Best use of parenthesis

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;typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int i
;int A(void){return C=getchar();}int B(m s){return strlen(s)
;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\n')
;if(C<0) return 0;i=0;if(C==';'){for
(defvar q=
";typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int iY;int A(void){return C=getchar();}int B(m s){return strlen(s)Y;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\n')Y;if(C<0) return 0;i=0;if(C==';'){forY(defvar q=Y~sY;C!='\n';A()Y);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=CY;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\n')Y;b[i] = 0;return b;}typedef defvar*format;m E(void){Y;m a=R();if(!a) return 0;if(*a==34)return aY;if(*a=='#'){c[0]=a[2]=='N'?'\n':a[2];return c;}if(*a=='q')return wY;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return wY;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37Y;m s=E();s[B(s)+1]=0;s[B(s)]=34;printf(f+1,s);R()Y;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;forY(format t ;*a;a++)*a=*a==o?p:*aY;R();return r;}else if(*a=='c'){c[0]=*E()-32/*Y(substitute #\Newline (char-upcase #\y ) q= )q= );*/Y;R();return c;}else{n z=*a;int d=atoi(E()),e=atoi(E())Y;sprintf(c,y,z-'+'?z-'-'?z-'*'?d/e:d*e:d-e:d+e);R();return cY;}}return a;}int main(void){while(C+1)E();return 0;}Y"
;C!='\n';A()
);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=C
;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\n')
;b[i] = 0;return b;}typedef defvar*format;m E(void){
;m a=R();if(!a) return 0;if(*a==34)return a
;if(*a=='#'){c[0]=a[2]=='N'?'\n':a[2];return c;}if(*a=='q')return w
;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return w
;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37
;m s=E();s[B(s)+1]=0;s[B(s)]=34;printf(f+1,s);R()
;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;for
(format t ;*a;a++)*a=*a==o?p:*a
;R();return r;}else if(*a=='c'){c[0]=*E()-32/*
(substitute #\Newline (char-upcase #\y ) q= )q= );*/
;R();return c;}else{n z=*a;int d=atoi(E()),e=atoi(E())
;sprintf(c,y,z-'+'?z-'-'?z-'*'?d/e:d*e:d-e:d+e);R();return c
;}}return a;}int main(void){while(C+1)E();return 0;}

xxxxxxxxxx
 
;typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int i;int A(void){return C=getchar();}int B(m s){return strlen(s);}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\n');if(C<0) return 0;i=0;if(C==';'){for(defvar q=";typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int iY;int A(void){return C=getchar();}int B(m s){return strlen(s)Y;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\n')Y;if(C<0) return 0;i=0;if(C==';'){forY(defvar q=Y~sY;C!='\n';A()Y);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=CY;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\n')Y;b[i] = 0;return b;}typedef defvar*format;m E(void){Y;m a=R();if(!a) return 0;if(*a==34)return aY;if(*a=='#'){c[0]=a[2]=='N'?'\n':a[2];return c;}if(*a=='q')return wY;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return wY;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37Y;m s=E();s[B(s)+1]=0;s[B(s)]=34;printf(f+1,s);R()Y;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;forY(format t ;*a;a++)*a=*a==o?p:*aY;R();return r;}else if(*a=='c'){c[0]=*E()-32/*Y(substitute #\Newline (char-upcase #\y ) q= )q= );*/Y;R();return c;}else{n z=*a;int d=atoi(E()),e=atoi(E())Y;sprintf(c,y,z-'+'?z-'-'?z-'*'?d/e:d*e:d-e:d+e);R();return cY;}}return a;}int main(void){while(C+1)E();return 0;}Y";C!='\n';A());R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=C;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\n');b[i] = 0;return b;}typedef defvar*format;m E(void){;m a=R();if(!a) return 0;if(*a==34)return a;if(*a=='#'){c[0]=a[2]=='N'?'\n':a[2];return c;}if(*a=='q')return w;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return w;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37;m s=E();s[B(s)+1]=0;s[B(s)]=34;printf(f+1,s);R();}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;for(format t ;*a;a++)*a=*a==o?p:*a;R();return r;}else if(*a=='c'){c[0]=*E()-32/*(substitute #\Newline (char-upcase #\y ) q= )q= );*/;R();return c;}else{n z=*a;int d=atoi(E()),e=atoi(E());sprintf(c,y,z-'+'?z-'-'?z-'*'?d/e:d*e:d-e:d+e);R();return c;}}return a;}int main(void){while(C+1)E();return 0;}

引用元：https://www.ioccc.org/2005/mikeash/mikeash.c

審査員・作者による説明：https://www.ioccc.org/2005/mikeash/hint.text

動作

Common Lispで書かれたQuine。

$ clisp mikeash.c | diff -s - mikeash.c
Files - and mikeash.c are identical

C言語としてコンパイルすると、ものすごく制限されたCommon Lispインタプリタ風に動くバイナリになる。自分自身をCommon Lispとして実行するとQuineになる。

