From 33800c4a88ea59ade69cdfd9f39c958bce47df71 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Mon, 16 Oct 2023 12:05:36 -0400
Subject: [PATCH] Implement comparison for optional pair.

---
 src/compare/compare_field.rs | 101 +++++++++++++++++++++++++++++++++++
 src/compare/util.rs          |   9 ++++
 2 files changed, 110 insertions(+)

diff --git a/src/compare/compare_field.rs b/src/compare/compare_field.rs
index 01896aad..3f662e20 100644
--- a/src/compare/compare_field.rs
+++ b/src/compare/compare_field.rs
@@ -288,6 +288,107 @@ pub(crate) fn compare_property_set_of_quoted_string<
     Ok(ComparePropertiesResult::NoChange)
 }
 
+pub(crate) fn compare_property_optional_pair<
+    'b,
+    's,
+    'x,
+    R,
+    RV: AsRef<str> + std::fmt::Debug,
+    ROV: AsRef<str> + std::fmt::Debug,
+    RG: Fn(R) -> Option<(Option<ROV>, RV)>,
+>(
+    _source: &'s str,
+    emacs: &'b Token<'s>,
+    rust_node: R,
+    emacs_field: &'x str,
+    rust_value_getter: RG,
+) -> Result<ComparePropertiesResult<'b, 's>, Box<dyn std::error::Error>> {
+    let value = get_property(emacs, emacs_field)?
+        .map(Token::as_list)
+        .map_or(Ok(None), |r| r.map(Some))?;
+    let rust_value = rust_value_getter(rust_node);
+    match (value, &rust_value) {
+        (None, None) => {}
+        (None, Some(_)) | (Some(_), None) => {
+            let this_status = DiffStatus::Bad;
+            let message = Some(format!(
+                "{} mismatch (emacs != rust) {:?} != {:?}",
+                emacs_field, value, rust_value
+            ));
+            return Ok(ComparePropertiesResult::SelfChange(this_status, message));
+        }
+        (Some(el), Some((Some(_), _))) if el.len() != 3 => {
+            let this_status = DiffStatus::Bad;
+            let message = Some(format!(
+                "{} mismatch (emacs != rust) {:?} != {:?}",
+                emacs_field, value, rust_value
+            ));
+            return Ok(ComparePropertiesResult::SelfChange(this_status, message));
+        }
+        (Some(el), Some((None, _))) if el.len() != 1 => {
+            let this_status = DiffStatus::Bad;
+            let message = Some(format!(
+                "{} mismatch (emacs != rust) {:?} != {:?}",
+                emacs_field, value, rust_value
+            ));
+            return Ok(ComparePropertiesResult::SelfChange(this_status, message));
+        }
+        (Some(el), Some((Some(orl), rl))) => {
+            let e = el
+                .first()
+                .map(Token::as_atom)
+                .map_or(Ok(None), |r| r.map(Some))?
+                .map(unquote)
+                .map_or(Ok(None), |r| r.map(Some))?
+                .expect("Above match proved length to be 3.");
+            let oe = el
+                .get(2)
+                .map(Token::as_atom)
+                .map_or(Ok(None), |r| r.map(Some))?
+                .map(unquote)
+                .map_or(Ok(None), |r| r.map(Some))?
+                .expect("Above match proved length to be 3.");
+            let r = rl.as_ref();
+            let or = orl.as_ref();
+            if e != r {
+                let this_status = DiffStatus::Bad;
+                let message = Some(format!(
+                    "{} mismatch (emacs != rust) {:?} != {:?}. Full list: {:?} != {:?}",
+                    emacs_field, e, r, value, rust_value
+                ));
+                return Ok(ComparePropertiesResult::SelfChange(this_status, message));
+            }
+            if oe != or {
+                let this_status = DiffStatus::Bad;
+                let message = Some(format!(
+                    "{} mismatch (emacs != rust) {:?} != {:?}. Full list: {:?} != {:?}",
+                    emacs_field, e, r, value, rust_value
+                ));
+                return Ok(ComparePropertiesResult::SelfChange(this_status, message));
+            }
+        }
+        (Some(el), Some((None, rl))) => {
+            let e = el
+                .first()
+                .map(Token::as_atom)
+                .map_or(Ok(None), |r| r.map(Some))?
+                .map(unquote)
+                .map_or(Ok(None), |r| r.map(Some))?
+                .expect("Above match proved length to be 1.");
+            let r = rl.as_ref();
+            if e != r {
+                let this_status = DiffStatus::Bad;
+                let message = Some(format!(
+                    "{} mismatch (emacs != rust) {:?} != {:?}. Full list: {:?} != {:?}",
+                    emacs_field, e, r, value, rust_value
+                ));
+                return Ok(ComparePropertiesResult::SelfChange(this_status, message));
+            }
+        }
+    }
+    Ok(ComparePropertiesResult::NoChange)
+}
+
 pub(crate) fn compare_property_boolean<'b, 's, 'x, R, RG: Fn(R) -> bool>(
     _source: &'s str,
     emacs: &'b Token<'s>,
diff --git a/src/compare/util.rs b/src/compare/util.rs
index db160482..f3b26c7b 100644
--- a/src/compare/util.rs
+++ b/src/compare/util.rs
@@ -2,6 +2,7 @@ use std::str::FromStr;
 
 use super::compare_field::compare_property_list_of_list_of_list_of_ast_nodes;
 use super::compare_field::compare_property_list_of_quoted_string;
+use super::compare_field::compare_property_optional_pair;
 use super::compare_field::compare_property_quoted_string;
 use super::compare_field::ComparePropertiesResult;
 use super::diff::DiffEntry;
@@ -377,6 +378,14 @@ where
                 ret.push(diff);
             }
             AffiliatedKeywordValue::OptionalPair { optval, val } => {
+                let diff = compare_property_optional_pair(
+                    source,
+                    emacs,
+                    rust,
+                    emacs_property_name.as_str(),
+                    |_| Some((*optval, *val)),
+                )?;
+                ret.push(diff);
                 // todo
             }
             AffiliatedKeywordValue::ObjectTree(_) => {