I'm having trouble with inserting into my expression tree. My Expression tree is made up of Expression nodes. These Expression nodes contain either an enum, Operation, or a string. Each Expression node also having a leftArgument/rightArgument pointers to Expressions (leftNode address and rightNode address).
Of course, my addNode function is clearly not implemented fully, however I expect this code to insert (5) Expression nodes, and each being inserted to the left, creating a very left-heavy tree.
However, it seems to only be rewriting the Expression node in the second level of my tree when executing. There is something wrong with my pointers/addresses within my main() or addNode() function and after hours, I can't seem to figure it out.
Any hints or observations would be greatly appreciated! Thank you so much.
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#include "expressions.h"
typedef enum Operation {
FIRST = 1,
REST = 2,
CONS = 3,
} Operation;
union Data {
Operation operation;
char *string;
};
struct Expression {
Data data;
Expression *leftArgument;
Expression *rightArgument;
};
char* eval(Expression e) {
return "0";
}
Expression *addNode(Expression *e, Expression *tree) {
if (tree == NULL) {
tree = malloc(sizeof(Expression));
tree->data = e->data;
tree->leftArgument = NULL;
tree->rightArgument = NULL;
printf("added new node\n");
} else if (tree->data.operation == FIRST || tree->data.operation == REST) {
printf("%d\n", tree->data.operation);
addNode(e, tree->leftArgument);
}
return tree;
}
int main() {
Expression *tree = NULL;
printf("----------[INSERT]-----------\n");
Expression e1;
e1.data.operation = FIRST;
tree = addNode(&e1, tree);
printf("-----------------------------\n\n");
printf("----------[INSERT]-----------\n");
Expression e2;
e2.data.operation = REST;
tree = addNode(&e2, tree);
printf("-----------------------------\n\n");
printf("----------[INSERT]-----------\n");
Expression e3;
e3.data.operation = FIRST;
tree = addNode(&e3, tree);
printf("-----------------------------\n\n");
printf("----------[INSERT]-----------\n");
Expression e4;
e4.data.operation = REST;
tree = addNode(&e4, tree);
printf("-----------------------------\n\n");
}
