Struct Query 

pub struct Query<'query> { /* private fields */ }

A compiled CSS query ready to be executed against an HTML document.

A Query encapsulates a tree of QuerySections, each representing one CSS selector, compiled into an automaton of internal transitions. The automaton is evaluated during streaming parsing to match elements efficiently in a single pass.

NFA Execution Model

Under the hood, a Query is compiled into a Non-Deterministic Finite Automaton (NFA).

• Fictitious States: The NFA states themselves are implicit. They simply represent the position (the integer index) between sequential transitions within the automaton’s evaluation path.
• Transitions: Defined by the internal Transition struct, each edge consists of a guard (a topological Combinator dictating depth requirements like > or ) and a predicate (an ElementPredicate matching tags, classes, etc.).
• Branches: A QuerySection represents a linear sequence of these transitions (usually representing a single string selector). Branching your query with QueryBuilder::then creates new sections that form a directed tree of sub-automata.

Building a Query

Use Query::all or Query::first as entry points, then chain with QueryBuilder::all, QueryBuilder::first, or QueryBuilder::then, and finalise with QueryBuilder::build.

use scah::{Query, Save};

// Simple: find all <a> tags
let q1 = Query::all("a", Save::all()).build();

// Compound: find sections, then extract links and text within them
let q2 = Query::all("section", Save::none())
    .then(|s| [
        s.all("a[href]", Save::all()),
        s.first("p",     Save::only_text_content()),
    ])
    .build();

Implementations

impl<'query> Query<'query>

pub fn first(query: &'query str, save: Save) -> QueryBuilder<'query>

Start building a query that matches only the first element satisfying the given CSS selector.

Using first enables an early-exit optimisation: once the match is found and its content captured, parsing of this branch can stop early.

pub fn all(query: &'query str, save: Save) -> QueryBuilder<'query>

Start building a query that matches all elements satisfying the given CSS selector.

This is the most common entry point. The returned QueryBuilder can be chained with .all(), .first(), .then(), and finally .build() to produce a Query.

Example

use scah::{Query, Save};

let query = Query::all("a[href]", Save::all()).build();

Trait Implementations

impl<'query> Clone for Query<'query>

fn clone(&self) -> Query<'query>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'query> Debug for Query<'query>

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

Formats the value using the given formatter.

impl<'query> PartialEq for Query<'query>

fn eq(&self, other: &Query<'query>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'query> StructuralPartialEq for Query<'query>