parse.cpp

   1 #include"parse.h"
   2 using namespace std;
   3
   4 int number_from_pos(string form, int& index)
   5 {
   6     if (index < 0 || index >= form.length())
   7     {
   8         return 0;
   9     }
  10     int res = 0;
  11     while (isdigit(form.at(index)))
  12     {
  13         res *= 10;
  14         res += (form[index] - '0');
  15         if (++index >= form.length())
  16         {
  17             break;
  18         }
  19     }
  20     return res;
  21 }
  22
  23 vector<int> parse_from_pos(string form, vector<element> e, int& index)
  24 {
  25     int i = index;
  26     vector<int> result;
  27     vector<int> tmpres;
  28     result.resize(e.size());
  29     tmpres.resize(e.size());
  30     if (i >= form.size())
  31     {
  32         cerr << "Index greater than size of formula!" << endl;
  33     }
  34     else if (i < 0)
  35     {
  36         cerr << "Index is negative!" << endl;
  37     }
  38     while (i < form.size())
  39     {
  40         char c = form[i];
  41         if (c == '(')
  42         {
  43             i++;
  44             tmpres = parse_from_pos(form, e, i);
  45             // i now points at the first character *AFTER* closing parenthesis
  46             if (i < form.size() && isdigit(form[i]))
  47             {
  48                 int multiply = number_from_pos(form, i);
  49                 mulv(tmpres, multiply);
  50             }
  51         }
  52         else if (c == ')')
  53         {
  54             i++;
  55             break;
  56         }
  57         else if (isalpha(c))
  58         {
  59             string z;
  60             while (i < form.size() && isalpha(c = form[i++]))
  61             {
  62                 z.push_back(c);
  63                 int fi;
  64                 if ((fi = find_symbol(e, z)) != -1)
  65                 {
  66                     bool flag = false;
  67                     flag |= (i >= form.size());
  68                     if (i < form.size())
  69                     {
  70                         flag |= !islower(form[i]);
  71                     }
  72                     if (flag)
  73                     {
  74                         tmpres[fi]++;
  75                         break;
  76                     }
  77                 }
  78             }
  79             if (isdigit(form[i]))
  80             {
  81                 int multiply = number_from_pos(form, i);
  82                 mulv(tmpres, multiply);
  83             }
  84         }
  85         addv(result, tmpres);
  86         tmpres.clear();
  87         tmpres.resize(e.size());
  88     }
  89     index = i;
  90     return result;
  91 }
  92
  93 void parse(string form, vector<element> e, vector<int>& result)
  94 {
  95     int _i = 0;
  96     result = parse_from_pos(form, e, _i);
  97     if (_i != form.length())
  98     {
  99         cerr << "Final index is NOT the length of formula string." << endl;
 100     }
 101     return;
 102 }