/*
 * symtab.h - header for simple symbol tables
 * CSE 413 au07 assignment 5
 * (to be modified later for compiler project)
 */

#ifndef SYMTAB_H
#define SYMTAB_H

/*----- data definitions ------*/

/* Pointer to a symbol table node */
typedef struct sym* symptr;

/* BST node for a single symbol */
typedef struct sym {
  char * name;       /* name of this symbol (also node key)       */
  symptr left;       /* pointer to left subtree or NULL if empty  */
  symptr right;      /* pointer to right subtree or NULL if empty */
} symbol;

/* Symbol table data structure */
typedef struct {
  symptr root;  /* root of unbalanced binary search tree of symbols, */
                /* or NULL if the tree is empty                      */
} symtab;


/*----- operations ------*/

/* 
 * Initialize new symbol table st (must be called before any use of st).
 * Precondition: Pointer variables inside of st do not refer to 
 * any dynamically allocated data.
 */
void st_init(symtab* st);

/*
 * Add a new symbol with string (key) s to the symbol table st if not
 * already present in st, otherwise do nothing.
 * Return a pointer to the new symbol's node if it was added to the tree,
 * or return NULL if the tree was not changed.
 */
symptr st_add(char* s, symtab* st);

/*
 * Return a pointer to the node containing symbol s if present in st,
 * otherwise return NULL.
 */
symptr st_find(char* s, symtab* st);

/*
 * Set st to empty and delete any dynamic data previously allocated to it.
 */
void st_delete(symtab* st);

#endif