PATCH: Add g:: parameter expansion flag

[Mikael Magnusson <mikachu@gmail.com>]

Okay, how's this? I swapped the order so g happens first, and changed
the docs as discussed.

---
 Doc/Zsh/expn.yo        |   17 ++++++++++++--
 Src/subst.c            |   55 ++++++++++++++++++++++++++++++++++++++++++++++++
 Test/D04parameter.ztst |   17 ++++++++++++++
 3 files changed, 86 insertions(+), 3 deletions(-)

diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo
index 1cad3d2..d3a08c5 100644
--- a/Doc/Zsh/expn.yo
+++ b/Doc/Zsh/expn.yo
@@ -863,6 +863,14 @@ item(tt(F))(
 Join the words of arrays together using newline as a separator.
 This is a shorthand for `tt(pj:\n:)'.
 )
+item(tt(g:opts:))(
+Process escape sequences like the echo builtin when no options are given
+(tt(g::)).  With the tt(o) option, octal escapes don't take a leading
+zero.  With the tt(c) option, sequences like `tt(^X)' are also processed.
+With the tt(e) option, processes `tt(\M-t)' and similar sequences like the
+print builtin.  With both of the tt(o) and tt(e) options, behaves like the
+print builtin except that in none of these modes is `tt(\c)' interpreted.
+)
 item(tt(i))(
 Sort case-insensitively.  May be combined with `tt(n)' or `tt(O)'.
 )
@@ -1108,7 +1116,9 @@ Force field splitting at the
 separator var(string).  Note that a var(string) of two or more
 characters means that all of them must match in sequence; this differs from
 the treatment of two or more characters in the tt(IFS) parameter.
-See also the tt(=) flag and the tt(SH_WORD_SPLIT) option.
+See also the tt(=) flag and the tt(SH_WORD_SPLIT) option.  An empty
+string may also be given in which case every character will be a separate
+element.
 
 For historical reasons, the usual behaviour that empty array elements
 are retained inside double quotes is disabled for arrays generated
@@ -1292,8 +1302,9 @@ item(tt(11.) em(Case modification))(
 Any case modification from one of the flags tt((L)), tt((U)) or tt((C))
 is applied.
 )
-item(tt(12.) em(Prompt evaluation))(
-Any prompt-style formatting from the tt((%)) family of flags is applied.
+item(tt(12.) em(Escape sequence replacement))(
+First any replacements from the tt((g)) flag are performed, then any
+prompt-style formatting from the tt((%)) family of flags is applied.
 )
 item(tt(13.) em(Quote application))(
 Any quoting or unquoting using tt((q)) and tt((Q)) and related flags
diff --git a/Src/subst.c b/Src/subst.c
index 5d7a8b4..7aa07b5 100644
--- a/Src/subst.c
+++ b/Src/subst.c
@@ -1607,6 +1607,10 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int ssub)
      */	
     int presc = 0;
     /*
+     * The (g) flag.  Process escape sequences with various GETKEY_ flags.
+     */
+    int getkeys = -1;
+    /*
      * The (@) flag; interacts obscurely with qt and isarr.
      * This is one of the things that decides whether multsub
      * will produce an array, but in an extremely indirect fashion.
@@ -1932,6 +1936,36 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int ssub)
 		    presc++;
 		    break;
 
+		case 'g':
+		    t = get_strarg(++s, &arglen);
+		    if (getkeys < 0)
+			getkeys = 0;
+		    if (*t) {
+			sav = *t;
+			*t = 0;
+			while (*++s) {
+			    switch (*s) {
+			    case 'e':
+				getkeys |= GETKEY_EMACS;
+				break;
+			    case 'o':
+				getkeys |= GETKEY_OCTAL_ESC;
+				break;
+			    case 'c':
+				getkeys |= GETKEY_CTRL;
+				break;
+
+			    default:
+				*t = sav;
+				goto flagerr;
+			    }
+			}
+			*t = sav;
+			s = t + arglen - 1;
+		    } else
+			goto flagerr;
+                    break;
+
 		case 'z':
 		    shsplit = LEXFLAGS_ACTIVE;
 		    break;
@@ -3100,6 +3134,27 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int ssub)
 	}
     }
     /*
+     * Process echo- and print-style escape sequences.
+     */
+    if (getkeys >= 0) {
+	if (isarr) {
+	    char **ap;
+
+	    if (!copied)
+		aval = arrdup(aval), copied = 1;
+	    ap = aval;
+	    for (; *ap; ap++) {
+		int len;
+		*ap = getkeystring(*ap, &len, getkeys, NULL);
+	    }
+	} else {
+	    int len;
+	    if (!copied)
+		val = dupstring(val), copied = 1;
+	    val = getkeystring(val, &len, getkeys, NULL);
+	}
+    }
+    /*
      * Perform prompt-style modifications.
      */
     if (presc) {
diff --git a/Test/D04parameter.ztst b/Test/D04parameter.ztst
index b91caaa..7322872 100644
--- a/Test/D04parameter.ztst
+++ b/Test/D04parameter.ztst
@@ -298,6 +298,23 @@
 >Howzat
 >usay
 
+  foo='\u65\123'
+  print -r ${(g:o:)foo}
+  foo='\u65\0123'
+  print -r ${(g::)foo}
+  foo='\u65^X'
+  print -r ${(V)${(g:c:)foo}}
+  foo='\u65\C-x\M-a'
+  print -r ${(V)${(g:e:)foo}}
+  foo='\u65\123\C-x'
+  print -r ${(V)${(g:eo:)foo}}
+0:${(g)...}
+>eS
+>eS
+>e^X
+>e^X\M-a
+>eS^X
+
   foo='I'\''m nearly out of my mind with tedium'
   bar=foo
   print ${(P)bar}
-- 
1.7.4-rc1