Simple golfing interpreter

Question

Challenge:

Your job is to create a simple interpreter for a simple golfing language.

---

Input:

Input will be in the form of string separated by spaces.

You can replace space separation with what you want

---

Output:

Output the result (a number or a string) obtained after performing all operations. If there are more than one output join the together to give a single result (no separators). The variable's initial value is always zero. i.e: It start at 0

---

Language Syntax :

The language has following operators :

inc  ---> add one to variable
dec  ---> remove one from variable
mult ---> multiply variable by 2
half ---> divide the variable by 2
Pri  ---> print the variable to console (or whatever your language has)
exit ---> end the program (anything after this is ignored)

---

Examples:

inc inc inc dec Pri exit                 ---> 2
dec inc mult inc inc Pri                 ---> 2
inc inc inc mult half Pri exit inc       ---> 3
inc Pri inc Pri inc Pri exit half mult   ---> 123
Pri exit                                 ---> 0
inc half Pri exit                        ---> 0.5 

---

Restriction:

This is code-golf so shortest code in bytes for each language will win.

---

Note:

• Input will always be valid . (string of operators separated with space)
• You can round down to nearest integer if you don't want decimal places.

Answer 1

shell + sed + dc, 56 61 bytes

sed '1i0
s/.//2g;y"idmhe"+-*/q";i1
/[*/]/i1+
/P/crdn'|dc

Try it online!

Converts the program into a dc program, then evaluates it as dc code. This takes the input separated by newlines. Note that dc is stack-based and uses reverse polish notation, so 5 2- gives 3, and numbers are always rounded down.

The input is first piped to sed

1i0 on the first line of input, insert (prepend) a 0, this will be the accumulator

s/.//2g remove everything but the first character on each line

y"idmhe"+-*/q" transliterate idmhe into +-*/q respectively, + - * / are the arithmetic commands and q quits the program

i1 on every line insert a 1 - this satisfies addition and subtraction

/[*/]/ on every line containing * or /, i1+ additionally insert 1+ because of the preceding 1, which dc will eventually evaluate into 2

/P/ on every line containing P, crdn change it into rdn, equivalent to reverse the top two elements, to rid the inserted 1, and duplicate and output as a number without newline (whilst popping it, hence the earlier duplicate) in dc

Now this is evaluated as a dc expression.

Answer 2

Jelly, 21 bytes

ḲḢ€O%11ị⁾’‘j“IȮḤH”¤VI

Try it online!

---

Note that the ASCII values of the first characters (idmhPe) modulo 11 are unique modulo 6.

---

Using modulo 16:

Jelly, 21 bytes

ḲḢ€O%⁴ị“ḢwġḞkz’ṃØJ¤VI

Try it online!

The string that is used to index into is ḤH‘’IȮ in this case. The ‘’ are no longer on the boundaries.

Answer 3

R, 128 125 bytes

Reduce(function(x,y)switch(y,i=x+1,d=x-1,m=x*2,h=x/2,P={cat(x);x}),substr(el(strsplit(gsub("e.*$","",scan(,""))," ")),1,1),0)

Try it online!

Must be called with source(echo=FALSE) to prevent the return value from being printed automatically. The alternative would be to wrap everything in invisible but that's much less golfy (and ruins my [still] nice byte count).

Answer 4

05AB1E, 25 bytes

΀¬"idmhPe"S"><·;=q"S‡J.V

Try it online!

Maps each of the language function with the corresponding 05AB1E function (using the first char of each function), and then executes the resulting string as 05AB1E code.

Answer 5

Python 3, 110 91 82 bytes

exit will cause the program to exit with an error.

x=0
for c in input():c=='P'==print(x,end='');x+=(1,-1,x,-x/2,c,0)['ndmhx'.find(c)]

Try it online!

Answer 6

Red, 121 bytes

func[s][v: 0 parse s[any[["i"(v: v + 1)|"d"(v: v - 1)|"m"(v: v * 2)|"h"(v: v / 2.0)|"P"(prin v)|"e"(exit)]thru" "| end]]]

Try it online!

Readable:

f: func [s] [
    v: 0
    parse s [
        any [
            [ "i" (v: v + 1)
            | "d" (v: v - 1)
            | "m" (v: v * 2)
            | "h" (v: v / 2.0)
            | "P" (prin v)
            | "e" (exit)]
            thru [" " | end]
        ]
    ]
] 

Answer 7

Python 2, 131 125 122 121 118 117 115 bytes

v=0;o=""
for x in input().split("x")[0].split():
 if"Q">x:o+=`v`
 else:v+=(1,-1,v,-v/2.)['idmh'.find(x[0])]
print o

Try it online!

