Information Dictionary Issues

The information dictionary class extended the base dictionary class by adding a vector for additional information and was implemented as a class template (see post from October 6).  The additional information in the constant string dictionary contained a pointer to a string instance (see post from October 6).

The memory leak in the constant string dictionary was caused by how the information dictionary template and constant string information classes were implemented.  The problem occurred when a string in an entry of the information vector was replaced with the same string.  A new information instance was created with a new string pointer, which was put into the information vector, and the old string instance was lost (a memory leak).

When an old program line was dereferenced after the new replacement line was encoded, a string being replaced by the same string had its reference incremented in the dictionary from one to two by the encode, then the dereference decremented the count back to one.  However, when the dereference was moved to after the encode, the reference count of the string went from one to zero and the dictionary entry was freed, but not the entry in the information vector.  When the new line was encoded, a new string instance was created overwriting the old string instance pointer.

While this problem was not difficult to correct, another issue was discovered, this time with the constant number dictionary where its additional information consisted of a double value and an integer value contained in a structure (see post from October 6).  Each double value was aligned on a double boundary (eight bytes) and because an integer is half of a double (four bytes), four bytes of padding is inserted by the compiler between each element in the vector (wasted memory).

The only way to correct this is to separate the two sets of values by having a double value vector and an integer value vector.  Unfortunately, the information dictionary template class only allows for a single information vector.  A new design is needed for information dictionaries.