⚡️ Speed up method FlexBox._check_empty_layout by 35%

[codeflash-ai]

📄 35% (0.35x) speedup for FlexBox._check_empty_layout in src/bokeh/models/layouts.py

⏱️ Runtime : 56.1 microseconds → 41.5 microseconds (best of 6 runs)

📝 Explanation and details

The optimization removes the unnecessary use of itertools.chain() and list() conversion in the _check_empty_layout method, replacing the complex if not list(chain(self.children)): check with a simple if not self.children:.

Key Performance Improvements:

• Eliminated import overhead: Removed the from itertools import chain import, which has a small but measurable cost when the method is called
• Removed unnecessary function calls: itertools.chain() creates an iterator that flattens iterables, but since self.children is already a simple list (as defined in the FlexBox model), this adds no value
• Eliminated list conversion: The list(chain(self.children)) creates a new list object unnecessarily, when the truthiness check can be performed directly on the existing list

Why This Works:
In Python, empty lists are falsy, so if not self.children: is equivalent to the original logic but much more direct. The original code was over-engineered for a simple empty check, creating intermediate objects and function calls that provided no benefit since children is guaranteed to be a list by Bokeh's property system.

Performance Impact:
The test results show consistent 23-44% speedups across various empty layout scenarios, with the optimization being particularly effective for simple empty checks. This suggests the function may be called frequently during layout validation, making even small per-call improvements meaningful for overall application performance.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 17 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests and Runtime

from typing import List as TypingList

# imports
import pytest
from bokeh.models.layouts import FlexBox


# Minimal stubs for UIElement and FlexBox dependencies
class UIElement:
    pass
from bokeh.models.layouts import FlexBox

# ------------------- UNIT TESTS -------------------

# 1. Basic Test Cases

def test_empty_children_returns_str():
    """Test with no children: should return str(self)."""
    fb = FlexBox()
    codeflash_output = fb._check_empty_layout(); result = codeflash_output # 7.00μs -> 4.86μs (44.2% faster)



def test_children_is_empty_list_returns_str():
    """Test with children explicitly set to empty list: should return str(self)."""
    fb = FlexBox(children=[])
    codeflash_output = fb._check_empty_layout(); result = codeflash_output # 8.61μs -> 6.40μs (34.4% faster)

# 2. Edge Test Cases
















def test_large_empty_list_returns_str():
    """Test with a large but empty list: should return str(self)."""
    fb = FlexBox(children=[])
    codeflash_output = fb._check_empty_layout(); result = codeflash_output # 9.10μs -> 6.29μs (44.7% faster)

import pytest
from bokeh.models.layouts import FlexBox


# Minimal stub classes to support FlexBox._check_empty_layout testing
class UIElement:
    pass
from bokeh.models.layouts import FlexBox

# ------------------- UNIT TESTS -------------------

# ---- Basic Test Cases ----

def test_empty_children_returns_str():
    """Test that _check_empty_layout returns self.__str__ when children is empty list."""
    fb = FlexBox(children=[])
    codeflash_output = fb._check_empty_layout(); result = codeflash_output # 8.28μs -> 6.35μs (30.4% faster)




def test_positional_and_keyword_args_raises():
    """Test that passing both positional and 'children' keyword raises ValueError."""
    with pytest.raises(ValueError):
        FlexBox(UIElement(), children=[UIElement()])




















def test_large_number_of_children_empty():
    """Test with a large empty list (length 0), should return str."""
    fb = FlexBox(children=[])
    codeflash_output = fb._check_empty_layout(); result = codeflash_output # 9.30μs -> 6.70μs (38.8% faster)









def test_mutation_does_not_affect_result():
    """Test that changing children after creation affects _check_empty_layout result."""
    fb = FlexBox(children=[])
    codeflash_output = fb._check_empty_layout()
    fb.children.append(UIElement())
    codeflash_output = fb._check_empty_layout()

def test_str_is_called_on_self():
    """Test that the returned string is exactly str(self) for empty children."""
    fb = FlexBox(children=[])
    codeflash_output = fb._check_empty_layout(); result = codeflash_output # 8.88μs -> 7.18μs (23.7% faster)
    # Changing __str__ changes the output
    fb.__str__ = lambda self: "changed"
    fb2 = FlexBox(children=[])
    fb2.__str__ = lambda self: "changed"
    codeflash_output = fb2._check_empty_layout() # 4.93μs -> 3.75μs (31.6% faster)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

from bokeh.core.validation.decorators import _validator
import pytest

def test__validator_<locals>_decorator_<locals>__wrapper():
    with pytest.raises(TypeError, match="FlexBox\\._check_empty_layout\\(\\)\\ missing\\ 1\\ required\\ positional\\ argument:\\ 'self'"):
        _validator.<locals>.decorator.<locals>._wrapper()

To edit these changes git checkout codeflash/optimize-FlexBox._check_empty_layout-mhwxkpya and push.