cohort 42.1 hw #19 & interpreter

Author: biblelamp

BerlinAIT/Cohort42.1/src/extend/Interpreter.java

@@ -6,13 +6,12 @@
  * AIT-TR, cohort 42.1, Java Basic, hw #10 ext
  *
  * @author Sergey Iryupin
- * @version 8,23-Feb-24
+ * @version 8,23,26,28-Feb-24
  */
 public class Interpreter {
 
-    static int[] values = new int[26];
-
     public static void main(String[] args) {
+        Variables variables = new Variables();
         Scanner scanner = new Scanner(System.in);
         String line;
         do {
@@ -21,55 +20,17 @@ public static void main(String[] args) {
             String[] tokens = line.split(" ");
             switch (tokens[0]) {
                 case "print":
-                    printValue(tokens[1]);
+                    Integer value = variables.getValue(tokens[1]);
+                    if (value != null) {
+                        System.out.println(value);
+                    }
                     break;
                 case "exit":
                     System.out.println("Exit from interpreter.");
                     break;
                 default:
-                    assignValue(line);
+                    variables.assignValue(line);
             }
         } while (!line.equals("exit"));
     }
-
-    static void assignValue(String line) {
-        String[] tokens = line.split("=");
-        String varName = tokens[0].trim();
-        String varValue = tokens[1].trim();
-        // check variable name
-        if (!validateVarName(varName)) {
-            return;
-        }
-        // transform 'a' -> 0
-        int idx = varName.charAt(0) - 'a';
-        // transform "123" -> 123
-        int value = Integer.valueOf(varValue);
-        // assign value
-        values[idx] = value;
-    }
-
-    static void printValue(String varName) {
-        // check variable name
-        if (!validateVarName(varName)) {
-            return;
-        }
-        // transform 'a' -> 0
-        int idx = varName.charAt(0) - 'a';
-        // print value of variable
-        System.out.println(values[idx]);
-    }
-
-    static boolean validateVarName(String varName) {
-        // check variable name length
-        if (varName.length() > 1) {
-            System.out.println("Error: variable name is too long");
-            return false;
-        }
-        if (varName.isEmpty()) {
-            System.out.println("Error: variable name is empty");
-            return false;
-        }
-        // TODO check if variable name in 'a'..'z'
-        return true;
-    }
 }

BerlinAIT/Cohort42.1/src/extend/Variables.java

@@ -0,0 +1,54 @@
+package extend;
+
+public class Variables {
+    private int[] values = new int[26];
+
+    public Integer getValue(String varName) {
+        // check variable name
+        if (!validateVarName(varName)) {
+            return null;
+        }
+        // transform 'a' -> 0
+        int idx = varName.charAt(0) - 'a';
+        return values[idx];
+    }
+
+    public void assignValue(String line) {
+        String[] tokens = line.split("=");
+        String varName = tokens[0].trim();
+        // if right side from '=' is not empty
+        if (tokens.length == 1) {
+            System.out.println("Error: invalid command");
+            return;
+        }
+        String varValue = tokens[1].trim();
+        // check variable name
+        if (!validateVarName(varName)) {
+            return;
+        }
+        // transform 'a' -> 0
+        int idx = varName.charAt(0) - 'a';
+        // transform "123" -> 123
+        int value = Integer.valueOf(varValue);
+        // assign value
+        values[idx] = value;
+    }
+
+    private boolean validateVarName(String varName) {
+        // check variable name length
+        if (varName.length() > 1) {
+            System.out.println("Error: variable name is too long");
+            return false;
+        }
+        if (varName.isEmpty()) {
+            System.out.println("Error: variable name is empty");
+            return false;
+        }
+        // check if variable name is in 'a'..'z'
+        if (varName.charAt(0) < 'a' || varName.charAt(0) > 'z') {
+            System.out.println("Error: variable name is invalid");
+            return false;
+        }
+        return true;
+    }
+}

BerlinAIT/Cohort42.1/src/lesson19/homework/HomeWork19.java

@@ -0,0 +1,24 @@
+package lesson19.homework;
+
+/**
+ * AIT-TR, cohort 42.1, Java Basic, hw #19
+ *
+ * @author Sergey Iryupin
+ * @version 28-Feb-24
+ */
+public class HomeWork19 {
+    public static void main(String[] args) {
+        RubberArray rb = new RubberArray();
+        rb.add(8);
+        rb.add(4);
+        rb.add(3);
+        rb.add(2);
+        rb.add(1);
+        System.out.println(rb);
+        System.out.println(rb.contains(12));
+        System.out.println(rb.indexOf(12));
+        System.out.println(rb.indexOf(5));
+        rb.add(-3, 3);
+        System.out.println(rb);
+    }
+}

BerlinAIT/Cohort42.1/src/lesson19/homework/RubberArray.java

@@ -0,0 +1,87 @@
+package lesson19.homework;
+
+import java.util.Arrays;
+
+public class RubberArray {
+
+    private final int INIT_DATA_SIZE = 10;
+    private final float EXTEND_INDEX = 1.5f;
+    private int[] data;
+    private int length;
+
+    public RubberArray() {
+        data = new int[INIT_DATA_SIZE];
+        length = 0;
+    }
+
+    public int get(int idx) {
+        return data[idx];
+    }
+
+    private void extendArrayIfNeed() {
+        if (length == data.length) {
+            // create new array, length * EXTEND_INDEX
+            int[] newData = new int[(int) (data.length * EXTEND_INDEX)];
+            // move all items to new array
+            for (int i = 0; i < data.length; i++) {
+                newData[i] = data[i];
+            }
+            // change link to new array
+            data = newData;
+        }
+    }
+
+    public void add(int value) {
+        extendArrayIfNeed();
+        // add value
+        data[length] = value;
+        length++;
+    }
+
+    public void add(int value, int idx) {
+        extendArrayIfNeed();
+        // insert value
+        // 0;1;2;3;4;5
+        // 8,4,3,2,1,1 -> i == 5
+        // 8,4,3,2,2,1 -> i == 4
+        for (int i = length; i > idx; i--) {
+            data[i] = data[i - 1];
+        }
+        System.out.println(Arrays.toString(data));
+        data[idx] = value;
+        length++;
+    }
+
+    public void remove(int idx) {
+        // move elements right to left from idx
+        for (int i = idx; i < data.length - 1; i++) {
+            data[i] = data[i + 1];
+        }
+        length--;
+    }
+
+    public boolean contains(int value) {
+        return indexOf(value) != -1;
+    }
+
+    public int indexOf(int value) {
+        for (int i = 0; i < length; i++) {
+            if (data[i] == value) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder("[");
+        for (int i = 0; i < length; i++) {
+            sb.append(data[i]);
+            if (i < length - 1) {
+                sb.append(", ");
+            }
+        }
+        return sb.append("]").toString();
+    }
+}