Category talk:Wren-array

Source code

<lang ecmascript>/* Module "array.wren" */

import "meta" for Meta import "./check" for Check

/*

  Array represents a List whose size cannot be changed after it has been constructed
  but whose elements can be changed. If an array is created from a list, the
  list is shallow-copied, not cloned.

• /

class Array is Sequence {

   // Constructs a new array from a List or other Sequence.
   construct from(a) {
       Check.seq("Argument", a)
       _a = a.toList // create a list or shallow copy if the argument is already a list.
   }

   // Constructs a new array from a List or other Sequence by fitting it to a given size
   // truncating if it's too big or filling out with a given value if it's too small.
   construct fit(size, a, v) {
       Check.nonNegInt("Size", size)
       Check.seq("Second argument", a)
       a = a.toList
       if (a.count == size) {
           _a = a
       } else if (a.count > size) {
           _a = a[0...size]
       } else {
           _a = a
           for (i in a.count...size) _a.add(v)
       }
   }

   // Convenience version of 'fit' which uses a default value of null.
   static fit(size, a) { fit(size, a, null) }

   // Constructs a new array of a given size and sets all elements to the same value 'v'.
   construct new(size, v) {
       Check.nonNegInt("Size", size)
       _a = List.filled(size, v)
   }

   // Convenience version of 'new' which sets all elements to null.
   static new(size) { new(size, null) }

   // Property
   count { _a.count }  // returns the number of elements in the array

   // Creates a shallow copy of the current instance.
   copy() { Array.from(_a) }

   // Resets all elements of the array to 'v'.
   reset(v) {
       for (i in 0..._a.count) _a[i] = v
   }

   // Gets the element at 'index.' If index is negative, it counts backwards
   // from the end of the array where -1 is the last element.
   // If index is a range it creates a new array from the appropriate elements.
   [index] { (index is Range) ? Array.from(_a[index]) : _a[index] }

   // Sets the element at 'index'. Negative indices are treated as in the getter.
   [index]=(v) { _a[index] = v }

   // Returns the index of 'value' in the current instance or -1 if 'value' is not found.
   indexOf(value) { _a.indexOf(value) }

   // Returns the index of the last occurrence of 'value' in the current instance
   // or -1 if 'value' is not found.
   lastIndexOf(value) {
       if (_a.count == 0) return 0
       for (i in _a.count-1..0) {
           if (_a[i] == value) return i
       }
       return -1
   }

   // Replaces all occurrences of 'old' by 'new' in the current instance
   // and returns ['old', 'new'].
   replace(old, new) {
       for (i in 0..._a.count) {
           if (_a[i] == old) _a[i] = new
       }
       return [old, new]
   }

   // Sorts the elements of the array in place and both overloads work in exactly
   // the same manner as the corresponding methods in the List class.
   sort()         { _a.sort() }
   sort(comparer) { _a.sort(comparer) }

   // Swaps the elements at index1 and index2 within the array.
   swap(index1, index2) { _a.swap(index1, index2) }

   // Applies a function to each element of the array.
   apply(fn) {
       Check.func("fn", fn, 1)
       for (i in 0..._a.count) _a[i] = fn.call(_a[i])
   }

   // Iterator protocol methods.
   iterate(iterator) { _a.iterate(iterator) }
   iteratorValue(iterator) { _a.iteratorValue(iterator) }

   // Returns the string representation of the underlying list.
   toString { _a.toString }

}

/*

   ArrayType creates a named class which inherits from Array and always has the same
   size and default values. The named class has four constructors:
   1. new(v)    - sets all elements to 'v'
   2. new()     - sets all elements to the default value
   3. fit(a, v) - fits the sequence 'a' to 'size' filling out with 'v' if too short
   4. fit(a)    - as (3) but fills out with the default value if too short 
   and four instance methods of its own:
   5. default   - returns the default value
   6. toArray   - converts the current instance to an Array
   7. copy()    - creates a shallow copy of the current instance
                - overriding the copy() method inherited from Array
   8. reset()   - resets all elements to the default value.

