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QoreNodeEvalOptionalRefHolder.h
1 /* -*- mode: c++; indent-tabs-mode: nil -*- */
2 /*
3  QoreNodeEvalOptionalRefHolder.h
4 
5  Qore Programming Language
6 
7  Copyright 2003 - 2013 David Nichols
8 
9  This library is free software; you can redistribute it and/or
10  modify it under the terms of the GNU Lesser General Public
11  License as published by the Free Software Foundation; either
12  version 2.1 of the License, or (at your option) any later version.
13 
14  This library is distributed in the hope that it will be useful,
15  but WITHOUT ANY WARRANTY; without even the implied warranty of
16  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  Lesser General Public License for more details.
18 
19  You should have received a copy of the GNU Lesser General Public
20  License along with this library; if not, write to the Free Software
21  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23 
24 #ifndef _QORE_QORENODEEVALOPTIONALREFHOLDER_H
25 
26 #define _QORE_QORENODEEVALOPTIONALREFHOLDER_H
27 
29 
38  private:
39  AbstractQoreNode *val;
40  ExceptionSink *xsink;
41  bool needs_deref;
42 
43  DLLLOCAL void discard_intern() {
44  if (needs_deref && val)
45  val->deref(xsink);
46  }
47 
50 
52  DLLLOCAL QoreNodeEvalOptionalRefHolder& operator=(const QoreNodeEvalOptionalRefHolder&);
53 
55 
57  DLLLOCAL void *operator new(size_t);
58 
59  public:
61  DLLLOCAL QoreNodeEvalOptionalRefHolder(ExceptionSink *n_xsink) : val(0), xsink(n_xsink), needs_deref(false) {
62  }
63 
65  DLLLOCAL QoreNodeEvalOptionalRefHolder(const AbstractQoreNode *exp, ExceptionSink *n_xsink) : xsink(n_xsink) {
66  if (exp)
67  val = exp->eval(needs_deref, xsink);
68  else {
69  val = 0;
70  needs_deref = false;
71  }
72  }
73 
76  discard_intern();
77  }
78 
80  DLLLOCAL void discard() {
81  discard_intern();
82  needs_deref = false;
83  val = 0;
84  }
85 
87  DLLLOCAL void assign(bool n_needs_deref, AbstractQoreNode *n_val) {
88  discard_intern();
89  needs_deref = n_needs_deref;
90  val = n_val;
91  }
92 
95  if (needs_deref)
96  needs_deref = false;
97  else if (val)
98  val->ref();
99  return val;
100  }
101 
103  DLLLOCAL const AbstractQoreNode *operator->() const { return val; }
104 
106  DLLLOCAL const AbstractQoreNode *operator*() const { return val; }
107 
109  DLLLOCAL operator bool() const { return val != 0; }
110 
112  DLLLOCAL bool isTemp() const { return needs_deref; }
113 
114 };
115 
116 #endif
DLLLOCAL void assign(bool n_needs_deref, AbstractQoreNode *n_val)
assigns a new value to this holder object
Definition: QoreNodeEvalOptionalRefHolder.h:87
DLLLOCAL const AbstractQoreNode * operator*() const
returns the object being managed
Definition: QoreNodeEvalOptionalRefHolder.h:106
DLLEXPORT AbstractQoreNode * eval(ExceptionSink *xsink) const
evaluates the object and returns a value (or 0)
DLLLOCAL void discard()
discards any temporary value evaluated by the constructor or assigned by "assign()" ...
Definition: QoreNodeEvalOptionalRefHolder.h:80
The base class for all value and parse types in Qore expression trees.
Definition: AbstractQoreNode.h:47
DLLLOCAL QoreNodeEvalOptionalRefHolder(ExceptionSink *n_xsink)
constructor used to create a holder object
Definition: QoreNodeEvalOptionalRefHolder.h:61
DLLEXPORT void ref() const
increments the reference count
container for holding Qore-language exception information and also for registering a "thread_exit" ca...
Definition: ExceptionSink.h:35
DLLEXPORT void deref(ExceptionSink *xsink)
decrements the reference count and calls derefImpl() if there_can_be_only_one is false, otherwise does nothing
DLLLOCAL const AbstractQoreNode * operator->() const
returns the object being managed
Definition: QoreNodeEvalOptionalRefHolder.h:103
DLLLOCAL QoreNodeEvalOptionalRefHolder(const AbstractQoreNode *exp, ExceptionSink *n_xsink)
constructor with a value that will call the class' eval(needs_deref) method
Definition: QoreNodeEvalOptionalRefHolder.h:65
DLLLOCAL AbstractQoreNode * getReferencedValue()
returns a referenced value - the caller will own the reference
Definition: QoreNodeEvalOptionalRefHolder.h:94
DLLLOCAL ~QoreNodeEvalOptionalRefHolder()
discards any temporary value evaluated by the constructor or assigned by "assign()" ...
Definition: QoreNodeEvalOptionalRefHolder.h:75
this class manages reference counts for the optional evaluation of AbstractQoreNode objects ...
Definition: QoreNodeEvalOptionalRefHolder.h:37
DLLLOCAL bool isTemp() const
returns true if the value is temporary (needs dereferencing)
Definition: QoreNodeEvalOptionalRefHolder.h:112