Token NSString em Objective-C

Qual é a melhor maneira de tokenizar / dividir um NSString no Objective-C?

Encontrei isso em http://borkware.com/quickies/one?topic=NSString (link útil):

NSString *string = @"oop:ack:bork:greeble:ponies";
NSArray *chunks = [string componentsSeparatedByString: @":"];

Espero que isto ajude!

Adão

Todos já mencionaram, componentsSeparatedByString:mas você também pode usar CFStringTokenizer(lembre-se de que NSStringe CFStringsão intercambiáveis) que também simbolizarão os idiomas naturais (como chinês / japonês, que não dividem palavras nos espaços).

Se você quiser apenas dividir uma string, use -[NSString componentsSeparatedByString:]. Para tokenização mais complexa, use a classe NSScanner.

Se suas necessidades de tokenização são mais complexas, confira meu kit de ferramentas de análise / análise de código-fonte Cocoa String: ParseKit:

http://parsekit.com

Para uma simples divisão de strings usando um delimitador char (como ':'), o ParseKit definitivamente seria um exagero. Porém, novamente, para necessidades complexas de tokenização, o ParseKit é extremamente poderoso / flexível.

Consulte também a documentação do ParseKit Tokenization .

Se você deseja tokenizar em vários caracteres, use os NSString componentsSeparatedByCharactersInSet. O NSCharacterSet possui alguns conjuntos pré-fabricados úteis, como o whitespaceCharacterSete o illegalCharacterSet. E possui inicializadores para intervalos Unicode.

Você também pode combinar conjuntos de caracteres e usá-los para tokenizar, assim:

// Tokenize sSourceEntityName on both whitespace and punctuation.
NSMutableCharacterSet *mcharsetWhitePunc = [[NSCharacterSet whitespaceAndNewlineCharacterSet] mutableCopy];
[mcharsetWhitePunc formUnionWithCharacterSet:[NSCharacterSet punctuationCharacterSet]];
NSArray *sarrTokenizedName = [self.sSourceEntityName componentsSeparatedByCharactersInSet:mcharsetWhitePunc];
[mcharsetWhitePunc release];

Esteja ciente de que componentsSeparatedByCharactersInSetproduzirá seqüências de caracteres em branco se encontrar mais de um membro do charSet em uma linha; portanto, convém testar comprimentos menores que 1.

Se você deseja tokenizar uma string em termos de pesquisa e preservar "frases entre aspas", aqui está uma NSStringcategoria que respeita vários tipos de pares de aspas:"" '' ‘’ “”

Uso:

NSArray *terms = [@"This is my \"search phrase\" I want to split" searchTerms];
// results in: ["This", "is", "my", "search phrase", "I", "want", "to", "split"]

Código:

@interface NSString (Search)
- (NSArray *)searchTerms;
@end

@implementation NSString (Search)

- (NSArray *)searchTerms {

    // Strip whitespace and setup scanner
    NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
    NSString *searchString = [self stringByTrimmingCharactersInSet:whitespace];
    NSScanner *scanner = [NSScanner scannerWithString:searchString];
    [scanner setCharactersToBeSkipped:nil]; // we'll handle whitespace ourselves

    // A few types of quote pairs to check
    NSDictionary *quotePairs = @{@"\"": @"\"",
                                 @"'": @"'",
                                 @"\u2018": @"\u2019",
                                 @"\u201C": @"\u201D"};

