Optimize truncated list check

CHANGELOG.md

@@ -11,6 +11,7 @@ All notable changes to this project will be documented in this file.
 ### Performance
 
 - Non-deterministic objects are no longer cached, rather than getting a unique attribute to force a cache miss. Negligible reduction in memory, unless you're caching huge shuffled lists.
+- The optimization of long truncated lists was modified to check list lengths against a pre-computed max length instead of calculating the minimum string length of each list. Minor speedup when working with a lot of lists.
 
 ## [0.1.1] - 2025-02-19
 

eerepr/html.py

@@ -7,6 +7,10 @@
 
 # Max characters to display for a list before truncating to "List (n elements)"
 MAX_INLINE_LENGTH = 50
+# Max elements in a list without definitely truncating, i.e. a list where each element
+# takes 1 character plus brackets and delimiters.
+MAX_LIST_LENGTH = MAX_INLINE_LENGTH // 3
+
 # Sorting priority for Earth Engine properties
 PROPERTY_PRIORITY = [
     "type",
@@ -57,11 +61,9 @@ def list_to_html(obj: list, key: Hashable | None = None) -> str:
     n = len(obj)
     header = f"{key}: " if key is not None else ""
 
-    # Skip the expensive stringification for lists that are definitely too long to
-    # include inline (counting whitespace and delimiters). This is a substantial
-    # performance improvement for large collections.
-    min_length = 3 * (n - 1) + 3
-    if min_length < MAX_INLINE_LENGTH and len(contents := str(obj)) < MAX_INLINE_LENGTH:
+    # Only stringify the list if it has few enough elements that it might not be
+    # truncated.
+    if n < MAX_LIST_LENGTH and len(contents := str(obj)) < MAX_INLINE_LENGTH:
         header += contents
     else:
         header += f"List ({n} {'element' if n == 1 else 'elements'})"