fix: Preserve dotted keys

src/encode.rs

@@ -86,23 +86,17 @@ impl Display for InlineTable {
             self.decor.prefix().unwrap_or(DEFAULT_VALUE_DECOR.0)
         )?;
         write!(f, "{}", self.preamble)?;
-        for (i, (key, value)) in self
-            .items
-            .iter()
-            .filter(|&(_, kv)| kv.value.is_value())
-            .map(|(_, kv)| {
-                (
-                    kv.key.decor.display(&kv.key, DEFAULT_INLINE_KEY_DECOR),
-                    kv.value.as_value().unwrap(),
-                )
-            })
-            .enumerate()
-        {
+
+        let mut children = Vec::new();
+        self.get_children(&mut children);
+        for (i, (key_path, value)) in children.into_iter().enumerate() {
+            let key = key_path_display(&key_path, DEFAULT_INLINE_KEY_DECOR);
             if i > 0 {
                 write!(f, ",")?;
             }
             write!(f, "{}={}", key, value)?;
         }
+
         write!(
             f,
             "}}{}",
@@ -125,7 +119,7 @@ impl Table {
 
         for kv in self.items.values() {
             match kv.value {
-                Item::Table(ref t) => {
+                Item::Table(ref t) if !t.is_dotted() => {
                     path.push(&kv.key);
                     t.visit_nested_tables(path, false, callback)?;
                     path.pop();
@@ -150,6 +144,9 @@ fn visit_table(
     path: &[&Key],
     is_array_of_tables: bool,
 ) -> Result {
+    let mut children = Vec::new();
+    table.get_children(&mut children);
+
     if path.is_empty() {
         // don't print header for the root node
     } else if is_array_of_tables {
@@ -170,7 +167,7 @@ fn visit_table(
             "]]{}",
             table.decor.suffix().unwrap_or(DEFAULT_TABLE_DECOR.1)
         )?;
-    } else if !(table.implicit && table.values_len() == 0) {
+    } else if !(table.implicit && children.is_empty()) {
         write!(
             f,
             "{}[",
@@ -190,19 +187,33 @@ fn visit_table(
         )?;
     }
     // print table body
-    for kv in table.items.values() {
-        if let Item::Value(ref value) = kv.value {
-            writeln!(
-                f,
-                "{}={}",
-                kv.key.decor.display(&kv.key, DEFAULT_KEY_DECOR),
-                value
-            )?;
-        }
+    for (key_path, value) in children {
+        let key = key_path_display(&key_path, DEFAULT_KEY_DECOR);
+        writeln!(f, "{}={}", key, value)?;
     }
     Ok(())
 }
 
+fn key_path_display(key_path: &[&Key], default: (&'static str, &'static str)) -> impl Display {
+    key_path
+        .iter()
+        .enumerate()
+        .map(|(ki, k)| {
+            let prefix = if ki == 0 {
+                default.0
+            } else {
+                DEFAULT_KEY_PATH_DECOR.0
+            };
+            let suffix = if ki + 1 == key_path.len() {
+                default.1
+            } else {
+                DEFAULT_KEY_PATH_DECOR.1
+            };
+            k.decor.display(k, (prefix, suffix))
+        })
+        .join(".")
+}
+
 impl Display for Table {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
         let mut path = Vec::new();

src/inline_table.rs

@@ -14,6 +14,8 @@ pub struct InlineTable {
     pub(crate) preamble: InternalString,
     // prefix before `{` and suffix after `}`
     pub(crate) decor: Decor,
+    // whether this is a proxy for dotted keys
+    pub(crate) dotted: bool,
     pub(crate) items: KeyValuePairs,
 }
 
@@ -169,6 +171,44 @@ impl InlineTable {
 }
 
 impl InlineTable {
+    /// Get key/values for values that are visually children of this table
+    ///
+    /// For example, this will return dotted keys
+    pub fn get_children<'s, 'c>(&'s self, children: &'c mut Vec<(Vec<&'s Key>, &'s Value)>) {
+        let root = Vec::new();
+        self.get_children_internal(&root, children);
+    }
+
+    fn get_children_internal<'s, 'c>(
+        &'s self,
+        parent: &[&'s Key],
+        children: &'c mut Vec<(Vec<&'s Key>, &'s Value)>,
+    ) {
+        for value in self.items.values() {
+            let mut path = parent.to_vec();
+            path.push(&value.key);
+            match &value.value {
+                Item::Value(Value::InlineTable(table)) if table.is_dotted() => {
+                    table.get_children_internal(&path, children);
+                }
+                Item::Value(value) => {
+                    children.push((path, value));
+                }
+                _ => {}
+            }
+        }
+    }
+
+    /// Check if this is a wrapper for dotted keys, rather than a standard table
+    pub fn is_dotted(&self) -> bool {
+        self.dotted
+    }
+
+    /// Change this table's dotted status
+    pub fn set_dotted(&mut self, yes: bool) {
+        self.dotted = yes;
+    }
+
     /// Sorts the key/value pairs by key.
     pub fn sort(&mut self) {
         sort_key_value_pairs(&mut self.items);

src/parser/document.rs

@@ -133,9 +133,9 @@ impl TomlParser {
         }
 
         let root = self.document.as_table_mut();
-        let table = Self::descend_path(root, self.current_table_path.as_slice(), 0)
+        let table = Self::descend_path(root, self.current_table_path.as_slice(), 0, false)
             .expect("the table path is valid; qed");
-        let table = Self::descend_path(table, &path, 0)?;
+        let table = Self::descend_path(table, &path, 0, true)?;
         if table.contains_key(kv.key.get()) {
             Err(CustomError::DuplicateKey {
                 key: kv.key.into(),

src/parser/inline_table.rs

@@ -48,7 +48,8 @@ fn descend_path<'a>(
 ) -> Result<&'a mut InlineTable, CustomError> {
     if let Some(key) = path.get(i) {
         let entry = table.entry_format(key).or_insert_with(|| {
-            let new_table = InlineTable::new();
+            let mut new_table = InlineTable::new();
+            new_table.set_dotted(true);
 