    // Scan
    NSMutableArray *results = [[NSMutableArray alloc] init];
    NSString *substring = nil;
    while (scanner.scanLocation < searchString.length) {
        // Check for quote at beginning of string
        unichar unicharacter = [self characterAtIndex:scanner.scanLocation];
        NSString *startQuote = [NSString stringWithFormat:@"%C", unicharacter];
        NSString *endQuote = [quotePairs objectForKey:startQuote];
        if (endQuote != nil) { // if it's a valid start quote we'll have an end quote
            // Scan quoted phrase into substring (skipping start & end quotes)
            [scanner scanString:startQuote intoString:nil];
            [scanner scanUpToString:endQuote intoString:&substring];
            [scanner scanString:endQuote intoString:nil];
        } else {
            // Single word that is non-quoted
            [scanner scanUpToCharactersFromSet:whitespace intoString:&substring];
        }
        // Process and add the substring to results
        if (substring) {
            substring = [substring stringByTrimmingCharactersInSet:whitespace];
            if (substring.length) [results addObject:substring];
        }
        // Skip to next word
        [scanner scanCharactersFromSet:whitespace intoString:nil];
    }

    // Return non-mutable array
    return results.copy;

}

@end

Se você estiver procurando dividir os recursos lingüísticos de uma string (palavras, parágrafos, caracteres, frases e linhas), use a enumeração de string:

NSString * string = @" \n word1!    word2,%$?'/word3.word4   ";

[string enumerateSubstringsInRange:NSMakeRange(0, string.length)
                           options:NSStringEnumerationByWords
                        usingBlock:
 ^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
     NSLog(@"Substring: '%@'", substring);
 }];

 // Logs:
 // Substring: 'word1'
 // Substring: 'word2'
 // Substring: 'word3'
 // Substring: 'word4' 

Essa API funciona com outros idiomas onde os espaços nem sempre são o delimitador (por exemplo, japonês). Também NSStringEnumerationByComposedCharacterSequencesé usada a maneira correta de enumerar os caracteres, pois muitos caracteres não ocidentais têm mais de um byte.

Eu tive um caso em que tive que dividir a saída do console após uma consulta LDAP com ldapsearch. Primeiro configure e execute o NSTask (encontrei um bom exemplo de código aqui: Execute um comando de terminal a partir de um aplicativo Cocoa ). Mas tive que dividir e analisar a saída para extrair apenas os nomes dos servidores de impressão da saída de consulta Ldap. Infelizmente, é uma manipulação tediosa de strings que não seria um problema se manipulássemos C-strings / arrays com operações simples de arranjos em C. Então, aqui está o meu código usando objetos de cacau. Se você tiver sugestões melhores, me avise.

//as the ldap query has to be done when the user selects one of our Active Directory Domains
//(an according comboBox should be populated with print-server names we discover from AD)
//my code is placed in the onSelectDomain event code

//the following variables are declared in the interface .h file as globals
@protected NSArray* aDomains;//domain combo list array
@protected NSMutableArray* aPrinters;//printer combo list array
@protected NSMutableArray* aPrintServers;//print server combo list array

@protected NSString* sLdapQueryCommand;//for LDAP Queries
@protected NSArray* aLdapQueryArgs;
@protected NSTask* tskLdapTask;
@protected NSPipe* pipeLdapTask;
@protected NSFileHandle* fhLdapTask;
@protected NSMutableData* mdLdapTask;

IBOutlet NSComboBox* comboDomain;
IBOutlet NSComboBox* comboPrinter;
IBOutlet NSComboBox* comboPrintServer;
//end of interface globals

//after collecting the print-server names they are displayed in an according drop-down comboBox
//as soon as the user selects one of the print-servers, we should start a new query to find all the
//print-queues on that server and display them in the comboPrinter drop-down list
//to find the shares/print queues of a windows print-server you need samba and the net -S command like this:
// net -S yourPrintServerName.yourBaseDomain.com -U yourLdapUser%yourLdapUserPassWord -W adm rpc share -l
//which dispalays a long list of the shares

- (IBAction)onSelectDomain:(id)sender
{
    static int indexOfLastItem = 0; //unfortunately we need to compare this because we are called also if the selection did not change!

    if ([comboDomain indexOfSelectedItem] != indexOfLastItem && ([comboDomain indexOfSelectedItem] != 0))
    {

        indexOfLastItem = [comboDomain indexOfSelectedItem]; //retain this index for next call

