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use std::fmt;
use std::iter::Peekable;
use memchr::{memchr, memchr2, memchr3};
use crate::email::EmailScanner;
use crate::scanner::Scanner;
use crate::url::{DomainScanner, UrlScanner};
/// A link found in the input text.
#[derive(Debug)]
pub struct Link<'t> {
text: &'t str,
start: usize,
end: usize,
kind: LinkKind,
}
impl<'t> Link<'t> {
/// The start index of the link within the input text.
#[inline]
pub fn start(&self) -> usize {
self.start
}
/// The end index of the link.
#[inline]
pub fn end(&self) -> usize {
self.end
}
/// Get the link text as a `str`.
#[inline]
pub fn as_str(&self) -> &'t str {
&self.text[self.start..self.end]
}
/// The type of the link.
#[inline]
pub fn kind(&self) -> &LinkKind {
&self.kind
}
}
/// The type of link that was found.
#[derive(Debug, Eq, PartialEq)]
#[non_exhaustive]
pub enum LinkKind {
/// URL links like "http://example.org".
Url,
/// E-mail links like "foo@example.org"
Email,
}
/// Span within the input text.
///
/// A span represents a substring of the input text,
/// which can either be a link, or plain text.
#[derive(Debug)]
pub struct Span<'t> {
text: &'t str,
start: usize,
end: usize,
kind: Option<LinkKind>,
}
impl<'t> Span<'t> {
/// The start index of the span within the input text.
#[inline]
pub fn start(&self) -> usize {
self.start
}
/// The end index of the span.
#[inline]
pub fn end(&self) -> usize {
self.end
}
/// Get the span text as a `str`.
#[inline]
pub fn as_str(&self) -> &'t str {
&self.text[self.start..self.end]
}
/// The type of link included in the span, if any.
///
/// Returns `None` if the span represents plain text.
#[inline]
pub fn kind(&self) -> Option<&LinkKind> {
self.kind.as_ref()
}
}
/// A configured link finder.
#[derive(Debug)]
pub struct LinkFinder {
email: bool,
email_domain_must_have_dot: bool,
url: bool,
url_must_have_scheme: bool,
url_can_be_iri: bool,
}
/// Iterator for finding links.
pub struct Links<'t> {
text: &'t str,
rewind: usize,
trigger_finder: Box<dyn Fn(&[u8]) -> Option<usize>>,
email_scanner: EmailScanner,
url_scanner: UrlScanner,
domain_scanner: DomainScanner,
}
/// Iterator over spans.
pub struct Spans<'t> {
text: &'t str,
position: usize,
links: Peekable<Links<'t>>,
}
impl LinkFinder {
/// Create a new link finder with the default options for finding all kinds
/// of links.
///
/// If you only want to find a certain kind of links, use the `kinds` method.
pub fn new() -> LinkFinder {
LinkFinder {
email: true,
email_domain_must_have_dot: true,
url: true,
url_must_have_scheme: true,
url_can_be_iri: true,
}
}
/// Require the domain parts of email addresses to have at least one dot.
/// Use `false` to also find addresses such as `root@localhost`.
pub fn email_domain_must_have_dot(&mut self, value: bool) -> &mut LinkFinder {
self.email_domain_must_have_dot = value;
self
}
/// Set whether URLs must have a scheme, defaults to `true`.
///
/// By default only URLs having a scheme defined are found.
/// By setting this to `false` you make the scheme of URLs optional, to also find URLs like
/// `example.org`. For some URLs the used scheme is important, and making the scheme optional
/// may lead to finding a lot of false positive URLs.
pub fn url_must_have_scheme(&mut self, url_must_have_scheme: bool) -> &mut LinkFinder {
self.url_must_have_scheme = url_must_have_scheme;
self
}
/// Sets whether URLs can be IRI according to RFC-3987.
/// The default is `true`.
/// Setting it to `false` means domains can contain ASCII characters only.
pub fn url_can_be_iri(&mut self, url_can_be_iri: bool) -> &mut LinkFinder {
self.url_can_be_iri = url_can_be_iri;
self
}
/// Restrict the kinds of links that should be found to the specified ones.
pub fn kinds(&mut self, kinds: &[LinkKind]) -> &mut LinkFinder {
self.email = false;
self.url = false;
for kind in kinds {
match *kind {
LinkKind::Email => self.email = true,
LinkKind::Url => self.url = true,
}
}
self
}
/// Find links in the specified input text.
