2016 Update

Task/Reverse-a-string/00DESCRIPTION

@@ -1,3 +1,14 @@
-Take a string and reverse it. For example, "asdf" becomes "fdsa".
+;Task:
+Take a string and reverse it.
 
-For extra credit, preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa".
+For example, "asdf" becomes "fdsa".
+
+
+;Extra credit:
+Preserve Unicode combining characters.
+
+For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa".
+
+
+{{Template:Strings}}
+<br><br>

Task/Reverse-a-string/360-Assembly/reverse-a-string.360

@@ -0,0 +1,30 @@
+*        Reverse a string          21/05/2016
+REVERSE  CSECT
+         USING  REVERSE,R13        base register
+         B      72(R15)            skip savearea
+         DC     17F'0'             savearea
+         STM    R14,R12,12(R13)    prolog
+         ST     R13,4(R15)         "
+         ST     R15,8(R13)         "
+         LR     R13,R15            "
+         MVC    TMP(L'C),C         tmp=c
+         LA     R8,C               @c[1]
+         LA     R9,TMP+L'C-1       @tmp[n-1]
+         LA     R6,1               i=1
+         LA     R7,L'C             n=length(c)
+LOOPI    CR     R6,R7              do i=1 to n
+         BH     ELOOPI             leave i
+         MVC    0(1,R8),0(R9)        substr(c,i,1)=substr(tmp,n-i+1,1)
+         LA     R8,1(R8)             @c=@c+1
+         BCTR   R9,0                 @tmp=@tmp-1
+         LA     R6,1(R6)             i=i+1
+         B      LOOPI              next i
+ELOOPI   XPRNT  C,L'C              print c
+         L      R13,4(0,R13)       epilog
+         LM     R14,R12,12(R13)    "
+         XR     R15,R15            "
+         BR     R14                exit
+C        DC     CL12'edoC attesoR'
+TMP      DS     CL12
+         YREGS
+         END    REVERSE

Task/Reverse-a-string/ALGOL-68/reverse-a-string.alg

@@ -0,0 +1,13 @@
+PROC reverse = (REF STRING s)VOID:
+  FOR i TO UPB s OVER 2 DO
+    CHAR c = s[i];
+    s[i] := s[UPB s - i + 1];
+    s[UPB s - i + 1] := c
+  OD;
+
+main:
+(
+  STRING text := "Was it a cat I saw";
+  reverse(text);
+  print((text, new line))
+)

Task/Reverse-a-string/AppleScript/reverse-a-string-1.applescript

@@ -1,5 +1,5 @@
 reverseString("Hello World!")
 
 on reverseString(str)
-	reverse of characters of str as string
+    reverse of characters of str as string
 end reverseString

Task/Reverse-a-string/AppleScript/reverse-a-string-2.applescript

@@ -0,0 +1,82 @@
+-- Using either a generic foldr(f, a, xs)
+
+-- reverse1 :: [a] -> [a]
+on reverse1(xs)
+    script rev
+        on lambda(a, x)
+            a & x
+        end lambda
+    end script
+
+    if class of xs is text then
+        foldr(rev, {}, xs) as text
+    else
+        foldr(rev, {}, xs)
+    end if
+end reverse1
+
+
+-- or the built-in reverse method for lists
+
+-- reverse2 :: [a] -> [a]
+on reverse2(xs)
+    if class of xs is text then
+        (reverse of characters of xs) as text
+    else
+        reverse of xs
+    end if
+end reverse2
+
+
+
+-- TESTING reverse1 and reverse2 with same string and list
+on run
+    script test
+        on lambda(f)
+            map(f, ["Hello there !", {1, 2, 3, 4, 5}])
+        end lambda
+    end script
+
+    map(test, [reverse1, reverse2])
+end run
+
+
+
+
+-- GENERIC LIBRARY FUNCTIONS
+
+-- foldr :: (a -> b -> a) -> a -> [b] -> a
+on foldr(f, startValue, xs)
+    tell mReturn(f)
+        set v to startValue
+        set lng to length of xs
+        repeat with i from lng to 1 by -1
+            set v to lambda(v, item i of xs, i, xs)
+        end repeat
+        return v
+    end tell
+end foldr
+
+-- map :: (a -> b) -> [a] -> [b]
+on map(f, xs)
+    tell mReturn(f)
+        set lng to length of xs
+        set lst to {}
+        repeat with i from 1 to lng
+            set end of lst to lambda(item i of xs, i, xs)
+        end repeat
+        return lst
+    end tell
+end map
+
+-- Lift 2nd class handler function into 1st class script wrapper
+-- mReturn :: Handler -> Script
+on mReturn(f)
+    if class of f is script then
+        f
+    else
+        script
+            property lambda : f
+        end script
+    end if
+end mReturn

