create 'flat' version of match spans already in getMatchTelemetry

common/python/nomadcore/simple_parser.py

@@ -737,6 +737,23 @@ class CompiledMatcher(object):
                     result['match'] = 1 # partial match
                 result['matcher_does_nothing'] = True
                 result['matcherName'] = 'coverageIgnore'
+        # flatten span:
+        #   original:
+        #     -- whole_re -- group1 -- group2 ------ group3 --------
+        #     [ [ (0,25) ], [ (4,5) ],     [],    [ (1,3), (10,15) ], ... ]
+        #   flattened:
+        #     [ 1, 0, 25,    1, 4, 5,       0,    2, 1, 3, 10, 15, ... ]
+        #   per group (first one 'global'/whole RE span):
+        #     number_of_captures, start1, end1, ...
+        #   this encoding scheme supports "optional" groups (r"(?P<blah>\d+)?")
+        #   and is future-compatible with multiple-captures-per-group
+        #   supported by modules regex / re2 (r"(?:(?P<blah>\d+)\s+)+")
+        span_flat = []
+        for g in result['span']:
+            span_flat.append(len(g))
+            for s in g:
+                span_flat.extend(s)
+        result['span_flat'] = span_flat
         result['matchFlags'] = (
             result['match'] | (result['coverageIgnore'] << 2) |
             targetStartEnd << 5 | int(result['matcher_does_nothing'] and result['match']) << 6)