Input ∩ Source Code

Question

Intro

The challenge is to create a program/function that prints the intersection of its own source code and a given string input. This is code golf and to be more precise:

• Let I be the input set
  • {"a","b","c"}
• Let S be the source code set
  • {"b","f"}
• Then the intersection is what they share
  • I ∩ S = {"b"}

Input

Input is flexible. It should be able to handle the character encoding used for the source code.

Output

Output is flexible. It should be the set of characters that the input and source code share. Also, sets are unordered collections of distinct objects. In summary:

• Output is flexible:
  • Could be any data structure (string or otherwise)
  • Could unordered
  • Could have a trailing \n
  • Should be distinct

Restriction

Similar to quine challenges, the program/function may not read its own source code and 0-byte solutions are not allowed.

Examples

• #1

functor x(I){ return I ∩ self; }

Inputs                                Outputs
------                                -------
enter preformatted text here      ->  {"e","n","t","r","f","o","x"}

["Albrt"," Einstin"]              ->  {"l","r","t","n","s"}

• #2

(_)->_&"(_)->&\"\\"

Inputs                                Outputs
------                                -------
"Security at the expense of       ->  "
usability comes at the expense 
of security."

(0____0)                          ->  (_)

• #3

ಠa益длф


Inputs                                Outputs
------                                -------
Far out in the uncharted backwaters ->"a"    
of the unfashionable end of the 
Western Spiral arm of the Galaxy lies 
a small unregarded yellow sun. 
Orbiting this at a distance of roughly 
ninety-eight million miles is an 
utterly insignificant little blue-green 
planet whose ape-descended life forms 
are so amazingly primitive that they 
still think digital watches are a pretty 
neat idea.

(ノಠ益ಠ)ノ彡┻━┻                      ->"ಠ益"

Test Cases

Albert Einstein

\__( O__O)_/

!@#$%^&*()_+{}|:"<>?

1234567890-=[]\;',./

(ノಠ益ಠ)ノ彡┻━┻

“¤>%,oỊȤʠ“ØụĊ5D³ṃṠɼQ»j;Ç;“;}¶”

┬──┬ ノ( ゜-゜ノ)

Far out in the uncharted backwaters of the unfashionable end of the Western Spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-eight million miles is an utterly insignificant little blue-green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.

Update

• [16-08-10]: sets are unordered collections of distinct objects
• [16-08-10]: trailing newline is acceptable

Answer 1

Pyth, 6 8 Bytes

{@"{@\"\

Expects input as a string.

Try it online!

Explanation:

 @     Q    Intersect implied input with:
  "{@\"\     The string containing {@"\
{          and then remove duplicates.

Answer 2

q (38 bytes)

Reads from stdin

"readint0\\\" "inter read0 0

edit: was missing backslash

Answer 3

MATLAB, 32 bytes

@(t)intersect(t,'@(t)inersc,''')

Essentially the same as Stewie Griffin's approach (the intersect built-in is hard to avoid), but this edition saves an entire 5 bytes over his by taking the input as an anonymous function, with the variable name t chosen to occur within intersect (any other character in that string would have done as well). Call as ans('yourInput').

Answer 4

Java 8, 131 129 131 bytes

a->{java.util.Set r=new java.util.HashSet();for(String s:a)if("a->{jv.utilSe r=nwHsh();fog:\"\\cd}".contains(s))r.add(s);return r;}

+2 bytes again due to a bug-fix

Explanation:

Try it here.

a->{                    // Method with String-array parameter and Set return-type
  java.util.Set r=new java.util.HashSet();
                        //  The result Set
  for(String s:a)       //  Loop over the input String-array
    if("a->{jv.utilSe r=nwHsh();fog:\"\\cd}".contains(s))
                        //   If the current character is part of the source-code:
      r.add(s);         //    Add it to the Set
                        //  End of loop (implicit / single-line body)
  return r;             //  Return the result-Set
}                       // End of method

Answer 5

Brachylog (newer), 18 bytes

{∈"{∈\\\"&}ˢd"&}ˢd

Try it online!

It's this plus the de-duplication predicate. Doesn't necessarily beat Fatalize's solution since his is in an older and very different version of the language.