             Value::InlineTable(new_table)
         });

src/parser/mod.rs

@@ -390,6 +390,7 @@ trimmed in raw strings.
             r#"{   }"#,
             r#"{a = 1e165}"#,
             r#"{ hello = "world", a = 1}"#,
+            r#"{ hello.world = "a" }"#,
         ];
         for input in &inputs {
             parsed_value_eq!(input);
@@ -495,6 +496,8 @@ that
 "#,
             r#"[parent . child]
 key = "value"
+"#,
+            r#"hello.world = "a"
 "#,
         ];
         for document in &documents {

src/parser/table.rs

@@ -83,11 +83,13 @@ impl TomlParser {
         table: &'a mut Table,
         path: &'a [Key],
         i: usize,
+        dotted: bool,
     ) -> Result<&'a mut Table, CustomError> {
         if let Some(key) = path.get(i) {
             let entry = table.entry_format(key).or_insert_with(|| {
                 let mut new_table = Table::new();
                 new_table.set_implicit(true);
+                new_table.set_dotted(dotted);
 
                 Item::Table(new_table)
             });
@@ -99,10 +101,10 @@ impl TomlParser {
                     let index = array.len() - 1;
                     let last_child = array.get_mut(index).unwrap();
 
-                    Self::descend_path(last_child, path, i + 1)
+                    Self::descend_path(last_child, path, i + 1, dotted)
                 }
                 Item::Table(ref mut sweet_child_of_mine) => {
-                    TomlParser::descend_path(sweet_child_of_mine, path, i + 1)
+                    TomlParser::descend_path(sweet_child_of_mine, path, i + 1, dotted)
                 }
                 _ => unreachable!(),
             }
@@ -118,7 +120,7 @@ impl TomlParser {
         let table = self.document.as_table_mut();
         self.current_table_position += 1;
 
-        let table = Self::descend_path(table, &path[..path.len() - 1], 0)?;
+        let table = Self::descend_path(table, &path[..path.len() - 1], 0, false)?;
         let key = &path[path.len() - 1];
 
         let decor = Decor::new(leading, trailing);
@@ -160,7 +162,7 @@ impl TomlParser {
         let table = self.document.as_table_mut();
 
         let key = &path[path.len() - 1];
-        let table = Self::descend_path(table, &path[..path.len() - 1], 0);
+        let table = Self::descend_path(table, &path[..path.len() - 1], 0, false);
 
         match table {
             Ok(table) => {

src/table.rs

@@ -14,6 +14,8 @@ pub struct Table {
     pub(crate) decor: Decor,
     // whether to hide an empty table
     pub(crate) implicit: bool,
+    // whether this is a proxy for dotted keys
+    pub(crate) dotted: bool,
     // used for putting tables back in their original order when serialising.
     // Will be None when the Table wasn't parsed from a file.
     pub(crate) position: Option<usize>,
@@ -79,7 +81,9 @@ impl Table {
     }
 
     /// Returns the number of key/value pairs in the table.
-    pub fn values_len(&self) -> usize {
+    ///
+    /// NOTE: Not accurate for dotted keys, see `get_children`
+    pub(crate) fn values_len(&self) -> usize {
         self.items.iter().filter(|i| (i.1).value.is_value()).count()
     }
 
@@ -182,6 +186,34 @@ impl Table {
 }
 
 impl Table {
+    /// Get key/values for values that are visually children of this table
+    ///
+    /// For example, this will return dotted keys
+    pub fn get_children<'s, 'c>(&'s self, children: &'c mut Vec<(Vec<&'s Key>, &'s Value)>) {
+        let root = Vec::new();
+        self.get_children_internal(&root, children);
+    }
+
+    fn get_children_internal<'s, 'c>(
+        &'s self,
+        parent: &[&'s Key],
+        children: &'c mut Vec<(Vec<&'s Key>, &'s Value)>,
+    ) {
+        for value in self.items.values() {
+            let mut path = parent.to_vec();
+            path.push(&value.key);
+            match &value.value {
+                Item::Table(table) if table.is_dotted() => {
+                    table.get_children_internal(&path, children);
+                }
+                Item::Value(value) => {
+                    children.push((path, value));
+                }
+                _ => {}
+            }
+        }
+    }
+
     /// If a table has no key/value pairs and implicit, it will not be displayed.
     ///
     /// # Examples
@@ -203,6 +235,16 @@ impl Table {
         self.implicit = implicit;
     }
 
+    /// Check if this is a wrapper for dotted keys, rather than a standard table
+    pub fn is_dotted(&self) -> bool {
+        self.dotted
+    }
+
+    /// Change this table's dotted status
+    pub fn set_dotted(&mut self, yes: bool) {
+        self.dotted = yes;
+    }
+
     /// Sorts Key/Value Pairs of the table.
     ///
     /// Doesn't affect subtables or subarrays.