--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.7/site-packages/galaxy/util/permutations.py	Sat May 02 07:14:21 2020 -0400
@@ -0,0 +1,116 @@
+""" There is some shared logic between matching/multiplying inputs in workflows
+and tools. This module is meant to capture some general permutation logic that
+can be applicable for both cases but will only be used in the newer tools case
+first.
+
+Maybe this doesn't make sense and maybe much of this stuff could be replaced
+with itertools product and permutations. These are open questions.
+"""
+from collections import OrderedDict
+
+from galaxy.exceptions import MessageException
+from galaxy.util.bunch import Bunch
+
+input_classification = Bunch(
+    SINGLE="single",
+    MATCHED="matched",
+    MULTIPLIED="multiplied",
+)
+
+
+class InputMatchedException(MessageException):
+    """ Indicates problem matching inputs while building up inputs
+    permutations. """
+
+
+def expand_multi_inputs(inputs, classifier, key_filter=None):
+    key_filter = key_filter or (lambda x: True)
+
+    single_inputs, matched_multi_inputs, multiplied_multi_inputs = __split_inputs(
+        inputs,
+        classifier,
+        key_filter
+    )
+
+    # Build up every combination of inputs to be run together.
+    input_combos = __extend_with_matched_combos(single_inputs, matched_multi_inputs)
+    input_combos = __extend_with_multiplied_combos(input_combos, multiplied_multi_inputs)
+
+    return input_combos
+
+
+def __split_inputs(inputs, classifier, key_filter):
+    key_filter = key_filter or (lambda x: True)
+
+    single_inputs = OrderedDict()
+    matched_multi_inputs = OrderedDict()
+    multiplied_multi_inputs = OrderedDict()
+
+    for input_key in filter(key_filter, inputs):
+        input_type, expanded_val = classifier(input_key)
+        if input_type == input_classification.SINGLE:
+            single_inputs[input_key] = expanded_val
+        elif input_type == input_classification.MATCHED:
+            matched_multi_inputs[input_key] = expanded_val
+        elif input_type == input_classification.MULTIPLIED:
+            multiplied_multi_inputs[input_key] = expanded_val
+
+    return (single_inputs, matched_multi_inputs, multiplied_multi_inputs)
+
+
+def __extend_with_matched_combos(single_inputs, multi_inputs):
+    """
+
+    {a => 1, b => 2} and {c => {3, 4}, d => {5, 6}}
+
+    Becomes
+
+    [ {a => 1, b => 2, c => 3, d => 5}, {a => 1, b => 2, c => 4, d => 6}, ]
+
+    """
+
+    if len(multi_inputs) == 0:
+        return [single_inputs]
+
+    matched_multi_inputs = []
+
+    first_multi_input_key = next(iter(multi_inputs.keys()))
+    first_multi_value = multi_inputs.get(first_multi_input_key)
+
+    for value in first_multi_value:
+        new_inputs = __copy_and_extend_inputs(single_inputs, first_multi_input_key, value)
+        matched_multi_inputs.append(new_inputs)
+
+    for multi_input_key, multi_input_values in multi_inputs.items():
+        if multi_input_key == first_multi_input_key:
+            continue
+        if len(multi_input_values) != len(first_multi_value):
+            raise InputMatchedException("Received %d inputs for '%s' and %d inputs for '%s', these should be of equal length" %
+                                        (len(multi_input_values), multi_input_key, len(first_multi_value), first_multi_input_key))
+
+        for index, value in enumerate(multi_input_values):
+            matched_multi_inputs[index][multi_input_key] = value
+
+    return matched_multi_inputs
+
+
+def __extend_with_multiplied_combos(input_combos, multi_inputs):
+    combos = input_combos
+
+    for multi_input_key, multi_input_value in multi_inputs.items():
+        iter_combos = []
+
+        for combo in combos:
+            for input_value in multi_input_value:
+                iter_combo = __copy_and_extend_inputs(combo, multi_input_key, input_value)
+                iter_combos.append(iter_combo)
+
+        combos = iter_combos
+
+    return combos
+
+
+def __copy_and_extend_inputs(inputs, key, value):
+    new_inputs = dict(inputs)
+    new_inputs[key] = value
+    return new_inputs