Indent a string using given parentheses

Question

Given the following input to the program:

1. List of block start characters
2. List of block end characters
3. A string to format

format the string with the blocks delimited by the two character sets indented.

Formatting is done with two spaces per level and the parentheses are placed as shown in the example below. You may assume the sets of opening and closing characters to be disjoint.

E.g. for {[(< and }])> as the opening and closing character sets and the following string:

abc{xyz{text[note{comment(t{ex}t)abc}]}}

the following output would be expected:

abc
{
  xyz
  {
    text
    [
      note
      {
        comment
        (
          t
          {
            ex
          }
          t
        )
        abc
      }
    ]
  }
}

You may not hard-code the list of “parentheses” characters. How input is given is not specified, though; this could be either command-line arguments or via standard input, as you wish.

Answer 1

Perl - 131 96 94 chars

$i="";for$_(split/([\Q$ARGV[0]$ARGV[1]\E])/,$ARGV[2]){$i=~s/..// if/[\Q$ARGV[1]\E]/;print "$i$_\n"if$_;$i.='  'if/[\Q$ARGV[0]\E]/;}

Seems like there should be room for eliminating common expressions, at least, but it's a quick take that handles the example, as well as Joey Adams's hypothetical about arbitrary brackets.

---

There was, indeed, plenty of room for improvement:

$_=pop;($s,$e)=map"[\Q$_\E]",@ARGV;for(split/($s|$e)/){print"  "x($i-=/$e/),"$_\n"if$_;$i+=/$s/}

---

...and still a little more:

$_=pop;($s,$e)=map"[\Q$_\E]",@ARGV;map{print"  "x($i-=/$e/),"$_\n"if$_;$i+=/$s/}split/($s|$e)/

Answer 2

Ruby, 106 101 96 95

s,e,i=$*
i.scan(/[#{z=Regexp.quote s+e}]|[^#{z}]*/){|l|puts'  '*(s[l]?~-$.+=1:e[l]?$.-=1:$.)+l}

Input is provided via the command line.

Answer 3

JavaScript, 255 227 205 characters

Hey, its length fits perfectly in a byte! :D

function(s,e,t){R=eval.bind(0,"Array(n).join(' ')");for(i=n=0,b=r='';c=t[i++];)~s.indexOf(c)?(r+=b,b='\n'+R(++n)+c+'\n '+R(++n)):~e.indexOf(c)?b+='\n'+((n-=2)?R()+' ':'')+c+'\n'+(n?R()+' ':''):b+=c;return r+b}

It's a function, pass it the start characters, the end characters, then the text.

Answer 4

Mathematica (non code golf)

indent[str_String]:=Module[{ind,indent,f},
ind=0;
indent[i_]:="\n"<>Nest["    "<>ToString[#]&,"",i];
f[c_] :=  (indent[ind] <> c <> indent[++ind]) /; StringMatchQ["[({",___~~c~~___];
f[c_] := ( indent[--ind] <> c <>indent[ind])  /; StringMatchQ["])}",___~~c~~___];
f[c_] := (c <>indent[ind])       /; StringMatchQ[";,",___~~c~~___];
f[c_] := c  ;
f /@ Characters@ str//StringJoin
]

Test

indent["abc{xyz{text[note{comment(t{ex}t)abc}]}}"]
abc
{
    xyz
    {
        text
        [
            note
            {
                comment
                (
                    t
                    {
                        ex
                    }
                    t
                )
                abc
            }

        ]

    }

}

As a bonus, following function can be used to format mathematica expression

format[expr_] := indent[expr // FullForm // ToString]

