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/********************************************************
* symbol -- handle the symbol table *
* *
* Functions *
* enter -- put a symbol in a symbol table *
* lookup -- get the data associated with a symbol *
********************************************************/
#include <stdio.h>
#include "symbol.h"
#include <string.h>
#include <stdlib.h>
/********************************************************
* enter -- enter a word into the symbol table *
* *
* Parameters *
* node -- top node of the symbol table for add *
* symbol -- symbol name to add (1 or 2 chars) *
* data -- data associated with the symbol *
********************************************************/
void enter(struct symbol **node_ptr, char *symbol, generic *data)
{
int result; /* result of strcmp */
/* New node that we are creating */
struct symbol *new_node_ptr;
/* see if we have reached the end */
if ((*node_ptr) == NULL) {
new_node_ptr = (struct symbol *) malloc(sizeof(struct symbol));
(void)strcpy(new_node_ptr->name, symbol);
new_node_ptr->data = data;
new_node_ptr->left_ptr = NULL;
new_node_ptr->right_ptr = NULL;
*node_ptr = new_node_ptr;
return;
}
/*
* Need to sub-divide the symbol table and try again
*/
result = strcmp((*node_ptr)->name, symbol);
if (result == 0)
return;
if (result > 0)
enter(&(*node_ptr)->left_ptr, symbol, data);
else
enter(&(*node_ptr)->right_ptr, symbol, data);
}
/********************************************************
* lookup -- lookup a symbol in a table *
* *
* Parameters *
* root -- root of the symbol table to search *
* name -- name to lookup. *
* *
* Returns *
* Pointer to the data or NULL if not found. *
********************************************************/
generic *lookup(struct symbol *root_ptr, char *name)
{
int result; /* Result of string compare */
if (root_ptr == NULL)
return (NULL);
result = strcmp(root_ptr->name, name);
if (result == 0) {
return (root_ptr->data);
}
if (result > 0)
return (lookup(root_ptr->left_ptr, name));
else
return (lookup(root_ptr->right_ptr, name));
}
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