Struct PatternLimits 

pub struct PatternLimits {
    pub max_pattern_depth: usize,
    pub max_fields_per_pattern: usize,
    pub arena_byte_budget: usize,
    pub max_states_per_pattern: usize,
}

Limits on pattern complexity to prevent OOM and stack exhaustion.

Four complementary limits, each catching a different attack vector:

• Nesting depth: prevents stack exhaustion and deep-nesting attacks
• Field count: prevents wide patterns with hundreds of fields
• Arena byte budget: essential backstop that catches all forms of automaton complexity
• State count: prevents exponential field-matcher blowup from mixed-type matchers

Defaults

• max_pattern_depth: 256 (jq precedent)
• max_fields_per_pattern: 256
• arena_byte_budget: 10 MB (regex crate precedent)
• max_states_per_pattern: 1024

Fields

max_pattern_depth: usize

Maximum nesting depth of a pattern (default: 256)

max_fields_per_pattern: usize

Maximum number of fields per pattern (default: 256)

arena_byte_budget: usize

Maximum arena byte size for the automaton (default: 10 MB)

max_states_per_pattern: usize

Maximum number of field-matcher states during pattern construction (default: 1024).

When a field has N mixed-type matchers (e.g. exact + prefix), the state count multiplies by N for each such field. With K fields of N matchers each, states grow as N^K. This limit caps the product to prevent exponential memory blowup. All-exact fields use a bulk optimization that doesn’t multiply states, so this limit only affects patterns mixing matcher types on the same field.

Trait Implementations

impl Clone for PatternLimits

fn clone(&self) -> PatternLimits

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PatternLimits

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for PatternLimits

fn default() -> Self

Returns the “default value” for a type.