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Matlab compatible short-circuit behavior for & and | operators
author John W. Eaton <jwe@octave.org>
date Fri, 08 Oct 2010 15:22:47 -0400
parents 57a59eae83cc
children fd0a3ac60b0e
comparison
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11090:2adf4736dafa 11091:5677f3f7b5fa
24 #ifdef HAVE_CONFIG_H 24 #ifdef HAVE_CONFIG_H
25 #include <config.h> 25 #include <config.h>
26 #endif 26 #endif
27 27
28 #include "error.h" 28 #include "error.h"
29 #include "defun.h"
29 #include "oct-obj.h" 30 #include "oct-obj.h"
30 #include "ov.h" 31 #include "ov.h"
31 #include "pt-binop.h" 32 #include "pt-binop.h"
32 #include "pt-bp.h" 33 #include "pt-bp.h"
33 #include "pt-walk.h" 34 #include "pt-walk.h"
35 #include "variables.h"
36
37 // TRUE means we mark | and & expressions for braindead short-circuit
38 // behavior.
39 static bool Vdo_braindead_shortcircuit_evaluation;
34 40
35 // Binary expressions. 41 // Binary expressions.
36 42
37 octave_value_list 43 octave_value_list
38 tree_binary_expression::rvalue (int nargout) 44 tree_binary_expression::rvalue (int nargout)
54 octave_value retval; 60 octave_value retval;
55 61
56 if (error_state) 62 if (error_state)
57 return retval; 63 return retval;
58 64
65 if (Vdo_braindead_shortcircuit_evaluation
66 && eligible_for_braindead_shortcircuit)
67 {
68 if (op_lhs)
69 {
70 octave_value a = op_lhs->rvalue1 ();
71
72 if (! error_state)
73 {
74 if (a.ndims () == 2 && a.rows () == 1 && a.columns () == 1)
75 {
76 bool result = false;
77
78 bool a_true = a.is_true ();
79
80 if (! error_state)
81 {
82 if (a_true)
83 {
84 if (etype == octave_value::op_el_or)
85 {
86 result = true;
87 goto done;
88 }
89 }
90 else
91 {
92 if (etype == octave_value::op_el_and)
93 goto done;
94 }
95
96 if (op_rhs)
97 {
98 octave_value b = op_rhs->rvalue1 ();
99
100 if (! error_state)
101 result = b.is_true ();
102 }
103
104 done:
105
106 if (! error_state)
107 return octave_value (result);
108 }
109 }
110 }
111 }
112 }
113
59 if (op_lhs) 114 if (op_lhs)
60 { 115 {
61 octave_value a = op_lhs->rvalue1 (); 116 octave_value a = op_lhs->rvalue1 ();
62 117
63 if (! error_state && a.is_defined () && op_rhs) 118 if (! error_state && a.is_defined () && op_rhs)
205 260
206 new_be->copy_base (*this); 261 new_be->copy_base (*this);
207 262
208 return new_be; 263 return new_be;
209 } 264 }
265
266 DEFUN (do_braindead_shortcircuit_evaluation, args, nargout,
267 "-*- texinfo -*-\n\
268 @deftypefn {Built-in Function} {@var{val} =} do_braindead_shortcircuit_evaluation ()\n\
269 @deftypefnx {Built-in Function} {@var{old_val} =} do_braindead_shortcircuit_evaluation (@var{new_val})\n\
270 Query or set the internal variable that controls whether Octave will\n\
271 do short-circuit evaluation of @samp{|} and @samp{&} operators inside the\n\
272 conditions of if or while statements.\n\
273 \n\
274 This feature is only provided for compatibility with Matlab and should\n\
275 not be used unless you are porting old code that relies on this feature.\n\
276 \n\
277 To obtain short-circuit behavior for logical expressions in new programs,\n\
278 you should always use the @samp{&&} and @samp{||} operators.\n\
279 @end deftypefn")
280 {
281 return SET_INTERNAL_VARIABLE (do_braindead_shortcircuit_evaluation);
282 }