Initial Error Handling

src/Assembler/Main.java

@@ -0,0 +1,79 @@
+package Assembler;
+
+import OperandPkg.Literal;
+import OperandPkg.OperandUtility;
+import SymbolPkg.*;
+
+import java.io.*;
+import java.util.LinkedList;
+
+//  NAME  :  Quazi Irfan
+//  CLASS  :  CSc 354
+//  ASSIGNMENT : 2
+//  DUE DATE : 10/5/16
+//  INSTRUCTOR :  Dr. Hamer
+//  DESCRIPTION : Assignment 2 : Expressions
+
+/**
+ * Assembler.Main is the Entry point Assignment 2 : Expressions
+ *
+ * Thic class checks if two arguments were supplied, or it prompts the user to enter them.
+ * If <2 arguments were supplied then it terminates the execution.
+ * The user has to reload the program to try again.
+ *
+ * After setting the input file, the program calls static methods to,
+ * 1. Populate the Symbol Table
+ * 2. Evaluate and print all valid expressions
+ * 3. Print the literals
+ *
+ */
+public class Main {
+    public static void main(String[] args) throws IOException{
+        SymbolTable symbolTable = new SymbolTable();
+        LinkedList<Literal> literalLnkdLst = new LinkedList<>();
+
+        // Set input files
+        String symbolFile, operandFile;
+        if(args.length < 2){
+            System.out.println("Missing command like argument.");
+            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
+            System.out.print("Enter Symbol File : ");
+            symbolFile = reader.readLine();
+            System.out.print("Enter Expressions File : ");
+            operandFile = reader.readLine();
+        } else {
+            symbolFile = args[0];
+            operandFile = args[1];
+        }
+
+        // Check the existence of both symbol and operand file
+        File f = new File(symbolFile);
+        if(!f.exists()) {
+            System.out.println(symbolFile + " not found. Please rerun the program to try again.");
+            return;
+        }
+
+        f = new File(operandFile);
+        if(!f.exists()) {
+            System.out.println(operandFile + " not found. Please rerun the program to try again.");
+            return;
+        }
+
+        // Populate Symbol Table
+        SymbolUtility.populateSymbolTable(symbolTable, symbolFile);
+        System.out.println("*** SYMBOL TABLE ***\nSymbol\t Value\t rflag\t iflag\t mflag\t");
+        symbolTable.view();
+
+        // Evaluate and print Expressions
+        System.out.println("\n*** EXPRESSIONS ***\nExpresion\t Value\t Relocatable n i x");
+        OperandUtility.evaluateOperand(symbolTable, literalLnkdLst, operandFile);
+
+        // Print contents of the literal table
+        System.out.println("\n*** LITERAL TABLE ***\nName\t\t Value\t\t Size\t Address");
+        for(Object o : literalLnkdLst){
+            System.out.println(o);
+        }
+    }
+
+
+}

src/Assembler/Utility.java

@@ -0,0 +1,25 @@
+package Assembler;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+/**
+ * This Utility class is meant for temporary code segments that doesn't fit in other classes.
+ *
+ */
+
+public class Utility {
+    /**
+     *  This method prompts the user the press Enter to continue.
+     */
+    public static void enterToContinue(){
+        System.out.print(" *** Press Enter to continue...");
+        try{
+            BufferedReader tempHalt = new BufferedReader(new InputStreamReader(System.in));
+            tempHalt.readLine();
+        } catch (IOException e){
+            System.out.println(e);
+        }
+    }
+}

src/OperandPkg/Literal.java

@@ -1,13 +1,26 @@
 package OperandPkg;
 
+/**
+ * Each literal is an entry to the Literal Table
+ *
+ * Literals are addressed 1,2...n. The starting address is a static number,
+ * and upon each successful entry to the literal table the static int is increased.
+ *
+ * Other attributes of literal are public.
+ */
 public class Literal {
     public static int staticAddress = 1;
 
     String name, value;
     int length, address;
 
+    /**
+     * Helper method that returns formatted attributes of a Literal
+     */
     public String toString() {
-        return name + " " + value + " " + length + " " + address;
+        String output = String.format("%1$-12s %2$-16s %3$-7d %4$d", name, value, length, address);
+
+        return output;
     }
 }
 

src/OperandPkg/Operand.java

@@ -1,16 +1,25 @@
 package OperandPkg;
 
+/**
+ * Each Operand is a processed non-literal Expression
+ */
 public class Operand {
     public String expression;
     public int value;
     public boolean relocability, nbit, ibit, xbit;
 
+    /*
+     * This method returns a formatted operand attribute
+     */
     public String toString() {
-        return expression + " " +
-                value + " " +
-                (relocability ? "Relative":"Absolute") + " " +
-                (nbit? "1":"0") + " " +
-                (ibit? "1":"0") + " " +
-                (xbit? "1":"0");
+        String output = String.format("%1$-16s %2$-7d %3$-11s %4$s %5$s %6$s",
+                expression,
+                value,
+                (relocability ? "Relative":"Absolute"),
+                (nbit? "1":"0"),
+                (ibit? "1":"0"),
+                (xbit? "1":"0"));
+
+        return output;
     }
 }