Read a tree's items in compiled code from a run the frame keeps, start a run at the finger's leaf, and move indices only for a list an index refers to (021)

- The frame keeps the run compiled code read a tree's item from last (the
  list as it was: its version); an item it holds is read from its column,
  else pure_run_item takes the item's run and steps.
- pure_list_run starts at the leaf the finger keeps when it holds the
  position (a slice found by key just before): no second descent; the
  run after it is found from the root (PureRun.pathless).
- LIST_APPEND and LIST_REMOVE move index states only for a list one
  refers to.
- A search (core only): 89 ms compiled (answers the executor's).

1 files changed, 4 insertions, 1 deletions

diff --git a/core/module-list.h b/core/module-list.h
index 0addcf0..6251786 100644
--- a/core/module-list.h
+++ b/core/module-list.h
@@ -37,10 +37,13 @@ typedef struct {
     size_t start;
     unsigned count;
     union { const double *numbers; const int64_t *integers; const PureSpan *texts; } column[16];
-    /* Where the run is in the list's tree, for the next one. */
+    /* Where the run is in the list's tree, for the next one (path[depth]
+     * its leaf); pathless: its leaf alone is known (the next is found from
+     * the root). */
     const void *path[16];
     uint8_t taken[16];
     unsigned depth;
+    bool pathless;
 } PureRun;
 
 /* A list holds up to PURE_LIST_ITEMS items, a run up to PURE_LIST_RUN. */