static double eval_fn(MSymbol* sym)
{
double args[4];
unsigned narg = 0;
if (!follows(MT_KET))
{
while (narg < 4)
{
MItem* exp = expression();
if (exp->n >= 0) serror("invalid use of list.");
args[narg++] = exp->val;
if (follows(MT_KET)) break;
if (!follows(MT_COMMA)) serror("',' expected.");
next_token();
}
}
next_token();
if (narg < (unsigned long) sym->data) serror("too few arguments to '%s'.", sym->name);
if (narg > (unsigned long) sym->data) serror("too many arguments to '%s'.", sym->name);
if (narg == 1)
return ((double (*)(double)) sym->built_in)(args[0]);
else if (narg == 2)
return ((double (*)(double, double)) sym->built_in)(args[0], args[1]);
error("Internal error.");
}
static double term()
{
double result = power();
while (follows(MT_STAR) || follows(MT_SLASH))
{
if (follows(MT_STAR)) { next_token(); result *= power(); }
else { next_token(); result /= power(); }
}
return result;
}
static double factor()
{
if (follows(MT_BRA))
{
next_token();
MItem* it = expression();
if (it->n >= 0)
serror("invalid use of list.");
if (!follows(MT_KET))
serror("')' expected.");
next_token();
return it->val;
}
else if (follows(MT_NUMBER))
{
double val = token->value;
next_token();
return val;
}
else if (follows(MT_IDENT))
{
MSymbol* sym = peek_symbol(token->text);
if (sym == NULL)
serror("unknown identifier '%s'.", token->text);
next_token();
if (follows(MT_BRA))
{
if (sym->built_in == NULL)
serror("unknown function '%s'.", sym->name);
next_token();
return eval_fn(sym);
}
else
{
if (sym->built_in != NULL)
serror("invalid use of function.");
if (sym->data->n >= 0)
serror("invalid use of list.");
return sym->data->val;
}
}
else {
serror("syntax error: '%s'", token->text);
return 0.0;
}
}
static void assignment(bool debug)
{
if (!follows(MT_IDENT)) serror("identifier expected.");
MSymbol* sym = get_symbol(token->text);
next_token();
if (!follows(MT_EQUAL)) serror("'=' expected.");
next_token();
sym->data = item();
// semicolon is optional
if (follows(MT_SEMICOL)) next_token();
// print numerical temporary variables
if (debug)
if (sym->data->n < 0)
info("%s = %.18g", sym->name, sym->data->val);
}
static double power()
{
double base = factor();
if (follows(MT_POWER))
{
next_token();
return pow(base, factor());
}
return base;
}
static void list(MItem* parent)
{
parent->list = NULL;
parent->n = 0;
if (follows(MT_END)) { next_token(); return; }
parent->list = item();
parent->n++;
MItem* it = parent->list;
while (follows(MT_COMMA))
{
next_token();
it->next = item();
parent->n++;
it = it->next;
};
if (!follows(MT_END)) serror("'}' expected.");
next_token();
}
static MItem* item()
{
if (follows(MT_BEGIN))
{
next_token();
MItem* it = new_item();
list(it);
return it;
}
else
return expression();
}
static void list(MItem* parent)
{
parent->list = NULL;
parent->n = 0;
if (follows(MT_END)) { next_token(); return; }
parent->list = item();
parent->n++;
MItem* it = parent->list;
while (follows(MT_COMMA))
{
next_token();
it->next = item();
parent->n++;
it = it->next;
};
if (follows(MT_SEMICOL))
{
bool one_word_processed = false;
while(!follows(MT_END))
{
next_token();
if(follows(MT_END))
break;
if(one_word_processed++)
parent->marker->append(" ");
it->next = item_string_marker();
if(token->type == MT_NUMBER) {
std::ostringstream sin;
sin << token->value;
parent->marker->append(sin.str());
}
else
parent->marker->append(token->text);
it = it->next;
}
}
if (!follows(MT_END)) serror("'}' expected.");
next_token();
}
void mesh_parser_run(bool debug)
{
next_token();
while (!follows(MT_EOF))
assignment(debug);
}
static MItem* expression()
{
// special case: expression is a list reference
if (follows(MT_IDENT))
{
MSymbol* list = peek_symbol(token->text);
if (list != NULL && list->built_in == NULL &&
list->data != NULL && list->data->n >= 0)
{
next_token();
// only "=", "}", ";" or "," must follow
if (!follows(MT_EQUAL) && !follows(MT_END) &&
!follows(MT_COMMA) && !follows(MT_SEMICOL))
serror("invalid use of list.");
return list->data;
}
}
// handle unary + and -
double unary = 1.0;
if (follows(MT_PLUS) || follows(MT_MINUS))
{
if (follows(MT_MINUS)) unary = -1.0;
next_token();
}
double result = unary * term();
while (follows(MT_PLUS) || follows(MT_MINUS))
{
if (follows(MT_PLUS)) { next_token(); result += term(); }
else { next_token(); result -= term(); }
}
MItem* it = new_item();
it->n = -1;
it->val = result;
return it;
}