ARB
lazy.h
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1 // ============================================================ //
2 // //
3 // File : lazy.h //
4 // Purpose : helpers for lazy evaluation //
5 // //
6 // Coded by Ralf Westram (coder@reallysoft.de) in July 2017 //
7 // http://www.arb-home.de/ //
8 // //
9 // ============================================================ //
10 
11 #ifndef LAZY_H
12 #define LAZY_H
13 
14 #ifndef ARB_ASSERT_H
15 #include <arb_assert.h>
16 #endif
17 #ifndef _GLIBCXX_CMATH
18 #include <cmath>
19 #endif
20 #ifndef ARBTOOLS_H
21 #include "arbtools.h"
22 #endif
23 
24 
25 template<typename T, T UNDEFINED>
26 class Lazy {
32  T val;
33 public:
34  Lazy() : val(UNDEFINED) {}
35  explicit Lazy(T init) : val(init) { arb_assert(has_value()); } // use to assign new value
36 
37  bool needs_eval() const { return val == UNDEFINED; }
38  bool has_value() const { return !needs_eval(); }
39 
40  operator T() const { // @@@ return const&?
41  arb_assert(has_value()); // no value assigned
42  return val;
43  }
44  const Lazy& operator = (const T& newval) {
45  val = newval;
47  return *this;
48  }
49 };
50 
51 template<typename T>
52 class LazyFloat {
55  T val;
56 
57 public:
58  LazyFloat() : val(NAN) {}
59  explicit LazyFloat(T init) : val(init) { arb_assert(has_value()); } // use to assign new value
60 
61  bool needs_eval() const { return is_nan(val); }
62  bool has_value() const { return !needs_eval(); }
63 
64  operator T() const { // @@@ return const&?
65  arb_assert(has_value()); // no value assigned
66  return val;
67  }
68  const LazyFloat& operator = (const T& newval) {
69  val = newval;
71  return *this;
72  }
73 };
74 
75 #else
76 #error lazy.h included twice
77 #endif // LAZY_H
#define arb_assert(cond)
Definition: arb_assert.h:245
CONSTEXPR_INLINE bool is_nan(const T &n)
Definition: arbtools.h:174
LazyFloat(T init)
Definition: lazy.h:59
bool needs_eval() const
Definition: lazy.h:61
const LazyFloat & operator=(const T &newval)
Definition: lazy.h:68
Lazy(T init)
Definition: lazy.h:35
Definition: lazy.h:26
bool has_value() const
Definition: lazy.h:38
LazyFloat()
Definition: lazy.h:58
const Lazy & operator=(const T &newval)
Definition: lazy.h:44
bool needs_eval() const
Definition: lazy.h:37
static ARB_init_perl_interface init
Definition: ARB_ext.c:101
bool has_value() const
Definition: lazy.h:62
Lazy()
Definition: lazy.h:34
Definition: trnsprob.h:20
Definition: lazy.h:52