extree.h

#ifndef EXTREE__H
#define EXTREE__H

#include "symbols.h"

typedef struct ex_tree {
    enum ex_type { EX_LIT = 1,
        /* Expression is a literal value */
        EX_SYM = 2,
        /* Expression has a symbol reference */
        EX_UNDEFINED_SYM = 3,
        /* Expression is undefined sym reference */
        EX_TEMP_SYM = 4,
        /* Expression is temp sym reference */

        EX_COM = 5,
        /* One's complement */
        EX_NEG = 6,
        /* Negate */
        EX_ERR = 7,
        /* Expression with an error */

        EX_ADD = 8,
        /* Add */
        EX_SUB = 9,
        /* Subtract */
        EX_MUL = 10,
        /* Multiply */
        EX_DIV = 11,
        /* Divide */
        EX_AND = 12,
        /* bitwise and */
        EX_OR = 13                     /* bitwise or */
    } type;

    char           *cp;         /* points to end of parsed expression */

    union {
        struct {
            struct ex_tree *left,
                           *right;      /* Left, right children */
        } child;
        unsigned        lit;    /* Literal value */
        SYMBOL         *symbol; /* Symbol reference */
    } data;
} EX_TREE;


EX_TREE        *new_ex_tree(
    void);
void            free_tree(
    EX_TREE *tp);

EX_TREE        *new_ex_lit(
    unsigned value);
EX_TREE        *ex_err(
    EX_TREE *tp,
    char *cp);

EX_TREE        *evaluate(
    EX_TREE *tp,
    int undef);


#endif