public static LinkedListNode <Lexeme> TryParseStruct(LinkedListNode <Lexeme> lexemes, out Stmt resultNode) { resultNode = null; var nextLexeme = DeclStmt.TryParse(lexemes, out var decl); if (decl != null) { resultNode = decl; return(nextLexeme); } return(lexemes); }
public static LinkedListNode <Lexeme> TryParse(LinkedListNode <Lexeme> lexemes, out ForLoop resultNode) { resultNode = null; if (lexemes.Value.Type != LT.KW_FOR) { return(lexemes); } var nextLexeme = lexemes.Next; if (nextLexeme.Value.Type != LT.OP_PAREN_O) { throw new Exception($"Missing loop header at {nextLexeme.Value.File}:{nextLexeme.Value.Line}"); } nextLexeme = nextLexeme.Next; nextLexeme = DeclStmt.TryParse(nextLexeme, out DeclStmt ds); if (ds == null || !(ds is DeclAssignStmt init)) { throw new Exception($"Cannot parse loop initializer at {nextLexeme.Value.File}:{nextLexeme.Value.Line}"); } nextLexeme = BinaryExpr.TryParseExpr(nextLexeme, out Expr cond); if (cond == null) { throw new Exception($"Cannot parse loop condition at {nextLexeme.Value.File}:{nextLexeme.Value.Line}"); } if (nextLexeme.Value.Type != LT.OP_SC) { throw new Exception($"Missing semicolon after loop condition at {nextLexeme.Value.File}:{nextLexeme.Value.Line}"); } nextLexeme = nextLexeme.Next; nextLexeme = AssignStmt.TryParse(nextLexeme, out AssignStmt upd, false); if (upd == null) { throw new Exception($"Cannot parse loop afterthought at {nextLexeme.Value.File}:{nextLexeme.Value.Line}"); } if (nextLexeme.Value.Type != LT.OP_PAREN_C) { throw new Exception($"Missing closing parenthesis for loop header at {nextLexeme.Value.File}:{nextLexeme.Value.Line}"); } nextLexeme = nextLexeme.Next; Stmt stmt; List <Stmt> stmts = new List <Stmt>(); if (nextLexeme.Value.Type == LT.OP_BRACE_O) { // block body nextLexeme = nextLexeme.Next; nextLexeme = Stmt.TryParse(nextLexeme, out stmt); while (stmt != null) { stmts.Add(stmt); nextLexeme = Stmt.TryParse(nextLexeme, out stmt); } if (nextLexeme.Value.Type != LT.OP_BRACE_C) { throw new Exception($"Missing closing bracket for loop body at {nextLexeme.Value.File}:{nextLexeme.Value.Line}"); } nextLexeme = nextLexeme.Next; } else { // single statement body nextLexeme = Stmt.TryParse(nextLexeme, out stmt); if (stmt == null) { throw new Exception($"Missing loop body at {nextLexeme.Value.File}:{nextLexeme.Value.Line}"); } stmts.Add(stmt); } resultNode = new ForLoop { Init = init, Condition = cond, Update = upd, Body = new BlockBody(stmts) }; return(nextLexeme); }