Prule: add quantity function for rules

docs/data-structures-and-functions.md

@@ -164,6 +164,26 @@ Parameters:
 
 Computes linear regression over samples in time and returns the slope.
 
+### Other functions
+
+#### `quantity`
+
+Creates Pint Quantity values.
+
+Parameters:
+* value (str or other)
+* unit (str, optional)
+
+Example:
+```
+> quantity('1 GB/s')
+  <class 'pint.Quantity'>
+  1.0 gigabyte / second
+> quantity(5, 'GB/s')
+  <class 'pint.Quantity'>
+  5 gigabyte / second
+```
+
 
 ## Rule format
 

prule/__init__.py

@@ -344,6 +344,21 @@ def rule_prepare_input(parameters, rules, clusters, job_meta, job_data):
     #for jn in job_names:
     #    globals[jn] = True
 
+    def quantity_create(value, unit=None):
+        if unit == None:
+            if type(value) == str:
+                return unit_registry.parse_expression(value)
+            else:
+                raise Exception("Unit creation: expected string, got {}".format(value))
+        else:
+            if type(value) == str and type(unit) == str:
+                return unit_registry.parse_expression(value+" "+unit)
+            elif type(unit) == str:
+                return unit_registry.Quantity(value, unit_registry.parse_units(unit))
+            else:
+                raise Exception("Unit creation: expected string for unit, got {}".format(unit))
+    globals["quantity"] = quantity_create
+
     # prepare job metadata
     job = JobMetadata()
     # copy all attributes from json to job object