AstNode* Parser::parseStatement() {
if (isKeyword(currentTokenValue())) {
if (currentTokenValue() == "function") {
return parseFunction();
} else if (currentTokenValue() == "for") {
return parseFor();
} else if (currentTokenValue() == "if") {
return parseIf();
} else if (currentTokenValue() == "while") {
return parseWhile();
} else if (currentTokenValue() == "print") {
return parsePrint();
} else if (currentTokenValue() == "int") {
return parseDeclaration(VT_INT);
} else if (currentTokenValue() == "double") {
return parseDeclaration(VT_DOUBLE);
} else if (currentTokenValue() == "string") {
return parseDeclaration(VT_STRING);
} else if (currentTokenValue() == "return") {
return parseReturn();
} else {
cout << "unhandled keyword " << currentTokenValue() << endl;
assert(false);
return 0;
}
}
if (currentToken() == tLBRACE) {
return parseBlock(true);
}
if ((currentToken() == tIDENT) && isAssignment(lookaheadToken(1))) {
return parseAssignment();
}
return parseExpression();
}
TokenType_T LLKParser::lookaheadType(int i)
{
TokenType_T ret = EOF;
if( lookahead != NULL )
{
Token* tok = lookaheadToken(i);
ret = (tok != NULL) ? tok->type() : EOF;
}
return ret;
}
AstNode* Parser::parseDeclaration(VarType type) {
// Skip type.
ensureToken(tIDENT);
const string& var = currentTokenValue();
if (!_currentScope->declareVariable(var, type)) {
error("Variable %s already declared", var.c_str());
}
if (lookaheadToken(1) == tASSIGN) {
return parseAssignment();
}
ensureToken(tIDENT);
ensureToken(tSEMICOLON);
return 0;
}
AstNode* Parser::parseUnary() {
if (isUnaryOp(currentToken())) {
TokenKind op = currentToken();
consumeToken();
return new UnaryOpNode(_currentTokenIndex, op, parseUnary());
} else if (currentToken() == tIDENT && lookaheadToken(1) == tLPAREN) {
AstNode* expr = parseCall();
return expr;
} else if (currentToken() == tIDENT) {
AstVar* var = _currentScope->lookupVariable(currentTokenValue());
if (var == 0) {
error("undeclared variable: %s", currentTokenValue().c_str());
}
LoadNode* result = new LoadNode(_currentTokenIndex, var);
consumeToken();
return result;
} else if (currentToken() == tDOUBLE) {
DoubleLiteralNode* result =
new DoubleLiteralNode(_currentTokenIndex,
parseDouble(currentTokenValue()));
consumeToken();
return result;
} else if (currentToken() == tINT) {
IntLiteralNode* result =
new IntLiteralNode(_currentTokenIndex,
parseInt(currentTokenValue()));
consumeToken();
return result;
} else if (currentToken() == tSTRING) {
StringLiteralNode* result =
new StringLiteralNode(_currentTokenIndex,
currentTokenValue());
consumeToken();
return result;
} else if (currentToken() == tLPAREN) {
consumeToken();
AstNode* expr = parseExpression();
ensureToken(tRPAREN);
return expr;
} else {
error("Unexpected token: %s", tokenStr(currentToken()));
return 0;
}
}
int lookaheadType(int i) {
return lookaheadToken(i).type();
}
