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Allow arbitrary expressions for empty() #54

Merged
merged 1 commit into from almost 2 years ago

3 participants

Nikita Popov Linus Unnebäck Account for PHP Pull Requests
Linus Unnebäck

I think that this is a great idea, thank you for taking the time to implement it!

Nikita Popov Allow arbitrary expressions for empty()
This change is as per RFC https://wiki.php.net/rfc/empty_isset_exprs.

The change allows passing the result of function calls and other
expressions to the empty() language construct. This is accomplished by
simply rewriting empty(expr) to !expr.

The change does not affect the suppression of errors when using empty()
on variables. empty($undefinedVar) will continue not to throw errors.
When an expression is used inside empty() on the other hand, errors will
not be suppressed. Thus empty($undefinedVar + $somethingElse) *will*
throw a notice.

The change also does not make empty() into a real function, so using
'empty' as a callback is still not possible.

In addition to the empty() changes the commit adds nicer error messages
when isset() is used on function call results or other expressions.
ec061a9
Account for PHP Pull Requests php-pulls merged commit ec061a9 into from
Account for PHP Pull Requests php-pulls closed this
Account for PHP Pull Requests
Collaborator

Comment on behalf of stas at php.net:

merged to master, thanks

Account for PHP Pull Requests
Collaborator

Comment on behalf of stas at php.net:

merged to master, thanks

Account for PHP Pull Requests php-pulls referenced this pull request from a commit
Dmitry Stogov Merge branch 'PHP-5.5'
* PHP-5.5: (101 commits)
  Renamed ZendOptimizerPlus.so into opcache.so
  "ZendOptimizerPlus" is renamed to "opcache" to de merged into PHP-5.5 under ext/opcache (the product name is still "Zend Optimizer+")
  More accurate restart scheduling
  Autogolobal $GLOBALS has to be pinged even if auto_globals_jit=0
  Allow only shared O+ build
  Fixed typos
  add tests into package
  Add test script for #57 (segfaults in drupal7)
  fixed memory leaks
  Fixed Issue #57 (segfaults in drupal7)
  Fixed issue #58 (PHP-5.2 compatibility)
  Allows exclusion of large files from being cached
  Add maintainers inot package.xml
  fix ANSI C90 compat
  Fixed test
  Fixed uninitialized variable
  Fixed bug #64353 (Built-in classes can be unavailable with dynamic includes and Optimizer+)
  Save a stat() call by calling sapi_module.get_stat()
  Fixed #54 (PECL install adds extension= instead of zend_extension= to php.ini)
  release 7.0.0
  ...
29a9e13
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Showing 1 unique commit by 1 author.

May 13, 2012
Nikita Popov Allow arbitrary expressions for empty()
This change is as per RFC https://wiki.php.net/rfc/empty_isset_exprs.

The change allows passing the result of function calls and other
expressions to the empty() language construct. This is accomplished by
simply rewriting empty(expr) to !expr.

The change does not affect the suppression of errors when using empty()
on variables. empty($undefinedVar) will continue not to throw errors.
When an expression is used inside empty() on the other hand, errors will
not be suppressed. Thus empty($undefinedVar + $somethingElse) *will*
throw a notice.

The change also does not make empty() into a real function, so using
'empty' as a callback is still not possible.

In addition to the empty() changes the commit adds nicer error messages
when isset() is used on function call results or other expressions.
ec061a9
This page is out of date. Refresh to see the latest.
3  NEWS
@@ -7,6 +7,9 @@ PHP                                                                        NEWS
7 7
   . World domination
8 8
   . Improve set_exception_handler while doing reset.(Laruence)
9 9
   . Support constant array/string dereferencing. (Laruence)
  10
+  . Add support for using empty() on the result of function calls and
  11
+    other expressions (https://wiki.php.net/rfc/empty_isset_exprs).
  12
+    (Nikita Popov)
10 13
 
11 14
 - Core:
12 15
   . Fixed bug #61681 (Malformed grammar). (Nikita Popov, Etienne, Laruence).
5  UPGRADING
@@ -28,6 +28,9 @@ PHP X.Y UPGRADE NOTES
28 28
 
29 29
 - Support constant array/string dereferencing. (Laruence)
30 30
   (https://wiki.php.net/rfc/constdereference)
  31
+- Add support for using empty() on the result of function calls and
  32
+  other expressions. Thus it is now possible to write empty(getArray()),
  33
+  for example. (https://wiki.php.net/rfc/empty_isset_exprs)
31 34
 
32 35
 ========================================
33 36
 2. Changes in SAPI modules
@@ -51,7 +54,7 @@ PHP X.Y UPGRADE NOTES
51 54
   - Implemented format character "Z": NUL-padded string
52 55
   - "a" now does not remove trailing NUL characters on unpack() anymore
53 56
   - "A" will now strip all trailing ASCII whitespace on unpack() (it used to
54  
-    remove only trailing spaces.
  57
+    remove only trailing spaces)
55 58
 
