2 files changed, 594 insertions, 0 deletions
diff --git a/Src/Modules/param_private.c b/Src/Modules/param_private.c
new file mode 100644
index 000000000..7f9aa7921
--- /dev/null
+++ b/Src/Modules/param_private.c
@@ -0,0 +1,587 @@
+/*
+ * param_private.c - bindings for private parameter scopes
+ *
+ * This file is part of zsh, the Z shell.
+ *
+ * Copyright (c) 2015 Barton E. Schaefer
+ * All rights reserved.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and to distribute modified versions of this software for any
+ * purpose, provided that the above copyright notice and the following
+ * two paragraphs appear in all copies of this software.
+ *
+ * In no event shall Barton E. Schaefer or the Zsh Development
+ * Group be liable to any party for direct, indirect, special, incidental, or
+ * consequential damages arising out of the use of this software and its
+ * documentation, even if Barton E. Schaefer and the Zsh
+ * Development Group have been advised of the possibility of such damage.
+ *
+ * Barton E. Schaefer and the Zsh Development Group
+ * specifically disclaim any warranties, including, but not limited to, the
+ * implied warranties of merchantability and fitness for a particular purpose.
+ * The software provided hereunder is on an "as is" basis, and
+ * Barton E. Schaefer and the Zsh Development Group have no
+ * obligation to provide maintenance, support, updates, enhancements, or
+ * modifications.
+ *
+ */
+
+#include "param_private.mdh"
+#include "param_private.pro"
+
+struct gsu_closure {
+    union {
+	struct gsu_scalar s;
+	struct gsu_integer i;
+	struct gsu_float f;
+	struct gsu_array a;
+	struct gsu_hash h;
+    } u;
+    void *g;
+};
+
+const struct gsu_scalar scalar_private_gsu =
+{ pps_getfn, pps_setfn, pps_unsetfn };
+
+const struct gsu_integer integer_private_gsu =
+{ ppi_getfn, ppi_setfn, ppi_unsetfn };
+
+const struct gsu_float float_private_gsu =
+{ ppf_getfn, ppf_setfn, ppf_unsetfn };
+
+const struct gsu_array array_private_gsu =
+{ ppa_getfn, ppa_setfn, ppa_unsetfn };
+
+const struct gsu_hash hash_private_gsu =
+{ pph_getfn, pph_setfn, pph_unsetfn };
+
+/*
+ * The trick here is:
+ *
+ * bin_private() opens a new parameter scope, then calls bin_typeset().
+ *
+ * bin_typeset() handles the usual parameter creation and error checks.
+ *
+ * makeprivate() then finds all parameters created in the new scope and
+ * rejects them if they can't be "promoted" to the surrounding scope.
+ * Otherwise it swaps out their GSU structure and promotes them so they
+ * will be removed when the surrounding scope ends.
+ *
+ * bin_private() then ends the current scope, which discards any of the
+ * parameters rejected by makeprivate().
+ *
+ */
+
+static int makeprivate_error = 0;
+
+static void
+makeprivate(HashNode hn, UNUSED(int flags))
+{
+    Param pm = (Param)hn;
+    if (pm->level == locallevel) {
+	if (pm->ename || (pm->node.flags & PM_NORESTORE) ||
+	    (pm->old &&
+	     (pm->old->level == locallevel - 1 ||
+	      ((pm->node.flags & (PM_SPECIAL|PM_REMOVABLE)) == PM_SPECIAL &&
+	       /* typeset_single() line 2300 discards PM_REMOVABLE -- why? */
+	       !is_private(pm->old))))) {
+	    zwarnnam("private", "can't change scope of existing param: %s",
+		     pm->node.nam);
+	    makeprivate_error = 1;
+	    return;
+	}
+	struct gsu_closure *gsu = zhalloc(sizeof(struct gsu_closure));
