public Binder(DiagnosticsReport diagnostics, SymbolTable symbols)
: base(diagnostics, symbols)
{
exprBinder = new ExpressionBinder(Symbols, Diagnostics);
}
internal static Expression BindVariables(Expression e)
{
ExpressionBinder eb = new ExpressionBinder();
return(eb.Visit(e));
}
private void ResolveConstants()
{
var exprBinder = new ExpressionBinder(Symbols, new DiagnosticsReport(Diagnostics.FilePath));
while (constantsToResolve.Count > 0)
{
var c = constantsToResolve.Dequeue();
if (!IsExprConstant(c.Constant, c.Initializer))
{
continue;
}
var constantInitializer = exprBinder.Visit(c.Initializer) !;
if (constantInitializer.IsInvalid)
{
constantsToResolve.Enqueue(c); // try again
}
else
{
var numUnresolved = CountUnresolvedDependencies(constantInitializer);
if (numUnresolved == 0)
{
// reduce the initializer to a literal
c.Constant.Initializer = ((BasicType)constantInitializer.Type !).TypeCode switch
{
BasicTypeCode.Bool => new BoundBoolLiteralExpression(Evaluator.Evaluate(constantInitializer)[0].AsUInt64 == 1),
BasicTypeCode.Int => new BoundIntLiteralExpression(Evaluator.Evaluate(constantInitializer)[0].AsInt32),
BasicTypeCode.Float => new BoundFloatLiteralExpression(Evaluator.Evaluate(constantInitializer)[0].AsFloat),
BasicTypeCode.String => constantInitializer, // if it is a STRING it should already be a literal
_ => throw new System.InvalidOperationException(),
};
}
else
{
if (numUnresolved < c.NumUnresolved)
{
constantsToResolve.Enqueue((c.Constant, c.Initializer, numUnresolved)); // try again
}
else
{
Diagnostics.AddError($"The constant '{c.Constant.Name}' involves a circular definition", c.Initializer.Source);
}
}
}
}
bool IsExprConstant(VariableSymbol targetConstant, Expression expr)
{
if (expr is IdentifierExpression idExpr)
{
switch (Symbols.Lookup(idExpr.Identifier))
{
case VariableSymbol v when !v.IsConstant:
Diagnostics.AddError($"The expression assigned to '{targetConstant.Name}' must be constant. The variable '{idExpr.Identifier}' is not constant", idExpr.Source);
return(false);
case null:
Diagnostics.AddError($"Unknown symbol '{idExpr.Identifier}'", idExpr.Source);
return(false);
}
}
return(expr.Children.Where(c => c is Expression).All(e => IsExprConstant(targetConstant, (Expression)e)));
}
