Strip block comments: Difference between revisions
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Added Java solution |
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* Another comment. |
* Another comment. |
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*/</pre> |
*/</pre> |
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=={{header|Java}}== |
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<lang java>import java.io.*; |
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import java.lang.StringBuilder; |
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public class StripBlockComments{ |
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public static void main( String[] args ){ |
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if( args.length < 3 ){ |
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System.out.println("Usage: BeginToken EndToken StringToProcess"); |
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} |
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else{ |
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String beginToken = args[0]; |
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String endToken = args[1]; |
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String inputFile = args[2]; |
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System.out.println(inputFile); |
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String input = ""; |
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try{ |
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BufferedReader reader = new BufferedReader( new FileReader( inputFile ) ); |
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StringBuilder fileContents = new StringBuilder(); |
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char[] buffer = new char[4096]; |
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while( reader.read(buffer, 0, 4096) > 0 ){ |
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fileContents.append( buffer ); |
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} |
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input = fileContents.toString(); |
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} |
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catch( Exception e ){ |
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e.printStackTrace(); |
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System.exit(1); |
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} |
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StringBuilder output = new StringBuilder(); |
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while(true){ |
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int begin = input.indexOf(beginToken); |
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int end = input.indexOf(endToken, begin+beginToken.length()); |
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if( begin == -1 ){ |
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output.append( input ); |
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break; |
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} |
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output.append( input.substring( 0, begin ) ); |
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input = input.substring( end + endToken.length(), input.length() ); |
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} |
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System.out.println( output.toString() ); |
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} |
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System.exit(0); |
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} |
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}</lang> |
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=={{header|Go}}== |
=={{header|Go}}== |
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For the extra credit: No optional parameters in Go, but documented below is an efficient technique for letting the caller specify the delimiters. |
