Enum cudb::query::Constraint

pub enum Constraint {
    MatchesDocument(ConstraintDocument),
    Equals(Value),
    LessThan(Value),
    GreaterThan(Value),
    In(Vec<Value>),
    Or(Box<Constraint>, Box<Constraint>),
    And(Box<Constraint>, Box<Constraint>),
}

A single query constraint on a field.

Note that Constraints applied to an array value will map the constraint over the array.

Variants

MatchesDocument(ConstraintDocument)

Constraints on subdocuments (hashtables).

Tuple Fields of MatchesDocument

0: ConstraintDocument

Equals(Value)

Equality constraint on a value.

Tuple Fields of Equals

0: Value

LessThan(Value)

Less-than constraint on a value.

Tuple Fields of LessThan

0: Value

GreaterThan(Value)

Greater-than constraint on a value.

Tuple Fields of GreaterThan

0: Value

In(Vec<Value>)

Constraint if value is in specified list of values.

Tuple Fields of In

0: Vec<Value>

Or(Box<Constraint>, Box<Constraint>)

Disjunction of constraints on a single field.

Tuple Fields of Or

0: Box<Constraint>1: Box<Constraint>

And(Box<Constraint>, Box<Constraint>)

Conjunction of constraints on a single field.

Tuple Fields of And

0: Box<Constraint>1: Box<Constraint>

Implementations

impl Constraint

pub fn get_value_type(&self) -> Option<Value>

Determine the type of a constraint. Return None if the Constraint is invalid due to mismatched subconstraints.

pub fn matches(&self, value: &Value) -> bool

Whether a Value matches a constraint.

pub fn generate_value_ranges(&self) -> Vec<(Bound<Value>, Bound<Value>)>

Generate the value range(s) for this constraint.

Note: for the time being, this generates inclusive ranges only, because we cannot mix inclusive and exclusive ranges in a multi-field index. Note that since we also cannot mix unbounded ranges, one-sided ranges (such as inequalities) use a predefined min/max value. For unbounded numbers, this limits the range of valid numbers that can be returned with a range. This can be considered a “feature” of our implementation due to the limitations of using the builtin BTreeMap implementation. An alternative implementation is to create a special value type that represents the extrema of a type (which would probably be a cleaner and more robust solution if only I had thought of it earlier).

Note: disjunction (OR) operator assumes ranges are non-overlapping.

Trait Implementations

impl Clone for Constraint

fn clone(&self) -> Constraint

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Constraint

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

Formats the value using the given formatter.