⚡ Bolt: [performance improvement] Optimize Value Display Allocations

[ashyanSpada]

💡 What: Optimized the std::fmt::Display implementation for the Value enum in src/value.rs by writing directly to std::fmt::Formatter.
🎯 Why: The previous implementation was creating intermediate strings using String::from("["), repeatedly calling format!() inside loops for List and Map types, and making redundant .clone() calls. This resulted in O(N) heap allocations for formatting composite data structures, which is an unnecessary overhead during logging, debugging, or displaying results.
📊 Impact: Reduces heap allocations when printing/formatting Value objects, improving the efficiency of the fmt::Display implementation. The optimization was cleanly done in < 50 lines.
🔬 Measurement: Verified the optimization by creating a micro-benchmark using Criterion in benches/display_value.rs. Ran the benchmark locally before and after the change (cargo bench). Tests and format checks (cargo fmt, cargo test) were also passed successfully to verify the output wasn't impacted.

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PR created automatically by Jules for task 16581379178332284800 started by @ashyanSpada

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.55%. Comparing base (9a4a6cc) to head (3f123c1).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #54   +/-   ##
=======================================
  Coverage   89.55%   89.55%           
=======================================
  Files          11       11           
  Lines        1063     1063           
=======================================
  Hits          952      952           
  Misses        111      111           

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[gemini-code-assist]

Code Review

This pull request optimizes the fmt::Display implementation for the Value enum by writing directly to the formatter and removing redundant clones, and introduces a benchmark for value display. The review feedback suggests refining the output of lists and maps by omitting trailing separators for the final elements to improve readability.

[gemini-code-assist]

The current implementation adds a trailing comma for every element in the list, resulting in output like [1,2,3,]. While this preserves the previous behavior, it is generally considered better practice to omit the trailing separator for the last element to improve readability.

Suggested change

	for value in values {
	s.push_str(format!("{},", value.clone()).as_str());
	write!(f, "{},", value)?;
	}
	for (i, value) in values.iter().enumerate() {
	if i > 0 {
	write!(f, ",")?;
	}
	write!(f, "{}", value)?;
	}

[gemini-code-assist]

The current implementation adds a trailing semicolon and space for every entry in the map, resulting in output like {key: k,value: v; key: k2,value: v2; }. It is generally preferred to omit the trailing separator for the last entry to improve the clarity of the output.

                for (i, (k, v)) in m.iter().enumerate() {
                    if i > 0 {
                        write!(f, "; ")?;
                    }
                    write!(f, "key: {},value: {}", k, v)?;
                }

[Copilot]

Pull request overview

Optimizes the fmt::Display implementation for the Value enum to reduce heap allocations when formatting composite values, and adds a Criterion micro-benchmark to measure formatting performance.

Changes:

• Refactors Value’s Display implementation to write directly into fmt::Formatter (removing intermediate String building and redundant clones).
• Adds a new Criterion benchmark for Value formatting performance (benches/display_value.rs).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/value.rs	Streams formatted output directly to the formatter for List/Map to avoid per-element allocations.
benches/display_value.rs	Introduces a Criterion benchmark for Value display formatting.

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[Copilot]

This Criterion benchmark target likely won't compile/run under cargo bench unless it is registered in Cargo.toml with harness = false. Without an explicit [[bench]] entry, Cargo uses the default benchmark harness, which conflicts with criterion_main! generating its own main (typically causing a duplicate/unknown main harness error). Add a [[bench]] name = "display_value" entry with harness = false so the new benchmark works consistently.