Task/Reverse-a-string/AppleScript/reverse-a-string-3.applescript

@@ -0,0 +1,2 @@
+{{"! ereht olleH", {5, 4, 3, 2, 1}},
+ {"! ereht olleH", {5, 4, 3, 2, 1}}}

Task/Reverse-a-string/Ela/reverse-a-string-1.ela

@@ -0,0 +1,7 @@
+reverse_string str = rev len str
+  where len = length str
+        rev 0 str = ""
+        rev n str = toString (str : nn) +> rev nn str
+          where nn = n - 1
+
+reverse_string "Hello"

Task/Reverse-a-string/Ela/reverse-a-string-2.ela

@@ -0,0 +1,2 @@
+open string
+fromList <| reverse <| toList "Hello" ::: String

Task/Reverse-a-string/Elena/reverse-a-string.elena

@@ -0,0 +1,14 @@
+#import system.
+#import system'routines.
+#import extensions.
+
+#class(extension) extension
+{
+    #method reversedLiteral
+        = self toArray reverse summarize:(String new) literal.
+}
+
+#symbol program =
+[
+    console writeLine:("Hello World" reversedLiteral).
+].

Task/Reverse-a-string/Emacs-Lisp/reverse-a-string.l

@@ -1 +1 @@
-(concat (reverse (append "Hello World" nil)))
+(reverse "Hello World")

Task/Reverse-a-string/Forth/reverse-a-string-3.fth

@@ -0,0 +1,9 @@
+: xreverse {: c-addr u -- c-addr2 u :}
+    u allocate throw u + c-addr swap over u + >r begin ( from to r:end)
+	over r@ u< while
+	    over r@ over - x-size dup >r - 2dup r@ cmove
+	    swap r> + swap repeat
+    r> drop nip u ;
+
+\ example use
+s" ώщыē" xreverse type \ outputs "ēыщώ"

Task/Reverse-a-string/Groovy/reverse-a-string-2.groovy

@@ -0,0 +1,15 @@
+def string = "as⃝df̅"
+
+List combiningBlocks = [
+    Character.UnicodeBlock.COMBINING_DIACRITICAL_MARKS,
+    Character.UnicodeBlock.COMBINING_DIACRITICAL_MARKS_SUPPLEMENT,
+    Character.UnicodeBlock.COMBINING_HALF_MARKS,
+    Character.UnicodeBlock.COMBINING_MARKS_FOR_SYMBOLS
+]
+List chars = string as List
+chars[1..-1].eachWithIndex { ch, i ->
+    if (Character.UnicodeBlock.of((char)ch) in combiningBlocks) {
+        chars[i..(i+1)] = chars[(i+1)..i]
+    }
+}
+println chars.reverse().join()

Task/Reverse-a-string/JavaScript/reverse-a-string-2.js

@@ -0,0 +1,18 @@
+(() => {
+
+    // .reduceRight() can be useful when reversals
+    // are composed with some other process
+
+    let reverse1 = s => Array.from(s)
+        .reduceRight((a, x) => a + (x !== ' ' ? x : ' <- '), ''),
+
+        // but ( join . reverse . split ) is faster for
+        // simple string reversals in isolation
+
+        reverse2 = s => s.split('').reverse().join('');
+
+
+    return [reverse1, reverse2]
+        .map(f => f("Some string to be reversed"));
+
+})();

Task/Reverse-a-string/JavaScript/reverse-a-string-3.js

@@ -0,0 +1 @@
+["desrever <- eb <- ot <- gnirts <- emoS", "desrever eb ot gnirts emoS"]

Task/Reverse-a-string/Kotlin/reverse-a-string.kotlin

@@ -0,0 +1,3 @@
+fun main(args: Array<String>) {
+    println("asdf".reversed())
+}

