463 lines
16 KiB
Rust
463 lines
16 KiB
Rust
/// This module implements a simple text/gemini parser based on the description
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/// here: https://gemini.circumlunar.space/docs/specification.html
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use std::io::{self, Write};
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/// Build a gemini document up from a series of nodes.
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#[derive(Default)]
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pub struct Builder {
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nodes: Vec<Node>,
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}
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impl Builder {
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pub fn new() -> Builder {
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Builder::default()
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}
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pub fn text<T: Into<String>>(mut self, data: T) -> Builder {
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self.nodes.push(Node::Text(data.into()));
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self
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}
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/// Append a single blank line to the document
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///
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/// This is equivilent to calling [`text()`] with an empty string, or pushing a blank
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/// [`Node`]
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///
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/// ```
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/// # use gemtext::Builder;
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/// let greeting = Builder::new()
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/// .text("Hello")
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/// .blank_line()
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/// .text("universe")
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/// .to_string();
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///
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/// assert_eq!(greeting.trim(), "Hello\n\nuniverse");
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/// ```
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///
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/// [`text()`]: Self::text()
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pub fn blank_line(mut self) -> Self {
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self.nodes.push(Node::blank());
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self
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}
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pub fn link<T: Into<String>>(mut self, to: T, name: Option<String>) -> Builder {
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self.nodes.push(Node::Link {
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to: to.into(),
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name: name,
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});
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self
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}
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pub fn preformatted<T: Into<String>>(mut self, data: T) -> Builder {
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self.nodes.push(Node::Preformatted(data.into()));
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self
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}
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pub fn heading<T: Into<String>>(mut self, level: u8, body: T) -> Builder {
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self.nodes.push(Node::Heading {
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level: level,
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body: body.into(),
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});
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self
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}
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pub fn list_item<T: Into<String>>(mut self, item: T) -> Builder {
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self.nodes.push(Node::ListItem(item.into()));
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self
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}
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pub fn quote<T: Into<String>>(mut self, body: T) -> Builder {
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self.nodes.push(Node::Quote(body.into()));
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self
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}
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pub fn build(self) -> Vec<Node> {
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self.nodes
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}
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}
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impl ToString for Builder {
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/// Render a document to a string
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///
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/// This produces a text/gemini compliant text document, represented as a string
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fn to_string(&self) -> String {
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let len: usize = self.nodes.iter().map(Node::estimate_len).sum(); // sum up node lengths
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let mut bytes = Vec::with_capacity(len + self.nodes.len()); // add in inter-node newlines
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render(self, &mut bytes).unwrap(); // Writing to a string shouldn't produce errors
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unsafe {
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// This is safe because bytes is composed of Strings. We could have this as
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// pure safe code by replicating the `render()` method and switching it to use
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// a fmt::Write (or even `String::push()`)instead of a io::Write, but this has
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// the same effect, with much DRYer code.
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String::from_utf8_unchecked(bytes)
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}
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}
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}
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impl AsRef<[Node]> for Builder {
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/// Get a reference to the internal node list of this builder
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fn as_ref(&self) -> &[Node] {
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self.nodes.as_ref()
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}
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}
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impl AsMut<[Node]> for Builder {
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/// Get a mutable reference to the internal node list of this builder
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fn as_mut(&mut self) -> &mut [Node] {
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self.nodes.as_mut()
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}
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}
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impl From<Builder> for Vec<Node> {
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/// Convert into a collection of [`Node`]s.
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///
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/// Equivilent to calling [`Builder::build()`]
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fn from(builder: Builder) -> Self {
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builder.build()
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}
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}
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/// Render a set of nodes as a document to a writer.
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pub fn render(nodes: impl AsRef<[Node]>, out: &mut impl Write) -> io::Result<()> {
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use Node::*;
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for node in nodes.as_ref() {
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match node {
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Text(body) => {
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let special_prefixes = ["=>", "```", "#", "*", ">"];
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if special_prefixes.iter().any(|prefix| body.starts_with(prefix)) {
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write!(out, " ")?;
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}
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write!(out, "{}\n", body)?
