Value IdentExpr::Evaluate(SymbolTable* scope, EvalContext& context, bool asbool)
{
/// Scope override; must do this for every expression that might contain an identifier
if(this->scope != NULL)
scope = this->scope;
//context.file = this->file;
//context.line = this->linenumber;
// To evaluate an identifier expression:
// First, we have to look up the symbol and check the type of its value.
// If it's a constant, we just evaluate the constant (provided there are no
// parameters given; if there are parameters, we should report an error.)
// If it's a command, we need to:
// - bind each argument expression to the corresponding symbol in the commands
// parameter list.
// - invoke the command.
Module* module = context.module;
SymbolTable* lookupScope = scope;
// If the ident expr's "file" field is not empty, we'll look it up in a different module
if(!file.empty()) {
Module* mod = module->GetSiblingContext(file);
if(!mod) {
Error("reference to nonexistent module '" + file + "'");
return Value::Null;
}
lookupScope = mod->GetRootTable();
}
Value found = lookupScope->Lookup(name);
if(found != Value::Undefined) {
// In most cases, we just return the value.
if(found.GetType() != Type::Macro)
{
// However, evaluated vars are not importable.
if(lookupScope != scope) {
Error("cannot access local variable declaration '" + name + "' in module '" + file + "'");
return Value::Null;
}
return found;
}
Node* node = found.GetNode();
Value result;
if(node->GetType() == conststmt)
{
if(hasparens) {
Error("'" + GetFullName() + "' refers to a constant; cannot use parentheses");
return Value();
}
result = dynamic_cast<ConstDef*>(node)->EvaluateExpr(scope, context, asbool);
}
else if(node->GetType() == commandstmt)
{
for(unsigned int i = 0; i < args.size(); ++i)
args[i]->scope = scope;
CommandDef* cmd = dynamic_cast<CommandDef*>(found.GetNode());
if(cmd->GetArgCount() != args.size())
Error("incorrect number of parameters to command '" + GetFullName() + "'");
else
result = cmd->Invoke(context, args);
}
else if(node->GetType() == ambiguousid)
{
AmbiguousID* ambig = dynamic_cast<AmbiguousID*>(found.GetNode());
Error(ambig->ToString(""));
result = Value::Null;
}
else if(node->IsExpression())
{
result = dynamic_cast<Expression*>(node)->Evaluate(scope, context, asbool);
}
else
{
Error("invalid type");
}
return result;
}
// Didn't find it in the symbol table, check the jumps table
Anchor* foundanchor = lookupScope->LookupAnchor(name);
if(foundanchor) {
if(hasparens) {
Error("'" + GetFullName() + "' refers to a label; cannot use parentheses");
return Value();
}
String* val = new String();
val->Long(foundanchor->GetTarget());
// The targeted label might not have its address computed yet, so we register a
// reference to the target label (unless refs are forbidden by the context)
if(!context.norefs)
val->AddReference(val->GetPos()-4, foundanchor);
return Value(val);
}
Error("use of undefined identifier '" + GetFullName() + "'");
return Value();
}
