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#include "cps/Parser.h"
using namespace cps;
int Parser::getNextToken() {
return CurTok = Lex.gettok();
}
std::unique_ptr<ExprAST> Parser::ParseNumberExpr() {
auto Result = std::make_unique<NumberExprAST>(Lex.NumVal);
getNextToken();
return Result;
}
std::unique_ptr<ExprAST> Parser::ParseIdentifierExpr() {
std::string IdName = Lex.IdentifierStr;
getNextToken();
return std::make_unique<VariableExprAST>(IdName);
}
std::unique_ptr<ExprAST> Parser::ParseExpression() {
if (CurTok == tok_number)
return ParseNumberExpr();
if (CurTok == tok_identifier)
return ParseIdentifierExpr();
return nullptr;
}
std::vector<std::unique_ptr<StmtAST>> Parser::Parse() {
std::vector<std::unique_ptr<StmtAST>> Statements;
while (CurTok != tok_eof) {
if (CurTok == tok_declare) {
// DECLARE <id> : INTEGER
getNextToken(); // eat DECLARE
if (CurTok != tok_identifier) break; // Error
std::string Name = Lex.IdentifierStr;
getNextToken(); // eat Name
if (CurTok != tok_colon) break; // Error: expected ':'
getNextToken(); // eat ':'
if (CurTok != tok_integer_kw) break; // Error: expected INTEGER
getNextToken(); // eat INTEGER
Statements.push_back(std::make_unique<DeclareStmtAST>(Name));
}
else if (CurTok == tok_identifier) {
// <id> <- <expr>
std::string Name = Lex.IdentifierStr;
getNextToken(); // eat Name
if (CurTok != tok_assign) break; // Error: expected '<-'
getNextToken(); // eat '<-'
auto Expr = ParseExpression();
Statements.push_back(std::make_unique<AssignStmtAST>(Name, std::move(Expr)));
}
else if (CurTok == tok_input) {
// INPUT <id>
getNextToken(); // eat INPUT
if (CurTok != tok_identifier) break;
Statements.push_back(std::make_unique<InputStmtAST>(Lex.IdentifierStr));
getNextToken();
}
else if (CurTok == tok_output) {
// OUTPUT <expr>
getNextToken(); // eat OUTPUT
auto Expr = ParseExpression();
Statements.push_back(std::make_unique<OutputStmtAST>(std::move(Expr)));
}
else {
getNextToken(); // Skip unknown
}
}
return Statements;
}
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