/// <summary>
/// variable_access : variable
/// | procedure_call
/// | member_access
///
/// member_access : variable_access DOT variable_access
///
/// procedure_call : identifier params
///
/// params : LPAREN actual_param_list RPAREN
///
/// actual_param_list : actual_param_list COMMA param
/// | empty
///
/// param : statement
///
/// variable : identifier
/// </summary>
private IdentifierAstNode ParseVariableAccess(IdentifierAstNode parentNode = null)
{
IdentifierAstNode node;
var token = CurrentToken;
Eat(TokenType.IDENTIFIER);
EatWhiteSpace();
if (CurrentToken.Type != TokenType.LPAREN)
{
node = new IdentifierVariableAccessAstNode(token);
}
else
{
node = ParseProcedureCall(token);
EatWhiteSpace();
}
if (CurrentToken.Type == TokenType.DOT)
{
Eat(TokenType.DOT);
EatWhiteSpace();
node = ParseVariableAccess(node);
}
if (parentNode != null)
{
parentNode.MemberIdentifier = node;
}
return(parentNode ?? node);
}
public void Visit(IdentifierAstNode visitable)
{
if (!_context.HasVariable(visitable.Name))
{
throw new UndefinedVariableException(visitable.Name);
}
_exprType = _context.GetVariableType(visitable.Name);
}
/// <summary>
/// each_loop : each variable in variable QM statement
///
/// TODO: The lexer should return reserved keywords as tokens
/// </summary>
/// <returns></returns>
private AstNode ParseEachLoop()
{
if (CurrentToken.Type != TokenType.IDENTIFIER && CurrentToken.Value != "each")
{
throw new Exception($"Invalid token, expected 'each' keyword at position {CurrentToken.Position}");
}
var eachToken = CurrentToken;
Eat(TokenType.IDENTIFIER);
EatWhiteSpace();
// Extract variable name
var loopVariable = new IdentifierAstNode(CurrentToken);
Eat(TokenType.IDENTIFIER);
EatWhiteSpace();
// 'in' keyword
if (CurrentToken.Type != TokenType.IDENTIFIER && CurrentToken.Value == "in")
{
throw new Exception($"Invalid token, expect 'in' keyword at position {CurrentToken.Position}");
}
Eat(TokenType.IDENTIFIER);
EatWhiteSpace();
var enumerable = new IdentifierAstNode(CurrentToken);
Eat(TokenType.IDENTIFIER);
EatWhiteSpace();
Eat(TokenType.QM);
EatWhiteSpace();
var loopBody = ParseStatement();
return(new EachLoopAstNode(eachToken, loopVariable, enumerable, loopBody));
}
public abstract void VisitIdentifier(IdentifierAstNode node);
public virtual object Visit(IdentifierAstNode node)
{
return(null);
}
public void TestIdentifier(IdentifierAstNode expect, IdentifierAstNode actual,
string traceMessage)
{
Assert.IsNotNull(actual, traceMessage);
Assert.AreEqual(expect, actual, traceMessage);
}
public void Visit(IdentifierAstNode visitable)
{
}
public override void VisitIdentifier(IdentifierAstNode node)
{
}
