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Removed lengths property of HuffmanTable.

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This commit is contained in:
Timofey Solomko
2016-12-04 19:42:34 +03:00
parent b9b3df58e7
commit 445eb2ec61
1 changed files with 10 additions and 11 deletions
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Sources/HuffmanTable.swift
+10 -11
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@@ -26,31 +26,30 @@ class HuffmanTable: CustomStringConvertible {
}
var lengths: [HuffmanLength]
var tree: [HuffmanLength?]
let leafCount: Int
var description: String {
return self.lengths.reduce("HuffmanTable:\n") { $0.appending("\($1)\n") }
return self.tree.reduce("HuffmanTree:\n") { $0.appending("\($1)\n") }
}
init(bootstrap: [Array<Int>]) {
// Fills the 'lengths' array with numerous HuffmanLengths from a 'bootstrap'
var newLengths: [HuffmanLength] = []
var lengths: [HuffmanLength] = []
var start = bootstrap[0][0]
var bits = bootstrap[0][1]
for pair in bootstrap[1..<bootstrap.count] {
let finish = pair[0]
let endbits = pair[1]
if bits > 0 {
newLengths.append(contentsOf:
lengths.append(contentsOf:
(start..<finish).map { HuffmanLength(code: $0, bits: bits, symbol: nil) })
}
start = finish
bits = endbits
}
// Sort the lengths' array so finding of symbols will be more efficient
self.lengths = newLengths.sorted()
// Sort the lengths' array to calculate symbols correctly
lengths.sort()
func reverse(bits: Int, in symbol: Int) -> Int {
// Auxiliarly function, which generates reversed order of bits in a number
@@ -69,24 +68,24 @@ class HuffmanTable: CustomStringConvertible {
// Calculates symbols for each length in 'lengths' array
var loopBits = -1
var symbol = -1
for index in 0..<self.lengths.count {
for index in 0..<lengths.count {
symbol += 1
let length = self.lengths[index]
let length = lengths[index]
// We sometimes need to make symbol to have length.bits bit length
if length.bits != loopBits {
symbol <<= (length.bits - loopBits)
loopBits = length.bits
}
self.lengths[index].symbol = reverse(bits: loopBits, in: symbol)
lengths[index].symbol = reverse(bits: loopBits, in: symbol)
}
// Calculate maximum amount of leaves possible in a tree
self.leafCount = Int(pow(Double(2), Double(self.lengths.last!.bits + 1)))
self.leafCount = Int(pow(Double(2), Double(lengths.last!.bits + 1)))
// Create a tree (array, actually) with all leaves equal nil
self.tree = Array(repeating: nil, count: leafCount)
// Populate necessary leaves with HuffmanLengths
for length in self.lengths {
for length in lengths {
var symbol = length.symbol!
let bits = length.bits
var index = 0