For the extra credit: No optional parameters in Go, but documented below is an efficient technique for letting the caller specify the delimiters. |
Revision as of 03:40, 20 August 2011
You are encouraged to solve this task according to the task description, using any language you may know.
A block comment begins with a beginning delimiter and ends with a ending delimiter, including the delimiters. These delimiters are often multi-character sequences.
Task: Strip block comments from program text (of a programming language much like classic C). Your demos should at least handle simple, non-nested and multiline block comment delimiters. The beginning delimiter is the two-character sequence “/*” and the ending delimiter is “*/”.
Sample text for stripping:
/** * Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */ /** * Another comment. */ function something() { }
Extra credit: Ensure that the stripping code is not hard-coded to the particular delimiters described above, but instead allows the caller to specify them. (If your language supports them, optional parameters may be useful for this.)
C.f: Strip comments from a string
Ada
strip.adb: <lang Ada>with Ada.Strings.Fixed; with Ada.Strings.Unbounded; with Ada.Text_IO; with Ada.Command_Line;
procedure Strip is
use Ada.Strings.Unbounded; procedure Print_Usage is begin Ada.Text_IO.Put_Line ("Usage:"); Ada.Text_IO.New_Line; Ada.Text_IO.Put_Line (" strip <file> [<opening> [<closing>]]"); Ada.Text_IO.New_Line; Ada.Text_IO.Put_Line (" file: file to strip"); Ada.Text_IO.Put_Line (" opening: string for opening comment"); Ada.Text_IO.Put_Line (" closing: string for closing comment"); Ada.Text_IO.New_Line; end Print_Usage;
Opening_Pattern : Unbounded_String := To_Unbounded_String ("/*"); Closing_Pattern : Unbounded_String := To_Unbounded_String ("*/"); Inside_Comment : Boolean := False;
function Strip_Comments (From : String) return String is use Ada.Strings.Fixed; Opening_Index : Natural; Closing_Index : Natural; Start_Index : Natural := From'First; begin if Inside_Comment then Start_Index := Index (Source => From, Pattern => To_String (Closing_Pattern)); if Start_Index < From'First then return ""; end if; Inside_Comment := False; Start_Index := Start_Index + Length (Closing_Pattern); end if; Opening_Index := Index (Source => From, Pattern => To_String (Opening_Pattern), From => Start_Index); if Opening_Index < From'First then return From (Start_Index .. From'Last); else Closing_Index := Index (Source => From, Pattern => To_String (Closing_Pattern), From => Opening_Index + Length (Opening_Pattern)); if Closing_Index > 0 then return From (Start_Index .. Opening_Index - 1) & Strip_Comments (From ( Closing_Index + Length (Closing_Pattern) .. From'Last)); else Inside_Comment := True; return From (Start_Index .. Opening_Index - 1); end if; end if; end Strip_Comments;
File : Ada.Text_IO.File_Type;
begin
if Ada.Command_Line.Argument_Count < 1 or else Ada.Command_Line.Argument_Count > 3 then Print_Usage; return; end if; if Ada.Command_Line.Argument_Count > 1 then Opening_Pattern := To_Unbounded_String (Ada.Command_Line.Argument (2)); if Ada.Command_Line.Argument_Count > 2 then Closing_Pattern := To_Unbounded_String (Ada.Command_Line.Argument (3)); else Closing_Pattern := Opening_Pattern; end if; end if; Ada.Text_IO.Open (File => File, Mode => Ada.Text_IO.In_File, Name => Ada.Command_Line.Argument (1)); while not Ada.Text_IO.End_Of_File (File => File) loop declare Line : constant String := Ada.Text_IO.Get_Line (File); begin Ada.Text_IO.Put_Line (Strip_Comments (Line)); end; end loop; Ada.Text_IO.Close (File => File);
end Strip;</lang>
output:
function subroutine() { a = b + c ; } function something() { }
C
<lang C>#include<stdio.h>
- include<string.h>
- include<stdlib.h>
char*ca="/*",*cb="*/"; int al=2,bl=2;
void pause(){
puts("Press Enter"); getchar();
}
char*loadfile(char*s){
