From 7ce8b59596184d48db56c1b075ddc3546b1fdc7e Mon Sep 17 00:00:00 2001
From: "Garen J. Torikian" <gjtorikian@users.noreply.github.com>
Date: Tue, 30 Jan 2024 17:12:21 -0500
Subject: [PATCH] it can talk!

---
 README.md                    | 14 +++++++--
 ext/commonmarker/src/node.rs | 20 +++++++++++++
 test/sourcepos_test.rb       | 55 ++++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index ea875b22..1ee95ec3 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@ require 'commonmarker'
 Commonmarker.to_html('"Hi *there*"', options: {
     parse: { smart: true }
 })
-# <p>“Hi <em>there</em>”</p>\n
+# => <p>“Hi <em>there</em>”</p>\n
 ```
 
 (The second argument is optional--[see below](#options-and-plugins) for more information.)
@@ -49,10 +49,10 @@ require 'commonmarker'
 doc = Commonmarker.parse("*Hello* world", options: {
     parse: { smart: true }
 })
-puts(doc.to_html) # <p><em>Hello</em> world</p>\n
+puts(doc.to_html) # => <p><em>Hello</em> world</p>\n
 
 doc.walk do |node|
-  puts node.type # [:document, :paragraph, :emph, :text, :text]
+  puts node.type # => [:document, :paragraph, :emph, :text, :text]
 end
 ```
 
@@ -66,6 +66,14 @@ When it comes to modifying the document, you can perform the following operation
 - `append_child`
 - `detach`
 
+You can also get the source position of a node by calling `source_position`:
+
+```ruby
+doc = Commonmarker.parse("*Hello* world")
+puts doc.first_child.first_child.source_position
+# => {:start_line=>1, :start_column=>1, :end_line=>1, :end_column=>7}
+```
+
 You can also modify the following attributes:
 
 - `url`
diff --git a/ext/commonmarker/src/node.rs b/ext/commonmarker/src/node.rs
index 4801b663..476bf2ec 100644
--- a/ext/commonmarker/src/node.rs
+++ b/ext/commonmarker/src/node.rs
@@ -219,6 +219,21 @@ impl CommonmarkerNode {
         })
     }
 
+    fn get_sourcepos(&self) -> Result<RHash, magnus::Error> {
+        let node = self.inner.borrow();
+
+        let result = RHash::new();
+        result.aset(Symbol::new("start_line"), node.data.sourcepos.start.line)?;
+        result.aset(
+            Symbol::new("start_column"),
+            node.data.sourcepos.start.column,
+        )?;
+        result.aset(Symbol::new("end_line"), node.data.sourcepos.end.line)?;
+        result.aset(Symbol::new("end_column"), node.data.sourcepos.end.column)?;
+
+        Ok(result)
+    }
+
     fn insert_node_before(&self, new_sibling: &CommonmarkerNode) -> Result<bool, magnus::Error> {
         let node = new_sibling.inner.clone();
         node.detach();
@@ -546,6 +561,11 @@ pub fn init(m_commonmarker: RModule) -> Result<(), magnus::Error> {
 
     c_node.define_method("detach", method!(CommonmarkerNode::detach_node, 0))?;
 
+    c_node.define_method(
+        "source_position",
+        method!(CommonmarkerNode::get_sourcepos, 0),
+    )?;
+
     c_node.define_method("url", method!(CommonmarkerNode::get_url, 0))?;
     c_node.define_method("url=", method!(CommonmarkerNode::set_url, 1))?;
     c_node.define_method("title", method!(CommonmarkerNode::get_title, 0))?;
diff --git a/test/sourcepos_test.rb b/test/sourcepos_test.rb
index 0f2049c3..d50278ce 100644
--- a/test/sourcepos_test.rb
+++ b/test/sourcepos_test.rb
@@ -20,4 +20,59 @@ def test_to_html
 
     assert_equal(expected, Commonmarker.to_html(md, options: { render: { sourcepos: true } }))
   end
+
+  def test_can_generate_source_positions
+    md = <<~MARKDOWN
+      ## Try CommonMark
+
+      You can try CommonMark here.  This dingus is powered by
+      [commonmark.js](https://github.com/jgm/commonmark.js), the
+      JavaScript reference implementation.
+
+      1. item one
+      2. item two
+         - sublist
+         - sublist
+    MARKDOWN
+    doc = Commonmarker.parse(md)
+
+    source_positions = []
+
+    doc.walk do |node|
+      source_positions << node.source_position
+    end
+
+    source_positions.delete_if { |h| h.values.all?(&:zero?) }
+
+    assert_equal(
+      [
+        { start_line: 1, start_column: 1, end_line: 10, end_column: 12 },
+        { start_line: 1, start_column: 1, end_line: 1, end_column: 17 },
+        { start_line: 1, start_column: 4, end_line: 1, end_column: 17 },
+        { start_line: 3, start_column: 1, end_line: 5, end_column: 36 },
+        { start_line: 3, start_column: 1, end_line: 3, end_column: 55 },
+        { start_line: 3, start_column: 56, end_line: 3, end_column: 56 },
+        { start_line: 4, start_column: 1, end_line: 4, end_column: 53 },
+        { start_line: 4, start_column: 2, end_line: 4, end_column: 14 },
+        { start_line: 4, start_column: 54, end_line: 4, end_column: 58 },
+        { start_line: 4, start_column: 59, end_line: 4, end_column: 59 },
+        { start_line: 5, start_column: 1, end_line: 5, end_column: 36 },
+        { start_line: 7, start_column: 1, end_line: 10, end_column: 12 },
+        { start_line: 7, start_column: 1, end_line: 7, end_column: 11 },
+        { start_line: 7, start_column: 4, end_line: 7, end_column: 11 },
+        { start_line: 7, start_column: 4, end_line: 7, end_column: 11 },
+        { start_line: 8, start_column: 1, end_line: 10, end_column: 12 },
+        { start_line: 8, start_column: 4, end_line: 8, end_column: 11 },
+        { start_line: 8, start_column: 4, end_line: 8, end_column: 11 },
+        { start_line: 9, start_column: 4, end_line: 10, end_column: 12 },
+        { start_line: 9, start_column: 4, end_line: 9, end_column: 12 },
+        { start_line: 9, start_column: 6, end_line: 9, end_column: 12 },
+        { start_line: 9, start_column: 6, end_line: 9, end_column: 12 },
+        { start_line: 10, start_column: 4, end_line: 10, end_column: 12 },
+        { start_line: 10, start_column: 6, end_line: 10, end_column: 12 },
+        { start_line: 10, start_column: 6, end_line: 10, end_column: 12 },
+      ],
+      source_positions,
+    )
+  end
 end