Mercurial > hg > octave-lyh
changeset 319:42fe4794ded9
[project @ 1994-01-28 07:16:43 by jwe]
author | jwe |
---|---|
date | Fri, 28 Jan 1994 07:16:47 +0000 |
parents | 1412ea9fc828 |
children | 781f2e240975 |
files | liboctave/Array.cc liboctave/Array.h |
diffstat | 2 files changed, 93 insertions(+), 38 deletions(-) [+] |
line wrap: on
line diff
--- a/liboctave/Array.cc +++ b/liboctave/Array.cc @@ -833,40 +833,6 @@ template <class T> T& -DiagArray<T>::elem (int r, int c) -{ - static T foo (0); - return (r == c) ? Array<T>::elem (r) : foo; -} - -template <class T> -T& -DiagArray<T>::checkelem (int r, int c) -{ - static T foo (0); - if (r < 0 || c < 0 || r >= nr || c >= nc) - { - (*current_liboctave_error_handler) ("range error"); - return foo; - } - return (r == c) ? Array<T>::elem (r) : foo; -} - -template <class T> -T& -DiagArray<T>::operator () (int r, int c) -{ - static T foo (0); - if (r < 0 || c < 0 || r >= nr || c >= nc) - { - (*current_liboctave_error_handler) ("range error"); - return foo; - } - return (r == c) ? Array<T>::elem (r) : foo; -} - -template <class T> -T& DiagArray<T>::xelem (int r, int c) { static T foo (0);
--- a/liboctave/Array.h +++ b/liboctave/Array.h @@ -1,7 +1,7 @@ // Template array classes -*- C++ -*- /* -Copyright (C) 1993 John W. Eaton +Copyright (C) 1993, 1994 John W. Eaton This file is part of Octave. @@ -211,11 +211,72 @@ /* * A two-dimensional array with diagonal elements only. + * + * Idea and example code for Proxy class and functions from: + * + * From: kanze@us-es.sel.de (James Kanze) + * Subject: Re: How to overload [] to do READ/WRITE differently ? + * Message-ID: <KANZE.93Nov29151407@slsvhdt.us-es.sel.de> + * Sender: news@us-es.sel.de + * Date: 29 Nov 1993 14:14:07 GMT + * -- + * James Kanze email: kanze@us-es.sel.de + * GABI Software, Sarl., 8 rue du Faisan, F-67000 Strasbourg, France */ template <class T> class DiagArray : public Array<T> { +private: + + class Proxy + { + public: + + Proxy (DiagArray<T> *ref, int r, int c) : object (ref), i (r), j (c) { } + + const Proxy& operator = (const T& val) const + { + if (i == j) + { + if (object) + object->set (val, i); + } + else + (*current_liboctave_error_handler) + ("assignment to off-diagonal element attempted for diagonal array"); + + return *this; + } + + operator T () const + { + if (object) + return object->get (i); + else + { + static T foo (0); + return foo; + } + } + + private: + +// XXX FIXME XXX -- this is declared private to keep the user from +// taking the address of a Proxy. Maybe it should be implemented by +// means of a companion function in the DiagArray class. + + T *operator& () const; + + int i; + int j; + + DiagArray<T> *object; + + }; + +friend class Proxy; + protected: int nr; @@ -242,9 +303,32 @@ int cols (void) const; int columns (void) const; - T& elem (int r, int c); - T& checkelem (int r, int c); - T& operator () (int r, int c); + Proxy elem (int r, int c) + { + return Proxy (this, r, c); + } + + Proxy checkelem (int r, int c) + { + if (r < 0 || c < 0 || r >= nr || c >= nc) + { + (*current_liboctave_error_handler) ("range error"); + return Proxy (0, r, c); + } + else + return Proxy (this, r, c); + } + + Proxy operator () (int r, int c) + { + if (r < 0 || c < 0 || r >= nr || c >= nc) + { + (*current_liboctave_error_handler) ("range error"); + return Proxy (0, r, c); + } + else + return Proxy (this, r, c); + } // No checking. T& xelem (int r, int c); @@ -255,6 +339,11 @@ void resize (int n, int m); void resize (int n, int m, const T& val); + +private: + + T get (int i) { return Array<T>::elem (i); } + void set (const T& val, int i) { Array<T>::elem (i) = val; } }; #if defined (__GNUG__) && ! defined (USE_EXTERNAL_TEMPLATES)