/**
* Parse a set.
*
* @param token the initial token.
* @return the root of the generated parse subtree.
* @throws Exception if an error occurred.
*/
private ICodeNode parseSet(Token token) throws Exception {
ICodeNode rootNode = ICodeFactory.createICodeNode(SETS);
int tempInteger = 0;
token = nextToken(); // consume left bracket
while (token.getType() != RIGHT_BRACKET) {
if (token.getType() == INTEGER) {
tempInteger = (int) token.getValue();
rootNode.addChild(parseTerm(token));
token = currentToken();
} else if (token.getType() == IDENTIFIER) {
ICodeNode var = parseFactor(token);
rootNode.addChild(var);
token = currentToken();
}
if (token.getType() == COMMA) {
token = nextToken(); // consume next token
if (token.getType() == COMMA) {
errorHandler.flag(token, EXTRA_COMMA, this);
}
} else if (token.getType() == RIGHT_BRACKET) { // do nothing
} else if (token.getType() == SEMICOLON) {
errorHandler.flag(token, MISSING_CLOSE_SQUARE_BRACKET, this);
break;
} else if (token.getType() == DOT_DOT) {
token = nextToken(); // consume the integer.
// Create a STRING_CONSTANT node as the root node.
ICodeNode node = ICodeFactory.createICodeNode(SUBRANGE);
// denotes the maximum value of the range.
if (token.getType() != INTEGER) {
errorHandler.flag(token, MISSING_MAX_VAL_SUBRANGE, this);
} else {
int value = (int) token.getValue();
node.setAttribute(VALUE, value);
}
rootNode.addChild(node);
token = nextToken();
} else {
errorHandler.flag(token, MISSING_COMMA, this);
}
}
if (token.getType() != SEMICOLON) {
token = nextToken(); // consume right bracket
}
return rootNode;
}
/**
* Parse a factor.
*
* @param token the initial token.
* @return the root of the generated parse subtree.
* @throws Exception if an error occurred.
*/
private ICodeNode parseFactor(Token token) throws Exception {
TokenType tokenType = token.getType();
ICodeNode rootNode = null;
switch ((PascalTokenType) tokenType) {
case IDENTIFIER:
{
// Look up the identifier in the symbol table stack.
// Flag the identifier as undefined if it's not found.
String name = token.getText().toLowerCase();
SymTabEntry id = symTabStack.lookup(name);
if (id == null) {
errorHandler.flag(token, IDENTIFIER_UNDEFINED, this);
id = symTabStack.enterLocal(name);
}
rootNode = ICodeFactory.createICodeNode(VARIABLE);
rootNode.setAttribute(ID, id);
id.appendLineNumber(token.getLineNumber());
token = nextToken(); // consume the identifier
break;
}
case INTEGER:
{
// Create an INTEGER_CONSTANT node as the root node.
rootNode = ICodeFactory.createICodeNode(INTEGER_CONSTANT);
rootNode.setAttribute(VALUE, token.getValue());
token = nextToken(); // consume the number
break;
}
case REAL:
{
// Create an REAL_CONSTANT node as the root node.
rootNode = ICodeFactory.createICodeNode(REAL_CONSTANT);
rootNode.setAttribute(VALUE, token.getValue());
token = nextToken(); // consume the number
break;
}
case STRING:
{
String value = (String) token.getValue();
// Create a STRING_CONSTANT node as the root node.
rootNode = ICodeFactory.createICodeNode(STRING_CONSTANT);
rootNode.setAttribute(VALUE, value);
token = nextToken(); // consume the string
break;
}
case NOT:
{
token = nextToken(); // consume the NOT
// Create a NOT node as the root node.
rootNode = ICodeFactory.createICodeNode(ICodeNodeTypeImpl.NOT);
// Parse the factor. The NOT node adopts the
// factor node as its child.
rootNode.addChild(parseFactor(token));
break;
}
case LEFT_PAREN:
{
token = nextToken(); // consume the (
// Parse an expression and make its node the root node.
rootNode = parseExpression(token);
// Look for the matching ) token.
token = currentToken();
if (token.getType() == RIGHT_PAREN) {
token = nextToken(); // consume the )
} else {
errorHandler.flag(token, MISSING_RIGHT_PAREN, this);
}
break;
}
case LEFT_BRACKET:
{
rootNode = parseSet(token);
break;
}
default:
{
errorHandler.flag(token, UNEXPECTED_TOKEN, this);
break;
}
}
return rootNode;
}