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},
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Link { to, name } => match name {
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Some(name) => write!(out, "=> {} {}\n", to, name)?,
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None => write!(out, "=> {}\n", to)?,
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},
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Preformatted(body) => write!(out, "```\n{}\n```\n", body)?,
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Heading { level, body } => write!(out, "{} {}\n", "#".repeat(*level as usize), body)?,
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ListItem(body) => write!(out, "* {}\n", body)?,
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Quote(body) => write!(out, "> {}\n", body)?,
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};
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}
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Ok(())
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}
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/// Individual nodes of the document. Each node correlates to a line in the file.
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#[derive(Debug, PartialEq, Eq, Clone)]
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pub enum Node {
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/// Text lines are the most fundamental line type - any line which does not
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/// match the definition of another line type defined below defaults to
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/// being a text line. The majority of lines in a typical text/gemini document will be text lines.
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Text(String),
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/// Lines beginning with the two characters "=>" are link lines, which have the following syntax:
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///
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/// ```gemini
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/// =>[<whitespace>]<URL>[<whitespace><USER-FRIENDLY LINK NAME>]
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/// ```
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///
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/// where:
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///
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/// * `<whitespace>` is any non-zero number of consecutive spaces or tabs
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/// * Square brackets indicate that the enclosed content is optional.
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/// * `<URL>` is a URL, which may be absolute or relative. If the URL
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/// does not include a scheme, a scheme of `gemini://` is implied.
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Link { to: String, name: Option<String> },
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/// Any line whose first three characters are "```" (i.e. three consecutive
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/// back ticks with no leading whitespace) are preformatted toggle lines.
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/// These lines should NOT be included in the rendered output shown to the
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/// user. Instead, these lines toggle the parser between preformatted mode
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/// being "on" or "off". Preformatted mode should be "off" at the beginning
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/// of a document. The current status of preformatted mode is the only
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/// internal state a parser is required to maintain. When preformatted mode
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/// is "on", the usual rules for identifying line types are suspended, and
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/// all lines should be identified as preformatted text lines (see 5.4.4).
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///
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/// Preformatted text lines should be presented to the user in a "neutral",
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/// monowidth font without any alteration to whitespace or stylistic
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/// enhancements. Graphical clients should use scrolling mechanisms to present
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/// preformatted text lines which are longer than the client viewport, in
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/// preference to wrapping. In displaying preformatted text lines, clients
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/// should keep in mind applications like ASCII art and computer source
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/// code: in particular, source code in languages with significant whitespace
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/// (e.g. Python) should be able to be copied and pasted from the client into
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/// a file and interpreted/compiled without any problems arising from the
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/// client's manner of displaying them.
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Preformatted(String),
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/// Lines beginning with "#" are heading lines. Heading lines consist of one,
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/// two or three consecutive "#" characters, followed by optional whitespace,
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/// followed by heading text. The number of # characters indicates the "level"
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/// of header; #, ## and ### can be thought of as analogous to `<h1>`, `<h2>`
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/// and `<h3>` in HTML.
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///
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/// Heading text should be presented to the user, and clients MAY use special
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/// formatting, e.g. a larger or bold font, to indicate its status as a header
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/// (simple clients may simply print the line, including its leading #s,
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/// without any styling at all). However, the main motivation for the
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/// definition of heading lines is not stylistic but to provide a
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/// machine-readable representation of the internal structure of the document.
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/// Advanced clients can use this information to, e.g. display an automatically
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/// generated and hierarchically formatted "table of contents" for a long
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/// document in a side-pane, allowing users to easily jump to specific sections
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/// without excessive scrolling. CMS-style tools automatically generating menus
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/// or Atom/RSS feeds for a directory of text/gemini files can use first
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/// heading in the file as a human-friendly title.