FILE*f; int l; if(f=fopen(s,"rb")){ fseek(f,0,SEEK_END); s=malloc((l=ftell(f))+1); rewind(f); if(s)fread(s,1,l,f); fclose(f); } return s;
}
void stripcomments(char*s){
char*a,*b; int l=strlen(s)+1; while(a=strstr(s,ca)){ b=strstr(a+al,cb); if(!b)break; b+=bl; memmove(a,b,l-(b-a)); }
}
int main(int argc,char**argv){
char*s="input.txt"; if(argc>=2)s=argv[1]; s=loadfile(s); if(argc==4){ al=strlen(ca=argv[2]); bl=strlen(cb=argv[3]); } stripcomments(s); puts(s); pause(); return 0;
} </lang> Usage: Specify an input file via the first command line argument, and optionally specify comment opening and closing delimiters with the next two args, or defaults of /* and */ are assumed.
Output:
function subroutine() { a = b + c ; } function something() { } Press Enter
C++
<lang C++>#include <string>
- include <iostream>
- include <iterator>
- include <fstream>
- include <boost/regex.hpp>
int main( ) {
std::ifstream codeFile( "samplecode.txt" ) ; if ( codeFile ) { boost::regex commentre( "/\\*.*?\\*/" ) ;//comment start and end, and as few characters in between as possible std::string my_erase( "" ) ; //erase them std::string stripped ; std::string code( (std::istreambuf_iterator<char>( codeFile ) ) ,
std::istreambuf_iterator<char>( ) ) ;
codeFile.close( ) ; stripped = boost::regex_replace( code , commentre , my_erase ) ; std::cout << "Code unstripped:\n" << stripped << std::endl ; return 0 ; } else { std::cout << "Could not find code file!" << std::endl ; return 1 ; }
}</lang> Output:
Code unstripped: function subroutine() { a = b + c ; } function something() { }
C#
<lang C sharp> using System;
class Program { private static string BlockCommentStrip(string commentStart, string commentEnd, string sampleText) { while (sampleText.IndexOf(commentStart) > -1 && sampleText.IndexOf(commentEnd, sampleText.IndexOf(commentStart) + commentStart.Length) > -1) { int start = sampleText.IndexOf(commentStart); int end = sampleText.IndexOf(commentEnd, start + commentStart.Length); sampleText = sampleText.Remove( start, (end + commentEnd.Length) - start ); } return sampleText; } }
</lang>
Clojure
<lang Clojure>(defn comment-strip [txt & args]
(let [args (conj {:delim ["/*" "*/"]} (apply hash-map args)) ; This is the standard way of doing keyword/optional arguments in Clojure
[opener closer] (:delim args)]
(loop [out "", txt txt, delim-count 0] ; delim-count is needed to handle nested comments (let [[hdtxt resttxt] (split-at (count opener) txt)] ; This splits "/* blah blah */" into hdtxt="/*" and restxt="blah blah */"
(printf "hdtxt=%8s resttxt=%8s out=%8s txt=%16s delim-count=%s\n" (apply str hdtxt) (apply str resttxt) out (apply str txt) delim-count) (cond (empty? hdtxt) (str out (apply str txt)) (= (apply str hdtxt) opener) (recur out resttxt (inc delim-count)) (= (apply str hdtxt) closer) (recur out resttxt (dec delim-count)) (= delim-count 0)(recur (str out (first txt)) (rest txt) delim-count) true (recur out (rest txt) delim-count))))))</lang>
user> (comment-strip "This /* is */ some /* /* /* */ funny */ */ text") hdtxt= Th resttxt=is /* is */ some /* /* /* */ funny */ */ text out= txt=This /* is */ some /* /* /* */ funny */ */ text delim-count=0 hdtxt= hi resttxt=s /* is */ some /* /* /* */ funny */ */ text out= T txt=his /* is */ some /* /* /* */ funny */ */ text delim-count=0 hdtxt= is resttxt= /* is */ some /* /* /* */ funny */ */ text out= Th txt=is /* is */ some /* /* /* */ funny */ */ text delim-count=0 hdtxt= s resttxt=/* is */ some /* /* /* */ funny */ */ text out= Thi txt=s /* is */ some /* /* /* */ funny */ */ text delim-count=0 hdtxt= / resttxt=* is */ some /* /* /* */ funny */ */ text out= This txt= /* is */ some /* /* /* */ funny */ */ text delim-count=0 hdtxt= /* resttxt= is */ some /* /* /* */ funny */ */ text out= This txt=/* is */ some /* /* /* */ funny */ */ text delim-count=0 hdtxt= i resttxt=s */ some /* /* /* */ funny */ */ text out= This txt= is */ some /* /* /* */ funny */ */ text delim-count=1 hdtxt= is resttxt= */ some /* /* /* */ funny */ */ text out= This txt=is */ some /* /* /* */ funny */ */ text delim-count=1 hdtxt= s resttxt=*/ some /* /* /* */ funny */ */ text out= This txt=s */ some /* /* /* */ funny */ */ text delim-count=1 hdtxt= * resttxt=/ some /* /* /* */ funny */ */ text out= This txt= */ some /* /* /* */ funny */ */ text delim-count=1 hdtxt= */ resttxt= some /* /* /* */ funny */ */ text out= This txt=*/ some /* /* /* */ funny */ */ text delim-count=1 hdtxt= s resttxt=ome /* /* /* */ funny */ */ text out= This txt= some /* /* /* */ funny */ */ text delim-count=0 hdtxt= so resttxt=me /* /* /* */ funny */ */ text out= This txt=some /* /* /* */ funny */ */ text delim-count=0 hdtxt= om resttxt=e /* /* /* */ funny */ */ text out= This s txt=ome /* /* /* */ funny */ */ text delim-count=0 hdtxt= me resttxt= /* /* /* */ funny */ */ text out=This so txt=me /* /* /* */ funny */ */ text delim-count=0 hdtxt= e resttxt=/* /* /* */ funny */ */ text out=This som txt=e /* /* /* */ funny */ */ text delim-count=0 hdtxt= / resttxt=* /* /* */ funny */ */ text out=This some txt= /* /* /* */ funny */ */ text delim-count=0 hdtxt= /* resttxt= /* /* */ funny */ */ text out=This some txt=/* /* /* */ funny */ */ text delim-count=0 hdtxt= / resttxt=* /* */ funny */ */ text out=This some txt= /* /* */ funny */ */ text delim-count=1 hdtxt= /* resttxt= /* */ funny */ */ text out=This some txt=/* /* */ funny */ */ text delim-count=1 hdtxt= / resttxt=* */ funny */ */ text out=This some txt= /* */ funny */ */ text delim-count=2 hdtxt= /* resttxt= */ funny */ */ text out=This some txt=/* */ funny */ */ text delim-count=2 hdtxt= * resttxt=/ funny */ */ text out=This some txt= */ funny */ */ text delim-count=3 hdtxt= */ resttxt= funny */ */ text out=This some txt=*/ funny */ */ text delim-count=3 hdtxt= f resttxt=unny */ */ text out=This some txt= funny */ */ text delim-count=2 hdtxt= fu resttxt=nny */ */ text out=This some txt=funny */ */ text delim-count=2 hdtxt= un resttxt=ny */ */ text out=This some txt= unny */ */ text delim-count=2 hdtxt= nn resttxt=y */ */ text out=This some txt= nny */ */ text delim-count=2 hdtxt= ny resttxt= */ */ text out=This some txt= ny */ */ text delim-count=2 hdtxt= y resttxt=*/ */ text out=This some txt= y */ */ text delim-count=2 hdtxt= * resttxt=/ */ text out=This some txt= */ */ text delim-count=2 hdtxt= */ resttxt= */ text out=This some txt= */ */ text delim-count=2 hdtxt= * resttxt= / text out=This some txt= */ text delim-count=1 hdtxt= */ resttxt= text out=This some txt= */ text delim-count=1 hdtxt= t resttxt= ext out=This some txt= text delim-count=0 hdtxt= te resttxt= xt out=This some txt= text delim-count=0 hdtxt= ex resttxt= t out=This some t txt= ext delim-count=0 hdtxt= xt resttxt= out=This some te txt= xt delim-count=0 hdtxt= t resttxt= out=This some tex txt= t delim-count=0 hdtxt= resttxt= out=This some text txt= delim-count=0 "This some text"
D
<lang d>import std.stdio ; import std.regexp, std.algorithm ;
string[] sepComment(string s, string cpat[] ...) {
assert(cpat.length == 2, "sepComment : 2 pattern arguments for comment begin & end") ; string[] res = new string[](2) ; int p = 0, q = 0 /* cursors */, ic = 0 ; // inside comment? int[] plen = new int[](2) ; // this's for handling /*/
bool advCursor() { auto m = std.regexp.search(s[p..$], cpat[ic]) ; if(m is null) return false ; plen[ic] = max(0, plen[ic], m[0].length) ; q = p + m.pre.length ; // got comment head if(ic) { q += m[0].length ; } // or comment tail if(std.regexp.find(m[0], "\n|\r") != -1) // special adjust for \n\r q-- ; return true ; }
while(true) { if(!advCursor()) break ; res[ic] ~= s[p..q] ; // save slice of result if( ic && (q - p < plen[0] + plen[1])) { // this handle /*/ pattern p = q ; if(!advCursor()) break ; res[ic] ~= s[p..q] ; // save result again } p = q ; // advance cursor ic = 1 - ic ; // toggle search type } if(ic) throw new Exception("Mismatched Comment") ; res[ic] ~= s[p..$] ; // save rest(non-comment) return res ;
}
void main() {
string s = ` /** * Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */
