typst/src/engine.rs

88 lines
2.4 KiB
Rust

//! Core typesetting engine.
use std::fmt;
use crate::parsing::{SyntaxTree, Node};
use crate::doc::{Document, Style, Page, Text, TextCommand};
use crate::font::Font;
/// A type that can be typesetted into a document.
pub trait Typeset {
/// Generate a document from self.
fn typeset(self) -> TypeResult<Document>;
}
impl Typeset for SyntaxTree<'_> {
fn typeset(self) -> TypeResult<Document> {
Engine::new(self).typeset()
}
}
/// Result type used for parsing.
type TypeResult<T> = std::result::Result<T, TypesetError>;
/// Errors occuring in the process of typesetting.
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct TypesetError {
message: String,
}
impl fmt::Display for TypesetError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(&self.message)
}
}
/// Transforms an abstract syntax tree into a document.
#[derive(Debug, Clone)]
struct Engine<'s> {
tree: SyntaxTree<'s>,
}
impl<'s> Engine<'s> {
/// Create a new generator from a syntax tree.
fn new(tree: SyntaxTree<'s>) -> Engine<'s> {
Engine { tree }
}
/// Generate the abstract document.
fn typeset(&mut self) -> TypeResult<Document> {
let style = Style::default();
// Load font defined by style
let font_family = style.font_families.first().unwrap();
let program = std::fs::read(format!("../fonts/{}-Regular.ttf", font_family)).unwrap();
let font = Font::new(program).unwrap();
let mut text = String::new();
for node in &self.tree.nodes {
match node {
Node::Space if !text.is_empty() => text.push(' '),
Node::Space | Node::Newline => (),
Node::Word(word) => text.push_str(word),
Node::ToggleItalics | Node::ToggleBold | Node::ToggleMath => unimplemented!(),
Node::Func(_) => unimplemented!(),
}
}
let page = Page {
width: style.paper_size[0],
height: style.paper_size[1],
text: vec![Text {
commands: vec![
TextCommand::Move(style.margins[0], style.paper_size[1] - style.margins[1]),
TextCommand::SetFont(0, style.font_size),
TextCommand::Text(text)
]
}],
};
Ok(Document {
pages: vec![page],
fonts: vec![font],
})
}
}