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Heading { level: u8, body: String },
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/// Lines beginning with "* " are unordered list items. This line type exists
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/// purely for stylistic reasons. The * may be replaced in advanced clients by
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/// a bullet symbol. Any text after the "* " should be presented to the user as
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/// if it were a text line, i.e. wrapped to fit the viewport and formatted
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/// "nicely". Advanced clients can take the space of the bullet symbol into
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/// account when wrapping long list items to ensure that all lines of text
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/// corresponding to the item are offset an equal distance from the left of the screen.
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ListItem(String),
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/// Lines beginning with ">" are quote lines. This line type exists so that
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/// advanced clients may use distinct styling to convey to readers the important
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/// semantic information that certain text is being quoted from an external
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/// source. For example, when wrapping long lines to the the viewport, each
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/// resultant line may have a ">" symbol placed at the front.
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Quote(String),
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}
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impl Node {
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pub fn blank() -> Node {
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Node::Text("".to_string())
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}
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/// Cheaply estimate the length of this node
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///
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/// This measures length in bytes, *not characters*. So if the user includes
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/// non-ascii characters, a single one of these characters may add several bytes to
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/// the length, despite only displaying as one character.
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///
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/// This does include any newlines, but not any trailing newlines. For example, a
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/// preformatted text block containing a single line reading "trans rights! 🏳️⚧️"
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/// would have a length of 30: 3 backticks, a newline, the text (including 16 bytes
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/// for the trans flag), another newline, and another 3 backticks.
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///
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/// ```
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/// # use gemtext::Node;
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/// let simple_text = Node::Text(String::from("Henlo worl"));
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/// let linky_link = Node::Link { to: "gemini://cetacean.club/maj/".to_string(), name: Some("Maj".to_string()) };
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/// let human_rights = Node::Preformatted("trans rights! 🏳️⚧️".to_string());;
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///
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/// assert_eq!(
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/// simple_text.estimate_len(),
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/// "Henlo worl".as_bytes().len()
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/// );
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/// assert_eq!(
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/// linky_link.estimate_len(),
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/// "=> gemini://cetacean.club/maj/ Maj".as_bytes().len()
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/// );
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/// assert_eq!(
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/// human_rights.estimate_len(),
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/// "```\ntrans rights! 🏳️⚧️\n```".as_bytes().len()
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/// );
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/// ```
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pub fn estimate_len(&self) -> usize {
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match self {
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Self::Text(text) => text.len(),
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Self::Link { to, name } => 3 + to.as_bytes().len() +
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name.as_ref().map(|n| n.as_bytes().len() + 1).unwrap_or(0),
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Self::Preformatted(text) => text.as_bytes().len() + 8,
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Self::Heading { level, body } => *level as usize + 1 + body.as_bytes().len(),
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Self::ListItem(item) | Self::Quote(item)=> 2 + item.as_bytes().len(),
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}
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}
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}
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pub fn parse(doc: &str) -> Vec<Node> {
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let mut result: Vec<Node> = vec![];
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let mut collect_preformatted: bool = false;
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let mut preformatted_buffer: Vec<u8> = vec![];
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for line in doc.lines() {
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if line.starts_with("```") {
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collect_preformatted = !collect_preformatted;
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if !collect_preformatted {
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result.push(Node::Preformatted(
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String::from_utf8(preformatted_buffer)
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.unwrap()
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.trim_end()
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.to_string(),
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));
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preformatted_buffer = vec![];
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}
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continue;
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}
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if collect_preformatted && line != "```" {
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write!(preformatted_buffer, "{}\n", line).unwrap();
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continue;
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}
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// Quotes
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if line.starts_with(">") {
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result.push(Node::Quote(line[1..].trim().to_string()));
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continue;
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}
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// List items
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if line.starts_with("*") {
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result.push(Node::ListItem(line[1..].trim().to_string()));
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continue;
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}
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// Headings
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if line.starts_with("###") {
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result.push(Node::Heading {
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level: 3,
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body: line[3..].trim().to_string(),
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});
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continue;
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}
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if line.starts_with("##") {
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result.push(Node::Heading {
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level: 2,