-6 and -3 with thanks to @Rod

-3 and -2 with thanks to @etene

-1 by replacing "Pri"==x with "P"in x

Answer 8

JavaScript (ES6), 83 79 bytes

Saved 4 bytes thanks to @l4m2

Iteratively replaces the instructions with either the output or empty strings.

s=>s.replace(/\S+./g,w=>m<s?'':w<{}?m:(m+={d:-1,e:w,i:1,m}[w[0]]||-m/2,''),m=0)

Try it online!

Commented

s =>                       // given the input string s
  s.replace(/\S+./g, w =>  // for each word w in s:
    m < s ?                //   if m is a string:
      ''                   //     ignore this instruction
    :                      //   else:
      w < {} ?             //     if w is 'Pri' ({} is coerced to '[object Object]'):
        m                  //       output the current value of m
      : (                  //     else:
          m +=             //       add to m:
            { d: -1,       //         -1 if w is 'dec'
              e: w,        //         w  if w is 'exit' (which turns m into a string)
              i: 1,        //         1  if w is 'inc'
              m            //         m  if w is 'mult'
            }[w[0]]        //       using the first character of w to decide
            || -m / 2,     //       or add -m/2 (for 'half') if the above result was falsy
        ''),               //       do not output anything
    m = 0                  //   m = unique register of our mighty CPU, initialized to 0
  )                        // end of replace()

Answer 9

Charcoal, 37 35 bytes

≔⁰ηＦ⎇№θx…θ⌕θxθ≡ιn≦⊕ηd≦⊖ηm≦⊗ηh≦⊘ηrＩη

Try it online! Link is to verbose version of code. Inspired by @RickHitchcock's answer. Explanation:

≔⁰η

Clear the variable.

Ｆ⎇№θx…θ⌕θxθ≡ι

Truncate the input at the x if there is one, then loop over and switch on each character of (the remainder of) the input.

n≦⊕η

n increments the variable.

d≦⊖η

d decrements the variable.

m≦⊗η

m multiplies the variable by two (i.e. doubles).

h≦⊘η

h halves the variable.

rＩη

r prints the variable cast to string.

Answer 10

JavaScript (ES6), 77 75 bytes

(Borrowed (stole) @Arnauld's trick of using m as the variable name, saving 2 bytes.)

f=([c,...s],m=0)=>c<'x'?(c=='P'?m:'')+f(s,m+({h:-m/2,d:-1,n:1,m}[c]||0)):''

Recursively walks the string, looking for distinct letters per instruction and ignoring the rest:

• n: inc
• d: dec
• m: mult
• h: half
• P: Pri
• x: exit

Takes advantage of the fact that undefined is neither greater than nor less than 'x', causing the recursion to stop at the end of the string or when it encounters the 'x' in exit.

f=([c,...s],n=0)=>c<'x'?(c=='P'?n:'')+f(s,n+({h:-n/2,d:-1,n:1,m}[c]||0)):''

console.log(f('inc inc inc dec Pri exit'));                 //--> 2
console.log(f('dec inc mult inc inc Pri'));                 //--> 2
console.log(f('inc inc inc mult half Pri exit inc'));       //--> 3
console.log(f('inc Pri inc Pri inc Pri exit half mult'));   //--> 123
console.log(f('Pri exit'));                                 //--> 0
console.log(f('inc half Pri exit'));                        //--> 0.5 

Answer 11

JavaScript (Node.js), 107 bytes

f=s=>s.split` `.map(([o])=>F?0:o=="i"?i++:o=="d"?i--:o=="m"?i*=2:o=="h"?i/=2:o=="P"?S+=i:F=1,F=i=0,S="")&&S

Try it online!

Answer 12

JavaScript (Node.js), 91 bytes

_=>_.split` `.map(o=>o<{}>!_?S+=+i:o<"e"?i--:o<"f"?++_:o<"i"?i/=2:o<"j"?i++:i*=2,i=S="")&&S

Try it online!

JavaScript (Node.js), 96 bytes

_=>_.split` `.map(o=>F?0:o<"Q"?S+=i:o<"e"?i--:o<"f"?F=1:o<"i"?i/=2:o<"j"?i++:i*=2,F=i=0,S="")&&S

Try it online!

JavaScript (Node.js), 99 bytes

s=>s.split` `.map(_=>eval('++i7--i7++e7u+=+i7i*=27i/=2'.split(7)[Buffer(e+_)[0]%11%6]),e=i=u='')&&u

Try it online!

Answer 13

JavaScript, 107 bytes

s=>eval('x=0;x'+(s.split` `.map(v=>({i:"++",d:"--",m:"*=2",h:"/=2",P:";alert(x)",e:"//"})[v[0]]).join`;x`))

Answer 14

Haskell, 93 bytes

(0!)
a!(c:t)|c=='P'=show a++a!t|c>'w'=""|1<2=(a+sum(lookup c$zip"ndmh"[1,-1,a,-a/2]))!t;a!e=e

Try it online!

