Crate z157 

Parse filter fields according to https://opensource.zalando.com/restful-api-guidelines/#157.

Example

use z157::Tree;

// Select fields to include
let tree = Tree::parse(
    "(name,bio(height(meters,centimeters),age))",
)
.unwrap();

assert!(!tree.negation());
let height = tree.index(&["bio", "height"]).unwrap();
assert!(
    height
        .children()
        .any(|field| field.name() == "meters")
);
assert!(
    height
        .children()
        .any(|field| field.name() == "centimeters")
);

let nested_fields: Vec<_> = tree
    .walk()
    .map(|field| field.path().join("."))
    .collect();
assert_eq!(
    nested_fields,
    [
        "name",
        "bio",
        "bio.height",
        "bio.height.meters",
        "bio.height.centimeters",
        "bio.age",
    ]
);

// Select fields to exclude
let tree = Tree::parse("!(bio)").unwrap();

assert!(tree.negation());

Specification

From the Zalando RESTful API guidelines:

<fields>            ::= [ <negation> ] <fields_struct>
<fields_struct>     ::= "(" <field_items> ")"
<field_items>       ::= <field> [ "," <field_items> ]
<field>             ::= <field_name> | <fields_substruct>
<fields_substruct>  ::= <field_name> <fields_struct>
<field_name>        ::= <dash_letter_digit> [ <field_name> ]
<dash_letter_digit> ::= <dash> | <letter> | <digit>
<dash>              ::= "-" | "_"
<letter>            ::= "A" | ... | "Z" | "a" | ... | "z"
<digit>             ::= "0" | ... | "9"
<negation>          ::= "!"

Structs

Field

One node in the tree of fields.

Tree

Contains fields parsed from a filtering string.

Unparsable

Returned when parsing of a string into a Tree fails.