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body: line[2..].trim().to_string(),
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});
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continue;
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}
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if line.starts_with("#") {
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result.push(Node::Heading {
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level: 1,
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body: line[1..].trim().to_string(),
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});
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continue;
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}
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// Links
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if line.starts_with("=>") {
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let sp = line[2..].split_ascii_whitespace().collect::<Vec<&str>>();
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match sp.len() {
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1 => result.push(Node::Link {
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to: sp[0].trim().to_string(),
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name: None,
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}),
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_ => result.push(Node::Link {
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to: sp[0].trim().to_string(),
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name: Some(sp[1..].join(" ").trim().to_string()),
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}),
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}
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continue;
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}
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result.push(Node::Text(line.to_string()));
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}
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result
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn basic() {
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let _ = pretty_env_logger::try_init();
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let msg = include_str!("../../majc/src/help.gmi");
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let doc = super::parse(msg);
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assert_ne!(doc.len(), 0);
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}
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#[test]
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fn quote() {
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let _ = pretty_env_logger::try_init();
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let msg = ">hi there";
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let expected: Vec<Node> = vec![Node::Quote("hi there".to_string())];
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assert_eq!(expected, parse(msg));
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}
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#[test]
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fn list() {
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let _ = pretty_env_logger::try_init();
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let msg = "*hi there";
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let expected: Vec<Node> = vec![Node::ListItem("hi there".to_string())];
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assert_eq!(expected, parse(msg));
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}
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#[test]
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fn preformatted() {
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let _ = pretty_env_logger::try_init();
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let msg = "```\n\
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hi there\n\
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```\n\
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\n\
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Test\n";
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let expected: Vec<Node> = vec![
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Node::Preformatted("hi there".to_string()),
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Node::Text(String::new()),
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Node::Text("Test".to_string()),
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];
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assert_eq!(expected, parse(msg));
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}
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#[test]
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fn header() {
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let _ = pretty_env_logger::try_init();
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let msg = "#hi\n##there\n### my friends";
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let expected: Vec<Node> = vec![
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Node::Heading {
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level: 1,
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body: "hi".to_string(),
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},
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Node::Heading {
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level: 2,
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body: "there".to_string(),
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},
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Node::Heading {
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level: 3,
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body: "my friends".to_string(),
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},
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];
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assert_eq!(expected, parse(msg));
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}
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#[test]
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fn link() {
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let _ = pretty_env_logger::try_init();
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let msg = "=>/\n=> / Go home";
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let expected: Vec<Node> = vec![
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Node::Link {
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to: "/".to_string(),
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name: None,
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},
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Node::Link {
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to: "/".to_string(),
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name: Some("Go home".to_string()),
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},
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];
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assert_eq!(expected, parse(msg));
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}
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#[test]
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fn ambiguous_preformatted() {
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let _ = pretty_env_logger::try_init();
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let msg = include_str!("../../testdata/ambig_preformatted.gmi");
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let expected: Vec<Node> = vec![
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Node::Preformatted("FOO".to_string()),
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Node::Text("Foo bar".to_string()),
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];
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assert_eq!(expected, parse(msg));
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}
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#[test]
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fn ambiguous_text() {
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let _ = pretty_env_logger::try_init();
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let original = Node::Text("#1 World's Best Coder".to_string());
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let expected = " #1 World's Best Coder\n";
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let mut rendered: Vec<u8> = vec![];
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render(vec![original], &mut rendered).unwrap();
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let rendered = String::from_utf8(rendered).unwrap();
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assert_eq!(expected, rendered)
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}
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}
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