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#include "cps/Parser.h"
#include "cps/FunctionAST.h"
#include <cstdio>
using namespace cps;
// Array-parameter bounds live in the signature, not the AST, so they must be
// integer literals (an optional leading '-' is allowed).
bool Parser::ParseSignedIntBound(int64_t &Out) {
bool Negative = false;
if (CurTok == '-') {
Negative = true;
getNextToken();
}
if (CurTok != tok_number_int) {
fprintf(stderr, "Error: Array parameter bounds must be integer literals at line %d\n",
Lex.getLine());
return false;
}
Out = Negative ? -Lex.NumVal : Lex.NumVal;
getNextToken();
return true;
}
// ( [BYREF|BYVAL] <name> : <type>
// | <name> : ARRAY OF <type> -- rank 1, bounds from the argument
// | <name> : ARRAY[<int>:<int>,...] OF <type> , ... )
// The pass mode is sticky across parameters (guide §8.3: "the BYVAL or BYREF
// keyword need not be repeated"); unannotated parameters default to BYVAL
// (§8.1). BYREF is procedure-only (§8.3), gated by AllowByRef.
std::optional<std::vector<ParamDecl>> Parser::ParsePrototypeArgs(bool AllowByRef) {
std::vector<ParamDecl> Params;
if (CurTok != '(') return Params;
getNextToken();
PassMode Current = PassMode::ByVal;
while (CurTok != ')') {
if (CurTok == tok_byref) {
if (!AllowByRef) {
fprintf(stderr, "Error: BYREF parameters are not allowed in a FUNCTION (procedures only) at line %d\n",
Lex.getLine());
return std::nullopt;
}
Current = PassMode::ByRef;
getNextToken();
} else if (CurTok == tok_byval) {
Current = PassMode::ByVal;
getNextToken();
}
if (CurTok != tok_identifier) {
fprintf(stderr, "Error: Expected argument name at line %d\n", Lex.getLine());
return std::nullopt;
}
ParamDecl P;
P.Name = Lex.IdentifierStr;
P.Mode = Current;
getNextToken();
if (CurTok != tok_colon) {
fprintf(stderr, "Error: Expected ':' after argument name at line %d\n", Lex.getLine());
return std::nullopt;
}
getNextToken();
if (CurTok == tok_array) {
getNextToken();
P.IsArray = true;
if (CurTok == '[') {
getNextToken();
while (true) {
int64_t Lo = 0, Hi = 0;
if (!ParseSignedIntBound(Lo)) return std::nullopt;
if (CurTok != tok_colon) {
fprintf(stderr, "Error: Expected ':' between array parameter bounds at line %d\n",
Lex.getLine());
return std::nullopt;
}
getNextToken();
if (!ParseSignedIntBound(Hi)) return std::nullopt;
P.DeclaredBounds.emplace_back(Lo, Hi);
if (CurTok == ']') break;
if (CurTok != ',') {
fprintf(stderr, "Error: Expected ',' or ']' in array parameter bounds at line %d\n",
Lex.getLine());
return std::nullopt;
}
getNextToken();
}
getNextToken(); // eat ']'
P.Rank = static_cast<int>(P.DeclaredBounds.size());
} else {
P.Rank = 1; // ARRAY OF T: bounds travel with the argument
}
if (CurTok != tok_of) {
fprintf(stderr, "Error: Expected OF after ARRAY in parameter '%s' at line %d\n",
P.Name.c_str(), Lex.getLine());
return std::nullopt;
}
getNextToken();
}
P.TypeName = ParseTypeName(false);
if (P.TypeName.empty()) {
fprintf(stderr, "Error: Expected argument type for '%s'\n", P.Name.c_str());
return std::nullopt;
}
for (const ParamDecl &Prev : Params) {
if (Prev.Name == P.Name) {
fprintf(stderr, "Error: Duplicate parameter name '%s' at line %d\n",