    //the print-servers-list has to be loaded on a per univeristy or domain basis from a file dynamically or from AN LDAP-QUERY

    //initialize an LDAP-Query-Task or console-command like this one with console output
    /*

     ldapsearch -LLL -s sub -D "cn=yourLdapUser,ou=yourOuWithLdapUserAccount,dc=yourDomain,dc=com" -h "yourLdapServer.com" -p 3268 -w "yourLdapUserPassWord" -b "dc=yourBaseDomainToSearchIn,dc=com" "(&(objectcategory=computer)(cn=ps*))" "dn"

//our print-server names start with ps* and we want the dn as result, wich comes like this:

     dn: CN=PSyourPrintServerName,CN=Computers,DC=yourBaseDomainToSearchIn,DC=com

     */

    sLdapQueryCommand = [[NSString alloc] initWithString: @"/usr/bin/ldapsearch"];


    if ([[comboDomain stringValue] compare: @"firstDomain"] == NSOrderedSame) {

      aLdapQueryArgs = [NSArray arrayWithObjects: @"-LLL",@"-s", @"sub",@"-D", @"cn=yourLdapUser,ou=yourOuWithLdapUserAccount,dc=yourDomain,dc=com",@"-h", @"yourLdapServer.com",@"-p",@"3268",@"-w",@"yourLdapUserPassWord",@"-b",@"dc=yourFirstDomainToSearchIn,dc=com",@"(&(objectcategory=computer)(cn=ps*))",@"dn",nil];
    }
    else {
      aLdapQueryArgs = [NSArray arrayWithObjects: @"-LLL",@"-s", @"sub",@"-D", @"cn=yourLdapUser,ou=yourOuWithLdapUserAccount,dc=yourDomain,dc=com",@"-h", @"yourLdapServer.com",@"-p",@"3268",@"-w",@"yourLdapUserPassWord",@"-b",@"dc=yourSecondDomainToSearchIn,dc=com",@"(&(objectcategory=computer)(cn=ps*))",@"dn",nil];

    }


    //prepare and execute ldap-query task

    tskLdapTask = [[NSTask alloc] init];
    pipeLdapTask = [[NSPipe alloc] init];//instead of [NSPipe pipe]
    [tskLdapTask setStandardOutput: pipeLdapTask];//hope to get the tasks output in this file/pipe

    //The magic line that keeps your log where it belongs, has to do with NSLog (see /programming/412562/execute-a-terminal-command-from-a-cocoa-app and here http://www.cocoadev.com/index.pl?NSTask )
    [tskLdapTask setStandardInput:[NSPipe pipe]];

    //fhLdapTask  = [[NSFileHandle alloc] init];//would be redundand here, next line seems to do the trick also
    fhLdapTask = [pipeLdapTask fileHandleForReading];
    mdLdapTask  = [NSMutableData dataWithCapacity:512];//prepare capturing the pipe buffer which is flushed on read and can overflow, start with 512 Bytes but it is mutable, so grows dynamically later
    [tskLdapTask setLaunchPath: sLdapQueryCommand];
    [tskLdapTask setArguments: aLdapQueryArgs];

#ifdef bDoDebug
    NSLog (@"sLdapQueryCommand: %@\n", sLdapQueryCommand);
    NSLog (@"aLdapQueryArgs: %@\n", aLdapQueryArgs );
    NSLog (@"tskLdapTask: %@\n", [tskLdapTask arguments]);
#endif

    [tskLdapTask launch];

    while ([tskLdapTask isRunning]) {
      [mdLdapTask appendData: [fhLdapTask readDataToEndOfFile]];
    }
    [tskLdapTask waitUntilExit];//might be redundant here.

