feat: add Document::title & Document::keywords

src/ast/document.rs

@@ -0,0 +1,64 @@
+use rowan::ast::AstNode;
+
+use crate::Org;
+
+use super::{Document, Keyword, SyntaxKind};
+
+impl Document {
+    /// ```rust
+    /// use orgize::{Org, ast::Document};
+    ///
+    /// let org = Org::parse(r#"
+    /// #+TITLE: hello
+    /// #+TITLE: world
+    /// #+DATE: tody
+    /// #+AUTHOR: poi"#);
+    /// let doc = org.first_node::<Document>().unwrap();
+    /// assert_eq!(doc.keywords().count(), 4);
+    /// ```
+    pub fn keywords(&self) -> impl Iterator<Item = Keyword> {
+        self.syntax
+            .first_child()
+            .filter(|c| c.kind() == SyntaxKind::SECTION)
+            .into_iter()
+            .flat_map(|section| section.children().filter_map(Keyword::cast))
+    }
+
+    /// Returns the value in `#+TITLE`
+    ///
+    /// ```rust
+    /// use orgize::{Org, ast::Document};
+    ///
+    /// let org = Org::parse("#+TITLE: hello\n#+TITLE: world");
+    /// let doc = org.first_node::<Document>().unwrap();
+    /// assert_eq!(doc.title().unwrap(), "hello world");
+    ///
+    /// let org = Org::parse("");
+    /// let doc = org.first_node::<Document>().unwrap();
+    /// assert!(doc.title().is_none());
+    /// ```
+    pub fn title(&self) -> Option<String> {
+        self.keywords()
+            .filter(|kw| kw.key().eq_ignore_ascii_case("TITLE"))
+            .fold(Option::<String>::None, |acc, cur| {
+                let mut s = acc.unwrap_or_default();
+                if !s.is_empty() {
+                    s.push(' ');
+                }
+                s.push_str(cur.value().trim());
+                Some(s)
+            })
+    }
+}
+
+impl Org {
+    /// Equals to `self.document().title()`, see [Document::title]
+    pub fn title(&self) -> Option<String> {
+        self.document().title()
+    }
+
+    /// Equals to `self.document().keywords()`, see [Document::keywords]
+    pub fn keywords(&self) -> impl Iterator<Item = Keyword> {
+        self.document().keywords()
+    }
+}

src/ast/mod.rs

@@ -6,6 +6,7 @@ mod affiliated_keyword;
 mod block;
 mod clock;
 mod comment;
+mod document;
 mod drawer;
 mod entity;
 mod fixed_width;