25255: add anonymous function capability

4 files changed, 170 insertions, 28 deletions

diff --git a/ChangeLog b/ChangeLog
index a5d5bd9eb..7a49bf6ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2008-06-30  Peter Stephenson  <pws@csr.com>
+
+	* 25255: Doc/Zsh/func.yo, Src/exec.c, Test/C04funcdef.ztst:
+	anonymous functions using "() { ... }" and "function { ... }".
+
 2008-06-24  Clint Adams  <clint@zsh.org>
 
 	* 25243: Completion/X/Command/_xrandr: patch from Chris Lamb to add
diff --git a/Doc/Zsh/func.yo b/Doc/Zsh/func.yo
index 6b6202831..65bcd9abc 100644
--- a/Doc/Zsh/func.yo
+++ b/Doc/Zsh/func.yo
@@ -150,6 +150,42 @@ executing tt(myfunc), use:
 
 example(autoload +X myfunc)
 
+sect(Anonymous Functions)
+cindex(anonymous functions)
+cindex(functions, anonymous)
+
+If no name is given for a function, it is `anonymous' and is handled
+specially.  Either form of function definition may be used: a `tt(())' with
+no preceding name, or a `tt(function)' with an immediately following open
+brace.  The function is executed immediately at the point of definition and
+is not stored for future use.  The function name is set to `tt((anon))' and
+the parameter list passed to the function is empty.  Note that this means
+the argument list of any enclosing script or function is hidden.
+Redirections may be applied to the anonymous function in the same manner as
+to a current-shell structure enclosed in braces.  The main use of anonymous
+functions is to provide a scope for local variables.  This is particularly
+convenient in start-up files as these do not provide their own local
+variable scope.
+
+For example,
+
+example(variable=outside
+function {
+  local variable=inside
+  print "I am $variable"
+}
+print "I am $variable")
+
+outputs the following:
+
+example(I am inside
+I am outside)
+
+Note that function definitions with arguments that expand to nothing,
+for example `tt(name=; function $name { )var(...)tt( })', are not
+treated as anonymous functions.  Instead, they are treated as normal
+function definitions where the definition is silently discarded.
+
 sect(Special Functions)
 Certain functions, if defined, have special meaning to the shell.
 
diff --git a/Src/exec.c b/Src/exec.c
index 74f389a8d..7ce657032 100644
--- a/Src/exec.c
+++ b/Src/exec.c
@@ -3853,7 +3853,7 @@ static int
 execfuncdef(Estate state, UNUSED(int do_exec))
 {
     Shfunc shf;
-    char *s;
+    char *s = NULL;
     int signum, nprg, sbeg, nstrs, npats, len, plen, i, htok = 0;
     Wordcode beg = state->pc, end;
     Eprog prog;
@@ -3861,10 +3861,7 @@ execfuncdef(Estate state, UNUSED(int do_exec))
     LinkList names;
 
     end = beg + WC_FUNCDEF_SKIP(state->pc[-1]);
-    if (!(names = ecgetlist(state, *state->pc++, EC_DUPTOK, &htok))) {
-	state->pc = end;
-	return 0;
-    }
+    names = ecgetlist(state, *state->pc++, EC_DUPTOK, &htok);
     nprg = end - beg;
     sbeg = *state->pc++;
     nstrs = *state->pc++;
@@ -3874,21 +3871,32 @@ execfuncdef(Estate state, UNUSED(int do_exec))
     plen = nprg * sizeof(wordcode);
     len = plen + (npats * sizeof(Patprog)) + nstrs;
 
-    if (htok)
+    if (htok && names)
 	execsubst(names);
 
-    while ((s = (char *) ugetnode(names))) {
-	prog = (Eprog) zalloc(sizeof(*prog));
+    while (!names || (s = (char *) ugetnode(names))) {
+	if (!names) {
+	    prog = (Eprog) zhalloc(sizeof(*prog));
+	    prog->nref = -1; /* on the heap */
+	} else {
+	    prog = (Eprog) zalloc(sizeof(*prog));
+	    prog->nref = 1; /* allocated from permanent storage */
+	}
 	prog->npats = npats;
-	prog->nref = 1; /* allocated from permanent storage */
 	prog->len = len;
-	if (state->prog->dump) {
-	    prog->flags = EF_MAP;
-	    incrdumpcount(state->prog->dump);
-	    prog->pats = pp = (Patprog *) zalloc(npats * sizeof(Patprog));
+	if (state->prog->dump || !names) {
+	    if (!names) {
+		prog->flags = EF_HEAP;
+		prog->dump = NULL;
+		prog->pats = pp = (Patprog *) zhalloc(npats * sizeof(Patprog));
+	    } else {
+		prog->flags = EF_MAP;
+		incrdumpcount(state->prog->dump);
+		prog->dump = state->prog->dump;
+		prog->pats = pp = (Patprog *) zalloc(npats * sizeof(Patprog));
+	    }
 	    prog->prog = state->pc;
 	    prog->strs = state->strs + sbeg;
-	    prog->dump = state->prog->dump;
 	} else {
 	    prog->flags = EF_REAL;
 	    prog->pats = pp = (Patprog *) zalloc(len);
@@ -3906,23 +3914,37 @@ execfuncdef(Estate state, UNUSED(int do_exec))
 	shf->funcdef = prog;
 	shf->node.flags = 0;
 