+	switch (PM_TYPE(pm->node.flags)) {
+	case PM_SCALAR:
+	    gsu->g = (void *)(pm->gsu.s);
+	    gsu->u.s = scalar_private_gsu;
+	    pm->gsu.s = (GsuScalar)gsu;
+	    break;
+	case PM_INTEGER:
+	    gsu->g = (void *)(pm->gsu.i);
+	    gsu->u.i = integer_private_gsu;
+	    pm->gsu.i = (GsuInteger)gsu;
+	    break;
+	case PM_EFLOAT:
+	case PM_FFLOAT:
+	    gsu->g = (void *)(pm->gsu.f);
+	    gsu->u.f = float_private_gsu;
+	    pm->gsu.f = (GsuFloat)gsu;
+	    break;
+	case PM_ARRAY:
+	    gsu->g = (void *)(pm->gsu.a);
+	    gsu->u.a = array_private_gsu;
+	    pm->gsu.a = (GsuArray)gsu;
+	    break;
+	case PM_HASHED:
+	    gsu->g = (void *)(pm->gsu.h);
+	    gsu->u.h = hash_private_gsu;
+	    pm->gsu.h = (GsuHash)gsu;
+	    break;
+	default:
+	    makeprivate_error = 1;
+	    break;
+	}
+	/* PM_HIDE so new parameters in deeper scopes do not shadow */
+	pm->node.flags |= (PM_HIDE|PM_SPECIAL|PM_REMOVABLE);
+	pm->level -= 1;
+    }
+}
+
+/**/
+static int
+is_private(Param pm)
+{
+    switch (PM_TYPE(pm->node.flags)) {
+    case PM_SCALAR:
+	if (!pm->gsu.s || pm->gsu.s->unsetfn != pps_unsetfn)
+	    return 0;
+	break;
+    case PM_INTEGER:
+	if (!pm->gsu.i || pm->gsu.i->unsetfn != ppi_unsetfn)
+	    return 0;
+	break;
+    case PM_EFLOAT:
+    case PM_FFLOAT:
+	if (!pm->gsu.f || pm->gsu.f->unsetfn != ppf_unsetfn)
+	    return 0;
+	break;
+    case PM_ARRAY:
+	if (!pm->gsu.a || pm->gsu.a->unsetfn != ppa_unsetfn)
+	    return 0;
+	break;
+    case PM_HASHED:
+	if (!pm->gsu.h || pm->gsu.h->unsetfn != pph_unsetfn)
+	    return 0;
+	break;
+    default:
+	/* error */
+	return 0;
+    }
+    return 1;
+}
+
+static int fakelevel;
+
+/**/
+static int
+bin_private(char *nam, char **args, LinkList assigns, Options ops, int func)
+{
+    int from_typeset = 1;
+    makeprivate_error = 0;
+
+    if (!OPT_ISSET(ops, 'P'))
+	return bin_typeset(nam, args, assigns, ops, func);
+    else if (OPT_ISSET(ops, 'T')) {
+	zwarn("bad option: -T");
+	return 1;
+    }
+
+    if (locallevel == 0) {
+	if (isset(WARNCREATEGLOBAL))
+	    zwarnnam(nam, "invalid local scope, using globals");
+	return bin_typeset("private", args, assigns, ops, func);
+    }
+
+    ops->ind['g'] = 2;	/* force bin_typeset() to behave as "local" */
+
+    queue_signals();
+    fakelevel = locallevel;
+    startparamscope();
+    from_typeset = bin_typeset("private", args, assigns, ops, func);
+    scanhashtable(paramtab, 0, 0, 0, makeprivate, 0);
+    endparamscope();
+    fakelevel = 0;
+    unqueue_signals();
+
+    return makeprivate_error | from_typeset;
+}
+
+static void
+setfn_error(Param pm)
+{
+    pm->node.flags |= PM_UNSET;
+    zerr("%s: attempt to assign private in nested scope", pm->node.nam);
+}
+
+/*
+ * How the GSU functions work:
+ *
+ * The getfn and setfn family compare to locallevel and then call through
+ * to the original getfn or setfn.  This means you can't assign at a
+ * deeper scope to any parameter declared private unless you first declare
+ * it local again at the new scope.  Testing locallevel in getfn is most
+ * likely unnecessary given the scopeprivate() wrapper installed below.
+ *
+ * The unsetfn family compare locallevel and restore the old GSU before
+ * calling the original unsetfn.  This assures that if the old unsetfn
+ * wants to use its getfn or setfn, they're unconditionally present.
