Add new FOREACH_FROM variants of the queue(3) FOREACH macros which can

optionally start the traversal from a previously found element by passing the
element in as "var". Passing a NULL "var" retains the same semantics as the
regular FOREACH macros.

Kudos to phk for suggesting the "FROM" suffix instead of my original proposal.

Reviewed by:	jhb (previous version), rpaulo
MFC after:	1 week

1 files changed, 151 insertions, 1 deletions

diff --git a/share/man/man3/queue.3 b/share/man/man3/queue.3
index e531ac0..2b7ad44 100644
--- a/share/man/man3/queue.3
+++ b/share/man/man3/queue.3
@@ -32,7 +32,7 @@
 .\"	@(#)queue.3	8.2 (Berkeley) 1/24/94
 .\" $FreeBSD$
 .\"
-.Dd Sep 12, 2012
+.Dd June 17, 2013
 .Dt QUEUE 3
 .Os
 .Sh NAME
@@ -40,7 +40,9 @@
 .Nm SLIST_ENTRY ,
 .Nm SLIST_FIRST ,
 .Nm SLIST_FOREACH ,
+.Nm SLIST_FOREACH_FROM ,
 .Nm SLIST_FOREACH_SAFE ,
+.Nm SLIST_FOREACH_FROM_SAFE ,
 .Nm SLIST_HEAD ,
 .Nm SLIST_HEAD_INITIALIZER ,
 .Nm SLIST_INIT ,
@@ -56,7 +58,9 @@
 .Nm STAILQ_ENTRY ,
 .Nm STAILQ_FIRST ,
 .Nm STAILQ_FOREACH ,
+.Nm STAILQ_FOREACH_FROM ,
 .Nm STAILQ_FOREACH_SAFE ,
+.Nm STAILQ_FOREACH_FROM_SAFE ,
 .Nm STAILQ_HEAD ,
 .Nm STAILQ_HEAD_INITIALIZER ,
 .Nm STAILQ_INIT ,
@@ -73,7 +77,9 @@
 .Nm LIST_ENTRY ,
 .Nm LIST_FIRST ,
 .Nm LIST_FOREACH ,
+.Nm LIST_FOREACH_FROM ,
 .Nm LIST_FOREACH_SAFE ,
+.Nm LIST_FOREACH_FROM_SAFE ,
 .Nm LIST_HEAD ,
 .Nm LIST_HEAD_INITIALIZER ,
 .Nm LIST_INIT ,
@@ -89,9 +95,13 @@
 .Nm TAILQ_ENTRY ,
 .Nm TAILQ_FIRST ,
 .Nm TAILQ_FOREACH ,
+.Nm TAILQ_FOREACH_FROM ,
 .Nm TAILQ_FOREACH_SAFE ,
+.Nm TAILQ_FOREACH_FROM_SAFE ,
 .Nm TAILQ_FOREACH_REVERSE ,
+.Nm TAILQ_FOREACH_REVERSE_FROM ,
 .Nm TAILQ_FOREACH_REVERSE_SAFE ,
+.Nm TAILQ_FOREACH_REVERSE_FROM_SAFE ,
 .Nm TAILQ_HEAD ,
 .Nm TAILQ_HEAD_INITIALIZER ,
 .Nm TAILQ_INIT ,
@@ -113,7 +123,9 @@ lists and tail queues
 .Fn SLIST_ENTRY "TYPE"
 .Fn SLIST_FIRST "SLIST_HEAD *head"
 .Fn SLIST_FOREACH "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME"
+.Fn SLIST_FOREACH_FROM "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME"
 .Fn SLIST_FOREACH_SAFE "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME" "TYPE *temp_var"
+.Fn SLIST_FOREACH_FROM_SAFE "TYPE *var" "SLIST_HEAD *head" "SLIST_ENTRY NAME" "TYPE *temp_var"
 .Fn SLIST_HEAD "HEADNAME" "TYPE"
 .Fn SLIST_HEAD_INITIALIZER "SLIST_HEAD head"
 .Fn SLIST_INIT "SLIST_HEAD *head"
@@ -130,7 +142,9 @@ lists and tail queues
 .Fn STAILQ_ENTRY "TYPE"
 .Fn STAILQ_FIRST "STAILQ_HEAD *head"
 .Fn STAILQ_FOREACH "TYPE *var" "STAILQ_HEAD *head" "STAILQ_ENTRY NAME"
+.Fn STAILQ_FOREACH_FROM "TYPE *var" "STAILQ_HEAD *head" "STAILQ_ENTRY NAME"
 .Fn STAILQ_FOREACH_SAFE "TYPE *var" "STAILQ_HEAD *head" "STAILQ_ENTRY NAME" "TYPE *temp_var"
+.Fn STAILQ_FOREACH_FROM_SAFE "TYPE *var" "STAILQ_HEAD *head" "STAILQ_ENTRY NAME" "TYPE *temp_var"
 .Fn STAILQ_HEAD "HEADNAME" "TYPE"
 .Fn STAILQ_HEAD_INITIALIZER "STAILQ_HEAD head"
