spider_scraper 0.3.0

A css scraper using html5ever
Documentation 
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//! HTML documents and fragments.

use ego_tree::iter::Nodes;
use ego_tree::{NodeId, Tree};
use html5ever::serialize::SerializeOpts;
use html5ever::tree_builder::QuirksMode;
use html5ever::QualName;
use html5ever::{driver, serialize};
use tendril::TendrilSink;

use crate::element_ref::ElementRef;
use crate::node::Node;
use crate::selector::Selector;

use self::tree_sink::HtmlBuilder;

lazy_static! {
    static ref HTML_SELECTOR: Selector = Selector::parse("html").unwrap();
}

/// An HTML tree.
///
/// Parsing does not fail hard. Instead, the `quirks_mode` is set and errors are added to the
/// `errors` field. The `tree` will still be populated as best as possible.
///
/// Implements the `TreeSink` trait from the `html5ever` crate, which allows HTML to be parsed.
#[derive(Debug, Clone)]
pub struct Html {
    /// The quirks mode.
    pub quirks_mode: QuirksMode,
    /// The node tree.
    pub tree: Tree<Node>,
    /// The html language of the document.
    pub lang: String,
}

impl Html {
    /// Creates an empty HTML document.
    pub fn new_document() -> Self {
        Html {
            quirks_mode: QuirksMode::NoQuirks,
            tree: Tree::new(Node::Document),
            lang: Default::default(),
        }
    }

    /// Creates an empty HTML fragment.
    pub fn new_fragment() -> Self {
        Html {
            quirks_mode: QuirksMode::NoQuirks,
            tree: Tree::new(Node::Fragment),
            lang: Default::default(),
        }
    }

    /// Parses a string of HTML as a document.
    ///
    /// ```
    /// use scraper::Html;
    ///
    /// let html = Html::parse_document("<p>hello</p>");
    /// assert_eq!(html.root_element().html().is_empty(), false);
    /// ```
    pub fn parse_document(document: &str) -> Self {
        let parser = driver::parse_document(HtmlBuilder::new_document(), Default::default());
        parser.one(document)
    }

    /// Parses a string of HTML as a fragment.
    pub fn parse_fragment(fragment: &str) -> Self {
        let parser = driver::parse_fragment(
            HtmlBuilder::new_fragment(),
            Default::default(),
            QualName::new(None, ns!(html), local_name!("body")),
            Vec::new(),
            false,
        );
        parser.one(fragment)
    }

    /// Returns an iterator over elements matching a selector.
    pub fn select<'a, 'b>(&'a self, selector: &'b Selector) -> Select<'a, 'b> {
        Select {
            inner: self.tree.nodes(),
            selector,
        }
    }

    /// Returns the root `<html>` element.
    pub fn root_element(&self) -> ElementRef {
        let root_node = self
            .tree
            .root()
            .children()
            .find(|child| child.value().is_element())
            .expect("html node missing");
        ElementRef::wrap(root_node).unwrap()
    }

    /// Set the html language of the document by getting the lang attr
    pub fn set_language(&mut self, lang: String) {
        self.lang = lang;
    }

    /// Get the language for the page.
    pub fn get_lang(&self) -> &str {
        if self.lang.is_empty() {
            if let Some(element) = self.select(&HTML_SELECTOR).next() {
                if let Some(lang) = element.value().attr("lang") {
                    return lang;
                }
            }
            &self.lang
        } else {
            &self.lang
        }
    }

    /// Serialize entire document into HTML.
    pub fn html(&self) -> String {
        let opts = SerializeOpts {
            scripting_enabled: false, // It's not clear what this does.
            traversal_scope: html5ever::serialize::TraversalScope::IncludeNode,
            create_missing_parent: false,
        };
        let mut buf = Vec::new();
        let _ = serialize(&mut buf, self, opts);
        auto_encoder::auto_encode_bytes(&buf)
    }

    /// Find and remove a node
    pub fn remove_node(&mut self, node_id: NodeId) {
        if let Some(mut node) = self.tree.get_mut(node_id) {
            node.detach();
        }
    }
}

/// Iterator over elements matching a selector.
#[derive(Debug)]
pub struct Select<'a, 'b> {
    inner: Nodes<'a, Node>,
    selector: &'b Selector,
}

impl<'a, 'b> Iterator for Select<'a, 'b> {
    type Item = ElementRef<'a>;

    fn next(&mut self) -> Option<ElementRef<'a>> {
        for node in self.inner.by_ref() {
            if let Some(element) = ElementRef::wrap(node) {
                if element.parent().is_some() && self.selector.matches(&element) {
                    return Some(element);
                }
            }
        }
        None
    }
}

impl<'a, 'b> DoubleEndedIterator for Select<'a, 'b> {
    fn next_back(&mut self) -> Option<Self::Item> {
        for node in self.inner.by_ref().rev() {
            if let Some(element) = ElementRef::wrap(node) {
                if element.parent().is_some() && self.selector.matches(&element) {
                    return Some(element);
                }
            }
        }
        None
    }
}

mod serializable;
mod tree_sink;

#[cfg(test)]
mod tests {
    use super::Html;
    use super::Selector;

    /// Compile-time assertion that the parsed `Html` is `Send`.
    /// This is the whole point of the spider-html5ever / spider-tendril
    /// fork swap — `Html` (and the futures that hold it) can now move
    /// across thread boundaries on a multi-threaded async runtime.
    ///
    /// `Sync` is NOT asserted: `Tendril` contains a `Cell<NonZeroUsize>`
    /// pointer field that is intentionally `!Sync`. Spider_scraper owns
    /// its tree directly (no `Arc`), so `Send` is the only bound we need
    /// for cross-thread movement.
    #[test]
    fn parsed_html_is_send() {
        fn assert_send<T: Send>(_: &T) {}
        let html = Html::parse_document("<p>hi</p>");
        assert_send(&html);
    }

    #[test]
    fn root_element_fragment() {
        let html = Html::parse_fragment(r#"<a href="http://github.com">1</a>"#);
        let root_ref = html.root_element();
        let href = root_ref
            .select(&Selector::parse("a").unwrap())
            .next()
            .unwrap();
        assert_eq!(href.inner_html(), "1");
        assert_eq!(href.value().attr("href").unwrap(), "http://github.com");
    }

    #[test]
    fn root_element_document_doctype() {
        let html = Html::parse_document("<!DOCTYPE html>\n<title>abc</title>");
        let root_ref = html.root_element();
        let title = root_ref
            .select(&Selector::parse("title").unwrap())
            .next()
            .unwrap();
        assert_eq!(title.inner_html(), "abc");
    }

    #[test]
    fn root_element_document_comment() {
        let html = Html::parse_document("<!-- comment --><title>abc</title>");
        let root_ref = html.root_element();
        let title = root_ref
            .select(&Selector::parse("title").unwrap())
            .next()
            .unwrap();
        assert_eq!(title.inner_html(), "abc");
    }

    #[test]
    fn select_is_reversible() {
        let html = Html::parse_document("<p>element1</p><p>element2</p><p>element3</p>");
        let selector = Selector::parse("p").unwrap();
        let result: Vec<_> = html
            .select(&selector)
            .rev()
            .map(|e| e.inner_html())
            .collect();
        assert_eq!(result, vec!["element3", "element2", "element1"]);
    }
}