bc_interpreter.h

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#include "../../include/rdesc.h"
#include "../../src/detail.h"
 
#include "../grammar/bc.h"
 
#include <string.h>
#include <stdlib.h>
 
 
#ifndef BC_INTERPRETER_H
#define BC_INTERPRETER_H
 
 
static inline double bc_pow10(int i)
{
    double r = 1;
 
    while (i--)
        r *= 10;
 
    return r;
}
 
static inline double bc_interpreter(struct rdesc_node *n)
{
    size_t v = n->n.nt.variant; /* variant */
    struct rdesc_node **c = n->n.nt.children; /* children */
 
    switch (n->n.nt.id) {
    case NT_UNSIGNED:
        switch (v) {
        case 0:
            return strtod(c[0]->n.tk.seminfo, NULL);
        case 1:
            return strtod(c[1]->n.tk.seminfo, NULL) /\
                bc_pow10(strlen(c[1]->n.tk.seminfo));
        default:
            return strtod(c[0]->n.tk.seminfo, NULL) + \
                strtod(c[2]->n.tk.seminfo, NULL) / \
                bc_pow10(strlen(c[2]->n.tk.seminfo));
        }
 
    case NT_OPTSIGN:
        return (v == 0) ? -1 : 1;
 
    case NT_SIGNED:
        return bc_interpreter(c[0]) * bc_interpreter(c[1]);
 
    case NT_EXPR:
        return bc_interpreter(c[0]) + bc_interpreter(c[1]);
 
    case NT_EXPR_REST:
        switch (v) {
        case 0:
            return bc_interpreter(c[1]);
        case 1:
            return -bc_interpreter(c[1]);
        default:
            return 0;
        }
 
    case NT_TERM:
        return bc_interpreter(c[0]) * bc_interpreter(c[1]);
 
    case NT_TERM_REST:
        switch (v) {
        case 0:
            return bc_interpreter(c[1]);
        case 1:
            return 1 / bc_interpreter(c[1]);
        default:
            return 1;
        }
 
    case NT_FACTOR:
        switch (v) {
        case 0:
            return bc_interpreter(c[0]);
        default:
            return bc_interpreter(c[1]);
        }
 
    case NT_STMT:
        return bc_interpreter(c[0]);
    }
 
    unreachable(); // GCOV_EXCL_LINE
}
 
static inline void bc_tk_destroyer(struct rdesc_token *tk)
{
    if (tk->seminfo)
        free(tk->seminfo);
}
 
 
#endif