---

EDIT(non code golf) Updated with fine granular control over the way newlines are rendered

indent[str_String, ob_String, cb_String, delim_String] := 
  Module[{ind, indent, f, tab}, ind = 0; tab = "    ";
   indent[i_, tab_, nl_] := nl <> Nest[tab <> ToString[#] &, "", i];
   f[c_] := (indent[ind, "", " "] <> c <> indent[++ind, tab, "\n"]) /;StringMatchQ[ob, ___ ~~ c ~~ ___];
   f[c_] := (indent[--ind, "", " "] <> c <> indent[ind, tab, "\n"]) /;StringMatchQ[cb, ___ ~~ c ~~ ___];
   f[c_] := (c <> indent[ind, tab, "\n"]) /;StringMatchQ[delim, ___ ~~ c ~~ ___];
   f[c_] := c;
   f /@ Characters@str // StringJoin];
format[expr_] := indent[expr // InputForm // ToString, "[({", "])}", ";"];

format[Hold@Module[{ind, indent, f, tab}, ind = 0; tab = "    ";
 indent[i_, tab_, nl_] := nl <> Nest[tab <> ToString[#] &, "", i];
 f[c_] := (indent[ind, "", " "] <> c <> indent[++ind, tab, "\n"]) /;StringMatchQ[ob, ___ ~~ c ~~ ___];
 f[c_] := (indent[--ind, "", " "] <> c <> indent[ind, tab, "\n"]) /;StringMatchQ[cb, ___ ~~ c ~~ ___];
 f[c_] := (c <> indent[ind, tab, "\n"]) /;StringMatchQ[delim, ___ ~~ c ~~ ___];
 f[c_] := c;
 f /@ Characters@str // StringJoin]]

Output

Hold [
    Module [
         {
            ind, indent, f, tab }
        , ind = 0;
         tab = "    ";
         indent [
            i_, tab_, nl_ ]
         := StringJoin [
            nl, Nest [
                StringJoin [
                    tab, ToString [
                        #1 ]
                     ]
                 & , "", i ]
             ]
        ;
         f [
            c_ ]
         := StringJoin [
            indent [
                ind, "", " " ]
            , c, indent [
                ++ind, tab, "\n" ]
             ]
         /;
         StringMatchQ [
            ob, ___~~c~~___ ]
        ;
         f [
            c_ ]
         := StringJoin [
            indent [
                --ind, "", " " ]
            , c, indent [
                ind, tab, "\n" ]
             ]
         /;
         StringMatchQ [
            cb, ___~~c~~___ ]
        ;
         f [
            c_ ]
         := StringJoin [
            c, indent [
                ind, tab, "\n" ]
             ]
         /;
         StringMatchQ [
            delim, ___~~c~~___ ]
        ;
         f [
            c_ ]
         := c;
         StringJoin [
            f / @
                 Characters [
                    str ]
                 ]
             ]
         ]

Answer 5

C - 213 209

^{I hate stupid mistakes... >.<}

#include<stdio.h>
#include<string.h>
int main(int i,char**s){for(char q,r,c,t,a=0;~(c=getchar());t=q|r){q=!!strchr(s[1],c);a-=r=!!strchr(s[2],c);for(i=0;t|q|r&&i<2*a+1;putchar(i++?' ':'\n'));a+=q;putchar(c);}}

Reads left-parens from first command-line argument, right-parens from second argument, and input to indent on stdin.

Pretty-printed & commented:

int main(int i, char **s) {
  for (char q, r, /* is left-paren? is right-paren? */
            c,    /* character read from input */
            t,    /* last char was a paren-char */
            a=0;  /* indentation */
       ~(c = getchar());
       t = q|r) {
         q = !!strchr(s[1],c);
    a -= r = !!strchr(s[2],c);
    for (i=0; t|q|r && i<2*a+1; putchar(i++? ' ' : '\n'));
    a += q;
    putchar(c);
  }
}

Answer 6

Python – 162 chars

i=f=0
s=""
l,r,z=[raw_input()for c in'   ']
o=lambda:s+("\n"+"  "*i)*f+c
for c in z:
 if c in l:f=1;s=o();i+=1
 elif c in r:i-=1;f=1;s=o()
 else:s=o();f=0
print s

Answer 7

Python 2.7.X - 136 chars

import sys
a,c=sys.argv,0
for i in a[3]:
 if not(i in a[2]):print ' '*c+i
 else:print ' '*(c-4)+i
 if i in a[1]:c+=4
 if i in a[2]:c-=4

