[記錄] Objective-c 的正規表示式問題排除.

經過網友的提醒發現，正規表示式裡頭存在著重複的規則，所以就把它移掉來測試一下。
因為以實況來說，我已經用 c 重新改寫了本來那個 method 的運作流程，也沒好掉這麼多地時間；而且一併拿來進行測試， test unit & ouput report 我就懶得打了 ^^"

讓數據證明一切，用看的吧 ~

test unit :

	// ------------------------------------------------------------------------------------------------
	- ( void ) testRegExObjC1
	{
	NSPredicate * predicate;
	predicate = [NSPredicate predicateWithFormat: @"SELF MATCHES %@", @"([^*|:\"<>?]|[ ]|\\w)+@[1-9][0-9]*[xX]$"];
	[predicate evaluateWithObject: @"1234567890123456789012345"];
	}
	// ------------------------------------------------------------------------------------------------
	- ( void ) testRegExObjC2
	{
	NSPredicate * predicate;
	predicate = [NSPredicate predicateWithFormat: @"SELF MATCHES %@", @"([^*|:\"<>?])+@[1-9][0-9]*[xX]$"];
	[predicate evaluateWithObject: @"1234567890123456789012345"];
	}
	// ------------------------------------------------------------------------------------------------
	- ( void ) testRegExObjC3
	{
	NSPredicate * predicate;
	predicate = [NSPredicate predicateWithFormat: @"SELF MATCHES %@", @"([^*|:\"<>?])+@[1-9][0-9]*[xX]$"];
	[predicate evaluateWithObject: @"123456789012345678901234567890"];
	}
	// ------------------------------------------------------------------------------------------------
	- ( void ) testRegExObjC4
	{
	NSPredicate * predicate;
	predicate = [NSPredicate predicateWithFormat: @"SELF MATCHES %@", @"([^*|:\"<>?])+@[1-9][0-9]*[xX]$"];
	[predicate evaluateWithObject: @"123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890"];
	}
	// ------------------------------------------------------------------------------------------------
	- ( void ) testRegExC1
	{
	NSString * parseString;
	parseString = @"1234567890123456789012345";
	[parseString compareByRegularExpression: @"([^*|:\"<>?]|[ ]|\\w)+@[1-9][0-9]*[xX]$"];
	}
	// ------------------------------------------------------------------------------------------------
	- ( void ) testRegExC2
	{
	NSString * parseString;
	parseString = @"1234567890123456789012345";
	[parseString compareByRegularExpression: @"([^*|:\"<>?])+@[1-9][0-9]*[xX]$"];
	}
	// ------------------------------------------------------------------------------------------------
	- ( void ) testRegExC3
	{
	NSString * parseString;
	parseString = @"123456789012345678901234567890";
	[parseString compareByRegularExpression: @"([^*|:\"<>?])+@[1-9][0-9]*[xX]$"];
	}
	// ------------------------------------------------------------------------------------------------
	- ( void ) testRegExC4
	{
	NSString * parseString;
	parseString = @"123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890";
	[parseString compareByRegularExpression: @"([^*|:\"<>?])+@[1-9][0-9]*[xX]$"];
	}
	// ------------------------------------------------------------------------------------------------

view raw gistfile1.m hosted with ❤ by GitHub

output report :

	Test Case '-[TechDNSStringTest testRegExC1]' started.
	Test Case '-[TechDNSStringTest testRegExC1]' passed (0.001 seconds).
	Test Case '-[TechDNSStringTest testRegExC2]' started.
	Test Case '-[TechDNSStringTest testRegExC2]' passed (0.000 seconds).
	Test Case '-[TechDNSStringTest testRegExC3]' started.
	Test Case '-[TechDNSStringTest testRegExC3]' passed (0.000 seconds).
	Test Case '-[TechDNSStringTest testRegExC4]' started.
	Test Case '-[TechDNSStringTest testRegExC4]' passed (0.000 seconds).
	Test Case '-[TechDNSStringTest testRegExObjC1]' started.
	Test Case '-[TechDNSStringTest testRegExObjC1]' passed (17.567 seconds).
	Test Case '-[TechDNSStringTest testRegExObjC2]' started.
	Test Case '-[TechDNSStringTest testRegExObjC2]' passed (0.001 seconds).
	Test Case '-[TechDNSStringTest testRegExObjC3]' started.
	Test Case '-[TechDNSStringTest testRegExObjC3]' passed (0.001 seconds).
	Test Case '-[TechDNSStringTest testRegExObjC4]' started.
	Test Case '-[TechDNSStringTest testRegExObjC4]' passed (0.001 seconds).

view raw gistfile1.m hosted with ❤ by GitHub

可以比較出來，如果正規表示式條件沒有調整到很正確的狀況時，Objective-C 的處理時間會比 C 處理的時間還要多出許多。
( 因為 C 的語法也經過一定程度判斷簡化了 )


用 c 的語法改寫正規表示式檢查方式的 code :

	// ------------------------------------------------------------------------------------------------
	- ( BOOL ) compareByRegularExpression:(NSString *)regularExpression
	{
	// NSParameterAssert( regularExpression );
	//
	// NSPredicate * predicate;
	//
	// predicate = [NSPredicate predicateWithFormat: @"SELF MATCHES %@", regularExpression];
	// NSParameterAssert( predicate );
	// return [predicate evaluateWithObject: self];
	NSParameterAssert( regularExpression );
	regex_t regular;
	int result;
	regmatch_t matches[1];
	char errorMsg[BUFSIZ];
	memset( &matches, 0, sizeof(matches) );
	memset( &errorMsg, 0, sizeof( errorMsg ) );
	result = regcomp( &regular, [regularExpression cStringUsingEncoding: NSASCIIStringEncoding], REG_EXTENDED );
	if ( 0 != result )
	{
	regerror( result, &regular, errorMsg, sizeof( errorMsg ) );
	regfree( &regular );
	return NO;
	}
	result = regexec( &regular, [self cStringUsingEncoding: NSASCIIStringEncoding], 1, matches, 0 );
	if ( REG_NOMATCH == result )
	{
	regerror( result, &regular, errorMsg, sizeof( errorMsg ) );
	regfree( &regular );
	return NO;
	}
	// must all character equal for regular expression.
	if ( 0 != matches[0].rm_so ) // check start character.
	{
	regfree( &regular );
	return NO;
	}
	if ( ( [self length] ) != matches[0].rm_eo ) // check match length equal or not.
	{
	regfree( &regular );
	return NO;
	}
	regfree( &regular );
	return YES;
	}
	// ------------------------------------------------------------------------------------------------

view raw gistfile1.m hosted with ❤ by GitHub

※ 其中的

    regmatch_t                      matches[1];

    // ...

    result                          = regexec( &regular, [self cStringUsingEncoding: NSASCIIStringEncoding], 1, matches, 0 );

因為這個這個函式的功能只判斷，字串是否符合該正規表示式，所以整體運算流程只需要執行個一次就好了，也不需要讓 regexec 這個函式反覆進行判斷


PS: 當我在把函式中的 character set 調整成 UTF8 之後， c 的處理時間有些微的上漲了 0.001 秒 XD