Expression *Parser::ParseAExpr() {
Token* tk = lexer_->GetToken();
lexer_->Advance();
switch(tk->type()) {
case Token::INT:
return new ENum(tk, atoi(tk->TokenStr().c_str()));
case Token::ID:
return new EVar(tk, tk->TokenStr());
case Token::PACK: {
Advance(Token::LBRACE);
Token* left = lexer_->GetToken();
if (left->type() != Token::INT) {
throw ParseException(left, "expect a INT here");
}
int tag = atoi(left->TokenStr().c_str());
lexer_->Advance();
Advance(Token::COMMA);
Token* right = lexer_->GetToken();
if (right->type() != Token::INT) {
throw ParseException(right, "expect a INT here");
}
int arity = atoi(right->TokenStr().c_str());
lexer_->Advance();
Advance(Token::RBRACE);
return new EConstructor(tk, tag, arity);
}
case Token::LPAREN: {
lexer_->Advance();
Expression* result = ParseExpr();
Advance(Token::RPAREN);
return result;
}
default:
throw ParseException(tk, "Should Not Get Here");
}
}
Expression *Parser::ParseCmpExpr() {
// PlusExpr [ Op PlusExpr ] *
Expression* current = ParsePlusExpr();
while (IsCmpOperator(lexer_->GetToken()->type())) {
Token* token = lexer_->GetToken();
lexer_->Advance();
Expression * right = ParsePlusExpr();
current = new EApplication(token,
new EApplication(token,
new EVar(token, token->TokenStr()),
current),
right);
}
return current;
}
Expression *Parser::ParseAndExpr() {
// CmpExpr [ and CmpExpr ] *
Expression * current = ParseCmpExpr();
while (lexer_->GetToken()->type() == Token::AND) {
Token* token = lexer_->GetToken();
lexer_->Advance();
Expression * right = ParseCmpExpr();
current = new EApplication(token,
new EApplication(token,
new EVar(token, token->TokenStr()),
current),
right);
}
return current;
}
Expression *Parser::ParsePlusExpr() {
// FactorExpr [ +/- FactorExpr ] *
Expression* current = ParseFactor();
while (lexer_->GetToken()->type() == Token::PLUS ||
lexer_->GetToken()->type() == Token::MINUS) {
Token* token = lexer_->GetToken();
lexer_->Advance();
Expression * right = ParseFactor();
current = new EApplication(token,
new EApplication(token,
new EVar(token, token->TokenStr()),
current),
right);
}
return current;
}
Expression *Parser::ParseFactor() {
// SExpr [ *// SExpr ] *
Expression* current = ParseSExpr();
while (lexer_->GetToken()->type() == Token::STAR ||
lexer_->GetToken()->type() == Token::DIVIDE) {
Token* token = lexer_->GetToken();
lexer_->Advance();
Expression * right = ParseSExpr();
current = new EApplication(token,
new EApplication(token,
new EVar(token, token->TokenStr()),
current),
right);
}
return current;
}
SuperCombinatorDef *Parser::ParseSCDef() {
if (lexer_->GetToken()->type() != Token::ID) {
throw ParseException(lexer_->GetToken(), "expected a function name");
}
Token* token = lexer_->GetToken();
lexer_->Advance();
SuperCombinatorDef::Symbol name = token->TokenStr();
SuperCombinatorDef::SymbolList vars;
while (lexer_->GetToken()->type() == Token::ID) {
vars.push_back(lexer_->GetToken()->TokenStr());
lexer_->Advance();
}
Advance(Token::ASSIGN);
Expression* body = ParseExpr();
return new SuperCombinatorDef(token, name, vars, body);
}