Usage : $ ./foo.py '(' ')' '(ab(cd(ef)gh)ij)'

Resulting Output:

(
    a
    b
    (
        c
        d
        (
            e
            f
        )
        g
        h
    )
    i
    j
)

Answer 8

Groovy, 125

p=args;i=0;s={a,b->"\n"+"\t"*(b?i++:--i)+a+"\n"+"\t"*i};p[0].each{c->print p[1].contains(c)?s(c,1):p[2].contains(c)?s(c,0):c}

You can save the script in a file indent.groovy and try it with:
groovy indent.groovy "abc{xyz{text[note{comment(t{ex}t)abc}]}}" "{[(" ")]}"

Answer 9

Python - 407

from sys import*;o=argv[1];c=argv[2];t=argv[3];p=0;n=False;a=lambda:h not in e;b=lambda s:print(s+(" "*p)+h);r="";e=o+c
for h in t:
 for k in o:
  if h==k:
   if(r in e)and(r!=""):b("")
   else:b("\n")
   p+=2;n=True;break
 for k in c:
  if h==k:
   p-=2
   if(r in e)and(r!=""):b("")
   else:b("\n")
   n=True;break
 if a()and n:print((" "*p)+h,end="");n=False
 elif a():print(h,end="")
 r=h

An ungolfed version of the program:

import sys

open_set = sys.argv[1]
close_set = sys.argv[2]
text = sys.argv[3]
spaces = 0
newline = False
a = lambda : char not in b_set
b = lambda s: print(s + (" " * spaces) + char)
prev = ""
b_set = open_set + close_set

for char in text:
    for bracket in open_set:
        if char == bracket:
            if (prev in b_set) and (prev != ""):
                b("")
            else:
            b("\n")
        spaces += 2
        newline = True
        break
    for bracket in close_set:
        if char == bracket:
            spaces -= 2
            if (prev in b_set) and (prev != ""):
                b("")
            else:
                b("\n")
            newline = True
            break
    if a() and newline:
        print((" " * spaces) + char, end="")
        newline = False
    elif a():
        print(char, end="")
    prev = char

The arguments to the program are (in order): the opening parentheses, the closing parentheses, and the text to indent.

Example ($ is command line prompt):

$ python indent.py "{[(<" "}])>" "abc{xyz{text[note{comment(t{ex}t)abc}]}}"
abc
{
  xyz
  {
    text
    [
      note
      {
        comment
        (
          t
          {
            ex
          }
          t
        )
        abc
      }
    ]
  }
}

Answer 10

Python3, 184 182 chars

import sys
_,p,q,t=sys.argv
i,f,x=0,1,print
for e in t:
 if e in p:f or x();x(' '*i+e);i+=2;f=1
 elif e in q:f or x();i-=2;f=1;x(' '*i+e)
 else:not f or x(' '*i,end='');f=x(e,end='')

Example:

$ python3 ./a.py '{[(<' '}])>' 'abc{xyz{text[note{comment(t{ex}t)abc}]}}'
abc
{
  xyz
  {
    text
    [
      note
      {
        comment
        (
          t
          {
            ex
          }
          t
        )
        abc
      }
    ]
  }
}

Answer 11

C (159 225 chars)

#define q(s,c)strchr(s,c)
#define p(i,j,k)printf("\n%*s%c%c%*s",i,"",*s,k,j,"")
g(char*b,char*e,char*s){int i;for(i=0;*s;s++)q(b,*s)?p(i-2,i+=2,'\n'):q(e,*s)?q(b,*(s+1))||q(e,*(s+1))?p(i-=2,i-2,0):p(i-=2,i-2,'\n'):putchar(*s);}

It cost me 66 extra characters just to fix the bug with the empty lines :( Frankly, I need a fresh approach, but I'll call it a day for now.

#define p(i,j)printf("\n%*s%c\n%*s",i,"",*s,j,"")
f(char*b,char*e,char*s){int i;for(i=0;*s;s++){strchr(b,*s)?p(i-2,i+=2):strchr(e,*s)?p(i-=2,i-2):putchar(*s);}}

A rather quick & dirty approach. It has a bug of producing empty lines between consecutive closing parenthesis, but otherwise it does the job (or so I think). I will revisit it for a better & cleaner solution, sometime this week.

char *b is the opening parenthesis set, char *e is the closing parenthesis set and char *s is the input string.

