Compilers: Principles and Practice

12.5 Symbol Table

The Symbol Table is the most important data structure initiated by the Scanner and used throughout the compilation operations. There are various ways in which a Symbol Table can be built. In case of miniC compiler, we decided to use a Binary Search Tree (BST) as Symbol Table. In general, we do not need to delete an entry in a Symbol Table and that fact fits well with the characteristics of a BST. Each node in the Symbol Table tree has the structure:

typedef union{
  struct node_struct*N;
  char *S;
  long I;
  float F;
  void *P;
}util;
typedef struct node_struct{
struct node_struct *link[2]; // left = 0, right = 1
util u,v,w,x,y,z;
}Node;
typedef Node Symbol;

Further, the following definitions provide shortcuts to access various fields ...