From 6b90a9bfa8396d489a12c2f6e55c1c09febe4e10 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Tue, 10 Oct 2023 17:15:51 -0400
Subject: [PATCH 1/2] Add TODO.

---
 src/compare/diff.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/compare/diff.rs b/src/compare/diff.rs
index 40370c1..79f3667 100644
--- a/src/compare/diff.rs
+++ b/src/compare/diff.rs
@@ -537,6 +537,7 @@ fn compare_heading<'b, 's>(
     let mut child_status = Vec::new();
     let mut message = None;
 
+    // TODO: Add checks to compare values for additional properties.
     let additional_property_names: Vec<String> = rust
         .get_additional_properties()
         .map(|node_property| format!(":{}", node_property.property_name.to_uppercase()))

From 7cb71a5a0a524e7035d64568fa9470c7debb1a34 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Tue, 10 Oct 2023 17:40:27 -0400
Subject: [PATCH 2/2] Compare the additional properties on headlines.

---
 src/compare/compare_field.rs | 20 ++++++++++++++++++++
 src/compare/diff.rs          | 18 +++++++++++++++++-
 src/compare/util.rs          | 26 ++++++++++++++++++++++++++
 3 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/src/compare/compare_field.rs b/src/compare/compare_field.rs
index 030da71..3d0daad 100644
--- a/src/compare/compare_field.rs
+++ b/src/compare/compare_field.rs
@@ -32,6 +32,26 @@ pub(crate) enum ComparePropertiesResult<'b, 's> {
     DiffEntry(DiffEntry<'b, 's>),
 }
 
+impl<'b, 's> ComparePropertiesResult<'b, 's> {
+    pub(crate) fn apply(
+        self,
+        child_status: &mut Vec<DiffEntry<'b, 's>>,
+        this_status: &mut DiffStatus,
+        message: &mut Option<String>,
+    ) {
+        match self {
+            ComparePropertiesResult::NoChange => {}
+            ComparePropertiesResult::SelfChange(new_status, new_message) => {
+                *this_status = new_status;
+                *message = new_message
+            }
+            ComparePropertiesResult::DiffEntry(diff_entry) => child_status.push(diff_entry),
+        }
+
+        // foo
+    }
+}
+
 /// Do no comparison.
 ///
 /// This is for when you want to acknowledge that a field exists in the emacs token, but you do not have any validation for it when using the compare_properties!() macro. Ideally, this should be kept to a minimum since this represents untested values.
diff --git a/src/compare/diff.rs b/src/compare/diff.rs
index 79f3667..e1996a5 100644
--- a/src/compare/diff.rs
+++ b/src/compare/diff.rs
@@ -21,6 +21,7 @@ use super::elisp_fact::GetElispFact;
 use super::sexp::unquote;
 use super::sexp::Token;
 use super::util::assert_no_children;
+use super::util::compare_additional_properties;
 use super::util::compare_children;
 use super::util::compare_children_iter;
 use super::util::compare_standard_properties;
@@ -537,12 +538,27 @@ fn compare_heading<'b, 's>(
     let mut child_status = Vec::new();
     let mut message = None;
 
-    // TODO: Add checks to compare values for additional properties.
     let additional_property_names: Vec<String> = rust
         .get_additional_properties()
         .map(|node_property| format!(":{}", node_property.property_name.to_uppercase()))
         .collect();
 
+    let additional_properties: Vec<(String, &str)> = rust
+        .get_additional_properties()
+        .map(|node_property| {
+            (
+                format!(":{}", node_property.property_name.to_uppercase()),
+                node_property.value.unwrap_or(""),
+            )
+        })
+        .collect();
+
+    compare_additional_properties(emacs, additional_properties.into_iter())?.apply(
+        &mut child_status,
+        &mut this_status,
+        &mut message,
+    );
+
     compare_children(
         source,
         emacs,
diff --git a/src/compare/util.rs b/src/compare/util.rs
index 23099aa..4a4e684 100644
--- a/src/compare/util.rs
+++ b/src/compare/util.rs
@@ -1,5 +1,6 @@
 use std::str::FromStr;
 
+use super::compare_field::ComparePropertiesResult;
 use super::diff::DiffEntry;
 use super::diff::DiffStatus;
 use super::elisp_fact::GetElispFact;
@@ -311,3 +312,28 @@ pub(crate) fn assert_no_children<'b, 's>(
     }
     Ok(())
 }
+
+pub(crate) fn compare_additional_properties<'b, 's, RK, RV, RI>(
+    emacs: &'b Token<'s>,
+    rust_children: RI,
+) -> Result<ComparePropertiesResult<'b, 's>, Box<dyn std::error::Error>>
+where
+    RK: AsRef<str>,
+    RV: AsRef<str>,
+    RI: Iterator<Item = (RK, RV)> + ExactSizeIterator,
+{
+    for (rust_key, rust_value) in rust_children {
+        let rust_key = rust_key.as_ref();
+        let rust_value = rust_value.as_ref();
+        let emacs_value = get_property_quoted_string(emacs, rust_key)?;
+        if Some(rust_value) != emacs_value.as_ref().map(String::as_str) {
+            let this_status = DiffStatus::Bad;
+            let message = Some(format!(
+                "{} mismatch (emacs != rust) {:?} != {:?}",
+                rust_key, emacs_value, rust_value
+            ));
+            return Ok(ComparePropertiesResult::SelfChange(this_status, message));
+        }
+    }
+    Ok(ComparePropertiesResult::NoChange)
+}