WIP: fix: Preserve dotted-key ordering

Fixes toml-rs#163

src/encode.rs

@@ -87,7 +87,12 @@ impl Display for InlineTable {
         )?;
         write!(f, "{}", self.preamble)?;
 
-        let children = self.get_values();
+        let mut children = self.get_values();
+        children.sort_by_key(|(k, _)| {
+            let last_index = k.len() - 1;
+            k[last_index].position().unwrap_or(usize::MAX)
+        });
+
         for (i, (key_path, value)) in children.into_iter().enumerate() {
             let key = key_path_display(&key_path, DEFAULT_INLINE_KEY_DECOR);
             if i > 0 {
@@ -143,7 +148,11 @@ fn visit_table(
     path: &[&Key],
     is_array_of_tables: bool,
 ) -> Result {
-    let children = table.get_values();
+    let mut children = table.get_values();
+    children.sort_by_key(|(k, _)| {
+        let last_index = k.len() - 1;
+        k[last_index].position().unwrap_or(usize::MAX)
+    });
 
     if path.is_empty() {
         // don't print header for the root node

src/key.rs

@@ -32,6 +32,7 @@ pub struct Key {
     key: InternalString,
     pub(crate) repr: Repr,
     pub(crate) decor: Decor,
+    pub(crate) position: Option<usize>,
 }
 
 impl Key {
@@ -45,6 +46,7 @@ impl Key {
             key,
             repr,
             decor: Default::default(),
+            position: Default::default(),
         }
     }
 
@@ -54,6 +56,12 @@ impl Key {
         self
     }
 
+    /// While creating the `Key`, add a table position to it
+    pub fn with_position(mut self, position: Option<usize>) -> Self {
+        self.position = position;
+        self
+    }
+
     /// Returns the parsed key value.
     pub fn get(&self) -> &str {
         &self.key
@@ -74,6 +82,16 @@ impl Key {
         &mut self.decor
     }
 
+    /// Get the position relative to other keys in parent table
+    pub fn position(&self) -> Option<usize> {
+        return self.position;
+    }
+
+    /// Set the position relative to other keys in parent table
+    pub fn set_position(&mut self, position: Option<usize>) {
+        self.position = position;
+    }
+
     fn try_parse(s: &str) -> Result<Key, parser::TomlError> {
         use combine::EasyParser;
         let result = parser::key_parser().easy_parse(Stream::new(s));

src/parser/document.rs

@@ -131,6 +131,8 @@ impl TomlParser {
                 first_key.decor.suffix().unwrap_or_default(),
             );
         }
+        kv.key.set_position(Some(self.current_value_position));
+        self.current_value_position += 1;
 
         let root = self.document.as_table_mut();
         let table = Self::descend_path(root, self.current_table_path.as_slice(), 0, false)

src/parser/inline_table.rs

@@ -28,7 +28,9 @@ fn table_from_pairs(
         ..Default::default()
     };
 
-    for (path, kv) in v {
+    for (position, (path, mut kv)) in v.into_iter().enumerate() {
+        kv.key.set_position(Some(position));
+
         let table = descend_path(&mut root, &path, 0)?;
         if table.contains_key(kv.key.get()) {
             return Err(CustomError::DuplicateKey {

src/parser/mod.rs

@@ -26,6 +26,8 @@ pub(crate) struct TomlParser {
     document: Box<Document>,
     current_table_path: Vec<Key>,
     current_table_position: usize,
+    // Current position within a table, to help order dotted keys
+    current_value_position: usize,
 }
 
 impl Default for TomlParser {
@@ -34,6 +36,7 @@ impl Default for TomlParser {
             document: Box::new(Document::new()),
             current_table_path: Vec::new(),
             current_table_position: 0,
+            current_value_position: 0,
         }
     }
 }
@@ -391,6 +394,7 @@ trimmed in raw strings.
             r#"{a = 1e165}"#,
             r#"{ hello = "world", a = 1}"#,
             r#"{ hello.world = "a" }"#,
+            r#"{ hello.world = "a", goodbye = "b", hello.moon = "c" }"#,
         ];
         for input in &inputs {
             parsed_value_eq!(input);
@@ -498,6 +502,10 @@ that
 key = "value"
 "#,
             r#"hello.world = "a"
+"#,
+            r#"hello.world = "a"
+goodbye = "b"
+hello.moon = "c"
 "#,
         ];
         for document in &documents {

src/parser/table.rs

@@ -119,6 +119,7 @@ impl TomlParser {
         let leading = mem::take(&mut self.document.trailing);
         let table = self.document.as_table_mut();
         self.current_table_position += 1;
+        self.current_value_position = 0;
 
         let table = Self::descend_path(table, &path[..path.len() - 1], 0, false)?;
         let key = &path[path.len() - 1];
@@ -160,6 +161,7 @@ impl TomlParser {
 
         let leading = mem::take(&mut self.document.trailing);
         let table = self.document.as_table_mut();
+        self.current_value_position = 0;
 
         let key = &path[path.len() - 1];
         let table = Self::descend_path(table, &path[..path.len() - 1], 0, false);