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);
}
public static LinkedListNode <Lexeme> TryParse(LinkedListNode <Lexeme> lexemes, out WhileLoop resultNode)
{
resultNode = null;
if (lexemes.Value.Type != LT.KW_IF)
{
return(lexemes);
}
var nextLexeme = lexemes.Next;
if (nextLexeme.Value.Type != LT.OP_PAREN_O)
{
throw new Exception($"Missing if condition at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
Lexeme token = nextLexeme.Value;
nextLexeme = BinaryExpr.TryParseExpr(nextLexeme, out Expr expr);
if (expr == null)
{
throw new Exception($"Cannot parse if condition at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
if (nextLexeme.Value.Type != LT.OP_PAREN_C)
{
throw new Exception($"Missing closing parenthesis for if condition at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
nextLexeme = nextLexeme.Next;
Stmt stmt;
List <Stmt> stmts = new List <Stmt>();
if (nextLexeme.Value.Type == LT.OP_BRACE_O)
{
// block body
nextLexeme = nextLexeme.Next;
nextLexeme = Stmt.TryParse(nextLexeme, out stmt);
while (stmt != null)
{
stmts.Add(stmt);
nextLexeme = Stmt.TryParse(nextLexeme, out stmt);
}
if (nextLexeme.Value.Type != LT.OP_BRACE_C)
{
throw new Exception($"Missing closing bracket for while 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($"Missing while loop body at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
stmts.Add(stmt);
}
resultNode = new WhileLoop {
Condition = expr, Body = new BlockBody(stmts), Token = token
};
return(nextLexeme);
}
public static LinkedListNode <Lexeme> TryParse(LinkedListNode <Lexeme> lexemes, out IfStmt resultNode)
{
resultNode = null;
if (lexemes.Value.Type != LT.KW_IF)
{
return(lexemes);
}
var nextLexeme = lexemes.Next;
if (nextLexeme.Value.Type != LT.OP_PAREN_O)
{
throw new Exception($"Missing if condition at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
nextLexeme = BinaryExpr.TryParseExpr(nextLexeme.Next, out Expr expr);
if (expr == null)
{
throw new Exception($"Cannot parse if condition at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
if (nextLexeme.Value.Type != LT.OP_PAREN_C)
{
throw new Exception($"Missing closing parenthesis for if condition at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
nextLexeme = nextLexeme.Next;
Stmt stmt;
List <Stmt> stmts = new List <Stmt>();
bool elseAllowed = true;
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($"Missing closing bracket for if body at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
nextLexeme = nextLexeme.Next;
}
else
{
// single statement body
nextLexeme = Stmt.TryParse(nextLexeme, out stmt);
if (stmt == null)
{
throw new Exception($"Missing if body at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
stmts.Add(stmt);
if (stmt is IfStmt)
{
elseAllowed = false;
}
}
if (elseAllowed)
{
if (nextLexeme.Value.Type == LT.KW_ELSE)
{
List <Stmt> elseStmts = new List <Stmt>();
nextLexeme = nextLexeme.Next;
if (nextLexeme.Value.Type == LT.OP_BRACE_O)
{
// block body
nextLexeme = nextLexeme.Next;
nextLexeme = Stmt.TryParse(nextLexeme, out stmt);
while (stmt != null)
{
elseStmts.Add(stmt);
nextLexeme = Stmt.TryParse(nextLexeme, out stmt);
}
if (nextLexeme.Value.Type != LT.OP_BRACE_C)
{
throw new Exception($"Missing closing bracket for else body at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
nextLexeme = nextLexeme.Next;
}
else
{
// single statement body
nextLexeme = Stmt.TryParse(nextLexeme, out stmt);
if (stmt == null)
{
throw new Exception($"Missing else body at {nextLexeme.Value.File}:{nextLexeme.Value.Line}");
}
elseStmts.Add(stmt);
}
resultNode = new IfStmt {
Condition = expr, Body = new BlockBody(stmts), ElseBody = new BlockBody(elseStmts), Token = lexemes.Value
};
return(nextLexeme);
}
}
resultNode = new IfStmt {
Condition = expr, Body = new BlockBody(stmts), ElseBody = null, Token = lexemes.Value
};
return(nextLexeme);
}
