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qnum.h (1985B)

      1 /*
      2  * QNum Module
      3  *
      4  * Copyright (C) 2009 Red Hat Inc.
      5  *
      6  * Authors:
      7  *  Luiz Capitulino <lcapitulino@redhat.com>
      8  *  Anthony Liguori <aliguori@us.ibm.com>
      9  *  Marc-André Lureau <marcandre.lureau@redhat.com>
     10  *
     11  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
     12  * See the COPYING.LIB file in the top-level directory.
     13  */
     14 
     15 #ifndef QNUM_H
     16 #define QNUM_H
     17 
     18 #include "qapi/qmp/qobject.h"
     19 
     20 typedef enum {
     21     QNUM_I64,
     22     QNUM_U64,
     23     QNUM_DOUBLE
     24 } QNumKind;
     25 
     26 /*
     27  * QNum encapsulates how our dialect of JSON fills in the blanks left
     28  * by the JSON specification (RFC 8259) regarding numbers.
     29  *
     30  * Conceptually, we treat number as an abstract type with three
     31  * concrete subtypes: floating-point, signed integer, unsigned
     32  * integer.  QNum implements this as a discriminated union of double,
     33  * int64_t, uint64_t.
     34  *
     35  * The JSON parser picks the subtype as follows.  If the number has a
     36  * decimal point or an exponent, it is floating-point.  Else if it
     37  * fits into int64_t, it's signed integer.  Else if it fits into
     38  * uint64_t, it's unsigned integer.  Else it's floating-point.
     39  *
     40  * Any number can serve as double: qnum_get_double() converts under
     41  * the hood.
     42  *
     43  * An integer can serve as signed / unsigned integer as long as it is
     44  * in range: qnum_get_try_int() / qnum_get_try_uint() check range and
     45  * convert under the hood.
     46  */
     47 struct QNum {
     48     struct QObjectBase_ base;
     49     QNumKind kind;
     50     union {
     51         int64_t i64;
     52         uint64_t u64;
     53         double dbl;
     54     } u;
     55 };
     56 
     57 void qnum_unref(QNum *q);
     58 
     59 G_DEFINE_AUTOPTR_CLEANUP_FUNC(QNum, qnum_unref)
     60 
     61 QNum *qnum_from_int(int64_t value);
     62 QNum *qnum_from_uint(uint64_t value);
     63 QNum *qnum_from_double(double value);
     64 
     65 bool qnum_get_try_int(const QNum *qn, int64_t *val);
     66 int64_t qnum_get_int(const QNum *qn);
     67 
     68 bool qnum_get_try_uint(const QNum *qn, uint64_t *val);
     69 uint64_t qnum_get_uint(const QNum *qn);
     70 
     71 double qnum_get_double(QNum *qn);
     72 
     73 char *qnum_to_string(QNum *qn);
     74 
     75 #endif /* QNUM_H */