[Qemu-devel] [RFC 2/6] OptsVisitor: introduce list modes for interval flattening

[Laszlo Ersek]

The new modes are equal-rank, exclusive sub-modes of LM_IN_PROGRESS. Teach
opts_next_list(), opts_type_int() and opts_type_uint64() to handle them.

Also enumerate explicitly what functions are valid to call in what modes:
- opts_next_list() is valid to call while flattening a range,
- opts_end_list(): ditto,
- lookup_scalar() is invalid to call during flattening; generated qapi
  traversal code must continue asking for the same kind of signed/unsigned
  list element until the interval is fully flattened,
- processed(): ditto.

List mode restrictions are always formulated in positive / inclusive
sense. The restrictions for lookup_scalar() and processed() are
automatically satisfied by current qapi traversals if the schema to build
is compatible with OptsVisitor.

The new list modes are not entered yet.

Signed-off-by: Laszlo Ersek <address@hidden>
---
 qapi/opts-visitor.c |   44 ++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index ab9a602..e8e317f 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -22,7 +22,9 @@ enum ListMode
 {
     LM_NONE,             /* not traversing a list of repeated options */
     LM_STARTED,          /* opts_start_list() succeeded */
-    LM_IN_PROGRESS       /* opts_next_list() has been called */
+    LM_IN_PROGRESS,      /* opts_next_list() has been called */
+    LM_SIGNED_INTERVAL,  /* flattening an interval with signed bounds */
+    LM_UNSIGNED_INTERVAL /* flattening an interval with unsigned bounds */
 };
 
 typedef enum ListMode ListMode;
@@ -47,6 +49,15 @@ struct OptsVisitor
     ListMode list_mode;
     GQueue *repeated_opts;
 
+    /* When parsing a list of repeating options as integers, values of the form
+     * "a-b", representing a closed interval, are allowed. Elements in the
+     * range are generated individually.
+     */
+    union {
+        int64_t s;
+        uint64_t u;
+    } range_next, range_limit;
+
     /* If "opts_root->id" is set, reinstantiate it as a fake QemuOpt for
      * uniformity. Only its "name" and "str" fields are set. "fake_id_opt" does
      * not survive or escape the OptsVisitor object.
@@ -185,6 +196,22 @@ opts_next_list(Visitor *v, GenericList **list, Error 
**errp)
         link = list;
         break;
 
+    case LM_SIGNED_INTERVAL:
+    case LM_UNSIGNED_INTERVAL:
+        link = &(*list)->next;
+
+        if (ov->list_mode == LM_SIGNED_INTERVAL) {
+            if (ov->range_next.s < ov->range_limit.s) {
+                ++ov->range_next.s;
+                break;
+            }
+        } else if (ov->range_next.u < ov->range_limit.u) {
+            ++ov->range_next.u;
+            break;
+        }
+        ov->list_mode = LM_IN_PROGRESS;
+        /* range has been completed, fall through in order to pop option */
+
     case LM_IN_PROGRESS: {
         const QemuOpt *opt;
 
@@ -211,7 +238,10 @@ opts_end_list(Visitor *v, Error **errp)
 {
     OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
 
-    assert(ov->list_mode == LM_STARTED || ov->list_mode == LM_IN_PROGRESS);
+    assert(ov->list_mode == LM_STARTED ||
+           ov->list_mode == LM_IN_PROGRESS ||
+           ov->list_mode == LM_SIGNED_INTERVAL ||
+           ov->list_mode == LM_UNSIGNED_INTERVAL);
     ov->repeated_opts = NULL;
     ov->list_mode = LM_NONE;
 }
@@ -303,6 +333,11 @@ opts_type_int(Visitor *v, int64_t *obj, const char *name, 
Error **errp)
     long long val;
     char *endptr;
 
+    if (ov->list_mode == LM_SIGNED_INTERVAL) {
+        *obj = ov->range_next.s;
+        return;
+    }
+
     opt = lookup_scalar(ov, name, errp);
     if (!opt) {
         return;
@@ -328,6 +363,11 @@ opts_type_uint64(Visitor *v, uint64_t *obj, const char 
*name, Error **errp)
     const QemuOpt *opt;
     const char *str;
 
+    if (ov->list_mode == LM_UNSIGNED_INTERVAL) {
+        *obj = ov->range_next.u;
+        return;
+    }
+
     opt = lookup_scalar(ov, name, errp);
     if (!opt) {
         return;
-- 
1.7.1