pretty arrays

src/ser.rs

@@ -142,6 +142,7 @@ pub enum Error {
 #[derive(Debug, Default, Clone)]
 pub struct ArraySettings {
     indent: u64,
+    trailing_comma: bool,
 }
 
 /// Formatting Settings
@@ -224,6 +225,7 @@ impl<'a> Serializer<'a> {
             settings: Settings {
                 array: Some(ArraySettings {
                     indent: 4,
+                    trailing_comma: true,
                 }),
                 pretty_string: true,
             },
@@ -667,12 +669,18 @@ impl<'a, 'b> ser::SerializeSeq for SerializeSeq<'a, 'b> {
         match self.type_.get() {
             Some("table") => return Ok(()),
             Some(_) => {
-                if self.ser.settings.array.is_some() {
+                match self.ser.settings.array {
+                    Some(ref a) => {
+                        if a.trailing_comma {
+                            self.ser.dst.push_str(",");
+                        }
                         self.ser.dst.push_str("\n]");
-                } else {
+                    },
+                    None => {
                         self.ser.dst.push_str("]");
                     }
                 }
+            }
             None => {
                 assert!(self.first.get());
                 self.ser.emit_key("array")?;

tests/pretty.rs

@@ -5,6 +5,10 @@ use serde::ser::Serialize;
 
 const EXAMPLE: &str = "\
 [example]
+array = [
+    \"item 1\",
+    \"item 2\",
+]
 text = '''
 this is the first line
 this is the second line
@@ -16,5 +20,7 @@ fn test_pretty() {
     let value: toml::Value = toml::from_str(EXAMPLE).unwrap();
     let mut result = String::with_capacity(128);
     value.serialize(&mut toml::Serializer::pretty(&mut result)).unwrap();
+    println!("example:\n{}", EXAMPLE);
+    println!("result:\n{}", result);
     assert_eq!(EXAMPLE, &result);
 }