-	/* is this shell function a signal trap? */
-	if (!strncmp(s, "TRAP", 4) &&
-	    (signum = getsignum(s + 4)) != -1) {
-	    if (settrap(signum, NULL, ZSIG_FUNC)) {
-		freeeprog(shf->funcdef);
-		zfree(shf, sizeof(*shf));
-		state->pc = end;
-		return 1;
-	    }
-
+	if (!names) {
 	    /*
-	     * Remove the old node explicitly in case it has
-	     * an alternative name
+	     * Anonymous function, execute immediately.
+	     * Function name is "(anon)", parameter list is empty.
 	     */
-	    removetrapnode(signum);
+	    LinkList args = newlinklist();
+
+	    shf->node.nam = "(anon)";
+	    addlinknode(args, shf->node.nam);
+
+	    execshfunc(shf, args);
+	    break;
+	} else {
+	    /* is this shell function a signal trap? */
+	    if (!strncmp(s, "TRAP", 4) &&
+		(signum = getsignum(s + 4)) != -1) {
+		if (settrap(signum, NULL, ZSIG_FUNC)) {
+		    freeeprog(shf->funcdef);
+		    zfree(shf, sizeof(*shf));
+		    state->pc = end;
+		    return 1;
+		}
+
+		/*
+		 * Remove the old node explicitly in case it has
+		 * an alternative name
+		 */
+		removetrapnode(signum);
+	    }
+	    shfunctab->addnode(shfunctab, ztrdup(s), shf);
 	}
-	shfunctab->addnode(shfunctab, ztrdup(s), shf);
     }
     state->pc = end;
     return 0;
diff --git a/Test/C04funcdef.ztst b/Test/C04funcdef.ztst
index d297ea418..69b09686a 100644
--- a/Test/C04funcdef.ztst
+++ b/Test/C04funcdef.ztst
@@ -99,3 +99,82 @@
 ?ThisCommandDoesNotExistEither
 ?has gone down the tubes.  Sorry.
 ?(eval):7: command not found: ThisCommandDoesNotExistEither
+
+  local variable=outside
+  print "I am $variable"
+  function {
+    local variable=inside
+    print "I am $variable"
+  }
+  print "I am $variable"
+  () {
+    local variable="inside again"
+    print "I am $variable"
+  }
+  print "I am $variable"
+0:Anonymous function scope
+>I am outside
+>I am inside
+>I am outside
+>I am inside again
+>I am outside
+
+  integer i
+  for (( i = 0; i < 10; i++ )); do function {
+    case $i in
+    ([13579])
+    print $i is odd
+    ;|
+    ([2468])
+    print $i is even
+    ;|
+    ([2357])
+    print $i is prime
+    ;;
+    esac
+  }; done
+0:Anonymous function with patterns in loop
+>1 is odd
+>2 is even
+>2 is prime
+>3 is odd
+>3 is prime
+>4 is even
+>5 is odd
+>5 is prime
+>6 is even
+>7 is odd
+>7 is prime
+>8 is even
+>9 is odd
+
+  echo stuff in file >file.in
+  function {
+    sed 's/stuff/rubbish/'
+  } <file.in >file.out
+  cat file.out
+0:Anonymous function redirection
+>rubbish in file
+
+  variable="Do be do"
+  print $variable
+  function {
+     print $variable
+     local variable="Da de da"
+     print $variable
+     function {
+       print $variable
+       local variable="Dum da dum"
+       print $variable
+     }
+     print $variable
+  }
+  print $variable
+0:Nested anonymous functions
+>Do be do
+>Do be do
+>Da de da
+>Da de da
+>Dum da dum
+>Da de da
+>Do be do