 .Fn STAILQ_INIT "STAILQ_HEAD *head"
@@ -148,7 +162,9 @@ lists and tail queues
 .Fn LIST_ENTRY "TYPE"
 .Fn LIST_FIRST "LIST_HEAD *head"
 .Fn LIST_FOREACH "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME"
+.Fn LIST_FOREACH_FROM "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME"
 .Fn LIST_FOREACH_SAFE "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME" "TYPE *temp_var"
+.Fn LIST_FOREACH_FROM_SAFE "TYPE *var" "LIST_HEAD *head" "LIST_ENTRY NAME" "TYPE *temp_var"
 .Fn LIST_HEAD "HEADNAME" "TYPE"
 .Fn LIST_HEAD_INITIALIZER "LIST_HEAD head"
 .Fn LIST_INIT "LIST_HEAD *head"
@@ -165,9 +181,13 @@ lists and tail queues
 .Fn TAILQ_ENTRY "TYPE"
 .Fn TAILQ_FIRST "TAILQ_HEAD *head"
 .Fn TAILQ_FOREACH "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME"
+.Fn TAILQ_FOREACH_FROM "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME"
 .Fn TAILQ_FOREACH_SAFE "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME" "TYPE *temp_var"
+.Fn TAILQ_FOREACH_FROM_SAFE "TYPE *var" "TAILQ_HEAD *head" "TAILQ_ENTRY NAME" "TYPE *temp_var"
 .Fn TAILQ_FOREACH_REVERSE "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME"
+.Fn TAILQ_FOREACH_REVERSE_FROM "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME"
 .Fn TAILQ_FOREACH_REVERSE_SAFE "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME" "TYPE *temp_var"
+.Fn TAILQ_FOREACH_REVERSE_FROM_SAFE "TYPE *var" "TAILQ_HEAD *head" "HEADNAME" "TAILQ_ENTRY NAME" "TYPE *temp_var"
 .Fn TAILQ_HEAD "HEADNAME" "TYPE"
 .Fn TAILQ_HEAD_INITIALIZER "TAILQ_HEAD head"
 .Fn TAILQ_INIT "TAILQ_HEAD *head"
@@ -365,6 +385,19 @@ turn to
 .Fa var .
 .Pp
 The macro
+.Nm SLIST_FOREACH_FROM
+behaves identically to
+.Nm SLIST_FOREACH
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found SLIST element and begins the loop at
+.Fa var
+instead of the first element in the SLIST referenced by
+.Fa head .
+.Pp
+The macro
 .Nm SLIST_FOREACH_SAFE
 traverses the list referenced by
 .Fa head
@@ -379,6 +412,19 @@ as well as free it from within the loop safely without interfering with the
 traversal.
 .Pp
 The macro
+.Nm SLIST_FOREACH_FROM_SAFE
+behaves identically to
+.Nm SLIST_FOREACH_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found SLIST element and begins the loop at
+.Fa var
+instead of the first element in the SLIST referenced by
+.Fa head .
+.Pp
+The macro
 .Nm SLIST_INIT
 initializes the list referenced by
 .Fa head .
@@ -545,6 +591,19 @@ in turn to
 .Fa var .
 .Pp
 The macro
+.Nm STAILQ_FOREACH_FROM
+behaves identically to
+.Nm STAILQ_FOREACH
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found STAILQ element and begins the loop at
+.Fa var
+instead of the first element in the STAILQ referenced by
+.Fa head .
+.Pp
+The macro
 .Nm STAILQ_FOREACH_SAFE
 traverses the tail queue referenced by
 .Fa head
@@ -559,6 +618,19 @@ as well as free it from within the loop safely without interfering with the
