Quantity of minimum repetitions must be greater than zero

Error message

Quantity of minimum repetitions must be greater than zero

What it means

RegExpBuilder::with_minimum_repetitions panics with MINIMUM_REPETITIONS_MESSAGE when quantity is 0. A minimum repetition count of zero would make the 'repeat at least n times' conversion meaningless, so the configuration API rejects it eagerly. The default, if unset, is 1.

Solutions

Pass a quantity >= 1; omit the call entirely to use the default of 1
Clamp the input (quantity.max(1)) before calling the method
Validate the config/CLI value at parse time and reject 0 with a clear user-facing error

Example fix

// before
builder.with_minimum_repetitions(min_reps); // min_reps may be 0
// after
let min_reps = min_reps.max(1);
builder.with_minimum_repetitions(min_reps);

Defensive patterns

Strategy: validation

Validate before calling

if min_reps == 0 { return Err(anyhow!("--min-reps must be >= 1")); }
builder.with_minimum_repetitions(min_reps);

Try / catch

let b = std::panic::catch_unwind(|| { let mut b = RegExpBuilder::from(&cases); b.with_minimum_repetitions(q); b })
    .map_err(|_| "minimum repetitions must be > 0".to_string());

Prevention

Clamp parsed numeric config with .max(1) before applying it
Reject zero at the CLI/config parsing layer with a user-facing message
Remember the default is 1 — omit the call when you do not need a custom value

When it happens

Trigger: Calling builder.with_minimum_repetitions(0), typically because the value came from an unvalidated CLI flag, config file, or arithmetic expression that underflowed.

Common situations: A --min-reps CLI argument defaulted to 0; parsing user config where an empty/absent value became 0; subtracting values and hitting zero.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of pemistahl/grex@99cc347707 (2026-09-13). Data as JSON: /api/errors/44e68bc21cc339df. Report an issue: GitHub.

Appendix: source

Thrown at src/builder.rs:188

        self.config.is_case_insensitive_matching = true;
        self
    }

    /// Replaces non-capturing groups with capturing ones.
    pub fn with_capturing_groups(&mut self) -> &mut Self {
        self.config.is_capturing_group_enabled = true;
        self
    }

    /// Specifies the minimum quantity of substring repetitions to be converted if
    /// [`with_conversion_of_repetitions`](Self::with_conversion_of_repetitions) is set.
    ///
    /// If the quantity is not explicitly set with this method, a default value of 1 will be used.
    ///
    /// ⚠ Panics if `quantity` is zero.
    pub fn with_minimum_repetitions(&mut self, quantity: u32) -> &mut Self {
        if quantity == 0 {
            panic!("{}", MINIMUM_REPETITIONS_MESSAGE);
        }
        self.config.minimum_repetitions = quantity;
        self
    }

    /// Specifies the minimum length a repeated substring must have in order to be converted if
    /// [`with_conversion_of_repetitions`](Self::with_conversion_of_repetitions) is set.
    ///
    /// If the length is not explicitly set with this method, a default value of 1 will be used.
    ///
    /// ⚠ Panics if `length` is zero.
    pub fn with_minimum_substring_length(&mut self, length: u32) -> &mut Self {
        if length == 0 {
            panic!("{}", MINIMUM_SUBSTRING_LENGTH_MESSAGE);
        }
        self.config.minimum_substring_length = length;
        self
    }

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