56 59
 ========================================
57 60
 5. New Functions
32  Zend/tests/empty_with_expr.phpt
... ...
@@ -0,0 +1,32 @@
  1
+--TEST--
  2
+empty() with arbitrary expressions
  3
+--FILE--
  4
+<?php
  5
+
  6
+function getEmptyArray() { return []; }
  7
+function getNonEmptyArray() { return [1, 2, 3]; }
  8
+
  9
+var_dump(empty([]));
  10
+var_dump(empty([1, 2, 3]));
  11
+
  12
+var_dump(empty(getEmptyArray()));
  13
+var_dump(empty(getNonEmptyArray()));
  14
+
  15
+var_dump(empty([] + []));
  16
+var_dump(empty([1, 2, 3] + []));
  17
+
  18
+var_dump(empty("string"));
  19
+var_dump(empty(""));
  20
+var_dump(empty(true));
  21
+var_dump(empty(false));
  22
+--EXPECT--
  23
+bool(true)
  24
+bool(false)
  25
+bool(true)
  26
+bool(false)
  27
+bool(true)
  28
+bool(false)
  29
+bool(false)
  30
+bool(true)
  31
+bool(false)
  32
+bool(true)
8  Zend/tests/isset_expr_error.phpt
... ...
@@ -0,0 +1,8 @@
  1
+--TEST--
  2
+Error message for isset(func())
  3
+--FILE--
  4
+<?php
  5
+isset(1 + 1);
  6
+?>
  7
+--EXPECTF--
  8
+Fatal error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) in %s on line %d
8  Zend/tests/isset_func_error.phpt
... ...
@@ -0,0 +1,8 @@
  1
+--TEST--
  2
+Error message for isset(func())
  3
+--FILE--
  4
+<?php
  5
+isset(abc());
  6
+?>
  7
+--EXPECTF--
  8
+Fatal error: Cannot use isset() on the result of a function call (you can use "null !== func()" instead) in %s on line %d
11  Zend/zend_compile.c
@@ -6089,7 +6089,16 @@ void zend_do_isset_or_isempty(int type, znode *result, znode *variable TSRMLS_DC
6089 6089
 
6090 6090
 	zend_do_end_variable_parse(variable, BP_VAR_IS, 0 TSRMLS_CC);
6091 6091
 
6092  
-	zend_check_writable_variable(variable);
  6092
+	if (zend_is_function_or_method_call(variable)) {
  6093
+		if (type == ZEND_ISEMPTY) {
  6094
+			/* empty(func()) can be transformed to !func() */
  6095
+			zend_do_unary_op(ZEND_BOOL_NOT, result, variable TSRMLS_CC);
  6096
+		} else {
  6097
+			zend_error(E_COMPILE_ERROR, "Cannot use isset() on the result of a function call (you can use \"null !== func()\" instead)");
  6098
+		}
  6099
+
  6100
+		return;
  6101
+	}
6093 6102
 
6094 6103
 	if (variable->op_type == IS_CV) {
6095 6104
 		last_op = get_next_op(CG(active_op_array) TSRMLS_CC);
10  Zend/zend_language_parser.y
@@ -1158,6 +1158,7 @@ encaps_var_offset:
1158 1158
 internal_functions_in_yacc:
1159 1159
 		T_ISSET '(' isset_variables ')' { $$ = $3; }
1160 1160
 	|	T_EMPTY '(' variable ')'	{ zend_do_isset_or_isempty(ZEND_ISEMPTY, &$$, &$3 TSRMLS_CC); }
  1161
+	|	T_EMPTY '(' expr_without_variable ')' { zend_do_unary_op(ZEND_BOOL_NOT, &$$, &$3 TSRMLS_CC); }
1161 1162
 	|	T_INCLUDE expr 			{ zend_do_include_or_eval(ZEND_INCLUDE, &$$, &$2 TSRMLS_CC); }
1162 1163
 	|	T_INCLUDE_ONCE expr 	{ zend_do_include_or_eval(ZEND_INCLUDE_ONCE, &$$, &$2 TSRMLS_CC); }
1163 1164
 	|	T_EVAL '(' expr ')' 	{ zend_do_include_or_eval(ZEND_EVAL, &$$, &$3 TSRMLS_CC); }
@@ -1166,8 +1167,13 @@ internal_functions_in_yacc:
1166 1167
 ;
1167 1168
 
1168 1169
 isset_variables:
1169  
-		variable 				{ zend_do_isset_or_isempty(ZEND_ISSET, &$$, &$1 TSRMLS_CC); }
1170  
-	|	isset_variables ',' { zend_do_boolean_and_begin(&$1, &$2 TSRMLS_CC); } variable { znode tmp; zend_do_isset_or_isempty(ZEND_ISSET, &tmp, &$4 TSRMLS_CC); zend_do_boolean_and_end(&$$, &$1, &tmp, &$2 TSRMLS_CC); }
  1170
+		isset_variable			{ $$ = $1; }
  1171
+	|	isset_variables ',' { zend_do_boolean_and_begin(&$1, &$2 TSRMLS_CC); } isset_variable { zend_do_boolean_and_end(&$$, &$1, &$4, &$2 TSRMLS_CC); }
  1172
+;
  1173
+
  1174
+isset_variable:
  1175
+		variable				{ zend_do_isset_or_isempty(ZEND_ISSET, &$$, &$1 TSRMLS_CC); }
  1176
+	|	expr_without_variable	{ zend_error(E_COMPILE_ERROR, "Cannot use isset() on the result of an expression (you can use \"null !== expression\" instead)"); }
1171 1177
 ;
1172 1178
 
1173 1179
 class_constant:
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