32246: option "shift -p" pops arguments from end of array

ChangeLog

@@ -1,3 +1,9 @@
+2014-01-11  Peter Stephenson  <p.w.stephenson@ntlworld.com>
+
+	* 32246: Doc/Zsh/builtins.yo, Src/builtin.c, Test/.distfiles,
+	Test/B08shift.ztst: add "shift -p" to pop arguments from the end
+	of arrays.
+
 2014-01-10  Peter Stephenson  <p.w.stephenson@ntlworld.com>
 
 	* Koen Wilde: 32245: Completion/Unix/Command/_mpc: complete more

Doc/Zsh/builtins.yo

@@ -1500,12 +1500,15 @@ POSIX standard, but tt(setopt) is not.
 )
 findex(shift)
 cindex(parameters, positional)
-item(tt(shift) [ var(n) ] [ var(name) ... ])(
+item(tt(shift) [ tt(-p) ] [ var(n) ] [ var(name) ... ])(
 The positional parameters tt(${)var(n)PLUS()1tt(}) ... are renamed
 to tt($1) ..., where var(n) is an arithmetic expression that
 defaults to 1.
 If any var(name)s are given then the arrays with these names are
 shifted instead of the positional parameters.
+
+If the option tt(-p) is given arguments are instead removed (popped)
+from the end rather than the start of the array.
 )
 findex(source)
 item(tt(source) var(file) [ var(arg) ... ])(

Src/builtin.c

@@ -111,7 +111,7 @@ static struct builtin builtins[] =
     BUILTIN("return", BINF_PSPECIAL, bin_break, 0, 1, BIN_RETURN, NULL, NULL),
     BUILTIN("set", BINF_PSPECIAL | BINF_HANDLES_OPTS, bin_set, 0, -1, 0, NULL, NULL),
     BUILTIN("setopt", 0, bin_setopt, 0, -1, BIN_SETOPT, NULL, NULL),
-    BUILTIN("shift", BINF_PSPECIAL, bin_shift, 0, -1, 0, NULL, NULL),
+    BUILTIN("shift", BINF_PSPECIAL, bin_shift, 0, -1, 0, "p", NULL),
     BUILTIN("source", BINF_PSPECIAL, bin_dot, 1, -1, 0, NULL, NULL),
     BUILTIN("suspend", 0, bin_suspend, 0, 0, 0, "f", NULL),
     BUILTIN("test", BINF_HANDLES_OPTS, bin_test, 0, -1, BIN_TEST, NULL, NULL),
@@ -4509,7 +4509,7 @@ bin_print(char *name, char **args, Options ops, int func)
 
 /**/
 int
-bin_shift(char *name, char **argv, UNUSED(Options ops), UNUSED(int func))
+bin_shift(char *name, char **argv, Options ops, UNUSED(int func))
 {
     int num = 1, l, ret = 0;
     char **s;
@@ -4533,7 +4533,19 @@ bin_shift(char *name, char **argv, UNUSED(Options ops), UNUSED(int func))
 		    ret++;
 		    continue;
 		}
-		s = zarrdup(s + num);
+		if (OPT_ISSET(ops,'p')) {
+		    char **s2, **src, **dst;
+		    int count;
+		    l = arrlen(s);
+		    src = s;
+		    dst = s2 = (char **)zalloc((l - num + 1) * sizeof(char *));
+		    for (count = l - num; count; count--)
+			*dst++ = ztrdup(*src++);
+		    *dst = NULL;
+		    s = s2;
+		} else {
+		    s = zarrdup(s + num);
+		}
                 setaparam(*argv, s);
             }
     } else {
@@ -4542,9 +4554,16 @@ bin_shift(char *name, char **argv, UNUSED(Options ops), UNUSED(int func))
 	    ret = 1;
 	} else {
 	    s = zalloc((l - num + 1) * sizeof(char *));
-	    memcpy(s, pparams + num, (l - num + 1) * sizeof(char *));
-	    while (num--)
-		zsfree(pparams[num]);
+	    if (OPT_ISSET(ops,'p')) {
+		memcpy(s, pparams, (l - num) * sizeof(char *));
+		s[l-num] = NULL;
+		while (num--)
+		    zsfree(pparams[l-1-num]);
+	    } else {
+		memcpy(s, pparams + num, (l - num + 1) * sizeof(char *));
+		while (num--)
+		    zsfree(pparams[num]);
+	    }
 	    zfree(pparams, (l + 1) * sizeof(char *));
 	    pparams = s;
 	}

Test/.distfiles

@@ -15,6 +15,7 @@ B04read.ztst
 B05eval.ztst
 B06fc.ztst
 B07emulate.ztst
+B08shift.ztst
 C01arith.ztst
 C02cond.ztst
 C03traps.ztst

Test/B08shift.ztst

@@ -0,0 +1,33 @@
+# Test the shift builtin.
+
+%test
+
+  set -- one two three four five six seven eight nine ten
+  shift
+  print $*
+  shift 2
+  print $*
+  shift -p 3
+  print $*
+  shift -p
+  print $*
+0:shifting positional parameters
+>two three four five six seven eight nine ten
+>four five six seven eight nine ten
+>four five six seven
+>four five six
+
+  array=(yan tan tether mether pip azer sezar akker conter dick)
+  shift 2 array
+  print $array
+  shift array
+  print $array
+  shift -p 3 array
+  print $array
+  shift -p array
+  print $array
+0:shifting array
+>tether mether pip azer sezar akker conter dick
+>mether pip azer sezar akker conter dick
+>mether pip azer sezar
+>mether pip azer