class Matrix<of T>

	const minDimRank = 1
	const maxDimRank = 1_000_000
	const maxCount = 1_000_000_000
	
	var _dims as IList<of int>
	var _count = 1
	var _data as T[]

	cue init(dims as vari int)
		require dims.length > 0 and all for dim in dims get dim >= .minDimRank and dim <= .maxDimRank
		.init(dims.toList)

	cue init(dims as IList<of int>)
		require dims.count > 0 and all for dim in dims get dim >= .minDimRank and dim <= .maxDimRank
		base.init
		_dims = dims.clone
		for dim in dims, _count *= dim
		assert _count < .maxCount
		_data = T[](_count)
		assert _data.length == _count
	
	get count from var
	
	get dims as IList<of int>
		return _dims.clone

	pro [indexes as vari int] as T
		get
			require indexes.length == .dims.count
			return _data[_address(indexes)]
		set
			require indexes.length == .dims.count
			_data[_address(indexes)] = value

	def _address(indexes as vari int) as int
		assert indexes.length == _dims.count
		# The below calcs are "row-major order", if it matters.
		# See http://en.wikipedia.org/wiki/Row-major_order#Generalization_to_higher_dimensions
		address = 0
		len = indexes.length
		for i in len
			index = indexes[i]
			if index < 0 or index >= _dims[i]
				throw IndexOutOfRangeException('Array index [index] is out of range 0 - [_dims[i]] for dimension [i].')
			x = 1
			for j in i+1 : len, x *= _dims[j]
			x *= index
			address += x
		return address

	def equals(obj as Object?) as bool is override
		if obj inherits Matrix<of T>, return .equals(obj)
		return false

	def getHashCode as int is override
		throw InvalidOperationException()

	def equals(m as Matrix<of T>) as bool
		if m.count <> .count, return false
		if m._dims <> _dims, return false
		for i in _count, if m._data[i] <> _data[i], return false
		return true


class Test

	def main
		m = Matrix<of int>(1)
		assert m.count == 1
		assert m[0] == 0
		m[0] = 42
		assert m[0] == 42
		expect IndexOutOfRangeException, print m[1]
		
		m = Matrix<of int>(3, 7)
		assert m.count == 21
		for x in 3, for y in 7, m[x, y] = x*y
		for x in 3, for y in 7, assert m[x, y] == x*y
		expect IndexOutOfRangeException, print m[3, 7]
		expect IndexOutOfRangeException, print m[3, 0]
		expect IndexOutOfRangeException, print m[0, 7]
		expect IndexOutOfRangeException, print m[4, 8]
		
		d1, d2, d3 = 10, 5, 3
		m = Matrix<of int>(d1, d2, d3)
		assert m.count == d1 * d2 * d3
		for x in d1, for y in d2, for z in d3, m[x, y, z] = x*y*z
		for x in d1, for y in d2, for z in d3, assert m[x, y, z] == x*y*z
		
		dims = [d1, d2, d3]
		m2 = Matrix<of int>(dims)
		for x in d1, for y in d2, for z in d3, m2[x, y, z] = x*y*z
		for x in d1, for y in d2, for z in d3, assert m2[x, y, z] == x*y*z
		assert m2 == m
		m2[0, 0, 0] += 1
		assert m2 <> m