Cocoa / Objective-C中的简单字符串解析：将命令行解析为命令和参数 [英] Simple string parsing in Cocoa / Objective-C: parsing a command line into command and arguments

问题描述

下面是一段代码，用于接受代表命令行的字符串（NSString或NSAttributedString） input ，并将其解析为两个字符串，命令 cmd 和参数 args ：

Here's a piece of code to take a string (either NSString or NSAttributedString) input that represents a command line and parse it into two strings, the command cmd and the arguments args:

NSString* cmd = [[input mutableCopy] autorelease];
NSString* args = [[input mutableCopy] autorelease];
NSScanner* scanner = [NSScanner scannerWithString:[input string]];
[scanner scanUpToCharactersFromSet:[NSCharacterSet 
                                    whitespaceAndNewlineCharacterSet] 
                        intoString:&cmd];
if (![scanner scanUpToString:@"magicstring666" intoString:&args]) args = @"";

这似乎工作，但魔术字符串是一个很荒谬的黑客。此外，我不确定我是做自己的事情正确的自动释义。

That seems to work but the magic string is a pretty absurd hack. Also, I'm not at all sure I'm doing things right with the autoreleases.

添加：解决方案也应该是鲁棒的初始空格。此外，我最初有一个输入字符串 input 和 inStr 。对不起，这个混乱。

ADDED: The solution should also be robust to initial whitespace. Also, I originally had the input string called both input and inStr. Sorry for that confusion.

添加：我相信上述代码是正确的，答案到目前为止不是args不应该有任何初始空格。 / p>

ADDED: I believe one thing the above code gets right that the answers so far don't is that args should not have any initial whitespace.

推荐答案

NSString *cmd;
NSScanner *scanner = [NSScanner scannerWithString:[inStr string]];
[scanner scanUpToCharactersFromSet:[NSCharacterSet
                                    whitespaceAndNewlineCharacterSet] 
                        intoString:&cmd];
NSString *args = [[scanner string] substringFromIndex:[scanner scanLocation]];

您的autoreleases可以，但首先分配字符串是不必要的，因为NSScanner返回一个新的字符串参考。由于NSScanner的charactersToBeSkipped在默认情况下包含空格，因此它不应该被初始空格占用。

Your autoreleases were OK, but allocating strings in the first place was unnecessary since NSScanner returns a new string by reference. Since NSScanner's charactersToBeSkipped include whitespace by default, it shouldn't get tripped up by initial whitespace.

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