Enum rapidquery::Expression

pub enum Expression {
    Tag {
        tag: String,
    },
    KeyValue {
        key: String,
        value: String,
    },
    HasKey {
        key: String,
    },
    Parent {
        parent: String,
    },
    And {
        and: (Box<Expression>, Box<Expression>),
    },
    Or {
        or: (Box<Expression>, Box<Expression>),
    },
    Not {
        not: Box<Expression>,
    },
    Empty,
}

A parsed (or manually constructed) query expression.

An expression can be arbitrarily nested.

Variants

Tag

Tag expression.

Evaluates to resolver items where the tag is present.

Fields of Tag

tag: String

KeyValue

Key/Value expression.

Evaluates to resolver items where the given key/value pair is present.

Fields of KeyValue

key: Stringvalue: String

HasKey

HasKey expression.

Evaluates to resolver items where the given key is present (in any key/value pair).

Fields of HasKey

key: String

Parent

Parent expression.

Evaluates to resolver items having the provided value as a parent.

Fields of Parent

parent: String

And

And expression.

Evaluates to the intersection of its two sub-expressions.

Fields of And

and: (Box<Expression>, Box<Expression>)

Or

Or expression. Evaluates to the union of its two sub-expressions.

Fields of Or

or: (Box<Expression>, Box<Expression>)

Not

Not expression. Evaluates to the negation of its sub-expression.

Fields of Not

not: Box<Expression>

Empty

Empty expression. Evaluates to all items resolvable by the resolver.

Implementations

impl Expression

pub fn parse<S: AsRef<str>>(str_expr: S) -> Result<Self, Error>

Parse an expression from a string.

Returns an error if the provided string could not be parsed.

Examples

use rapidquery::Expression;

let expression = "a && b";
match Expression::parse(expression) {
    Ok(expr) => println!("Got expression: {:?}", expr),
    Err(e) => panic!("failed to parse")
}

pub fn evaluate<R, V, E>(&self, resolver: &R) -> Result<V, E> where
    V: BitAndAssign + BitOrAssign + Not<Output = V> + Span + Display,
    R: Resolver<V, Error = E>, 

Evaluate an expression using a resolver.

The resolver is tasked with resolving the sets corresponding to the various sub-expressions kinds (tags, key/value pairs, etc.). From there, the evaluator will recursively compute the query, calling the resolver when appropriate.

Examples

use rapidquery::{Expression, Resolver};

let resolver: Box<dyn Resolver<bool, Error = std::io::Error>> = {
    unimplemented!()
};

let expr = Expression::Empty;;

let evaluation: bool = expr.evaluate(&resolver)?;

Trait Implementations

impl Clone for Expression

fn clone(&self) -> Expression

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Expression

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

Formats the value using the given formatter.

impl Default for Expression

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Expression

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
    __D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.

impl Hash for Expression

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl PartialEq<Expression> for Expression

fn eq(&self, other: &Expression) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Expression) -> bool

This method tests for !=.

impl Serialize for Expression

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error> where
    __S: Serializer, 

Serialize this value into the given Serde serializer.

impl Eq for Expression

impl StructuralEq for Expression

impl StructuralPartialEq for Expression