feat(ast): Ast::to_gemtext

4 files changed, 151 insertions, 1 deletions

diff --git a/examples/ast_to_gemtext.rs b/examples/ast_to_gemtext.rs
new file mode 100644
index 0000000..5ceef21
--- /dev/null
+++ b/examples/ast_to_gemtext.rs
@@ -0,0 +1,53 @@
+// This file is part of Germ <https://github.com/gemrest/germ>.
+// Copyright (C) 2022-2022 Fuwn <[email protected]>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// Copyright (C) 2022-2022 Fuwn <[email protected]>
+// SPDX-License-Identifier: GPL-3.0-only
+
+const EXAMPLE_GEMTEXT: &str = r#"```This is alt-text
+Here goes the pre-formatted text.
+
+This continues the pre-formatted text on a new line after a blank line.
+```
+
+# This is a heading
+
+This is some text.
+
+This is more text after a blank line.
+
+* This is a single list item.
+* This is the next list item.
+
+* This is a new list.
+* This is the next item on the new list.
+
+## This is a sub-heading
+
+> This is a blockquote.
+
+### This is a sub-sub-heading.
+
+=> gemini://gem.rest/ This is a link to GemRest
+=> /somewhere
+
+That was a link without text."#;
+
+fn main() {
+  println!(
+    "{}",
+    germ::ast::Ast::from_string(EXAMPLE_GEMTEXT).to_gemtext()
+  );
+}
diff --git a/src/ast.rs b/src/ast.rs
index f432666..49ee1f6 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -215,6 +215,64 @@ impl Ast {
     }
   }
 
+  #[must_use]
+  pub fn to_gemtext(&self) -> String {
+    let mut gemtext = "".to_string();
+
+    for node in &self.inner {
+      match node {
+        Node::Text(text) => gemtext.push_str(&format!("{}\n", text)),
+        Node::Link {
+          to,
+          text,
+        } =>
+          gemtext.push_str(&format!(
+            "=> {}{}\n",
+            to,
+            text
+              .clone()
+              .map_or_else(|| "".to_string(), |text| format!(" {}", text)),
+          )),
+        Node::Heading {
+          level,
+          text,
+        } =>
+          gemtext.push_str(&format!(
+            "{} {}\n",
+            match level {
+              1 => "#",
+              2 => "##",
+              3 => "###",
+              _ => "",
+            },
+            text
+          )),
+        Node::List(items) =>
+          gemtext.push_str(&format!(
+            "{}\n",
+            items
+              .iter()
+              .map(|i| format!("* {}", i))
+              .collect::<Vec<String>>()
+              .join("\n"),
+          )),
+        Node::Blockquote(text) => gemtext.push_str(&format!("> {}\n", text)),
+        Node::PreformattedText {
+          alt_text,
+          text,
+        } =>
+          gemtext.push_str(&format!(
+            "```{}\n{}```\n",
+            alt_text.clone().unwrap_or_else(|| "".to_string()),
+            text
+          )),
+        Node::Whitespace => gemtext.push('\n'),
+      }
+    }
+
+    gemtext
+  }
+
   /// The actual AST of `Ast`
   ///
   /// # Example
diff --git a/src/convert/markdown.rs b/src/convert/markdown.rs
index c6899b7..a38da9f 100644
--- a/src/convert/markdown.rs
+++ b/src/convert/markdown.rs
@@ -69,7 +69,7 @@ pub fn convert(source: &[Node]) -> String {
           text
         ));
       }
-      Node::Whitespace => markdown.push_str("\n"),
+      Node::Whitespace => markdown.push('\n'),
     }
   }
 
diff --git a/tests/ast.rs b/tests/ast.rs
index 8b3882d..5f6cd5c 100644
--- a/tests/ast.rs
+++ b/tests/ast.rs
@@ -20,6 +20,35 @@
 mod test {
   use germ::ast::{Ast, Node};
 
+  const EXAMPLE_GEMTEXT: &str = r#"```This is alt-text
+Here goes the pre-formatted text.
+
+This continues the pre-formatted text on a new line after a blank line.
+```
+
+# This is a heading
+
+This is some text.
+
+This is more text after a blank line.
+
+* This is a single list item.
+* This is the next list item.
+
+* This is a new list.
+* This is the next item on the new list.
+
+## This is a sub-heading
+
+> This is a blockquote.
+
+### This is a sub-sub-heading.
+
+=> gemini://gem.rest/ This is a link to GemRest
+=> /somewhere
+
+That was a link without text."#;
+
   #[test]
   fn build_multi_line_list_with_text() {
     assert_eq!(
@@ -67,4 +96,14 @@ mod test {
       },
     );
   }
+
+  #[test]
+  fn gemtext_to_ast_then_ast_to_gemtext() {
+    assert_eq!(
+      Ast::from_string(EXAMPLE_GEMTEXT).to_gemtext(),
+      // `to_gemtext` appends a newline to all responses, so let's make sure we
+      // account for that.
+      format!("{}\n", EXAMPLE_GEMTEXT),
+    );
+  }
 }