Add support for avg, min, max, sum, toBoolean, convertsTo

fhirpathpy/engine/invocations/__init__.py

@@ -11,6 +11,7 @@
 import fhirpathpy.engine.invocations.logic as logic
 import fhirpathpy.engine.invocations.datetime as datetime
 import fhirpathpy.engine.invocations.types as types
+import fhirpathpy.engine.invocations.aggregate as aggregate
 
 invocations = {
     "empty": {"fn": existence.empty_fn},
@@ -44,6 +45,7 @@
     "iif": {"fn": misc.iif_macro, "arity": {2: ["Expr", "Expr"], 3: ["Expr", "Expr", "Expr"]}},
     "trace": {"fn": misc.trace_fn, "arity": {0: [], 1: ["String"]}},
     "toInteger": {"fn": misc.to_integer},
+    "toBoolean": {"fn": misc.to_boolean},
     "toDecimal": {"fn": misc.to_decimal},
     "toString": {"fn": misc.to_string},
     "toDate": {"fn": misc.to_date},
@@ -113,4 +115,12 @@
     "and": {"fn": logic.and_op, "arity": {2: [["Boolean"], ["Boolean"]]}},
     "xor": {"fn": logic.xor_op, "arity": {2: [["Boolean"], ["Boolean"]]}},
     "implies": {"fn": logic.implies_op, "arity": {2: [["Boolean"], ["Boolean"]]}},
+    "avg": {"fn": aggregate.avg_fn},
+    "sum": {"fn": aggregate.sum_fn},
+    "min": {"fn": aggregate.min_fn},
+    "max": {"fn": aggregate.max_fn},
+    "convertsToBoolean": {"fn": misc.create_converts_to_fn(misc.to_boolean, 'bool')},
+    "convertsToInteger": {"fn": misc.create_converts_to_fn(misc.to_integer, 'int')},
+    "convertsToDecimal": {"fn": misc.create_converts_to_fn(misc.to_decimal, 'float')},
+    "convertsToString": {"fn": misc.create_converts_to_fn(misc.to_string, 'str')},
 }

fhirpathpy/engine/invocations/aggregate.py

@@ -0,0 +1,27 @@
+from fhirpathpy.engine.invocations.existence import count_fn
+from fhirpathpy.engine.invocations.math import div
+
+
+def avg_fn(ctx, x):
+    if count_fn(ctx, x) == 0:
+        return []
+
+    return div(ctx, sum_fn(ctx, x), count_fn(ctx, x))
+
+
+def sum_fn(ctx, x):
+    return sum(x)
+
+
+def min_fn(ctx, x):
+    if count_fn(ctx, x) == 0:
+        return []
+
+    return min(x)
+
+
+def max_fn(ctx, x):
+    if count_fn(ctx, x) == 0:
+        return []
+
+    return max(x)

fhirpathpy/engine/invocations/misc.py

@@ -183,3 +183,47 @@ def to_date(ctx, coll):
             rtn.append(dateObject)
 
     return rtn
+
+
+def create_converts_to_fn(to_function, _type):
+    if isinstance(_type, str):
+        def in_function(ctx, coll):
+            if len(coll) != 1:
+                return []
+            return type(to_function(ctx, coll)).__name__ == _type
+        return in_function
+
+    def in_function(ctx, coll):
+        if len(coll) != 1:
+            return []
+
+        return isinstance(to_function(ctx, coll), _type)
+
+    return in_function
+
+
+def to_boolean(ctx, coll):
+    true_strings = ['true', 't', 'yes', 'y', '1', '1.0']
+    false_strings = ['false', 'f', 'no', 'n', '0', '0.0']
+
+    if len(coll) != 1:
+        return []
+
+    val = coll[0]
+    var_type = type(val).__name__
+
+    if var_type == "bool":
+        return val
+    elif var_type == "int" or var_type == "float":
+        if val == 1 or val == 1.0:
+            return True
+        elif val == 0 or val == 0.0:
+            return False
+    elif var_type == "str":
+        lower_case_var = val.lower()
+        if lower_case_var in true_strings:
+            return True
+        if lower_case_var in false_strings:
+            return False
+
+    return []