$ gcc -m32 mikeash.c -o mikeash

$ ./mikeash < mikeash.c | diff -s - mikeash.c
Files - and mikeash.c are identical

解説

ポインタを返すライブラリ関数が暗黙的にintを返すものと扱われることを避けるため、-m32が必要。

Common Lispのインタプリタとは言うが、作者自身が認めている通り、いろいろ不完全である。変数はqの1つしか使えない、出力の最後に必ず"をつける、fで始まる関数はすべてformatになる、など。チューリング完全かどうかもわからないとのこと。

一応、次のようなコードは動く。

$ echo '(format t "~s" (* (+ 2 2 ) (- 5 (/ 9 3 ))))' | ./mikeash
8"

コードの難読化は、そこまで難しくはないと思う。 Common Lispの変数定義の(defvar q=を、C99のfor文の初期化for(char* q="..."; ...)と重ねてあるのは面白い。

Common Lispで動かすためには#includeを書けなかったとのことだが、現代のCommon Lispでは複数行コメントを使って書けるので修正を添付する。また、Common Lispの文字列リテラルで"\n"と書くと、当時は\とnの2文字の文字列として扱われていたらしい。現代ではnの1文字の文字列として扱われるように変わっていたので、この点も適当に修正した。

パッチ

--- mikeash.c
+++ mikeash.c
@@ -1,18 +1,29 @@
+;/*
+#|
+*/
+#define _DEFAULT_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+/*
+|#
+;*/
 ;typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int i
 ;int A(void){return C=getchar();}int B(m s){return strlen(s)
 ;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\n')
 ;if(C<0) return 0;i=0;if(C==';'){for
 (defvar q=
-";typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int iY;int A(void){return C=getchar();}int B(m s){return strlen(s)Y;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\n')Y;if(C<0) return 0;i=0;if(C==';'){forY(defvar q=Y~sY;C!='\n';A()Y);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=CY;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\n')Y;b[i] = 0;return b;}typedef defvar*format;m E(void){Y;m a=R();if(!a) return 0;if(*a==34)return aY;if(*a=='#'){c[0]=a[2]=='N'?'\n':a[2];return c;}if(*a=='q')return wY;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return wY;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37Y;m s=E();s[B(s)+1]=0;s[B(s)]=34;printf(f+1,s);R()Y;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;forY(format t ;*a;a++)*a=*a==o?p:*aY;R();return r;}else if(*a=='c'){c[0]=*E()-32/*Y(substitute #\Newline (char-upcase #\y ) q= )q= );*/Y;R();return c;}else{n z=*a;int d=atoi(E()),e=atoi(E())Y;sprintf(c,y,z-'+'?z-'-'?z-'*'?d/e:d*e:d-e:d+e);R();return cY;}}return a;}int main(void){while(C+1)E();return 0;}Y"
+";/*Y#|Y*/Y#define _DEFAULT_SOURCEY#include <stdio.h>Y#include <stdlib.h>Y#include <string.h>Y#include <ctype.h>Y/*Y|#Y;*/Y;typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int iY;int A(void){return C=getchar();}int B(m s){return strlen(s)Y;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\\n')Y;if(C<0) return 0;i=0;if(C==';'){forY(defvar q=Y~sY;C!='\\n';A()Y);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=C,i-=(b[i-2]==92&&C==92)Y;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\\n')Y;b[i] = 0;return b;}typedef defvar*format;m E(void){Y;m a=R();if(!a) return 0;if(*a==34)return aY;if(*a=='#'){c[0]=a[2]=='N'?'\\n':a[2];return c;}if(*a=='q')return wY;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return wY;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37Y;m s=E();char S[2048],*P=S,*p=s;for(;*p;p++){*P++=*p;*p==92&&(*P++=92);};*P++=34;*P=0;printf(f+1,S);R()Y;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;forY(format t ;*a;a++)*a=*a==o?p:*aY;R();return r;}else if(*a=='c'){c[0]=*E()-32/*Y(substitute #\\Newline (char-upcase #\\y ) q= )q= );*/Y;R();return c;}else{n z=*a;int d=atoi(E()),e=atoi(E())Y;sprintf(c,y,z-'+'?z-'-'?z-'*'?d/e:d*e:d-e:d+e);R();return cY;}}return a;}int main(void){while(C+1)E();return 0;}Y"
 ;C!='\n';A()
-);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=C
+);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=C,i-=(b[i-2]==92&&C==92)
 ;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\n')
 ;b[i] = 0;return b;}typedef defvar*format;m E(void){
 ;m a=R();if(!a) return 0;if(*a==34)return a
 ;if(*a=='#'){c[0]=a[2]=='N'?'\n':a[2];return c;}if(*a=='q')return w
 ;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return w
 ;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37
-;m s=E();s[B(s)+1]=0;s[B(s)]=34;printf(f+1,s);R()
+;m s=E();char S[2048],*P=S,*p=s;for(;*p;p++){*P++=*p;*p==92&&(*P++=92);};*P++=34;*P=0;printf(f+1,S);R()
 ;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;for
 (format t ;*a;a++)*a=*a==o?p:*a
 ;R();return r;}else if(*a=='c'){c[0]=*E()-32/*

