Use pre-compiled static Regex instances in ScalarNodeDeserializer#1088
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EdwardCooke merged 1 commit intoaaubry:masterfrom Apr 9, 2026
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Replace all Regex.IsMatch() calls with pre-compiled static readonly Regex instances using RegexOptions.Compiled. This eliminates repeated regex compilation overhead on every scalar deserialization call. Affected patterns: - Boolean true/false patterns (DeserializeBooleanHelper) - Hex, octal, float, infinity, NaN patterns (AttemptUnknownTypeDeserialization) All 7 regex patterns are now compiled once at class initialization.
This was referenced Apr 9, 2026
This was referenced Apr 13, 2026
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Problem
ScalarNodeDeserializer.cscallsRegex.IsMatch()with string patterns on every scalar deserialization. These patterns are constant strings but the regexes are not compiled or cached. On hot paths (large YAML documents), this creates repeated regex compilation overhead for every scalar value processed.Affected call sites:
DeserializeBooleanHelper()— boolean true/false patterns (2 calls)AttemptUnknownTypeDeserialization()— hex, octal, float, infinity, NaN patterns (5 calls)Fix
Converted all 7 regex patterns from inline
Regex.IsMatch(value, pattern)calls to pre-compiledstatic readonly Regexinstances withRegexOptions.Compiled. The regexes are compiled once at class initialization and reused for all subsequent calls.Uses the project's existing
StandardRegexOptions.Compiledpattern for consistency.Files Changed
YamlDotNet/Serialization/NodeDeserializers/ScalarNodeDeserializer.csValidation
All 326 serialization tests pass with no regressions.