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Checks whether a text matches a regular expression pattern. By default, the pattern is searched anywhere in the text (partial match). Returns true if the pattern matches, false otherwise.

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Parameters

ParameterTypeRequiredDefaultDescription
patternstringYes—The regular expression pattern to match
textstringYes—The text to search
full_matchbooleanNofalseIf true, the pattern must match the entire string; if false, a match anywhere in the text is sufficient

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Output

PropertyValueDescription
labeltrue or falseWhether the pattern matched
score1.0 or 0.0Numeric score (1.0 = match, 0.0 = no match)
OptimizationMaximizeHigher scores are better

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Configuring Inputs

Each evaluator parameter can be set to either a path (a JSONPath expression that extracts a value from the evaluation parameters) or a literal (a fixed value typed directly). Use paths to pull from dataset inputs, task outputs, reference data, or metadata. Use literals for static configuration like regex patterns. See Input Mapping for full details on mapping modes, resolution order, and examples.

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Usage Examples

Format compliance — A model that must produce output in a specific structural format (a date, phone number, or identifier). Pattern is the regular expression defining the required format, set as a literal value. Text is the model’s output field — use a direct path for a plain string response, or a nested path like output.date if the target value is embedded in a JSON object. Citation or reference checking — A RAG pipeline that must include a URL, citation marker, or other structured element in every response. Pattern matches the expected element (e.g., a URL regex or citation format); Text is the model’s full response. Partial match mode (the default) passes as long as the pattern appears anywhere in the output. Output type gating — A code assistant whose output should contain a function definition rather than prose. Pattern is anchored to the expected code structure; Text is the response field. If your model returns structured JSON with a code key, map Text to output.code rather than the entire response.

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Notes

Complex regex patterns can be slow on long inputs. Avoid patterns with nested quantifiers or excessive backtracking (e.g., (a+)+, .*.*). Prefer anchored patterns and specific character classes over broad wildcards. Test your pattern against representative inputs before deploying to a large dataset.

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See Also