private Token getPredictToken(List <Token> tokens, int loc)
{
Token predictToken;
if (loc < tokens.Count)
{
predictToken = tokens[loc];
}
else
{
predictToken = eof;
}
if (predictToken is Identifier)
{
predictToken = new Identifier(predictToken, "");
}
if (predictToken is IntLiteral)
{
predictToken = new IntLiteral(predictToken, "0");
}
if (predictToken is StringLiteral)
{
predictToken = new StringLiteral(predictToken, "");
}
if (predictToken is BoolLiteral)
{
predictToken = new BoolLiteral(predictToken, "");
}
return(predictToken);
}
private void initializeGrammar()
{
addKeywordOrNonTerminal("for");
addKeywordOrNonTerminal("in");
addKeywordOrNonTerminal("..", "\\.\\.");
addKeywordOrNonTerminal("do");
addKeywordOrNonTerminal("end");
addKeywordOrNonTerminal("var");
addKeywordOrNonTerminal(";");
addKeywordOrNonTerminal(":");
addKeywordOrNonTerminal(":=");
addKeywordOrNonTerminal("read");
addKeywordOrNonTerminal("print");
addKeywordOrNonTerminal("assert");
addKeywordOrNonTerminal("type");
addKeywordOrNonTerminal("int");
addKeywordOrNonTerminal("string");
addKeywordOrNonTerminal("bool");
addKeywordOrNonTerminal("(", "\\(");
addKeywordOrNonTerminal(")", "\\)");
addKeywordOrNonTerminal("prog");
addKeywordOrNonTerminal("stmts");
addKeywordOrNonTerminal("stmt");
addKeywordOrNonTerminal("expr");
addKeywordOrNonTerminal("expr2");
addKeywordOrNonTerminal("expr3");
addKeywordOrNonTerminal("opnd");
addKeywordOrNonTerminal("op");
addKeywordOrNonTerminal("unary_op");
addKeywordOrNonTerminal("maybeAssign");
addOperator("+");
addOperator("-");
addOperator("*");
addOperator("/");
addOperator("<");
addOperator("=");
addOperator("&");
//unary must be handled separately from binary because otherwise "abc"!"abc" is parseable
Token not = new Operator("!");
o.Add("!", not);
scanner.addOperator("!");
Token id = new Identifier("");
Token intV = new IntLiteral("0");
Token strV = new StringLiteral("");
Token boolV = new BoolLiteral("");
parser.addProduction(t["prog"], new List <Token> {
t["stmt"], t[";"], t["stmts"]
});
parser.addProduction(t["stmts"], new List <Token> {
t["stmt"], t[";"], t["stmts"]
});
parser.addProduction(t["stmts"], new List <Token> {
});
parser.addProduction(t["stmt"], new List <Token> {
t["var"], id, t[":"], t["type"], t["maybeAssign"]
});
parser.addProduction(t["stmt"], new List <Token> {
t["for"], id, t["in"], t["expr"], t[".."], t["expr"], t["do"], t["stmt"], t[";"], t["stmts"], t["end"], t["for"]
});
parser.addProduction(t["stmt"], new List <Token> {
id, t[":="], t["expr"]
});
parser.addProduction(t["stmt"], new List <Token> {
t["read"], id
});
parser.addProduction(t["stmt"], new List <Token> {
t["print"], t["expr"]
});
parser.addProduction(t["stmt"], new List <Token> {
t["assert"], t["("], t["expr"], t[")"]
});
parser.addProduction(t["expr"], new List <Token> {
t["expr2"]
});
parser.addProduction(t["expr"], new List <Token> {
t["unary_op"], t["opnd"]
});
parser.addProduction(t["expr2"], new List <Token> {
t["opnd"], t["expr3"]
});
parser.addProduction(t["expr3"], new List <Token> {
t["op"], t["opnd"]
});
parser.addProduction(t["expr3"], new List <Token> {
});
parser.addProduction(t["opnd"], new List <Token> {
intV
});
parser.addProduction(t["opnd"], new List <Token> {
strV
});
parser.addProduction(t["opnd"], new List <Token> {
boolV
});
parser.addProduction(t["opnd"], new List <Token> {
id
});
parser.addProduction(t["opnd"], new List <Token> {
t["("], t["expr"], t[")"]
});
parser.addProduction(t["type"], new List <Token> {
t["int"]
});
parser.addProduction(t["type"], new List <Token> {
t["string"]
});
parser.addProduction(t["type"], new List <Token> {
t["bool"]
});
parser.addProduction(t["maybeAssign"], new List <Token> {
t[":="], t["expr"]
});
parser.addProduction(t["maybeAssign"], new List <Token> {
});
parser.addProduction(t["unary_op"], new List <Token> {
not
});
parser.addProduction(t["unary_op"], new List <Token> {
o["-"]
});
parser.setStartSymbol(t["prog"]);
parser.prepareForParsing();
}