Task/Reverse-a-string/MIPS-Assembly/reverse-a-string.mips

@@ -0,0 +1,67 @@
+# First, it gets the length of the original string
+# Then, it allocates memory from the copy
+# Then it copies the pointer to the original string, and adds the strlen
+#     subtract 1, then that new pointer is at the last char.
+# while(strlen)
+#     copy char
+#     decrement strlen
+#     decrement source pointer
+#     increment target pointer
+
+.data
+	ex_msg_og: .asciiz "Original string:\n"
+	ex_msg_cpy: .asciiz "\nCopied string:\n"
+	string: .asciiz "Wow, what a string!"
+
+.text
+	main:
+		la $v1,string #load addr of string into $v0
+		la $t1,($v1)  #copy addr into $t0 for later access
+		lb $a1,($v1)  #load byte from string addr
+	strlen_loop:	
+		beqz $a1,alloc_mem
+		addi $a0,$a0,1 #increment strlen_counter
+		addi $v1,$v1,1 #increment ptr
+		lb $a1,($v1)   #load the byte
+		j strlen_loop
+		
+	alloc_mem:
+		li $v0,9 #alloc memory, $a0 is arg for how many bytes to allocate
+		         #result is stored in $v0
+		syscall
+		la $t0,($v0) #$v0 is static, $t0 is the moving ptr
+		la $v1,($t1) #get a copy we can increment
+		
+		add $t1,$t1,$a0 #add strlen to our original, static addr to equal last char
+		subi $t1,$t1,1  #previous operation is on NULL byte, i.e. off-by-one error.
+		                #this corrects.
+	copy_str:
+		lb $a1,($t1) #copy first byte from source
+
+	strcopy_loop:
+		beq $a0,0,exit_procedure
+		sb $a1,($t0)            #store the byte at the target pointer
+		addi $t0,$t0,1          #increment target ptr
+		subi $t1,$t1,1
+		subi $a0,$a0,1
+		lb $a1,($t1)            #load next byte from source ptr
+		j strcopy_loop
+		
+	exit_procedure:
+		la $a1,($v0) #store our string at $v0 so it doesn't get overwritten
+		li $v0,4 #set syscall to PRINT
+		
+		la $a0,ex_msg_og  #PRINT("original string:")
+		syscall
+		
+		la $a0,($v1)      #PRINT(original string)
+		syscall
+		
+		la $a0,ex_msg_cpy #PRINT("copied string:")
+		syscall
+		
+		la $a0,($a1)      #PRINT(strcopy)
+		syscall
+		
+		li $v0,10         #EXIT(0)
+		syscall

Task/Reverse-a-string/OCaml/reverse-a-string-4.ocaml

@@ -0,0 +1,6 @@
+let string_rev s =
+  let len = String.length s in
+  String.init len (fun i -> s.[len - 1 - i])
+
+let () =
+  print_endline (string_rev "Hello world!")

Task/Reverse-a-string/PARI-GP/reverse-a-string-2.pari

@@ -0,0 +1,12 @@
+\\ Return reversed string str.
+\\ 3/3/2016 aev
+sreverse(str)={return(Strchr(Vecrev(Vecsmall(str))))}
+
+{
+\\ TEST1
+print(" *** Testing sreverse from Version #2:");
+print(sreverse("ABCDEF"));
+my(s,sr,n=10000000);
+s="ABCDEFGHIJKL";
+for(i=1,n, sr=sreverse(s));
+}

Task/Reverse-a-string/PARI-GP/reverse-a-string-3.pari

@@ -0,0 +1,11 @@
+\\ Version #1 upgraded to complete function. Practically the same.
+reverse(str)={return(concat(Vecrev(str)))}
+
+{
+\\ TEST2
+print(" *** Testing reverse from Version #1:");
+print(reverse("ABCDEF"));
+my(s,sr,n=10000000);
+s="ABCDEFGHIJKL";
+for(i=1,n, sr=reverse(s));
+}

Task/Reverse-a-string/Perl-6/reverse-a-string.pl6

@@ -1,4 +1,2 @@
-# Not transformative.
-my $reverse = flip $string;
-# or
 say "hello world".flip;
+say "as⃝df̅".flip

Task/Reverse-a-string/PowerShell/reverse-a-string-7.psh

@@ -0,0 +1 @@
+[Regex]::Matches('abc','.','RightToLeft').Value -join ''

