From b6dcf0b70a8ad32d4f8c45ab7defb8a7ae66bed1 Mon Sep 17 00:00:00 2001
From: Thomas Kittelmann <thomas.kittelmann@ess.eu>
Date: Thu, 1 Oct 2026 06:39:49 +0000
Subject: [PATCH] mcrun: only take values made of numbers as scan syntax

Values which are not numbers separated by ":" or "," are now used as they
are, so NCrystal cfg-strings like
"Ge_sg227.ncmat;dir1=@crys_hkl:5,1,1@lab:0,0,1" (or Windows paths like
"C:\data\a.dat") can be given on the command line. With -L, values are
still lists separated by commas, where commas within an entry can now be
escaped as "\,".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 tools/Python/mcrun/mcrun.py | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/tools/Python/mcrun/mcrun.py b/tools/Python/mcrun/mcrun.py
index c2dc20dc9..cd5bb7758 100644
--- a/tools/Python/mcrun/mcrun.py
+++ b/tools/Python/mcrun/mcrun.py
@@ -12,6 +12,7 @@
 from decimal import Decimal, InvalidOperation
 from datetime import datetime
 import multiprocessing
+import re
 from mccode import McStas, Process
 from optimisation import Scanner, Scanner_split, LinearInterval, MultiInterval, Optimizer
 
@@ -131,7 +132,8 @@ def add_mcrun_adv_options(parser):
              ' 3) Any parameter given as "min:delta:max" is expanded into its '
              '   own explicit list of equidistant points and may be freely mixed '
              '   with other, explicitly-listed parameters '
-             '   (e.g. a list of filenames) under -L.')
+             '   (e.g. a list of filenames) under -L.'
+             ' Commas within a list entry must be escaped as "\\,".')
 
     add('-M', '--multi',
         action='store_true',
@@ -536,18 +538,29 @@ def get_parameters(options):
         if '=' in param:
             key, value = param.split('=', 1)
 
+            # Only values made of numbers separated by ":" or "," are scan
+            # syntax. Other values, like NCrystal cfg-strings (e.g.
+            # "Ge_sg227.ncmat;dir1=@crys_hkl:5,1,1@lab:0,0,1"), are used as
+            # they are, except with -L, where they are lists separated by
+            # commas (commas within an entry must be escaped as "\,"):
+            numeric = all(is_decimal(p) for p in re.split('[:,]', value) if p)
+            if not numeric and not options.list:
+                # Earlier versions of mcrun ignored trailing commas (with a
+                # warning), so keep doing that to not break existing commands:
+                if value.endswith(','):
+                    LOG.warning('Ignoring trailing comma(s) in parameter "%s"', key)
+                    value = value.rstrip(',')
+                fixed_params[key] = value
+                continue
+
             # "par=a:delta:b" - an equidistant scan specified by its bin
             # width (delta) rather than an explicit point count: mcrun
             # computes how many points are needed to cover [a, b] in steps
             # of (approximately - see rounding below) delta, rather than
             # the user needing to work out -N by hand. Checked before the
             # comma-based interval parsing below, since a colon can never
-            # appear in a numeric value/list, so a colon anywhere in the
-            # value would otherwise unambiguously mean this syntax was
-            # intended - EXCEPT double-colon syntax from NCrystal-backed
-            # reflections="stdlib::ZnO_sg186_ZincOxide.ncmat;temp=300K"
-            # used in context of PowderN. Filter out from the start:
-            if ':' in value and '::' not in value:
+            # appear in a numeric value/list:
+            if ':' in value and numeric:
                 parts = value.split(':')
                 if len(parts) != 3:
                     raise OptionValueError(
@@ -598,7 +611,7 @@ def get_parameters(options):
                               key, intervals[key], delta, n_points)
                 continue
 
-            interval = value.split(',')
+            interval = [v.replace('\\,', ',') for v in re.split(r'(?<!\\),', value)]
             # Protect against trailing (or doubled) commas (empty-string entries
             n_before = len(interval)
             interval = [v for v in interval if v != '']