• /

class ArrayType {

   // Creates a class for the ArrayType (with an underscore after the name), with a
   // given size and default value for its elements, and returns a reference to it.
   static create(name, size, default) {
       Check.ident("Name", name)
       Check.nonNegInt("Size", size)
       name = name +  "_"
       var s = "class %(name) is Array {\n"
       s = s + "    construct new(v) {\n"
       s = s + "        super(%(size), v)\n"
       s = s + "    }\n"
       s = s + "    construct new()  {\n"
       s = s + "        super(%(size), %(default))\n"
       s = s + "    }\n"
       s = s + "    construct fit(a, v) {\n"
       s = s + "        super(%(size), a, v)\n"
       s = s + "    }\n"
       s = s + "    construct fit(a) {\n"
       s = s + "        super(%(size), a, %(default))\n"
       s = s + "    }\n"
       s = s + "    default { %(default) }\n"
       s = s + "    toArray() { Array.from(this) }\n"
       s = s + "    copy() {\n"
       s = s + "        var d = %(name).new()\n"
       s = s + "        for (i in 0...%(size)) d[i] = this[i]\n"
       s = s + "        return d\n"
       s = s + "    }\n"
       s = s + "    reset() { reset(%(default)) }\n}\n"
       s = s + "return %(name)"
       return Meta.compile(s).call()
   }

   // Convenience version of 'create' which always uses a default value of null.
   static create(name, size ) { create(name, size, null) }

}

/*

  BitArray represents a List<Bool> whose size cannot be changed after it has been constructed
  but whose elements can be changed. It uses only 1/32nd as much memory as a 'normal' List<Bool>
  but is around 4 times slower to index. Also, unlike List<Bool>, BitArray is not a Sequence.

• /

class BitArray {

   // Constructs a new BitArray of a given size and sets all elements to the same value 'v'.
   // 'size' is rounded to the higher multiple of 32 where necessary.
   construct new(size, v) {
       Check.posInt("size", size)
       Check.bool("value", v)
       _len = (size / 32).ceil
       _a = List.filled(_len, v ? 4294967295 : 0)
   }

   // Convenience version of 'new' which sets all elements to false.
   static new(size) { new(size, false) }

   // Returns the number of elements in the BitArray.
   count { 32 * _len }

   // Creates a copy of the current instance.
   copy() { 
       var c = BitArray.new(count, false)
       for (i in 0...count) c[i] = this[i]
       return c
   }

   // Resets all elements of the BitArray to 'v'.
   reset(v) {
       Check.bool("value", v)
       var value = v ? 4294967295 : 0
       for (i in 0..._len) _a[i] = value
   }

   // Gets the element at 'index'. If index is negative, it counts backwards
   // from the end of the array where -1 is the last element.
   // To maximize access speed, this method doesn't validate the index.
   // Use the 'get' method instead if you need to do that.
   [index] {
       if (index < 0) index = count + index
       var ix = (index/32).floor
       var bit = index%32
       return ((_a[ix] >> bit) & 1) == 1
   }

   // Sets the element at 'index'. Negative indices are treated as in the getter.
   // To maximize access speed, this method doesn't validate the index nor the new value.
   // Use the 'set' method instead if you need to do that.
   [index]=(v) {
       if (index < 0) index = count + index
       var ix = (index/32).floor
       var bit = index%32
       _a[ix] = v ?  _a[ix] | (1 << bit) : _a[ix] & ~(1 << bit)
   }

   // As [index] method but validates the index. 
   get(index) {
        Check.int("index", index, -count, count-1)
        return this[index]
   }

   // As [index]=(v) method but validates the index and the new value.
   set(index, v) {
        Check.int("index", index, -count, count-1)
        Check.bool("value", v)
        this[index] = v
   }

   // Returns a List<Bool> using the normal 8 bytes for each element.
   toList {
       var bools = List.filled(count, false)
       for (i in 0...count) bools[i] = this[i]
       return bools
   }

   // Returns an Array<Bool> using the normal 8 bytes for each element.
   toArray {
       var bools = Array.new(count, false)
       for (i in 0...count) bools[i] = this[i]
       return bools
   }

   // Returns a bit string representation of this BitArray.
   toString {
       var bytes = List.filled(count, 0)
       for (i in 0...count) if (this[i]) bytes[i] = 1
       return bytes.join()
   }

}</lang>