Task/Reverse-a-string/Python/reverse-a-string-3.py

@@ -1,36 +1 @@
-'''
-  Reverse a Unicode string with proper handling of combining characters
-'''
-
-import unicodedata
-
-def ureverse(ustring):
-    '''
-    Reverse a string including unicode combining characters
-
-    Example:
-        >>> ucode = ''.join( chr(int(n, 16))
-                             for n in ['61', '73', '20dd', '64', '66', '305'] )
-        >>> ucoderev = ureverse(ucode)
-        >>> ['%x' % ord(char) for char in ucoderev]
-        ['66', '305', '64', '73', '20dd', '61']
-        >>>
-    '''
-    groupedchars = []
-    uchar = list(ustring)
-    while uchar:
-        if 'COMBINING' in unicodedata.name(uchar[0], ''):
-            groupedchars[-1] += uchar.pop(0)
-        else:
-            groupedchars.append(uchar.pop(0))
-    # Grouped reversal
-    groupedchars = groupedchars[::-1]
-
-    return ''.join(groupedchars)
-
-if __name__ == '__main__':
-    ucode = ''.join( chr(int(n, 16))
-                     for n in ['61', '73', '20dd', '64', '66', '305'] )
-    ucoderev = ureverse(ucode)
-    print (ucode)
-    print (ucoderev)
+''.join(reversed(string))

Task/Reverse-a-string/Python/reverse-a-string-4.py

@@ -0,0 +1,36 @@
+'''
+  Reverse a Unicode string with proper handling of combining characters
+'''
+
+import unicodedata
+
+def ureverse(ustring):
+    '''
+    Reverse a string including unicode combining characters
+
+    Example:
+        >>> ucode = ''.join( chr(int(n, 16))
+                             for n in ['61', '73', '20dd', '64', '66', '305'] )
+        >>> ucoderev = ureverse(ucode)
+        >>> ['%x' % ord(char) for char in ucoderev]
+        ['66', '305', '64', '73', '20dd', '61']
+        >>>
+    '''
+    groupedchars = []
+    uchar = list(ustring)
+    while uchar:
+        if 'COMBINING' in unicodedata.name(uchar[0], ''):
+            groupedchars[-1] += uchar.pop(0)
+        else:
+            groupedchars.append(uchar.pop(0))
+    # Grouped reversal
+    groupedchars = groupedchars[::-1]
+
+    return ''.join(groupedchars)
+
+if __name__ == '__main__':
+    ucode = ''.join( chr(int(n, 16))
+                     for n in ['61', '73', '20dd', '64', '66', '305'] )
+    ucoderev = ureverse(ucode)
+    print (ucode)
+    print (ucoderev)

Task/Reverse-a-string/REXX/reverse-a-string-3.rexx

@@ -1,3 +1,3 @@
                                    string2 = substr(string1,j,1) || string2
                                                 /*───── or ─────*/
-                                   string2=substr(string1,j,1)||string2
+                                   string2=substr(string1,j,1)string2

Task/Reverse-a-string/S-lang/reverse-a-string-1.slang

@@ -0,0 +1,10 @@
+variable sa = "Hello, World", aa = Char_Type[strlen(sa)+1];
+init_char_array(aa, sa);
+array_reverse(aa);
+% print(aa);
+
+% Unfortunately, strjoin() only joins strings, so we map char()
+% [sadly named: actually converts char into single-length string]
+% onto the array:
+
+print( strjoin(array_map(String_Type, &char, aa), "") );

Task/Reverse-a-string/S-lang/reverse-a-string-2.slang

@@ -0,0 +1,17 @@
+define init_unicode_array(a, buf)
+{
+  variable len = strbytelen(buf), ch, p0 = 0, p1 = 0;
+  while (p1 < len) {
+    (p1, ch) = strskipchar(buf, p1, 1);
+    if (ch < 0) print("oops.");
+    a[p0] = ch;
+    p0++;
+  }
+}
+
+variable su = "Σὲ γνωρίζω ἀπὸ τὴν κόψη";
+variable au = Int_Type[strlen(su)+1];
+init_unicode_array(au, su);
+array_reverse(au);
+% print(au);
+print(strjoin(array_map(String_Type, &char, au), "") );

Task/Reverse-a-string/Vala/reverse-a-string.vala

@@ -0,0 +1,12 @@
+int main (string[] args) {
+	if (args.length < 2) {
+		stdout.printf ("Please, input a string.\n");
+		return 0;
+	}
+	var str = new StringBuilder ();
+	for (var i = 1; i < args.length; i++) {
+		str.append (args[i] + " ");
+	}
+	stdout.printf ("%s\n", str.str.strip ().reverse ());
+	return 0;
+}