///
/// Returns an `Iterator` which only scans when `next` is called (lazy).
pub fn links<'t>(&self, text: &'t str) -> Links<'t> {
Links::new(
text,
self.url,
self.url_must_have_scheme,
self.email,
self.email_domain_must_have_dot,
self.url_can_be_iri,
)
}
/// Iterate over spans in the specified input text.
///
/// A span represents a substring of the input text,
/// which can either be a link, or plain text.
///
/// Returns an `Iterator` which only scans when `next` is called (lazy).
///
/// The spans that are returned by the `Iterator` are consecutive,
/// and when combined represent the input text in its entirety.
pub fn spans<'t>(&self, text: &'t str) -> Spans<'t> {
Spans {
text,
position: 0,
links: self.links(text).peekable(),
}
}
}
impl Default for LinkFinder {
fn default() -> Self {
LinkFinder::new()
}
}
impl<'t> Links<'t> {
fn new(
text: &'t str,
url: bool,
url_must_have_scheme: bool,
email: bool,
email_domain_must_have_dot: bool,
iri_parsing_enabled: bool,
) -> Links<'t> {
let url_scanner = UrlScanner {
iri_parsing_enabled,
};
let domain_scanner = DomainScanner {
iri_parsing_enabled,
};
let email_scanner = EmailScanner {
domain_must_have_dot: email_domain_must_have_dot,
};
// With optional schemes URLs don't have unique `:`, then search for `.` as well
let trigger_finder: Box<dyn Fn(&[u8]) -> Option<usize>> = match (url, email) {
(true, true) if url_must_have_scheme => Box::new(|s| memchr2(b':', b'@', s)),
(true, true) => Box::new(|s| memchr3(b':', b'@', b'.', s)),
(true, false) if url_must_have_scheme => Box::new(|s| memchr(b':', s)),
(true, false) => Box::new(|s| memchr2(b':', b'.', s)),
(false, true) => Box::new(|s| memchr(b'@', s)),
(false, false) => Box::new(|_| None),
};
Links {
text,
rewind: 0,
trigger_finder,
email_scanner,
url_scanner,
domain_scanner,
}
}
}
impl<'t> Iterator for Links<'t> {
type Item = Link<'t>;
fn next(&mut self) -> Option<Link<'t>> {
let slice = &self.text[self.rewind..];
let mut find_from = 0;
while let Some(i) = (self.trigger_finder)(slice[find_from..].as_bytes()) {
let trigger = slice.as_bytes()[find_from + i];
let (scanner, kind): (&dyn Scanner, LinkKind) = match trigger {
b':' => (&self.url_scanner, LinkKind::Url),
b'.' => (&self.domain_scanner, LinkKind::Url),
b'@' => (&self.email_scanner, LinkKind::Email),
_ => unreachable!(),
};
if let Some(range) = scanner.scan(slice, find_from + i) {
let start = self.rewind + range.start;
let end = self.rewind + range.end;
self.rewind = end;
let link = Link {
text: &self.text,
start,
end,
kind,
};
return Some(link);
} else {
// The scanner didn't find anything. But there could be more
// trigger characters later, so continue the search.
find_from += i + 1;
}
}
None
}
}
impl<'t> fmt::Debug for Links<'t> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Links").field("text", &self.text).finish()
}
}
impl<'t> Iterator for Spans<'t> {
type Item = Span<'t>;
fn next(&mut self) -> Option<Span<'t>> {
match self.links.peek() {
Some(ref link) => {
if self.position < link.start {
let span = Span {
text: &self.text,
start: self.position,
end: link.start,
kind: None,
};
self.position = link.start;
return Some(span);
}
}
None => {
if self.position < self.text.len() {
let span = Span {
text: &self.text,
start: self.position,
end: self.text.len(),
kind: None,
};
self.position = self.text.len();
return Some(span);
}
}
};
self.links.next().map(|link| {
self.position = link.end;
Span {
text: &self.text,
start: link.start,
end: link.end,
kind: Some(link.kind),
}
})
}
}
impl<'t> fmt::Debug for Spans<'t> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Spans").field("text", &self.text).finish()
}
}