 traversal.
 .Pp
 The macro
+.Nm STAILQ_FOREACH_FROM_SAFE
+behaves identically to
+.Nm STAILQ_FOREACH_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found STAILQ element and begins the loop at
+.Fa var
+instead of the first element in the STAILQ referenced by
+.Fa head .
+.Pp
+The macro
 .Nm STAILQ_INIT
 initializes the tail queue referenced by
 .Fa head .
@@ -735,6 +807,19 @@ in the forward direction, assigning each element in turn to
 .Fa var .
 .Pp
 The macro
+.Nm LIST_FOREACH_FROM
+behaves identically to
+.Nm LIST_FOREACH
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found LIST element and begins the loop at
+.Fa var
+instead of the first element in the LIST referenced by
+.Fa head .
+.Pp
+The macro
 .Nm LIST_FOREACH_SAFE
 traverses the list referenced by
 .Fa head
@@ -748,6 +833,19 @@ as well as free it from within the loop safely without interfering with the
 traversal.
 .Pp
 The macro
+.Nm LIST_FOREACH_FROM_SAFE
+behaves identically to
+.Nm LIST_FOREACH_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found LIST element and begins the loop at
+.Fa var
+instead of the first element in the LIST referenced by
+.Fa head .
+.Pp
+The macro
 .Nm LIST_INIT
 initializes the list referenced by
 .Fa head .
@@ -920,12 +1018,38 @@ is set to
 if the loop completes normally, or if there were no elements.
 .Pp
 The macro
+.Nm TAILQ_FOREACH_FROM
+behaves identically to
+.Nm TAILQ_FOREACH
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found TAILQ element and begins the loop at
+.Fa var
+instead of the first element in the TAILQ referenced by
+.Fa head .
+.Pp
+The macro
 .Nm TAILQ_FOREACH_REVERSE
 traverses the tail queue referenced by
 .Fa head
 in the reverse direction, assigning each element in turn to
 .Fa var .
 .Pp
+The macro
+.Nm TAILQ_FOREACH_REVERSE_FROM
+behaves identically to
+.Nm TAILQ_FOREACH_REVERSE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found TAILQ element and begins the reverse loop at
+.Fa var
+instead of the last element in the TAILQ referenced by
+.Fa head .
+.Pp
 The macros
 .Nm TAILQ_FOREACH_SAFE
 and
@@ -945,6 +1069,32 @@ as well as free it from within the loop safely without interfering with the
 traversal.
 .Pp
 The macro
+.Nm TAILQ_FOREACH_FROM_SAFE
+behaves identically to
+.Nm TAILQ_FOREACH_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found TAILQ element and begins the loop at
+.Fa var
+instead of the first element in the TAILQ referenced by
+.Fa head .
+.Pp
+The macro
+.Nm TAILQ_FOREACH_REVERSE_FROM_SAFE
+behaves identically to
+.Nm TAILQ_FOREACH_REVERSE_SAFE
+when
+.Fa var
+is NULL, else it treats
+.Fa var
+as a previously found TAILQ element and begins the reverse loop at
+.Fa var
+instead of the last element in the TAILQ referenced by
+.Fa head .
+.Pp
+The macro
 .Nm TAILQ_INIT
 initializes the tail queue referenced by
 .Fa head .