+ *
+ */ 
+
+/**/
+static char *
+pps_getfn(Param pm)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.s);
+    GsuScalar gsu = (GsuScalar)(c->g);
+
+    if (locallevel >= pm->level)
+	return gsu->getfn(pm);
+    else
+	return (char *) hcalloc(1);
+}
+
+/**/
+static void
+pps_setfn(Param pm, char *x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.s);
+    GsuScalar gsu = (GsuScalar)(c->g);
+    if (locallevel == pm->level)
+	gsu->setfn(pm, x);
+    else
+	setfn_error(pm);
+}
+
+/**/
+static void
+pps_unsetfn(Param pm, int x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.s);
+    GsuScalar gsu = (GsuScalar)(c->g);
+    pm->gsu.s = gsu;
+    if (locallevel <= pm->level)
+	gsu->unsetfn(pm, x);
+}
+
+/**/
+static zlong
+ppi_getfn(Param pm)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.i);
+    GsuInteger gsu = (GsuInteger)(c->g);
+    if (locallevel >= pm->level)
+	return gsu->getfn(pm);
+    else
+	return 0;
+}
+
+/**/
+static void
+ppi_setfn(Param pm, zlong x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.i);
+    GsuInteger gsu = (GsuInteger)(c->g);
+    if (locallevel == pm->level)
+	gsu->setfn(pm, x);
+    else
+	setfn_error(pm);
+}
+
+/**/
+static void
+ppi_unsetfn(Param pm, int x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.i);
+    GsuInteger gsu = (GsuInteger)(c->g);
+    pm->gsu.i = gsu;
+    if (locallevel <= pm->level)
+	gsu->unsetfn(pm, x);
+}
+
+/**/
+static double
+ppf_getfn(Param pm)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.f);
+    GsuFloat gsu = (GsuFloat)(c->g);
+    if (locallevel >= pm->level)
+	return gsu->getfn(pm);
+    else
+	return 0;
+}
+
+/**/
+static void
+ppf_setfn(Param pm, double x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.f);
+    GsuFloat gsu = (GsuFloat)(c->g);
+    if (locallevel == pm->level)
+	gsu->setfn(pm, x);
+    else
+	setfn_error(pm);
+}
+
+/**/
+static void
+ppf_unsetfn(Param pm, int x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.f);
+    GsuFloat gsu = (GsuFloat)(c->g);
+    pm->gsu.f = gsu;
+    if (locallevel <= pm->level)
+	gsu->unsetfn(pm, x);
+}
+
+/**/
+static char **
+ppa_getfn(Param pm)
+{
+    static char *nullarray = NULL;
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.a);
+    GsuArray gsu = (GsuArray)(c->g);
+    if (locallevel >= pm->level)
+	return gsu->getfn(pm);
+    else
+	return &nullarray;
+}
+
+/**/
+static void
+ppa_setfn(Param pm, char **x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.a);
+    GsuArray gsu = (GsuArray)(c->g);
+    if (locallevel == pm->level)
+	gsu->setfn(pm, x);
+    else
+	setfn_error(pm);
+}
+
+/**/
+static void
+ppa_unsetfn(Param pm, int x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.a);
+    GsuArray gsu = (GsuArray)(c->g);
+    pm->gsu.a = gsu;
+    if (locallevel <= pm->level)
+	gsu->unsetfn(pm, x);
+}
+
+static HashTable emptytable;
+
+/**/
+static HashTable
+pph_getfn(Param pm)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.h);
+    GsuHash gsu = (GsuHash)(c->g);
+    if (locallevel >= pm->level)
+	return gsu->getfn(pm);
+    else
+	return emptytable;
+}
+
+/**/
+static void
+pph_setfn(Param pm, HashTable x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.h);
+    GsuHash gsu = (GsuHash)(c->g);
+    if (locallevel == pm->level)
+	gsu->setfn(pm, x);
+    else
+	setfn_error(pm);
+}
+
+/**/
+static void
+pph_unsetfn(Param pm, int x)
+{
+    struct gsu_closure *c = (struct gsu_closure *)(pm->gsu.h);
+    GsuHash gsu = (GsuHash)(c->g);
+    pm->gsu.h = gsu;
+    if (locallevel <= pm->level)
+	gsu->unsetfn(pm, x);
+}
+
+/*
+ * How visibility works:
+ *
+ * Upon entering a new function scope, we find all the private parameters
+ * at this locallevel.  Any that we find are marked PM_UNSET.  If they are
+ * already unset, they are also marked as PM_NORESTORE.
+ *
+ * On exit from the scope, we find the same parameters again and remove
+ * the PM_UNSET and PM_NORESTORE flags as appropriate.  We're guaraneed
+ * by makeprivate() that PM_NORESTORE won't conflict with anything here.
