Struct jupiter::ig::docs::Query

pub struct Query { /* private fields */ }

Represents a pre-compiled query.

A query can be obtained using Doc::compile. And then repeatedly being executed using Query::execute{Query::execute}.

Compiling a query essentially splits the given query string at “.” and then resolves each part of the query into a Symbol. Therefore a query compiled for one Doc cannot be used for another as its result would be entirely undefined. Also note that compiling queries is rather fast, therefore ad-hoc queries can be executed using Element::query.

Implementations

impl Query

pub fn is_root_node_query(&self) -> bool

Determines if this is a root query (“.”).

impl Query

pub fn execute<'a>(&self, element: Element<'a>) -> Element<'a>

Executes the query against the given element.

Note that the element must be part of the same doc for which the query has been compiled otherwise the return value is undefined.

Example

let builder = DocBuilder::new();
let mut object_builder = builder.obj();
let mut inner_builder = builder.obj();
inner_builder.put_int("Bar", 42).unwrap();
object_builder.put_object("Foo", inner_builder).unwrap();

let doc = builder.build_object(object_builder);

let query = doc.compile("Foo.Bar");
assert_eq!(query.execute(doc.root()).as_int().unwrap(), 42);

let query = doc.compile("XXX.UNKNOWN");
assert!(query.execute(doc.root()).is_empty());

let query = doc.compile(".");
assert!(query.execute(doc.root()).is_object());

pub fn execute_all<'a>(&self, element: Element<'a>) -> Vec<Element<'a>>

Executes this query against the given element and returns all matches.

Example

There might be several matches if there is an inner list in the doc:

use yaml_rust::YamlLoader;
use jupiter::ig::yaml::list_to_doc;
let input = r#"
test:
    - foo:
        label: bar
    - foo:
        label: baz
        "#;

let rows = YamlLoader::load_from_str(input).unwrap();
let doc = list_to_doc(rows.as_slice(), |_| true).unwrap();


let query = doc.compile("test.foo.label");
let matches = query.execute_all(doc.root());
assert_eq!(matches.len(), 2);
assert_eq!(matches[0].as_str().unwrap(), "bar");
assert_eq!(matches[1].as_str().unwrap(), "baz");

Trait Implementations

impl Clone for Query

fn clone(&self) -> Query

Returns a copy of the value.

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

Performs copy-assignment from source.