Answer 12

Perl - 69 bytes

TMTOWTDI makes code simple

#!perl -p
s/([[{(<])|([]})>])|\w+/"  "x($1?$t++:$2?--$t:$t)."$&
"/ge

Answer 13

Scala(2.9), 211 characters

object P extends App{def x(j:Int)={"\n"+"  "*j}
var(i,n)=(0,"")
for(c<-args(2)){if(args(0).exists(_==c)){print(x(i)+c)
i+=1
n=x(i)}else{if(args(1).exists(_==c)){i-=1
print(x(i)+c)
n=x(i)}else{print(n+c)
n=""}}}}

Answer 14

Perl - 89 85 bytes

A version of Hojung Youn's answer which accepts the block characters via two arguments.

#!perl -p
BEGIN{$b=pop;$a=pop}s/([$a])|([$b])|\w+/"  "x($1?$t++:$2?--$t:$t)."$&
"/ge

Called like:

perl golf.pl<<<'abc{xyz{text[note{comment(t{ex}t)abc}]}}' '[{(<' ']})>'

Answer 15

C, 256

Parameters:

• e is the ending char,
• n is the indentation,
• b the opening brackets,
• d the closing brackets.

I broke the code up to avoid the horizontal scrollbar.

#define r char
#define P(c) putchar(c);
#define N P(x)
#define W printf("%*s",n,"");
r*s,x='\n';i(r e,int n,r*b,r*d){r*t=s,*p;int l=0;W while(*s!=e)    
{if(p=strchr(b,*s)){if(s!=t){N W}P(*s++)N i(d[p-b],n+2,b,d); N W 
P(*s++);l=1;}else{if(l){N W l=0;}P(*s++)}}}

Complete program is 363 characters.

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#define r char
#define P(c) putchar(c);
#define N P(x)
#define W printf("%*s",n,"");
r*s,x='\n';i(r e,int n,r*b,r*d)
{r*t=s,*p;int l=0;W while(*s!=e)
{if(p=strchr(b,*s)){if(s!=t){N W}
P(*s++)N i(d[p-b],n+2,b,d); N W
P(*s++);l=1;}else{if(l){N W l=0;}
P(*s++)}}}main(int c,r*v[]){s =
v[3];i('\0',0,v[1],v[2]);}

Answer 16

VB.net (?c)

Language isn't suited to code golfing, so I used an uncommon approach. Using a trace listener to output to the console.

Imports System.Diagnostics.Debug
Module Module1
  Sub Main(args() As String)
    IndentText(args(0), args(1), args(2)) 'openings, closings, text)
  End Sub
  Sub IndentText(o As String, e As String, t As String)
    Dim x = 0
    Listeners.Add(New Diagnostics.ConsoleTraceListener)
    IndentSize = 2
    For Each c In t
      If o.Contains(c) Then
        WriteLine("")
        WriteLine(c)
        Indent()
        x = 1
      ElseIf e.Contains(c) Then
        If x = 0 Then WriteLine("")
        Unindent()
        WriteLine(c)
        x = 1
      Else
        Write(c)
        x = 0
      End If
    Next
  End Sub
End Module

Uses commandline args for the input

args(0) is the indenting chars
args(1) is the undenting chars
args(2) is the text to be indented.