/** * Another comment. */ function something() { }` ;
writefln("==original:\n%s", s) ; auto t = sepComment(s, `/\*`, `\*/`) ; writefln("==comment stripped:\n%s\n==stripped comment:\n%s", t[0], t[1]) ;
s = "apples, pears # and bananas
apples, pears ; and bananas " ; // test for line comment
writefln("==original:\n%s", s) ; t = sepComment(s, `#|;`, `[\n\r]|$`) ; writefln("==comment stripped:\n%s\n==stripped comment:\n%s", t[0], t[1]) ;
}</lang> part of output:
==comment stripped: function subroutine() { a = b + c ; } function something() { } ==stripped comment: /** * Some comments * longer comments here that we can parse. * * Rahoo *//* inline comment *//*/ <-- tricky comments *//** * Another comment. */
Java
<lang java>import java.io.*; import java.lang.StringBuilder;
public class StripBlockComments{
public static void main( String[] args ){
if( args.length < 3 ){ System.out.println("Usage: BeginToken EndToken StringToProcess"); } else{ String beginToken = args[0]; String endToken = args[1]; String inputFile = args[2]; System.out.println(inputFile); String input = ""; try{ BufferedReader reader = new BufferedReader( new FileReader( inputFile ) ); StringBuilder fileContents = new StringBuilder(); char[] buffer = new char[4096]; while( reader.read(buffer, 0, 4096) > 0 ){ fileContents.append( buffer ); } input = fileContents.toString(); } catch( Exception e ){ e.printStackTrace(); System.exit(1); } StringBuilder output = new StringBuilder(); while(true){ int begin = input.indexOf(beginToken); int end = input.indexOf(endToken, begin+beginToken.length()); if( begin == -1 ){ output.append( input ); break; } output.append( input.substring( 0, begin ) ); input = input.substring( end + endToken.length(), input.length() ); } System.out.println( output.toString() ); } System.exit(0);
}
}</lang>
Go
For the extra credit: No optional parameters in Go, but documented below is an efficient technique for letting the caller specify the delimiters. <lang go>package main
import (
"fmt" "strings"
)
// idiomatic to name a function newX that allocates an object, initializes it, // and returns it ready to use. the object in this case is a closure. func newStripper(start, end string) func(string) string {
// default to c-style block comments if start == "" || end == "" { start, end = "/*", "*/" } // closes on variables start, end. return func(source string) string { for { cs := strings.Index(source, start) if cs < 0 { break } ce := strings.Index(source[cs+2:], end) if ce < 0 { break } source = source[:cs] + source[cs+ce+4:] } return source }
}
func main() {
// idiomatic is that zero values indicate to use meaningful defaults stripC := newStripper("", "")
// strip function now defined and can be called any number of times // without respecifying delimiters fmt.Println(stripC(` /** * Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */
/** * Another comment. */ function something() { }`))
}</lang>
Haskell
Comment delimiters can be changed by calling stripComments with different start and end parameters.
<lang Haskell>import Data.List
stripComments :: String -> String -> String -> String stripComments start end = notComment
where notComment :: String -> String notComment "" = "" notComment xs | start `isPrefixOf` xs = inComment $ drop (length start) xs | otherwise = head xs:(notComment $ tail xs) inComment :: String -> String inComment "" = "" inComment xs | end `isPrefixOf` xs = notComment $ drop (length end) xs | otherwise = inComment $ tail xs
main = interact (stripComments "/*" "*/")</lang> Output:
function subroutine() { a = b + c ; } function something() { }
Icon and Unicon
If one is willing to concede that the program file will fit in memory, then the following code works:
<lang Icon>procedure main()
every (unstripped := "") ||:= !&input || "\n" # Load file as one string write(stripBlockComment(unstripped,"/*","*/"))
end
procedure stripBlockComment(s1,s2,s3) #: strip comments between s2-s3 from s1