P.Name.c_str(), Lex.getLine());
return std::nullopt;
}
}
Params.push_back(std::move(P));
if (CurTok == ')') break;
if (CurTok != ',') {
fprintf(stderr, "Error: Expected ',' or ')'\n");
return std::nullopt;
}
getNextToken();
if (CurTok == ')') {
fprintf(stderr, "Error: Expected another parameter after ',' at line %d\n", Lex.getLine());
return std::nullopt;
}
}
getNextToken();
return Params;
}
std::unique_ptr<StmtAST> Parser::ParseFunction() {
getNextToken();
if (CurTok != tok_identifier) {
fprintf(stderr, "Error: Expected function name\n");
return nullptr;
}
std::string Name = Lex.IdentifierStr;
getNextToken();
auto Args = ParsePrototypeArgs(/*AllowByRef=*/false);
if (!Args) return nullptr;
std::string RetType = "INTEGER";
if (CurTok == tok_returns) {
getNextToken();
if (CurTok == tok_array) {
fprintf(stderr, "Error: A FUNCTION cannot RETURN an array; use a BYREF PROCEDURE parameter instead at line %d\n",
Lex.getLine());
return nullptr;
}
RetType = ParseTypeName(true);
if (RetType.empty()) {
fprintf(stderr, "Error: Expected return type for function '%s'\n", Name.c_str());
return nullptr;
}
}
auto Proto = std::make_unique<PrototypeAST>(Name, std::move(*Args), RetType);
std::vector<std::unique_ptr<StmtAST>> Body = ParseBlock({tok_endfunction});
if (CurTok != tok_endfunction) {
fprintf(stderr, "Error: expected ENDFUNCTION\n");
return nullptr;
}
getNextToken();
return std::make_unique<FunctionDefAST>(std::move(Proto), std::move(Body));
}
std::unique_ptr<StmtAST> Parser::ParseProcedure() {
getNextToken();
if (CurTok != tok_identifier) {
fprintf(stderr, "Error: Expected procedure name\n");
return nullptr;
}
std::string Name = Lex.IdentifierStr;
getNextToken();
auto Args = ParsePrototypeArgs(/*AllowByRef=*/true);
if (!Args) return nullptr;
auto Proto = std::make_unique<PrototypeAST>(Name, std::move(*Args), "VOID");
std::vector<std::unique_ptr<StmtAST>> Body = ParseBlock({tok_endprocedure});
if (CurTok != tok_endprocedure) {
fprintf(stderr, "Error: expected ENDPROCEDURE\n");
return nullptr;
}
getNextToken();
return std::make_unique<FunctionDefAST>(std::move(Proto), std::move(Body));
}
std::unique_ptr<StmtAST> Parser::ParseCallStmt() {
int Line = Lex.getLine();
getNextToken();
if (CurTok != tok_identifier) {
fprintf(stderr, "Error: Expected callee name after CALL\n");
return nullptr;
}
std::string Callee = Lex.IdentifierStr;
getNextToken();
std::vector<std::unique_ptr<ExprAST>> Args;
if (CurTok == '(') {
getNextToken();
auto Parsed = ParseExprList(')', true);
if (!Parsed) return nullptr;
Args = std::move(*Parsed);
}
return std::make_unique<CallStmtAST>(Callee, std::move(Args), Line);
}
std::unique_ptr<StmtAST> Parser::ParseReturnStmt() {
getNextToken();
std::unique_ptr<ExprAST> Expr = nullptr;
// A bare RETURN is recognized right before any block terminator.
if (CurTok != tok_endif && CurTok != tok_else && CurTok != tok_endfunction &&
CurTok != tok_endprocedure && CurTok != tok_endwhile && CurTok != tok_until &&
CurTok != tok_next && CurTok != tok_eof) {
Expr = ParseExpression();
if (!Expr) return nullptr;
}
return std::make_unique<ReturnStmtAST>(std::move(Expr));
}
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