added RCMatrix class

Sources/Internal/Reed Solomon/RCMatrix.swift

@@ -0,0 +1,104 @@
+//  MIT License
+
+//  Copyright (c) 2020 Haik Aslanyan
+
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+
+import Foundation
+
+final class RCMatrix {
+  
+  //MARK: Properties
+  let rows: Int
+  let columns: Int
+  private var data = [[Float32]]()
+  
+  //MARK: Inits
+  init(size: Int) {
+    self.rows = size
+    self.columns = size
+    for _ in 0..<size {
+      data.append(Array(repeating: 0, count: size))
+    }
+  }
+  
+  init(columns: Int, items: [Float32]) {
+    guard items.count % columns == 0 else {
+      fatalError("number of columns are not matching")
+    }
+    self.columns = columns
+    self.rows = items.count / columns
+    data = stride(from: 0, to: items.count, by: self.columns).map {
+      Array(items[$0 ..< min($0 + self.rows, items.count)])
+    }
+  }
+}
+
+//MARK: Public methods
+extension RCMatrix {
+  subscript(row: Int, column: Int) -> Float32 {
+    get {
+      guard (0...self.rows).contains(row), (0...self.columns).contains(column) else {
+        fatalError("out of bounds")
+      }
+      return data[row][column]
+    }
+    set {
+     data[row][column] = newValue
+    }
+  }
+  
+  func row(for index: Int) -> [Float32] {
+    return data[index]
+  }
+  
+  func column(for index: Int) -> [Float32] {
+    return data.compactMap({$0[index]})
+  }
+  
+  func swap(row firstRow: Int, with lastRow: Int) {
+    guard (0...self.rows).contains(firstRow) else {
+      fatalError("out of bounds")
+    }
+    data.swapAt(firstRow, lastRow)
+  }
+  
+  static func identity(size: Int) -> RCMatrix {
+    let matrix = RCMatrix(size: size)
+    for index in 0..<size {
+      matrix[index, index] = 1
+    }
+    return matrix
+  }
+}
+
+extension RCMatrix: Equatable {
+  static func == (lhs: RCMatrix, rhs: RCMatrix) -> Bool {
+    return lhs.data.flatMap({$0}) == rhs.data.flatMap({$0})
+  }
+}
+
+//MARK: CustomStringConvertible
+extension RCMatrix: CustomStringConvertible {
+  var description: String {
+    var message = "columns: \(columns), rows: \(rows)"
+    data.forEach({message += "\n \($0.description)"})
+    return message
+  }
+}