xxxxxxxxxx
 
--- mikeash.c+++ mikeash.c@@ -1,18 +1,29 @@+;/*+#|+*/+#define _DEFAULT_SOURCE+#include <stdio.h>+#include <stdlib.h>+#include <string.h>+#include <ctype.h>+/*+|#+;*/ ;typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int i ;int A(void){return C=getchar();}int B(m s){return strlen(s) ;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\n') ;if(C<0) return 0;i=0;if(C==';'){for (defvar q=-";typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int iY;int A(void){return C=getchar();}int B(m s){return strlen(s)Y;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\n')Y;if(C<0) return 0;i=0;if(C==';'){forY(defvar q=Y~sY;C!='\n';A()Y);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=CY;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\n')Y;b[i] = 0;return b;}typedef defvar*format;m E(void){Y;m a=R();if(!a) return 0;if(*a==34)return aY;if(*a=='#'){c[0]=a[2]=='N'?'\n':a[2];return c;}if(*a=='q')return wY;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return wY;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37Y;m s=E();s[B(s)+1]=0;s[B(s)]=34;printf(f+1,s);R()Y;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;forY(format t ;*a;a++)*a=*a==o?p:*aY;R();return r;}else if(*a=='c'){c[0]=*E()-32/*Y(substitute #\Newline (char-upcase #\y ) q= )q= );*/Y;R();return c;}else{n z=*a;int d=atoi(E()),e=atoi(E())Y;sprintf(c,y,z-'+'?z-'-'?z-'*'?d/e:d*e:d-e:d+e);R();return cY;}}return a;}int main(void){while(C+1)E();return 0;}Y"+";/*Y#|Y*/Y#define _DEFAULT_SOURCEY#include <stdio.h>Y#include <stdlib.h>Y#include <string.h>Y#include <ctype.h>Y/*Y|#Y;*/Y;typedef char n;typedef n*m;int C;n c[11];n y[]={37,100,0};n b[2048];int iY;int A(void){return C=getchar();}int B(m s){return strlen(s)Y;}n w[2048];typedef m defvar;m R(void){do A();while(isblank(C) || C == '\\n')Y;if(C<0) return 0;i=0;if(C==';'){forY(defvar q=Y~sY;C!='\\n';A()Y);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=C,i-=(b[i-2]==92&&C==92)Y;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\\n')Y;b[i] = 0;return b;}typedef defvar*format;m E(void){Y;m a=R();if(!a) return 0;if(*a==34)return aY;if(*a=='#'){c[0]=a[2]=='N'?'\\n':a[2];return c;}if(*a=='q')return wY;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return wY;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37Y;m s=E();char S[2048],*P=S,*p=s;for(;*p;p++){*P++=*p;*p==92&&(*P++=92);};*P++=34;*P=0;printf(f+1,S);R()Y;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;forY(format t ;*a;a++)*a=*a==o?p:*aY;R();return r;}else if(*a=='c'){c[0]=*E()-32/*Y(substitute #\\Newline (char-upcase #\\y ) q= )q= );*/Y;R();return c;}else{n z=*a;int d=atoi(E()),e=atoi(E())Y;sprintf(c,y,z-'+'?z-'-'?z-'*'?d/e:d*e:d-e:d+e);R();return cY;}}return a;}int main(void){while(C+1)E();return 0;}Y" ;C!='\n';A()-);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=C+);R();}else if(C=='('||C==')')b[i++]=C;else if(C==34)do b[i++]=C,i-=(b[i-2]==92&&C==92) ;while(A()!=34);else do b[i++]=C;while(!isblank(A())&&C!='\n') ;b[i] = 0;return b;}typedef defvar*format;m E(void){ ;m a=R();if(!a) return 0;if(*a==34)return a ;if(*a=='#'){c[0]=a[2]=='N'?'\n':a[2];return c;}if(*a=='q')return w ;if(*a=='('){a=R();if(*a=='d'){R();strcpy(w,E());R();return w ;}else if(*a=='f'){R();m f = strdup(E());*strchr(f,126)=37-;m s=E();s[B(s)+1]=0;s[B(s)]=34;printf(f+1,s);R()+;m s=E();char S[2048],*P=S,*p=s;for(;*p;p++){*P++=*p;*p==92&&(*P++=92);};*P++=34;*P=0;printf(f+1,S);R() ;}else if(*a=='s'){n p=*E();n o=*E();m r=strdup(E());a=r;for (format t ;*a;a++)*a=*a==o?p:*a ;R();return r;}else if(*a=='c'){c[0]=*E()-32/*

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