flake-info: Adapt RFC-166 style (#749)

* flake-info: Adapt RFC-166 style

* flake-info: Properly escape attrset keys

* flake-info: Stop owning values for pretty-printing

flake-info/src/data/import.rs

@@ -145,7 +145,7 @@ impl Serialize for DocValue {
                     md.to_owned()
                 }))
             }
-            DocValue::Value(v) => serializer.serialize_str(&print_value(v.to_owned())),
+            DocValue::Value(v) => serializer.serialize_str(&print_value(v)),
         }
     }
 }

flake-info/src/data/prettyprint.rs

@@ -15,11 +15,24 @@ impl Display for Indent {
     }
 }
 
-pub fn print_value(value: Value) -> String {
+pub fn print_value(value: &Value) -> String {
     print_value_indent(value, Indent(0))
 }
 
-fn print_value_indent(value: Value, indent: Indent) -> String {
+/// Formats an attrset key by adding quotes when necessary
+fn format_attrset_key(key: &str) -> String {
+    if key.contains("/")
+        || key.contains(" ")
+        || key.is_empty()
+        || (b'0'..=b'9').contains(&key.as_bytes()[0])
+    {
+        format!("{:?}", key)
+    } else {
+        key.to_string()
+    }
+}
+
+fn print_value_indent(value: &Value, indent: Indent) -> String {
     match value {
         Value::Null => "null".to_owned(),
         Value::Bool(b) => format!("{}", b),
@@ -44,6 +57,14 @@ fn print_value_indent(value: Value, indent: Indent) -> String {
             if a.is_empty() {
                 return "[ ]".to_owned();
             }
+            if a.len() == 1 {
+                // Return early if the wrapped value fits on one line
+                let val = print_value(a.first().unwrap());
+                if !val.contains("\n") {
+                    return format!("[ {} ]", val);
+                }
+            }
+
             let items = a
                 .into_iter()
                 .map(|v| print_value_indent(v, indent.next()))
@@ -63,9 +84,26 @@ fn print_value_indent(value: Value, indent: Indent) -> String {
             if o.is_empty() {
                 return "{ }".to_owned();
             }
+            if o.len() == 1 {
+                // Return early if the wrapped value fits on one line
+                let val = print_value(o.values().next().unwrap());
+                if !val.contains("\n") {
+                    return format!(
+                        "{{ {} = {}; }}",
+                        format_attrset_key(o.keys().next().unwrap()),
+                        val
+                    );
+                }
+            }
             let items = o
                 .into_iter()
-                .map(|(k, v)| format!("{} = {}", k, print_value_indent(v, indent.next())))
+                .map(|(k, v)| {
+                    format!(
+                        "{} = {}",
+                        format_attrset_key(&k),
+                        print_value_indent(v, indent.next())
+                    )
+                })
                 .collect::<Vec<_>>()
                 .join(&format!(";\n{}", indent.next()));
 
@@ -90,7 +128,7 @@ mod tests {
     #[test]
     fn test_string() {
         let json = json!("Hello World");
-        assert_eq!(print_value(json), "\"Hello World\"");
+        assert_eq!(print_value(&json), "\"Hello World\"");
     }
 
     #[test]
@@ -101,7 +139,7 @@ World
 !!!"#
         );
         assert_eq!(
-            print_value(json),
+            print_value(&json),
             r#"''
      Hello
   World
@@ -113,26 +151,46 @@ World
     #[test]
     fn test_num() {
         let json = json!(1);
-        assert_eq!(print_value(json), "1");
+        assert_eq!(print_value(&json), "1");
     }
 
     #[test]
     fn test_bool() {
         let json = json!(true);
-        assert_eq!(print_value(json), "true");
+        assert_eq!(print_value(&json), "true");
     }
 
     #[test]
     fn test_empty_list() {
         let json = json!([]);
-        assert_eq!(print_value(json), "[ ]");
+        assert_eq!(print_value(&json), "[ ]");
+    }
+
+    #[test]
+    fn test_list_one_item() {
+        let json = json!([1]);
+        assert_eq!(print_value(&json), "[ 1 ]");
+    }
+
+    #[test]
+    fn test_list_one_multiline_item() {
+        let json = json!(["first line\nsecond line"]);
+        assert_eq!(
+            print_value(&json),
+            r#"[
+  ''
+    first line
+    second line
+  ''
+]"#
+        );
     }
 
     #[test]
     fn test_filled_list() {
         let json = json!([1, "hello", true, null]);
         assert_eq!(
-            print_value(json),
+            print_value(&json),
             r#"[
   1
   "hello"
@@ -145,15 +203,42 @@ World
     #[test]
     fn test_empty_set() {
         let json = json!({});
-        assert_eq!(print_value(json), "{ }");
+        assert_eq!(print_value(&json), "{ }");
+    }
+
+    #[test]
+    fn test_set_one_item() {
+        let json = json!({ "hello": "world" });
+        assert_eq!(print_value(&json), "{ hello = \"world\"; }");
+    }
+
+    #[test]
+    fn test_set_number_key() {
+        let json = json!({ "1hello": "world" });
+        assert_eq!(print_value(&json), "{ \"1hello\" = \"world\"; }");
+    }
+
+    #[test]
+    fn test_set_one_multiline_item() {
+        let json = json!({ "hello": "pretty\nworld" });
+        assert_eq!(
+            print_value(&json),
+            "{
+  hello = ''
+    pretty
+    world
+  '';
+}"
+        );
     }
 
     #[test]
     fn test_filled_set() {
-        let json = json!({"hello": "world"});
+        let json = json!({"hello": "world", "another": "test"});
         assert_eq!(
-            print_value(json),
+            print_value(&json),
             "{
+  another = \"test\";
   hello = \"world\";
 }"
         );
@@ -176,7 +261,7 @@ World
         ]);
 
         assert_eq!(
-            print_value(json),
+            print_value(&json),
             r#"[
   "HDMI-0"
   {