Answer 17

D (300)

C[] i(C,S)(ref S s,C p){if(!*s)return[];static C[] w;w~=" ";C[] r;C c=s[0];while(c!=p){s=s[1..$];r~=(c=='{'||c=='['||c=='<'?"\n"~w~c~"\n"~i(s,cast(char)(c+2)):c=='('?"\n"~w~c~"\n"~i(s,')'):[c]);c=*s;}w=w[1..$];if(*s)s=s[1..$];c=*s;return" "~w~r~"\n"~w~(c=='}'||c==']'||c=='>'||c==')'?[p]:p~"\n"~w);}

needs a null terminated string for the bounds check (otherwise the if(*s) needs to be changed to if(s.length))

Answer 18

Java

Non codegolf version! Assuming we have this version of split() that includes delims,

public static String indent(String input, String openPars,
        String closingPars) {
    String re = "["
            + (openPars + closingPars).replace("[", "\\[").replace("]",
                    "\\]") + "]";
    String[] split = inclusiveSplit(input, re, 0);
    int indent = 0;
    StringBuilder sb = new StringBuilder();
    for (String string : split) {
        if (StringUtils.isEmpty(string))
            continue;
        if (closingPars.indexOf(string) != -1) {
            indent--;
        }
        sb.append(StringUtils.repeat(" ", indent * 2));
                    sb.append(string);
                    sb.append("\n");
        if (openPars.indexOf(string) != -1) {
            indent++;
        }
    }
    String string = sb.toString();
    return string;
}

Answer 19

C 284 Non White space Characters

I'm no fan of obfuscation but well...

#include<cstdio>
#include<cstring>
#define g printf
#define j char
int main(int a,j**b){int c=0;for(j*f=b[3];*f!='\0';++f){if(strchr(b[1],*f)!=0){g("\n%*c\n%*c",c,*f,c+2,'\0');c+=2;}else if(strchr(b[2],*(f))!=0){c-=2;g("\n%*c",c,*f);if(strchr(b[2],*(f+1))==0)g("\n%*c",c,'\0');}else putchar(*f);}}

Usage: ./program start_brackets end_brackets string_to_parse

Answer 20

php (187) (153)

function a($s,$o,$e){while(''!=$c=$s[$i++]){$a=strpbrk($c,$o)?2:0;$b=strpbrk($c,$e)?2:0;echo ($a+$b||$r)?"\n".str_pad('',$t-=$b):'',$c;$t+=$a;$r=$a+$b;}}

Function takes string, opening delimiters, ending delimiters as arguments.

Answer 21

Powershell, 146 Bytes

param([char[]]$s,[char[]]$e,[char[]]$f)$f|%{}{if($_-in$s){$o;'  '*$i+$_;$o='  '*++$i;}elseif($_-in$e){$o;'  '*--$i+$_;$o='  '*$i}else{$o+=$_}}{$o}

Ungolfed Explanation

param([char[]]$start,             # Cast as array of Chars
      [char[]]$end,
      [char[]]$string)
$string | foreach-object { } {    # For every char in string. Empty Begin block
    if ( $_ -in $start ) {        # If char is in start
        $o                        # Print stack ($o)
        '  ' * $i + $_            # Newline, indent, insert start char
        $o = '  ' * ++$i          # Set stack to ident (incremented)
    } elseif ( $_ -in $end ) {    # If char is in end
        $o                        # Print stack
        '  ' * --$i + $_          # Newline, decrement indent, insert end char
        $o = '  ' * $i            # Set stack to indent
    } else {
        $o+ = $_                  # Otherwise add character to stack
    }
} { $o }                          # Print remaining stack (if any)

Answer 22

C, 181 characters

#define d(m,f)if(strchr(v[m],*s)){puts("");for(j=f;j--;)printf("  ");}
i;main(j,v,s)char**v,*s;{for(s=v[3];*s;s++){d(1,i++)d(2,--i)putchar(*s);d(1,i)if(!strchr(v[2],*(s+1)))d(2,i)}}

Pretty much the most straightforward approach imaginable. Iterate through the string (v[3]), if it's a left brace (as defined in v[1]), increase the indent level, if it's a right brace (as defined in v[2]), decrease the indent level.

Answer 23

C, 114 121

main(i,x,s,c){while(~(c=getchar()))(s=x)|(x=2*!!strchr("(){}[]<>",c))?s=c-1&x,i-=x-2*s,printf("\n%*c",i-s,c):putchar(c);}

Not very nice, but a solution.. an empty line may appear before/after depending on whether input starts/finishes with a parentheses.

With the new restriction, this approach is almost useless for golfing.