ios - [NSString containString :] this function in ObjC? 使用了什么算法

Question

我想做一个带有地址簿的应用程序，需要添加搜索功能。我希望搜索功能可以支持字符串匹配，我在NSString类中找到了[NSString containString:]这个函数。为了高效，我想使用一个很好的字符串匹配算法来实现它，如KMP。所以想知道这个函数用的是什么算法。在哪里可以查看NSString函数的源代码？

谢谢。

Answer 1

程序集如下:

Foundation`-[NSString containsString:]:
->  0x10a128954 <+0>:  pushq  %rbp
    0x10a128955 <+1>:  movq   %rsp, %rbp
    0x10a128958 <+4>:  pushq  %r15
    0x10a12895a <+6>:  pushq  %r14
    0x10a12895c <+8>:  pushq  %rbx
    0x10a12895d <+9>:  pushq  %rax
    0x10a12895e <+10>: movq   %rdx, %r14
    0x10a128961 <+13>: movq   %rdi, %rbx
    0x10a128964 <+16>: movq   0x1836d5(%rip), %rsi      ; "length"
    0x10a12896b <+23>: movq   0x19ddee(%rip), %r15      ; (void *)0x000000010a4bb800: objc_msgSend
    0x10a128972 <+30>: callq  *%r15
    0x10a128975 <+33>: movq   0x185dc4(%rip), %rsi      ; "rangeOfString:options:range:locale:"
    0x10a12897c <+40>: movq   $0x0, (%rsp)
    0x10a128984 <+48>: xorl   %ecx, %ecx
    0x10a128986 <+50>: xorl   %r8d, %r8d
    0x10a128989 <+53>: movq   %rbx, %rdi
    0x10a12898c <+56>: movq   %r14, %rdx
    0x10a12898f <+59>: movq   %rax, %r9
    0x10a128992 <+62>: callq  *%r15
    0x10a128995 <+65>: movabsq $0x7fffffffffffffff, %rcx ; imm = 0x7FFFFFFFFFFFFFFF 
    0x10a12899f <+75>: cmpq   %rcx, %rax
    0x10a1289a2 <+78>: setne  %al
    0x10a1289a5 <+81>: addq   $0x8, %rsp
    0x10a1289a9 <+85>: popq   %rbx
    0x10a1289aa <+86>: popq   %r14
    0x10a1289ac <+88>: popq   %r15
    0x10a1289ae <+90>: popq   %rbp
    0x10a1289af <+91>: retq   

本质上就是下面的算法:

- (bool)containsString:(NSString *)stringToFind {

    if (stringToFind && stringToFind.length < self) {
        return (typeof(NSNotFound))[self rangeOfString:stringToFind options:NSLiteralSearch range:NSMakeRange(0, self.length) locale:nil].location != NSNotFound;
    }
    return false;
}

附言它不检查字符串是否为 nil 或检查其长度。它确实:

- (bool)containsString:(NSString *)stringToFind {

    return (typeof(NSNotFound))[self rangeOfString:stringToFind options:NSLiteralSearch range:NSMakeRange(0, self.length) locale:nil].location != NSNotFound;
}

没有安全检查。我不知道为什么我决定添加支票但是 w/e..

Range of String 有以下组件:

