feat: markdown export

src/export/html.rs

@@ -6,7 +6,7 @@ use std::fmt::Write as _;
 use super::event::{Container, Event};
 use super::TraversalContext;
 use super::Traverser;
-use crate::SyntaxKind;
+use crate::{SyntaxElement, SyntaxKind, SyntaxNode};
 
 /// A wrapper for escaping sensitive characters in html.
 ///
@@ -73,6 +73,22 @@ impl HtmlExport {
     pub fn finish(self) -> String {
         self.output
     }
+
+    /// Render syntax node to html string
+    ///
+    /// ```rust
+    /// use orgize::{Org, ast::Bold, export::HtmlExport, rowan::ast::AstNode};
+    ///
+    /// let org = Org::parse("* /hello/ *world*");
+    /// let bold = org.first_node::<Bold>().unwrap();
+    /// let mut html = HtmlExport::default();
+    /// html.render(bold.syntax());
+    /// assert_eq!(html.finish(), "<b>world</b>");
+    /// ```
+    pub fn render(&mut self, node: &SyntaxNode) {
+        let mut ctx = TraversalContext::default();
+        self.element(SyntaxElement::Node(node.clone()), &mut ctx);
+    }
 }
 
 impl Traverser for HtmlExport {

src/export/markdown.rs

@@ -0,0 +1,186 @@
+use std::cmp::min;
+use std::fmt::Write as _;
+
+use crate::{SyntaxElement, SyntaxNode};
+
+use super::event::{Container, Event};
+use super::TraversalContext;
+use super::Traverser;
+
+#[derive(Default)]
+pub struct MarkdownExport {
+    output: String,
+
+    inside_blockquote: bool,
+}
+
+impl MarkdownExport {
+    pub fn push_str(&mut self, s: impl AsRef<str>) {
+        self.output += s.as_ref();
+    }
+
+    /// Render syntax node to markdown string
+    ///
+    /// ```rust
+    /// use orgize::{Org, ast::Bold, export::MarkdownExport, rowan::ast::AstNode};
+    ///
+    /// let org = Org::parse("* /hello/ *world*");
+    /// let bold = org.first_node::<Bold>().unwrap();
+    /// let mut markdown = MarkdownExport::default();
+    /// markdown.render(bold.syntax());
+    /// assert_eq!(markdown.finish(), "**world**");
+    /// ```
+    pub fn render(&mut self, node: &SyntaxNode) {
+        let mut ctx = TraversalContext::default();
+        self.element(SyntaxElement::Node(node.clone()), &mut ctx);
+    }
+
+    pub fn finish(self) -> String {
+        self.output
+    }
+
+    fn follows_newline(&mut self) {
+        if !self.output.is_empty() && !self.output.ends_with(['\n', '\r']) {
+            self.output += "\n";
+        }
+    }
+}
+
+impl Traverser for MarkdownExport {
+    fn event(&mut self, event: Event, ctx: &mut TraversalContext) {
+        match event {
+            Event::Enter(Container::Document(_)) => {}
+            Event::Leave(Container::Document(_)) => {}
+
+            Event::Enter(Container::Headline(headline)) => {
+                self.follows_newline();
+                let level = min(headline.level(), 6);
+                let _ = write!(&mut self.output, "{} ", "#".repeat(level));
+                for elem in headline.title() {
+                    self.element(elem, ctx);
+                }
+            }
+            Event::Leave(Container::Headline(_)) => {}
+
+            Event::Enter(Container::Paragraph(_)) => {}
+            Event::Leave(Container::Paragraph(_)) => self.output += "\n",
+
+            Event::Enter(Container::Section(_)) => self.follows_newline(),
+            Event::Leave(Container::Section(_)) => {}
+
+            Event::Enter(Container::Italic(_)) => self.output += "*",
+            Event::Leave(Container::Italic(_)) => self.output += "*",
+
+            Event::Enter(Container::Bold(_)) => self.output += "**",
+            Event::Leave(Container::Bold(_)) => self.output += "**",
+
+            Event::Enter(Container::Strike(_)) => self.output += "~~",
+            Event::Leave(Container::Strike(_)) => self.output += "~~",
+
+            Event::Enter(Container::Underline(_)) => {}
+            Event::Leave(Container::Underline(_)) => {}
+
+            Event::Enter(Container::Verbatim(_))
+            | Event::Leave(Container::Verbatim(_))
+            | Event::Enter(Container::Code(_))
+            | Event::Leave(Container::Code(_)) => self.output += "`",
+
