implement the following methods:

1) public void enterSymbol(Node id, Node value)

2) public boolean isDeclaredLocally(Node id)

The goal is to perform simple semantic analysis where it can:

1) Check for undeclared variables

2) Check for multiple declarations of same variable

You have to use a symbol table and you are required to use Java HashMap to implement the symbol table.

CODE:

%{ import java.io.*; import java.util.*; import java.text.*; %} %token ID NUM ASSIGN PLUS MINUS %start s %% s : stmt_list { $$ = $1; printTree($$); System.out.println(" "); printNode($$); printSymbolTable(); } | {/* empty */} ; stmt_list : stmt { $$ = $1; } | stmt_list ';' stmt { $$ = makeNode(";", $1, $3); } ; stmt : ID ASSIGN expr { $$ = makeNode($2.token, $1, $3); if(isDeclaredLocally($1)) { /* YOUR CODE */ } else { /* YOUR CODE */ } } ; expr : expr PLUS term { $$ = makeNode("+", $1, $3); } | expr MINUS term { $$ = makeNode("-", $1, $3); } | term { $$ = $1; } ; term : ID { $$ = $1; /* YOUR CODE */ /* if (some condition) { ... } */ } | NUM { $$ = $1; } ; %% /*************************************** ***** YOUR CODE HERE ****************** ***************************************/ private HashMap symbol_table = new HashMap(); /* Parameters are Node types because all parse values are specified as a Node by using the -Jsemantic=Node flag (for the parser) in Makefile */ public void enterSymbol(Node id, Node value) { /* YOUR CODE */ } public boolean isDeclaredLocally(Node id) { /* YOUR CODE */ return false; } public void printSymbolTable() { System.out.println("--------Symbol Table Entries----------"); for (Map.Entry entry : symbol_table.entrySet()) { String key = entry.getKey(); String value = entry.getValue(); System.out.println("K: " + key + ", V: " + value ); } } /*************************************** ***** END OF YOUR CODE HERE *********** ***************************************/ /* Byacc/J expects a member method int yylex(). We need to provide one through this mechanism. See the jflex manual for more information. */ /* reference to the lexer object */ private Scanner lexer; /* interface to the lexer */ private int yylex() { int retVal = -1; try { retVal = lexer.yylex(); } catch (IOException e) { System.err.println("IO Error:" + e); } return retVal; } /* error reporting */ public void yyerror (String error) { System.err.println("Error : " + error + " at line " + lexer.getLine() + " column: " + lexer.getColumn()); System.err.println("String rejected"); } /* constructor taking in File Input */ public Parser (Reader r) { lexer = new Scanner (r, this); } public static void main (String [] args) throws IOException { Parser yyparser = new Parser(new FileReader(args[0])); yyparser.yyparse(); } Node makeNode(String token, Node left, Node right) { Node newNode = new Node(token); newNode.left = left; newNode.right = right; return newNode; } void printTree(Node tree) { int i; if (tree.left!=null || tree.right!=null) { System.out.print("( "); } System.out.print(tree.token + " "); if (tree.left!=null) { printTree(tree.left); } if (tree.right!=null) { printTree(tree.right); } if (tree.left!=null || tree.right!=null) { System.out.print(")"); } } public void printNode(Node root) { System.out.println("--------Structured View of Tree----------"); int maxLevel = maxLevel(root); printNodeInternal(Collections.singletonList(root), 1, maxLevel); } private void printNodeInternal(List nodes, int level, int maxLevel) { if (nodes.isEmpty() || isAllElementsNull(nodes)) return; int floor = maxLevel - level; int endgeLines = (int) Math.pow(2, (Math.max(floor - 1, 0))); int firstSpaces = (int) Math.pow(2, (floor)) - 1; int betweenSpaces = (int) Math.pow(2, (floor + 1)) - 1; printWhitespaces(firstSpaces); List newNodes = new ArrayList(); for (Node node : nodes) { if (node != null) { System.out.print(node.token); newNodes.add(node.left); newNodes.add(node.right); } else { newNodes.add(null); newNodes.add(null); System.out.print(" "); } printWhitespaces(betweenSpaces); } System.out.println(""); for (int i = 1; i <= endgeLines; i++) { for (int j = 0; j < nodes.size(); j++) { printWhitespaces(firstSpaces - i); if (nodes.get(j) == null) { printWhitespaces(endgeLines + endgeLines + i + 1); continue; } if (nodes.get(j).left != null) System.out.print("/"); else printWhitespaces(1); printWhitespaces(i + i - 1); if (nodes.get(j).right != null) System.out.print("\\"); else printWhitespaces(1); printWhitespaces(endgeLines + endgeLines - i); } System.out.println(""); } printNodeInternal(newNodes, level + 1, maxLevel); } private void printWhitespaces(int count) { for (int i = 0; i < count; i++) System.out.print(" "); } private int maxLevel(Node node) { if (node == null) return 0; return Math.max(maxLevel(node.left), maxLevel(node.right)) + 1; } private boolean isAllElementsNull(List list) { for (Object object : list) { if (object != null) return false; } return true; }