Foundation`-[NSString rangeOfString:options:range:locale:]:
->  0x10a031cfd <+0>:   pushq  %rbp
    0x10a031cfe <+1>:   movq   %rsp, %rbp
    0x10a031d01 <+4>:   pushq  %r15
    0x10a031d03 <+6>:   pushq  %r14
    0x10a031d05 <+8>:   pushq  %r13
    0x10a031d07 <+10>:  pushq  %r12
    0x10a031d09 <+12>:  pushq  %rbx
    0x10a031d0a <+13>:  subq   $0x48, %rsp
    0x10a031d0e <+17>:  movq   %r9, %r15
    0x10a031d11 <+20>:  movq   %r8, %r14
    0x10a031d14 <+23>:  movq   %rcx, -0x40(%rbp)
    0x10a031d18 <+27>:  movq   %rdx, %r13
    0x10a031d1b <+30>:  movq   %rsi, -0x48(%rbp)
    0x10a031d1f <+34>:  movq   %rdi, %r12
    0x10a031d22 <+37>:  movq   0x27a317(%rip), %rsi      ; "length"
    0x10a031d29 <+44>:  movq   0x294a30(%rip), %rbx      ; (void *)0x000000010a4bb800: objc_msgSend
    0x10a031d30 <+51>:  movq   %r13, %rdi
    0x10a031d33 <+54>:  callq  *%rbx
    0x10a031d35 <+56>:  movq   %rax, -0x50(%rbp)
    0x10a031d39 <+60>:  movq   0x27a300(%rip), %rsi      ; "length"
    0x10a031d40 <+67>:  movq   %r12, %rdi
    0x10a031d43 <+70>:  callq  *%rbx
    0x10a031d45 <+72>:  movq   %rax, %rbx
    0x10a031d48 <+75>:  subq   %r15, %rax
    0x10a031d4b <+78>:  jb     0x10a031d56               ; <+89>
    0x10a031d4d <+80>:  cmpq   %r14, %rax
    0x10a031d50 <+83>:  jae    0x10a031e07               ; <+266>
    0x10a031d56 <+89>:  callq  0x10a239912               ; symbol stub for: __CFStringNoteErrors
    0x10a031d5b <+94>:  testb  %al, %al
    0x10a031d5d <+96>:  je     0x10a031e07               ; <+266>
    0x10a031d63 <+102>: movl   $0x6, %edi
    0x10a031d68 <+107>: callq  0x10a2396b4               ; symbol stub for: _CFExecutableLinkedOnOrAfter
    0x10a031d6d <+112>: testb  %al, %al
    0x10a031d6f <+114>: je     0x10a031dc5               ; <+200>
    0x10a031d71 <+116>: movq   0x281420(%rip), %rax      ; (void *)0x000000010ac5a358: NSException
    0x10a031d78 <+123>: movq   %rax, -0x58(%rbp)
    0x10a031d7c <+127>: movq   0x294325(%rip), %rax      ; (void *)0x000000010ac74b38: NSRangeException
    0x10a031d83 <+134>: movq   (%rax), %rax
    0x10a031d86 <+137>: movq   %rax, -0x60(%rbp)
    0x10a031d8a <+141>: movq   %r12, %rdi
    0x10a031d8d <+144>: movq   -0x48(%rbp), %rsi
    0x10a031d91 <+148>: callq  0x10a11f7e0               ; _NSMethodExceptionProem
    0x10a031d96 <+153>: movq   %rax, %r8
    0x10a031d99 <+156>: movq   0x27a288(%rip), %rsi      ; "raise:format:"
    0x10a031da0 <+163>: movq   %rbx, 0x8(%rsp)
    0x10a031da5 <+168>: movq   %r15, (%rsp)
    0x10a031da9 <+172>: leaq   0x2a4e40(%rip), %rcx      ; @"%@: Range {%lu, %lu} out of bounds; string length %lu"
    0x10a031db0 <+179>: xorl   %eax, %eax
    0x10a031db2 <+181>: movq   -0x58(%rbp), %rdi
    0x10a031db6 <+185>: movq   -0x60(%rbp), %rdx
    0x10a031dba <+189>: movq   %r14, %r9
    0x10a031dbd <+192>: callq  *0x29499d(%rip)           ; (void *)0x000000010a4bb800: objc_msgSend
    0x10a031dc3 <+198>: jmp    0x10a031e07               ; <+266>
    0x10a031dc5 <+200>: movb   0x29326d(%rip), %al       ; rangeOfString:options:range:locale:.warnonce
    0x10a031dcb <+206>: testb  %al, %al
    0x10a031dcd <+208>: jne    0x10a031e07               ; <+266>
    0x10a031dcf <+210>: movb   $0x1, 0x293262(%rip)      ; compare:options:range:locale:.localeClass + 7
    0x10a031dd6 <+217>: movq   %r12, %rdi
    0x10a031dd9 <+220>: movq   -0x48(%rbp), %rsi
    0x10a031ddd <+224>: callq  0x10a11f7e0               ; _NSMethodExceptionProem
    0x10a031de2 <+229>: movq   %rax, %rbx
    0x10a031de5 <+232>: movq   %r14, %rdi
    0x10a031de8 <+235>: movq   %r15, %rsi
    0x10a031deb <+238>: callq  0x10a1212f0               ; NSStringFromRange
    0x10a031df0 <+243>: movq   %rax, %rcx
    0x10a031df3 <+246>: leaq   0x2a4e36(%rip), %rdi      ; @"*** %@: Invalid range %@; this will become an exception for apps linked on SnowLeopard. Warning shown once per app execution."
