 7 8'
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# With range comprehensions, you can loop in steps.
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results: x for x in [0..25] by 5
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ok results.join(' ') is '0 5 10 15 20 25'
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# And can loop downwards, with a negative step.
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results: x for x in [5..1] by -1
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ok results.join(' ') is '5 4 3 2 1'
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ok results.join(' ') is [(10-5)..(-2+3)].join(' ')
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# Multiline array comprehension with filter.
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evens: for num in [1, 2, 3, 4, 5, 6] when num % 2 is 0
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num *= -1
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num -= 2
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num * -1
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ok evens.join(', ') is '4, 6, 8'
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# The in operator still works, standalone.
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ok 2 of evens
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# Ensure that the closure wrapper preserves local variables.
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obj: {}
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for method in ['one', 'two', 'three']
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obj[method]: ->
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"I'm " + method
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ok obj.one() is "I'm one"
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ok obj.two() is "I'm two"
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ok obj.three() is "I'm three"
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# Even when referenced in the filter.
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list: ['one', 'two', 'three']
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methods: for num, i in list when num isnt 'two' and i isnt 1
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-> num + ' ' + i
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ok methods.length is 2
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ok methods[0]() is 'one 0'
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ok methods[1]() is 'three 2'
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# Naked ranges are expanded into arrays.
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array: [0..10]
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ok(num % 2 is 0 for num in array by 2)
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# Nested comprehensions.
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multiLiner:
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for x in [3..5]
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for y in [3..5]
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[x, y]
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singleLiner:
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[x, y] for y in [3..5] for x in [3..5]
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ok multiLiner.length is singleLiner.length
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ok 5 is multiLiner[2][2][1]
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ok 5 is singleLiner[2][2][1]
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# Comprehensions within parentheses.
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result: null
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store: (obj) -> result: obj
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store (x * 2 for x in [3, 2, 1])
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ok result.join(' ') is '6 4 2'
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# Closure-wrapped comprehensions that refer to the "arguments" object.
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expr: ->
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result: item * item for item in arguments
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ok expr(2, 4, 8).join(' ') is '4 16 64'
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