Essentially a translation of mbomb007's Python answer.

Answer 15

Lua, 207 bytes

s=0;n=0;for a in io.read():gmatch'.'do if s==0 then s=1;n=a=='i'and n+1 or a=='d'and n-1 or a=='m'and n*2 or a=='h'and n/2 or n;if a=='P'then print(n)elseif a=="e"then break end elseif a==' 'then s=0 end end

Answer 16

Python 3, 114 110 109 116 bytes

Actually would have taken two bytes less in Python 2 because exec is a statement and doesn't need parentheses...

• Saved 4 extra bytes thanks to @ElPedro

• Saved an extra byte by taking advantage of the fact that find returns -1 on error, which can then be used as an index

• +7 bytes because I hadn't noticed the no-newlines rule :(

i=0;exec(";".join("i+=1 i-=1 i*=2 i/=2 print(i,end='') exit()".split()["idmhP".find(h[0])]for h in input().split()))

Try it online!

Maps the first character of every input word to a piece of Python code. These are then concatenated and execed.

Pretty straightforward approach, that could probably be golfed a bit more. The difficulty mostly resides in finding the shortest form out of many possible ones...

Answer 17

Ruby + -na, 81 73 65 bytes

x=0;$F.map{|w|eval %w{x+=1 x-=1 1/0 $><<x x*=2 x/=2}[w.ord%11%6]}

Try it online!

Pretty straightforward. For the first letter of each word, find the corresponding command string and eval it. Uses integer division, and exits by throwing a ZeroDivisionError.

-5 bytes: Use .ord%11%6 instead of a string lookup. Credit goes to user202729

-3 bytes: .ord only considers the first character of the string, so I can skip a [0].

-8 bytes: Use -a flag to automatically split input, thanks to Kirill L.

Answer 18

Emojicode, 270 bytes

🐖🔥🍇🍮c 0🔂j🍡💣🐕🔟 🍇🍊😛j🔤inc🔤🍇🍮c➕c 1🍉🍋😛j🔤dec🔤🍇🍮c➖c 1🍉🍋😛j🔤mult🔤🍇🍮c✖️c 2🍉🍋😛j🔤half🔤🍇🍮c➗c 2🍉🍋😛j🔤Pri🔤🍇👄🔡c 10🍉🍓🍇🍎🍉🍉🍉

Try it online!

🐋🔡🍇
🐖🔥🍇
🍮c 0
🔂j🍡💣🐕🔟 🍇
🍊😛j🔤inc🔤🍇🍮c➕c 1🍉
🍋😛j🔤dec🔤🍇🍮c➖c 1🍉
🍋😛j🔤mult🔤🍇🍮c✖️c 2🍉
🍋😛j🔤half🔤🍇🍮c➗c 2🍉
🍋😛j🔤Pri🔤🍇👄🔡c 10🍉
🍓🍇🍎🍉🍉🍉🍉

🏁🍇
 🔥🔤inc inc inc dec Pri exit🔤
😀🔤🔤
 🔥🔤dec inc mult inc inc Pri🔤
😀🔤🔤
 🔥🔤inc inc inc mult half Pri exit inc🔤
😀🔤🔤
 🔥🔤inc Pri inc Pri inc Pri exit half mult🔤
😀🔤🔤
 🔥🔤Pri exit🔤
😀🔤🔤
 🔥🔤inc half Pri exit🔤
🍉

Answer 19

SNOBOL4 (CSNOBOL4), 165 bytes

	P =INPUT ' exit ' 
	x =0
S	P LEN(1) $ L ARB ' ' REM . P	:S($L)F(end)
i	X =X + 1	:(S)
d	X =X - 1	:(S)
P	O =O X		:(S)
m	X =X * 2	:(S)
h	X =X / 2.	:(S)
e	OUTPUT =O
END

Try it online!

Gross.

	P =INPUT ' exit ' 				;* append ' exit ' to the input to guarantee that the program will stop
	x =0						;* initialize x to 0 else it won't print properly if the program is 'Pri'
S	P LEN(1) $ L ARB ' ' REM . P	:S($L)F(end)	;* set L to the first letter of the word and goto the appropriate label
i	X =X + 1	:(S)
d	X =X - 1	:(S)
P	O =O X		:(S)				;* append X to the output string
m	X =X * 2	:(S)
h	X =X / 2.	:(S)				;* divide by 2. to ensure floating point
e	OUTPUT =O					;* print whatever's in O, which starts off as ''
END

Answer 20

C# (.NET Core), 186 Bytes

class P{static void Main(string[]a){int v=0;foreach(var s in a){var i=s[0];if(i=='i')v++;if(i=='d')v--;if(i=='m')v*=2;if(i=='h')v/=2;if(i=='P')System.Console.Write(v);if(i=='e')break;}}}

Answer 21

Perl 5 -a, 61 bytes

eval'$,'.qw(++ -- ;exit ;print$,||0 *=2 /=2)[(ord)%11%6]for@F

Try it online!