result := "" s1 ? { while result ||:= tab(find(s2)) do { move(*s2) tab(find(s3)|0) # or end of string move(*s3) } return result || tab(0) }
end</lang>
Otherwise, the following handles an arbitrary length input:
<lang Icon>procedure main()
every writes(stripBlockComment(!&input,"/*","*/"))
end
procedure stripBlockComment(s,s2,s3)
static inC # non-null when inside comment (s||"\n") ? while not pos(0) do { if /inC then if inC := 1(tab(find(s2))\1, move(*s2)) then suspend inC else return tab(0) else if (tab(find(s3))\1,move(*s3)) then inC := &null else fail }
end</lang>
J
<lang j>strip=:#~1 0 _1*./@:(|."0 1)2>4{"1(5;(0,"0~".;._2]0 :0);'/*'i.a.)&;:
1 0 0 0 2 0 2 3 2 0 2 2
)</lang>
Example data:
<lang j>example=: 0 :0
/** * Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */
/** * Another comment. */ function something() { }
)</lang>
Example use:
<lang j> strip example
function subroutine() { a = b + c ; }
function something() { }</lang>
Here is a version which allows the delimiters to be passed as an optional left argument as a pair of strings:
<lang j>stripp=:3 :0
('/*';'*/') stripp y
'open close'=. x marks=. (+./(-i._1+#open,close)|."0 1 open E. y) - close E.&.|. y y #~ -. (+._1&|.) (1 <. 0 >. +)/\.&.|. marks
)</lang>
Lua
It is assumed, that the code is in the file "Text1.txt". <lang lua>filename = "Text1.txt"
fp = io.open( filename, "r" ) str = fp:read( "*all" ) fp:close()
stripped = string.gsub( str, "/%*.-%*/", "" ) print( stripped )</lang>
Perl
<lang Perl>#!/usr/bin/perl -w use strict ; use warnings ;
open( FH , "<" , "samplecode.txt" ) or die "Can't open file!$!\n" ; my $code = "" ; {
local $/ ; $code = <FH> ; #slurp mode
} close FH ; $code =~ s,/\*.*?\*/,,sg ; print $code . "\n" ;</lang> Output:
function subroutine() { a = b + c ; } function something() { }
Perl 6
<lang perl6>sample().split(/ '/*' .+? '*/' /).print;
sub sample { ' /**
* Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */
/** * Another comment. */ function something() { }
'}</lang>
Output:
function subroutine() { a = b + c ; } function something() { }
PicoLisp
<lang PicoLisp>(in "sample.txt"
(while (echo "/*") (out "/dev/null" (echo "*/")) ) )</lang>
Output:
function subroutine() { a = b + c ; } function something() { }
PL/I
<lang PL/I> /* A program to remove comments from text. */ strip: procedure options (main); /* 8/1/2011 */
declare text character (80) varying; declare (j, k) fixed binary;
on endfile (sysin) stop;
do forever; get edit (text) (L); do until (k = 0); k = index(text, '/*'); if k > 0 then /* we have a start of comment. */ do; /* Look for end of comment. */ j = index(text, '*/', k+2); if j > 0 then do; text = substr(text, 1, k-1) || substr(text, j+2, length(text)-(j+2)+1); end; else do; /* The comment continues onto the next line. */ put skip list ( substr(text, 1, k-1) );
more: get edit (text) (L);
j = index(text, '*/'); if j = 0 then do; put skip; go to more; end; text = substr(text, j+2, length(text) - (j+2) + 1); end; end; end; put skip list (text); end;
end strip; </lang>
PureBasic
Solution using regular expressions. A procedure to stripBlocks() procedure is defined that will strip comments between any two delimeters. <lang PureBasic>Procedure.s escapeChars(text.s)
Static specialChars.s = "[\^$.|?*+()" Protected output.s, nextChar.s, i, countChar = Len(text) For i = 1 To countChar nextChar = Mid(text, i, 1) If FindString(specialChars, nextChar, 1) output + "\" + nextChar Else output + nextChar EndIf Next ProcedureReturn output
EndProcedure
Procedure.s stripBlocks(text.s, first.s, last.s)
Protected delimter_1.s = escapeChars(first), delimter_2.s = escapeChars(last) Protected expNum = CreateRegularExpression(#PB_Any, delimter_1 + ".*?" + delimter_2, #PB_RegularExpression_DotAll) Protected output.s = ReplaceRegularExpression(expNum, text, "") FreeRegularExpression(expNum) ProcedureReturn output
EndProcedure