Answer 6

Perl 6, 38 bytes

<say .comb∩$*IN.comb#<>~EVAL>~~.EVAL

Try it online!

The generalised quine still manages to beat out the trivial program by a few bytes

Perl 6, 41 bytes

say <$*. <>INabcmosy∩>.comb∩$*IN.comb

Try it online!

Answer 7

W, 12 bytes

34C+t"34C+tt

Explanation

34C+t"       % Everyone in the execution sequence excluding a quote
      34C+   % Add a (") quote
          t  % Trim out everything in this string in input
           t % Trim the string so that the intersection is kept

Answer 8

Python 3, 33 bytes

lambda a:{*"\"\lambd* :{}&"}&{*a}

Try it online!

Answer 9

Python, 48 bytes

First thing I though of. It can probably be golfed more.

Input comes from sdtin. Output goes to stdout as a set object

print set(raw_input())&set("raw_pint se(u)\&\"")

Answer 10

PHP, 61 bytes

<?=preg_filter("_<\?=[aefiglprtv$(\_[\],)\\;1\"]_",$argv[1]);

takes input from first command line argument.

no regex, 74 bytes

for(;""<$c=$argv[1][$i++];)if(strstr("aceghiosrtv()$<=[1]\;\"",$c))echo$c;

takes input from first command line argument. Run with -nr.

Note: ; needs no escaping; so PHP takes the backslash before the semicolon literally.

Answer 11

Java (OpenJDK 8), 58 bytes

s->s.filter("s->.filter(\"\\:cona)d"::contains).distinct()

Try it online!

Accepts the input as Stream<String>, whereas each character of the input is a stream element, and returns a filtered, distinct stream.

Answer 12

Lua, 91 bytes

Old challenge, but still lacking a Lua solution, so...

s=...(" s=.(\\\"):gub,fnctiod1awre"):gsub(".",function(c)c=s:find(c,1,1)and io.write(c)end)

Try it online!

Answer 13

J, 18 bytes

'''&()[-.'&([-.-.)

How it works

 ''&()[-.           the character set, '' stands for '
          &         is the left operand
           ([    )  the set> itself, ignore <the input
           (   -.)  the set> except any characters in <the input
                      (the wrong ones remain)
           ( -.  )  the set itself> except <the wrong characters

Try it online!

Answer 14

Husk, 7 bytes

n"n\\\"

Try it online!

n          The intersection of
 "n\\\"    the string n, \, "
           with the input.

I tried to work around having to escape the quote with a backslash, but that just made it longer:

Husk, 8 bytes

n:'""n:'

Try it online!

n         The intersection of
  '"      the character "
 :        prepended to
  "n:'    the string n, :, '
          with the input.

Another attempt to eliminate backslashes, which would be two bytes shorter if it didn't need to remove duplicates:

Husk, 7 bytes

uns"nsu

Try it online!

u          Without duplicate elements,
 n         the intersection of
  s        the string representation of
   "nsu    the string n, s, u
           with the input.

Answer 15

Burlesque, 10 bytes

#QupIN#Qvv

Try it online!

Turns out the lazy way worse than doing it generally because I can't get a quote within a quote nicely. "IN_+"'"_+IN

#Q  #Push the code onto the stack
up  #Convert to string
IN  #Intersection
#Q  #Make sure a #Q is captured
vv  #Drop the resulting push

Answer 16

brainfuck, 150 bytes

,[[>+>+<<-]>>[-[->>+<<]+>>]+>+[--<[-<<]>.>+>[-]]-<[-<<]>[-]<,] !"#$%&'()*/0123456789:;=?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\\^_`abcdefghijklmnopqrstuvwxyz{|}~

Try it online!

Support 32-126

main code(set remove dup) 62

Answer 17

Japt v2.0a0, 15 13 bytes

My very first "proper" quine. At long fecking last!

oQ+"oQ+ â"Q â

Try it

oQ+"..."Q â     :Implicit input of string
o               :Keep only those characters that appear in
 Q              :  Quotation mark
  +"..."        :  Append literal string
        Q       :  Passed as a second argument to the o method to disable the case insensitive flag (any truthy value would work)
          â     :Deduplicate