+            Event::Enter(Container::SourceBlock(block)) => {
+                self.follows_newline();
+                self.output += "```";
+                if let Some(language) = block.language() {
+                    self.output += &language;
+                }
+            }
+            Event::Leave(Container::SourceBlock(_)) => self.output += "```\n",
+
+            Event::Enter(Container::QuoteBlock(_)) => {
+                self.inside_blockquote = true;
+                self.follows_newline();
+                self.output += "> ";
+            }
+            Event::Leave(Container::QuoteBlock(_)) => self.inside_blockquote = false,
+
+            Event::Enter(Container::CommentBlock(_)) => self.output += "<!--",
+            Event::Leave(Container::CommentBlock(_)) => self.output += "-->",
+
+            Event::Enter(Container::Comment(_)) => self.output += "<!--",
+            Event::Leave(Container::Comment(_)) => self.output += "-->",
+
+            Event::Enter(Container::Subscript(_)) => self.output += "<sub>",
+            Event::Leave(Container::Subscript(_)) => self.output += "</sub>",
+
+            Event::Enter(Container::Superscript(_)) => self.output += "<sup>",
+            Event::Leave(Container::Superscript(_)) => self.output += "</sup>",
+
+            Event::Enter(Container::List(_list)) => {}
+            Event::Leave(Container::List(_list)) => {}
+
+            Event::Enter(Container::ListItem(list_item)) => {
+                self.follows_newline();
+                self.output += &" ".repeat(list_item.indent());
+                self.output += &list_item.bullet();
+            }
+            Event::Leave(Container::ListItem(_)) => {}
+
+            Event::Enter(Container::OrgTable(_table)) => {}
+            Event::Leave(Container::OrgTable(_)) => {}
+            Event::Enter(Container::OrgTableRow(_row)) => {}
+            Event::Leave(Container::OrgTableRow(_row)) => {}
+            Event::Enter(Container::OrgTableCell(_)) => {}
+            Event::Leave(Container::OrgTableCell(_)) => {}
+
+            Event::Enter(Container::Link(link)) => {
+                let path = link.path();
+                let path = path.trim_start_matches("file:");
+
+                if link.is_image() {
+                    let _ = write!(&mut self.output, "![]({path})");
+                    return ctx.skip();
+                }
+
+                if !link.has_description() {
+                    let _ = write!(&mut self.output, r#"[{}]({})"#, &path, &path);
+                    return ctx.skip();
+                }
+
+                self.output += "[";
+            }
+            Event::Leave(Container::Link(link)) => {
+                let _ = write!(&mut self.output, r#"]({})"#, &*link.path());
+            }
+
+            Event::Text(text) => {
+                if self.inside_blockquote {
+                    for (idx, line) in text.split('\n').enumerate() {
+                        if idx != 0 {
+                            self.output += "\n>  ";
+                        }
+                        self.output += line;
+                    }
+                } else {
+                    self.output += &*text;
+                }
+            }
+
+            Event::LineBreak(_) => {}
+
+            Event::Snippet(_snippet) => {}
+
+            Event::Rule(_) => self.output += "\n-----\n",
+
+            Event::Timestamp(_timestamp) => {}
+
+            Event::LatexFragment(latex) => {
+                let _ = write!(&mut self.output, "{}", &latex.syntax);
+            }
+            Event::LatexEnvironment(latex) => {
+                let _ = write!(&mut self.output, "{}", &latex.syntax);
+            }
+
+            Event::Entity(entity) => self.output += entity.utf8(),
+
+            _ => {}
+        }
+    }
+}

src/export/mod.rs

@@ -2,8 +2,10 @@
 
 mod event;
 mod html;
+mod markdown;
 mod traverse;
 
 pub use event::{Container, Event};
 pub use html::{HtmlEscape, HtmlExport};
+pub use markdown::MarkdownExport;
 pub use traverse::{from_fn, from_fn_with_ctx, FromFn, FromFnWithCtx, TraversalContext, Traverser};