Data commit

Task/Align-columns/Swift/align-columns.swift

@@ -0,0 +1,86 @@
+import Foundation
+
+extension String {
+  func dropLastIf(_ char: Character) -> String {
+    if last == char {
+      return String(dropLast())
+    } else {
+      return self
+    }
+  }
+}
+
+enum Align {
+  case left, center, right
+}
+
+func getLines(input: String) -> [String] {
+  input
+    .components(separatedBy: "\n")
+    .map({ $0.replacingOccurrences(of: " ", with: "").dropLastIf("$") })
+}
+
+func getColWidths(from: String) -> [Int] {
+  var widths = [Int]()
+  let lines = getLines(input: from)
+
+  for line in lines {
+    let lens = line.components(separatedBy: "$").map({ $0.count })
+
+    for (i, len) in lens.enumerated() {
+      if i < widths.count {
+        widths[i] = max(widths[i], len)
+      } else {
+        widths.append(len)
+      }
+    }
+  }
+
+  return widths
+}
+
+func alignCols(input: String, align: Align = .left) -> String {
+  let widths = getColWidths(from: input)
+  let lines = getLines(input: input)
+  var res = ""
+
+  for line in lines {
+    for (str, width) in zip(line.components(separatedBy: "$"), widths) {
+      let blanks = width - str.count
+      let pre: Int, post: Int
+
+      switch align {
+      case .left:
+        (pre, post) = (0, blanks)
+      case .center:
+        (pre, post) = (blanks / 2, (blanks + 1) / 2)
+      case .right:
+        (pre, post) = (blanks, 0)
+      }
+
+      res += String(repeating: " ", count: pre)
+      res += str
+      res += String(repeating: " ", count: post)
+      res += " "
+    }
+
+    res += "\n"
+  }
+
+  return res
+}
+
+let input = """
+            Given$a$text$file$of$many$lines,$where$fields$within$a$line$
+            are$delineated$by$a$single$'dollar'$character,$write$a$program
+            that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$
+            column$are$separated$by$at$least$one$space.
+            Further,$allow$for$each$word$in$a$column$to$be$either$left$
+            justified,$right$justified,$or$center$justified$within$its$column.
+            """
+
+print(alignCols(input: input))
+print()
+print(alignCols(input: input, align: .center))
+print()
+print(alignCols(input: input, align: .right))