From 37c2eb33be0d513f2640e6f72ab96d851bb91dc1 Mon Sep 17 00:00:00 2001
From: atuonufure <atuonufure@gmail.com>
Date: Mon, 28 Aug 2023 11:19:22 +0200
Subject: [PATCH] Refactor equivalence

---
 fhirpathpy/engine/invocations/equality.py | 48 +++++++++++++++--------
 1 file changed, 31 insertions(+), 17 deletions(-)

diff --git a/fhirpathpy/engine/invocations/equality.py b/fhirpathpy/engine/invocations/equality.py
index 6b23846..ea37106 100644
--- a/fhirpathpy/engine/invocations/equality.py
+++ b/fhirpathpy/engine/invocations/equality.py
@@ -19,6 +19,28 @@ def equality(ctx, x, y):
     return x == y
 
 
+def normalize_string(s):
+    return " ".join(s.lower().split())
+
+
+def decimal_places(a):
+    match = str(a).split(".")
+    return len(match[1]) if len(match) > 1 else 0
+
+
+def round_to_decimal_places(a, n):
+    rounding_format = Decimal("10") ** -n
+    return Decimal(a).quantize(rounding_format)
+
+
+def is_equivalent(a, b):
+    precision = min(decimal_places(a), decimal_places(b))
+    if precision == 0:
+        return round(a) == round(b)
+    else:
+        return round_to_decimal_places(a, precision) == round_to_decimal_places(b, precision)
+
+
 def equivalence(ctx, x, y):
     if util.is_empty(x) and util.is_empty(y):
         return True
@@ -26,25 +48,17 @@ def equivalence(ctx, x, y):
     if util.is_empty(x) or util.is_empty(y):
         return False
 
-    if type(x[0]) in DATETIME_NODES_LIST or type(y[0]) in DATETIME_NODES_LIST:
+    a = util.get_data(x[0])
+    b = util.get_data(y[0])
+
+    if type(a) in DATETIME_NODES_LIST or type(b) in DATETIME_NODES_LIST:
         return datetime_equality(ctx, x, y)
 
-    # string: the strings must be the same
-    # while ignoring case and normalizing whitespace.
-    if isinstance(x[0], str) and isinstance(y[0], str):
-        return " ".join(x[0].lower().split()) == " ".join(y[0].lower().split())
-
-    # decimal: values must be equal, comparison is done on values rounded
-    # to the precision of the least precise operand.
-    # Trailing zeroes are ignored in determining precision.
-    if isinstance(x[0], Decimal) or isinstance(y[0], Decimal):
-        precision_x = len(str(x[0]).split(".")[1]) if "." in str(x[0]) else 0
-        precision_y = len(str(y[0]).split(".")[1]) if "." in str(y[0]) else 0
-        least_precision = min(precision_x, precision_y)
-        rounding_format = Decimal("10") ** -least_precision
-        rounded_x = Decimal(x[0]).quantize(rounding_format)
-        rounded_y = Decimal(y[0]).quantize(rounding_format)
-        return rounded_x == rounded_y
+    if isinstance(a, str) and isinstance(b, str):
+        return normalize_string(a) == normalize_string(b)
+
+    if isinstance(a, Decimal) or isinstance(b, Decimal):
+        return is_equivalent(a, b)
 
     return x == y