revset: drop optimization about reordering "or" set elements

revset: drop optimization about reordering "or" set elements

The reordering optimization is more important for "and" than "or", given the
implementation details about "addset" and "filteredset" - reordering "or"
may help "__contains__" test but not iteration, reordering "and" could help
both. We are going to simplify the tree to remove ordering information.
Removing "or" reordering optimization would make things simpler.

This effectively reverts c63cb2d10d6d. It tracks back to the "orset"
function added by the initial commit of revset (c9ce8ecd6).

In the future, we might consider optimization at runtime (ex. do reordering
and rewrites inside "orset").

Differential Revision: https://phab.mercurial-scm.org/D561

--- a/mercurial/revsetlang.py	Tue Aug 29 17:51:54 2017 -0700
+++ b/mercurial/revsetlang.py	Mon Aug 28 23:44:47 2017 -0700
@@ -467,9 +467,6 @@
         flushss()
         if len(ts) == 1:
             return ws[0], ts[0] # 'or' operation is fully optimized out
-        if order != defineorder:
-            # reorder by weight only when f(a + b) == f(b + a)
-            ts = [wt[1] for wt in sorted(zip(ws, ts), key=lambda wt: wt[0])]
         return max(ws), (op, ('list',) + tuple(ts), order)
     elif op == 'not':
         # Optimize not public() to _notpublic() because we have a fast version

--- a/tests/test-revset.t	Tue Aug 29 17:51:54 2017 -0700
+++ b/tests/test-revset.t	Mon Aug 28 23:44:47 2017 -0700
@@ -2076,19 +2076,19 @@
       define)
     (or
       (list
-        ('symbol', '2')
         (range
           ('symbol', '0')
           ('symbol', '1')
-          follow))
+          follow)
+        ('symbol', '2'))
       follow)
     define)
   * set:
   <filteredset
     <spanset- 0:3>,
     <addset
-      <baseset [2]>,
-      <spanset+ 0:2>>>
+      <spanset+ 0:2>,
+      <baseset [2]>>>
   2
   1
   0
@@ -2569,69 +2569,6 @@
   1
   0
 
- 'A + B' can be rewritten to 'B + A' by weight only when the order doesn't
- matter (e.g. 'X & (A + B)' can be 'X & (B + A)', but '(A + B) & X' can't):
-
-  $ try -p optimized '0:2 & (reverse(contains("a")) + 2)'
-  * optimized:
-  (and
-    (range
-      ('symbol', '0')
-      ('symbol', '2')
-      define)
-    (or
-      (list
-        ('symbol', '2')
-        (func
-          ('symbol', 'reverse')
-          (func
-            ('symbol', 'contains')
-            ('string', 'a')
-            define)
-          follow))
-      follow)
-    define)
-  * set:
-  <filteredset
-    <spanset+ 0:3>,
-    <addset
-      <baseset [2]>,
-      <filteredset
-        <fullreposet+ 0:10>,
-        <contains 'a'>>>>
-  0
-  1
-  2
-
-  $ try -p optimized '(reverse(contains("a")) + 2) & 0:2'
-  * optimized:
-  (and
-    (range
-      ('symbol', '0')
-      ('symbol', '2')
-      follow)
-    (or
-      (list
-        (func
-          ('symbol', 'reverse')
-          (func
-            ('symbol', 'contains')
-            ('string', 'a')
-            define)
-          define)
-        ('symbol', '2'))
-      define)
-    define)
-  * set:
-  <addset
-    <filteredset
-      <spanset- 0:3>,
-      <contains 'a'>>,
-    <baseset [2]>>
-  1
-  0
-  2
-
 test sort revset
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