Stole @user202729's ord%11%6 trick

How?

-a            # split the input by whitespace, store in @F
eval          # Execute the string that results from:
'$,'          # $, (the accumulator)
.             # appending:
qw(           # create an array for the following whitespace separated values:
++ --            # operators for inc & dec
;exit            # exit
;print$,||0      # Pri  (||0 ensures that 0 is output if accumulator is null
*=2 /=2)         # mult div
[(ord)%11%6] # @user202729's trick selects one of the preceding operations
for@F        # for every term input

Answer 22

Pyth, 44 Bytes

Vmx"idmhPe"hdcwd=Z@[hZtZyZcZ2ZZ)NIqN4pZIqN6B

Test Suite

explanation

Vmx"idmhPe"hdcwd=Z@[hZtZyZcZ2ZZ)NIqN4pZIqN6B   ## full program
             cwd                               ## split input on space
Vmx"idmhPe"hd                                  ## iterate through list of numbers corresponding to operators
                =Z@[hZtZyZcZ2ZZ)N              ## assign the variable Z (initialliy Zero) it's new value
                                 IqN4pZ        ## print Z if the current operator is "Pri" (4)
                                       IqN6B   ## break if the current operator is "exit" (5)

Answer 23

TI-BASIC, 112 bytes

This takes advantage of some assumptions that are AFAIK perfectly acceptable. Number one being that all variables are initialized to zero prior to execution; number two being that input is taken via Ans.

Ans+" E→Str1
While 1
I+4→I
sub(Str1,I-3,1→Str2
A+(Ans="I")-(Ans="D
If inString("MH",Str2
Then
I+1→I
2AAns+A/2(1-Ans
End
If Str2="P
Disp A
If Str2="E
Stop
Ans→A
End

Answer 24

Java (OpenJDK 8), 164 bytes

a->{int c=0;for(String g:a.split(" ")){char b=g.charAt(0);if(b==105)c++;if(b==100)c--;if(b==109)c*=2;if(b==104)c/=2;if(b==80)System.out.print(c);if(b==101)return;}}

Try it online!

Above is my solution that rounds off to integers, but below is my solution that handles decimals. The obnoxious way that java prints doubles adds another 55 byes to the score. I left the new lines to make the code more readable in the second submission only because it’s essentially the same solution with one extra command and an import statement.

Java (OpenJDK 8), 219 bytes

a->{
double c=0;
for(String g:a.split(" ")){
char b=g.charAt(0);
if(b==105)c++;
if(b==100)c--;
if(b==109)c*=2;
if(b==104)c/=2;
if(b==80)System.out.print(new DecimalFormat("0.#").format(c));
if(b==101)return;}}

Try it online!

Answer 25

C (gcc), 120 114 111 bytes

-6 bytes thanks to ceilingcat.

x,d;f(char*s){for(x=0;s>1;s=index(d^1?s:"",32)+1)d=*s-100,x+=d?d==5:-1,x*=d^9?d^4?1:.5:2,d+20||printf("%d",x);}

Try it online!

124 bytes

Floating-point version:

d;f(char*s){for(float f=0;s>1;s=strchr(s,32)+1)d=*s-80,f+=d==25,f-=d==20,f*=d^29?d^24?1:.5:2,s=d^21?s:"",d?:printf("%f",f);}

Try it online!

I did not bother with a version that rounds down, but makes an exception for 0, which would be allowed, if I understand the comment-chain correctly.

Answer 26

33, 62 bytes

s'i'{1a}'d'{1m}'m'{2x}'h'{2d}'P'{o}'e'{@}It[mzsjk""ltqztItn1a]

Try it online!

This program takes the instructions delimited by newlines

Explanation:

It[mzsjk""ltqztItn1a]
  [mz            n1a] | Forever
It    jk       It     | - Get the first character of the next instruction
            qz        | - Call the function declared previously
     s  ""lt  t       | - Make sure we don't lose track of the variable

The code before that segment defines all the functions.

Answer 27

JavaScript (V8), 152 bytes

i=>{return n="",p=0,e=1,i.split(" ").map(i=>{e&&("inc"==i&&p++,"dec"==i&&p--,"mult"==i&&(p*=2),"half"==i&&(p/=2),"Pri"==i&&(n+=p),"exit"==i&&(e=0))}),n}

Try it online!