    [mdLdapTask appendData: [fhLdapTask readDataToEndOfFile]];//add another read for safety after process/command stops

    NSString* sLdapOutput = [[NSString alloc] initWithData: mdLdapTask encoding: NSUTF8StringEncoding];//convert output to something readable, as NSData and NSMutableData are mere byte buffers

#ifdef bDoDebug
    NSLog(@"LdapQueryOutput: %@\n", sLdapOutput);
#endif

    //Ok now we have the printservers from Active Directory, lets parse the output and show the list to the user in its combo box
    //output is formatted as this, one printserver per line
    //dn: CN=PSyourPrintServer,OU=Computers,DC=yourBaseDomainToSearchIn,DC=com

    //so we have to search for "dn: CN=" to retrieve each printserver's name
    //unfortunately splitting this up will give us a first line containing only "" empty string, which we can replace with the word "choose"
    //appearing as first entry in the comboBox

    aPrintServers = (NSMutableArray*)[sLdapOutput componentsSeparatedByString:@"dn: CN="];//split output into single lines and store it in the NSMutableArray aPrintServers

#ifdef bDoDebug
    NSLog(@"aPrintServers: %@\n", aPrintServers);
#endif

    if ([[aPrintServers objectAtIndex: 0 ] compare: @"" options: NSLiteralSearch] == NSOrderedSame){
      [aPrintServers replaceObjectAtIndex: 0 withObject: slChoose];//replace with localized string "choose"

#ifdef bDoDebug
      NSLog(@"aPrintServers: %@\n", aPrintServers);
#endif

    }

//Now comes the tedious part to extract only the print-server-names from the single lines
    NSRange r;
    NSString* sTemp;

    for (int i = 1; i < [aPrintServers count]; i++) {//skip first line with "choose". To get rid of the rest of the line, we must isolate/preserve the print server's name to the delimiting comma and remove all the remaining characters
      sTemp = [aPrintServers objectAtIndex: i];
      sTemp = [sTemp stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]];//remove newlines and line feeds

#ifdef bDoDebug
      NSLog(@"sTemp: %@\n", sTemp);
#endif
      r = [sTemp rangeOfString: @","];//now find first comma to remove the whole rest of the line
      //r.length = [sTemp lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
      r.length = [sTemp length] - r.location;//calculate number of chars between first comma found and lenght of string
#ifdef bDoDebug
      NSLog(@"range: %i, %i\n", r.location, r.length);
#endif

      sTemp = [sTemp stringByReplacingCharactersInRange:r withString: @"" ];//remove rest of line
#ifdef bDoDebug
      NSLog(@"sTemp after replace: %@\n", sTemp);
#endif

      [aPrintServers replaceObjectAtIndex: i withObject: sTemp];//put back string into array for display in comboBox

#ifdef bDoDebug
      NSLog(@"aPrintServer: %@\n", [aPrintServers objectAtIndex: i]);
#endif

    }

    [comboPrintServer removeAllItems];//reset combo box
    [comboPrintServer addItemsWithObjectValues:aPrintServers];
    [comboPrintServer setNumberOfVisibleItems:aPrintServers.count];
    [comboPrintServer selectItemAtIndex:0];

#ifdef bDoDebug
    NSLog(@"comboPrintServer reloaded with new values.");
#endif


//release memory we used for LdapTask
    [sLdapQueryCommand release];
    [aLdapQueryArgs release];
    [sLdapOutput release];

    [fhLdapTask release];

    [pipeLdapTask release];
//    [tskLdapTask release];//strangely can not be explicitely released, might be autorelease anyway
//    [mdLdapTask release];//strangely can not be explicitely released, might be autorelease anyway

    [sTemp release];

    }
}

Eu me deparei com uma instância em que não bastava separar a string por componente, muitas tarefas como
1) Categorizar token nos tipos
2) Adicionar novos tokens
3) Separar string entre fechamentos personalizados, como todas as palavras entre "{" e "} "
Para esses requisitos, achei o Parse Kit um salva - vidas.

Usei-o para analisar com êxito arquivos .PGN (notável tabela de jogos), muito rápido e leve.