From d06e4de7b035e708e9aac03008cbcc4dd1f51f84 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Fri, 6 Oct 2023 13:08:15 -0400
Subject: [PATCH] Starting a new macro for comparing fields.

This will help us assert that all fields are tested and that only expected fields are present.
---
 src/compare/diff.rs       |  5 ++++
 src/compare/elisp_fact.rs |  6 ++++
 src/compare/macros.rs     | 59 +++++++++++++++++++++++++++++++++++++++
 src/compare/mod.rs        |  1 +
 4 files changed, 71 insertions(+)
 create mode 100644 src/compare/macros.rs

diff --git a/src/compare/diff.rs b/src/compare/diff.rs
index d4af397..23d2575 100644
--- a/src/compare/diff.rs
+++ b/src/compare/diff.rs
@@ -13,6 +13,8 @@ use super::util::get_property_boolean;
 use super::util::get_property_numeric;
 use super::util::get_property_quoted_string;
 use super::util::get_property_unquoted_atom;
+use crate::compare::elisp_fact::EmacsField;
+use crate::compare::macros::compare_properties;
 use crate::types::AngleLink;
 use crate::types::AstNode;
 use crate::types::BabelCall;
@@ -2688,6 +2690,9 @@ fn compare_code<'b, 's>(
         ));
     }
 
+    let foo: Result<Option<(DiffStatus, Option<String>)>, Box<dyn std::error::Error>> =
+        compare_properties!(emacs, EmacsField::Required(":value"));
+
     Ok(DiffResult {
         status: this_status,
         name: rust.get_elisp_name(),
diff --git a/src/compare/elisp_fact.rs b/src/compare/elisp_fact.rs
index fd2810b..8f97ed3 100644
--- a/src/compare/elisp_fact.rs
+++ b/src/compare/elisp_fact.rs
@@ -550,3 +550,9 @@ impl<'s> ElispFact<'s> for PlainText<'s> {
         "plain-text".into()
     }
 }
+
+#[derive(Debug)]
+pub(crate) enum EmacsField<'s> {
+    Required(&'s str),
+    Optional(&'s str),
+}
diff --git a/src/compare/macros.rs b/src/compare/macros.rs
new file mode 100644
index 0000000..b71aa03
--- /dev/null
+++ b/src/compare/macros.rs
@@ -0,0 +1,59 @@
+/// Create iterators for ast nodes where it only has to iterate over children
+macro_rules! compare_properties {
+    ($emacs:expr, $($emacs_field:expr),+) => {
+        {
+            let mut this_status = DiffStatus::Good;
+            let mut message: Option<String> = None;
+            let children = $emacs.as_list()?;
+            let attributes_child = children
+            .iter()
+            .nth(1)
+            .ok_or("Should have an attributes child.")?;
+            let attributes_map = attributes_child.as_map()?;
+            let mut emacs_keys: BTreeSet<&str> = attributes_map.keys().map(|s| *s).collect();
+            $(
+            match $emacs_field {
+                EmacsField::Required(name) if emacs_keys.contains(name) => {
+                    emacs_keys.remove(name);
+                },
+                EmacsField::Optional(name) if emacs_keys.contains(name) => {
+                    emacs_keys.remove(name);
+                },
+                EmacsField::Required(name) => {
+                    this_status = DiffStatus::Bad;
+                    message = Some(format!(
+                        "Emacs token lacks required field: {}",
+                        name
+                    ));
+                },
+                EmacsField::Optional(_name) => {},
+            }
+            ),+
+
+            if !emacs_keys.is_empty() {
+                let unexpected_keys: Vec<&str> = emacs_keys.into_iter().collect();
+                let unexpected_keys = unexpected_keys.join(", ");
+                this_status = DiffStatus::Bad;
+                message = Some(format!(
+                    "Emacs token had extra field(s): {}",
+                    unexpected_keys
+                ));
+            }
+
+            $(
+            println!("{:?}", $emacs_field);
+            ),+
+
+            match this_status {
+                DiffStatus::Good => {
+                    Ok(None)
+                },
+                _ => {
+                    Ok(Some((this_status, message)))
+                }
+            }
+        }
+    };
+}
+
+pub(crate) use compare_properties;
diff --git a/src/compare/mod.rs b/src/compare/mod.rs
index 1a75e2e..e7bcde8 100644
--- a/src/compare/mod.rs
+++ b/src/compare/mod.rs
@@ -1,6 +1,7 @@
 mod compare;
 mod diff;
 mod elisp_fact;
+mod macros;
 mod parse;
 mod sexp;
 mod util;