+ *
+ */
+
+static void
+scopeprivate(HashNode hn, int onoff)
+{
+    Param pm = (Param)hn;
+    if (pm->level == locallevel) {
+	if (!is_private(pm))
+	    return;
+	if (onoff == PM_UNSET)
+	    if (pm->node.flags & PM_UNSET)
+		pm->node.flags |= PM_NORESTORE;
+	    else
+		pm->node.flags |= PM_UNSET;
+	else if (!(pm->node.flags & PM_NORESTORE))
+	    pm->node.flags &= ~PM_UNSET;
+	pm->node.flags &= ~PM_NORESTORE;
+    }
+}
+
+static struct funcwrap wrapper[] = {
+    WRAPDEF(wrap_private)
+};
+
+/**/
+static int
+wrap_private(Eprog prog, FuncWrap w, char *name)
+{
+    static int wraplevel = 0;
+
+    if (wraplevel < locallevel /* && strcmp(name, "(anon)") != 0 */) {
+	int owl = wraplevel;
+	wraplevel = locallevel;
+	scanhashtable(paramtab, 0, 0, 0, scopeprivate, PM_UNSET);
+	runshfunc(prog, w, name);
+	scanhashtable(paramtab, 0, 0, 0, scopeprivate, 0);
+	wraplevel = owl;
+	return 0;
+    }
+    return 1;
+}
+
+static HashNode (*getparamnode) _((HashTable, const char *));
+
+/**/
+static HashNode
+getprivatenode(HashTable ht, const char *nam)
+{
+    HashNode hn = getparamnode(ht, nam);
+    Param pm = (Param) hn;
+
+    while (!fakelevel && pm && locallevel > pm->level && is_private(pm))
+	pm = pm->old;
+    return (HashNode)pm;
+}
+
+/**/
+static HashNode
+getprivatenode2(HashTable ht, const char *nam)
+{
+    /* getparamnode() would follow autoloads, we must not do that here */
+    HashNode hn = gethashnode2(ht, nam);
+    Param pm = (Param) hn;
+
+    while (!fakelevel && pm && locallevel > pm->level && is_private(pm))
+	pm = pm->old;
+    return (HashNode)pm;
+}
+
+/**/
+static void
+printprivatenode(HashNode hn, int printflags)
+{
+    Param pm = (Param) hn;
+    while (pm && (!fakelevel ||
+		  (fakelevel > pm->level && (pm->node.flags & PM_UNSET))) &&
+	   locallevel > pm->level && is_private(pm))
+	pm = pm->old;
+    /* Ideally, we'd print the word "private" here instead of "typeset"
+     * when the parameter is in fact a private, but that would require
+     * re-implementing the entirety of printparamnode(). */
+    if (pm)
+	printparamnode((HashNode)pm, printflags);
+}
+
+/*
+ * Standard module configuration/linkage
+ */
+
+static struct builtin bintab[] = {
+    /* Copied from BUILTIN("local"), "P" added */
+    BUILTIN("private", BINF_PLUSOPTS | BINF_MAGICEQUALS | BINF_PSPECIAL | BINF_ASSIGN, (HandlerFunc)bin_private, 0, -1, 0, "AE:%F:%HL:%PR:%TUZ:%ahi:%lprtux", "P")
+};
+
+static struct features module_features = {
+    bintab, sizeof(bintab)/sizeof(*bintab),
+    NULL, 0,
+    NULL, 0,
+    NULL, 0,
+    0
+};
+
+static struct builtin save_local;
+static struct reswd reswd_private = {{NULL, "private", 0}, TYPESET};
+
+/**/
+int
+setup_(UNUSED(Module m))
+{
+    HashNode hn = builtintab->getnode(builtintab, "local");
+
+    /* Horrible, horrible hack */
+    getparamnode = realparamtab->getnode;
+    realparamtab->getnode = getprivatenode;
+    realparamtab->getnode2 = getprivatenode2;
+    realparamtab->printnode = printprivatenode;
+
+    /* Even more horrible hack */
+    save_local = *(Builtin)hn;
+    ((Builtin)hn)->handlerfunc = bintab[0].handlerfunc;
+    ((Builtin)hn)->optstr = bintab[0].optstr;
+
+    reswdtab->addnode(reswdtab, reswd_private.node.nam, &reswd_private);
+
+    return 0;
+}
+
+/**/
+int
+features_(Module m, char ***features)
+{
+    *features = featuresarray(m, &module_features);
+    return 0;
+}
+
+/**/
+int
+enables_(Module m, int **enables)
+{
+    return handlefeatures(m, &module_features, enables);
+}
+
+/**/
+int
+boot_(Module m)
+{
+    emptytable = newparamtable(1, "private");
+    return addwrapper(m, wrapper);
+}
+
+/**/
+int
+cleanup_(Module m)
+{
+    HashNode hn = builtintab->getnode(builtintab, "local");
+    *(Builtin)hn = save_local;
+
+    removehashnode(reswdtab, "private");
+    
+    realparamtab->getnode = getparamnode;
+    realparamtab->getnode2 = gethashnode2;
+    realparamtab->printnode = printparamnode;
+
+    deletewrapper(m, wrapper);
+    return setfeatureenables(m, &module_features, NULL);
+}
+
+/**/
+int
+finish_(UNUSED(Module m))
+{
+    deletehashtable(emptytable);
+    return 0;
+}
diff --git a/Src/Modules/param_private.mdd b/Src/Modules/param_private.mdd
new file mode 100644
index 000000000..e6eb3228f
--- /dev/null
+++ b/Src/Modules/param_private.mdd
@@ -0,0 +1,7 @@
+name=zsh/param/private
+link=dynamic
+load=yes
+
+autofeatures="b:private"
+
+objects="param_private.o"