⚡ Bolt: Optimize Value Display formatting

[ashyanSpada]

💡 What: Refactored fmt::Display implementation for Value enum (src/value.rs) to write directly to the fmt::Formatter (f).
🎯 Why: The original implementation constructed intermediate String objects, used inefficient string concatenation (format!), and unnecessarily .clone()'d values within loops when formatting lists and maps, creating unnecessary allocator pressure and overhead.
📊 Impact: Expected performance improvement in format times. Reduces heap allocations and redundant clone() calls per format invocation. The display_expression microbenchmark showed a ~4.5% execution time reduction (time went from ~3.23 µs to ~3.08 µs).
🔬 Measurement: Verify tests run successfully using cargo test and benchmark differences using cargo bench display_expression.

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PR created automatically by Jules for task 13182741000994383165 started by @ashyanSpada

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[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly optimizes the display formatting for the Value enum by rewriting its fmt::Display implementation. The previous approach created temporary String objects and performed redundant cloning, leading to increased memory pressure and slower execution. The new implementation directly writes to the formatter, drastically reducing heap allocations and improving overall formatting performance, as evidenced by a ~4.5% reduction in execution time for the display_expression microbenchmark.

Highlights

• Performance Optimization: The fmt::Display implementation for the Value enum in src/value.rs was refactored to write directly to the fmt::Formatter. This change eliminates intermediate String allocations, inefficient string concatenation, and unnecessary .clone() calls, especially when formatting lists and maps.

Changelog

• src/value.rs
  • Optimized the fmt::Display implementation for the Value enum to avoid intermediate string allocations and redundant cloning.

Activity

• The pull request was automatically created by Jules for a task started by @ashyanSpada.

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[gemini-code-assist]

Code Review

This pull request is a great optimization for the fmt::Display implementation of the Value enum. By writing directly to the formatter instead of creating intermediate strings, you've effectively reduced heap allocations and improved performance. I've included a couple of suggestions to further refine the output format for List and Map types by removing unnecessary trailing separators, which will result in a cleaner string representation.

[gemini-code-assist]

The current implementation for formatting a List adds a trailing comma for non-empty lists (e.g., [v1, v2] becomes [v1,v2,]). This is likely unintended. To avoid the trailing comma, you can handle the last element separately using split_last.

Suggested change

	for value in values {
	s.push_str(format!("{},", value.clone()).as_str());
	write!(f, "{},", value)?;
	}
	if let Some((last, head)) = values.split_last() {
	for value in head {
	write!(f, "{},", value)?;
	}
	write!(f, "{}", last)?;
	}

[gemini-code-assist]

Similar to the List formatting, the Map formatting includes a trailing separator (; ) after the last key-value pair. This can be avoided for a cleaner output. By treating ; as a separator between pairs rather than a terminator for each pair, you can use a peekable iterator to add it only when needed.

                let mut iter = m.iter().peekable();
                while let Some((k, v)) = iter.next() {
                    write!(f, "key: {},value: {}", k, v)?;
                    if iter.peek().is_some() {
                        write!(f, "; ")?;
                    }
                }

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.74%. Comparing base (5576973) to head (a5f9e7f).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #38   +/-   ##
=======================================
  Coverage   88.74%   88.74%           
=======================================
  Files          11       11           
  Lines        1066     1066           
=======================================
  Hits          946      946           
  Misses        120      120           

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