    0x10a031dfa <+253>: xorl   %eax, %eax
    0x10a031dfc <+255>: movq   %rbx, %rsi
    0x10a031dff <+258>: movq   %rcx, %rdx
    0x10a031e02 <+261>: callq  0x10a06c78a               ; NSLog
    0x10a031e07 <+266>: testq  %r13, %r13
    0x10a031e0a <+269>: jne    0x10a031e5e               ; <+353>
    0x10a031e0c <+271>: callq  0x10a239912               ; symbol stub for: __CFStringNoteErrors
    0x10a031e11 <+276>: testb  %al, %al
    0x10a031e13 <+278>: je     0x10a031e5e               ; <+353>
    0x10a031e15 <+280>: movq   0x28137c(%rip), %rax      ; (void *)0x000000010ac5a358: NSException
    0x10a031e1c <+287>: movq   %rax, -0x58(%rbp)
    0x10a031e20 <+291>: movq   0x294241(%rip), %rax      ; (void *)0x000000010ac74b40: NSInvalidArgumentException
    0x10a031e27 <+298>: movq   (%rax), %rax
    0x10a031e2a <+301>: movq   %rax, -0x60(%rbp)
    0x10a031e2e <+305>: movq   %r12, %rdi
    0x10a031e31 <+308>: movq   -0x48(%rbp), %rsi
    0x10a031e35 <+312>: callq  0x10a11f7e0               ; _NSMethodExceptionProem
    0x10a031e3a <+317>: movq   %rax, %rbx
    0x10a031e3d <+320>: movq   0x27a1e4(%rip), %rsi      ; "raise:format:"
    0x10a031e44 <+327>: leaq   0x2a4dc5(%rip), %rcx      ; @"%@: nil argument"
    0x10a031e4b <+334>: xorl   %eax, %eax
    0x10a031e4d <+336>: movq   -0x58(%rbp), %rdi
    0x10a031e51 <+340>: movq   -0x60(%rbp), %rdx
    0x10a031e55 <+344>: movq   %rbx, %r8
    0x10a031e58 <+347>: callq  *0x294902(%rip)           ; (void *)0x000000010a4bb800: objc_msgSend
    0x10a031e5e <+353>: movq   0x10(%rbp), %r9
    0x10a031e62 <+357>: movq   -0x40(%rbp), %rcx
    0x10a031e66 <+361>: testb  $0x4, %ch
    0x10a031e69 <+364>: jne    0x10a031ebe               ; <+449>
    0x10a031e6b <+366>: movabsq $0x7fffffffffffffff, %rbx ; imm = 0x7FFFFFFFFFFFFFFF 
    0x10a031e75 <+376>: xorl   %edx, %edx
    0x10a031e77 <+378>: testq  %r15, %r15
    0x10a031e7a <+381>: je     0x10a031ede               ; <+481>
    0x10a031e7c <+383>: cmpq   $0x0, -0x50(%rbp)
    0x10a031e81 <+388>: je     0x10a031ede               ; <+481>
    0x10a031e83 <+390>: leaq   (,%rcx,8), %r8
    0x10a031e8b <+398>: notl   %r8d
    0x10a031e8e <+401>: andq   $0x10, %r8
    0x10a031e92 <+405>: orq    %rcx, %r8
    0x10a031e95 <+408>: leaq   -0x38(%rbp), %rax
    0x10a031e99 <+412>: movq   %rax, (%rsp)
    0x10a031e9d <+416>: movq   %r12, %rdi
    0x10a031ea0 <+419>: movq   %r13, %rsi
    0x10a031ea3 <+422>: movq   %r14, %rdx
    0x10a031ea6 <+425>: movq   %r15, %rcx
    0x10a031ea9 <+428>: callq  0x10a239354               ; symbol stub for: CFStringFindWithOptionsAndLocale
    0x10a031eae <+433>: xorl   %edx, %edx
    0x10a031eb0 <+435>: testb  %al, %al
    0x10a031eb2 <+437>: je     0x10a031ede               ; <+481>
    0x10a031eb4 <+439>: movq   -0x38(%rbp), %rbx
    0x10a031eb8 <+443>: movq   -0x30(%rbp), %rdx
    0x10a031ebc <+447>: jmp    0x10a031ede               ; <+481>
    0x10a031ebe <+449>: movq   0x27c873(%rip), %rsi      ; "_rangeOfRegularExpressionPattern:options:range:locale:"
    0x10a031ec5 <+456>: movq   %r9, (%rsp)
    0x10a031ec9 <+460>: movq   %r12, %rdi
    0x10a031ecc <+463>: movq   %r13, %rdx
    0x10a031ecf <+466>: movq   %r14, %r8
    0x10a031ed2 <+469>: movq   %r15, %r9
    0x10a031ed5 <+472>: callq  *0x294885(%rip)           ; (void *)0x000000010a4bb800: objc_msgSend
    0x10a031edb <+478>: movq   %rax, %rbx
    0x10a031ede <+481>: movq   %rbx, %rax
    0x10a031ee1 <+484>: addq   $0x48, %rsp
    0x10a031ee5 <+488>: popq   %rbx
    0x10a031ee6 <+489>: popq   %r12
    0x10a031ee8 <+491>: popq   %r13
    0x10a031eea <+493>: popq   %r14
    0x10a031eec <+495>: popq   %r15
    0x10a031eee <+497>: popq   %rbp
    0x10a031eef <+498>: retq   

它运行一个正则表达式来检查一个字符串是否有另一个字符串并且它有安全检查..