Define source.s source.s = " /**" + #CRLF$ source.s + " * Some comments" + #CRLF$ source.s + " * longer comments here that we can parse." + #CRLF$ source.s + " *" + #CRLF$ source.s + " * Rahoo " + #CRLF$ source.s + " */" + #CRLF$ source.s + " function subroutine() {" + #CRLF$ source.s + " a = /* inline comment */ b + c ;" + #CRLF$ source.s + " }" + #CRLF$ source.s + " /*/ <-- tricky comments */" + #CRLF$ source.s + "" + #CRLF$ source.s + " /**" + #CRLF$ source.s + " * Another comment." + #CRLF$ source.s + " */" + #CRLF$ source.s + " function something() {" + #CRLF$ source.s + " }" + #CRLF$
If OpenConsole()
PrintN("--- source ---") PrintN(source) PrintN("--- source with block comments between '/*' and '*/' removed ---") PrintN(stripBlocks(source, "/*", "*/")) PrintN("--- source with block comments between '*' and '*' removed ---") PrintN(stripBlocks(source, "*", "*")) Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input() CloseConsole()
EndIf</lang> Sample output:
--- source --- /** * Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */ /** * Another comment. */ function something() { } --- source with block comments between '/*' and '*/' removed --- function subroutine() { a = b + c ; } function something() { } --- source with block comments between '*' and '*' removed --- / longer comments here that we can parse. Rahoo inline comment / <-- tricky comments Another comment. */ function something() { }
Python
The code has comment delimeters as an argument and will also strip nested block comments.
<lang python>def _commentstripper(txt, delim):
'Strips first nest of block comments' deliml, delimr = delim out = if deliml in txt: indx = txt.index(deliml) out += txt[:indx] txt = txt[indx+len(deliml):] txt = _commentstripper(txt, delim) assert delimr in txt, 'Cannot find closing comment delimiter in ' + txt indx = txt.index(delimr) out += txt[(indx+len(delimr)):] else: out = txt return out
def commentstripper(txt, delim=('/*', '*/')):
'Strips nests of block comments' deliml, delimr = delim while deliml in txt: txt = _commentstripper(txt, delim) return txt</lang>
Tests and sample output <lang python>def test():
print('\nNON-NESTED BLOCK COMMENT EXAMPLE:') sample = /** * Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */
/** * Another comment. */ function something() { } print(commentstripper(sample))
print('\nNESTED BLOCK COMMENT EXAMPLE:') sample = /** * Some comments * longer comments here that we can parse. * * Rahoo *//* function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */ */ /** * Another comment. */ function something() { } print(commentstripper(sample))
if __name__ == '__main__':
test()</lang>
NON-NESTED BLOCK COMMENT EXAMPLE: function subroutine() { a = b + c ; } function something() { } NESTED BLOCK COMMENT EXAMPLE: function something() { }
Ruby
<lang ruby>def remove_comments!(str, comment_start='/*', comment_end='*/')
while start_idx = str.index(comment_start) end_idx = str.index(comment_end, start_idx + comment_start.length) + comment_end.length - 1 str[start_idx .. end_idx] = "" end str
end
def remove_comments(str, comment_start='/*', comment_end='*/')
remove_comments!(str.dup, comment_start, comment_end)
end
example = <<END_OF_STRING
/** * Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */
/** * Another comment. */ function something() { }
END_OF_STRING
puts remove_comments example</lang>
outputs
function subroutine() { a = b + c ; } function something() { }
Tcl
<lang tcl>proc stripBlockComment {string {openDelimiter "/*"} {closeDelimiter "*/"}} {
# Convert the delimiters to REs by backslashing all non-alnum characters set openAsRE [regsub -all {\W} $openDelimiter {\\&}] set closeAsRE [regsub -all {\W} $closeDelimiter {\\&}]
# Now remove the blocks using a dynamic non-greedy regular expression regsub -all "$openAsRE.*?$closeAsRE" $string ""
}</lang> Demonstration code: <lang tcl>puts [stripBlockComment " /**
* Some comments * longer comments here that we can parse. * * Rahoo */ function subroutine() { a = /* inline comment */ b + c ; } /*/ <-- tricky comments */
/** * Another comment. */ function something() { }
"]</lang> Output:
function subroutine() { a = b + c ; } function something() { }