Data update

Task/Parsing-Shunting-yard-algorithm/Scala/parsing-shunting-yard-algorithm.scala

@@ -0,0 +1,48 @@
+import scala.util.control.Breaks._
+
+object ShuntingYard {
+
+  def main(args: Array[String]): Unit = {
+    val infix = "3 + 4 * 2 / ( 1 - 5 ) ^ 2 ^ 3"
+    println(s"infix:   $infix")
+    println(s"postfix: ${infixToPostfix(infix)}")
+  }
+
+  def infixToPostfix(infix: String): String = {
+    val ops = "-+/*^"
+    val sb = new StringBuilder
+    val s = scala.collection.mutable.Stack[Int]()
+
+    infix.split("\\s").foreach { token =>
+      if (token.nonEmpty) {
+        val c = token.head
+        val idx = ops.indexOf(c)
+
+        if (idx != -1) {
+          if (s.isEmpty) s.push(idx)
+          else {
+            breakable({
+            while (s.nonEmpty) {
+              val prec2 = s.top / 2
+              val prec1 = idx / 2
+              if (prec2 > prec1 || (prec2 == prec1 && c != '^')) sb.append(ops(s.pop)).append(' ')
+              else break
+            }
+            });
+            s.push(idx)
+          }
+        } else if (c == '(') {
+          s.push(-2) // -2 stands for '('
+        } else if (c == ')') {
+          // until '(' on stack, pop operators.
+          while (s.top != -2) sb.append(ops(s.pop)).append(' ')
+          s.pop()
+        } else {
+          sb.append(token).append(' ')
+        }
+      }
+    }
+    while (s.nonEmpty) sb.append(ops(s.pop)).append(' ')
+    sb.toString
+  }
+}

Task/Parsing-Shunting-yard-algorithm/Wren/parsing-shunting-yard-algorithm.wren

@@ -1,5 +1,5 @@
-import "/seq" for Stack
-import "/pattern" for Pattern
+import "./seq" for Stack
+import "./pattern" for Pattern
 
 /* To find out the precedence, we take the index of the
    token in the OPS string and divide by 2 (rounding down).