quoting possible booleans

fixes #53

parser/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "yaml-rust"
-version = "0.3.5"
+version = "0.3.6"
 authors = ["Yuheng Chen <yuhengchen@sensetime.com>"]
 homepage = "http://chyh1990.github.io/yaml-rust/"
 documentation = "http://chyh1990.github.io/yaml-rust/doc/yaml_rust/"

parser/src/emitter.rs

@@ -137,15 +137,12 @@ impl<'a> YamlEmitter<'a> {
             Yaml::Array(ref v) => {
                     try!(write!(self.writer, "["));
                     if self.level >= 0 {
-                        try!(write!(self.writer, "+ "));
+                        try!(write!(self.writer, ""));
                     }
-                    self.level += 1;
                     for (cnt, x) in v.iter().enumerate() {
-                        try!(self.write_indent());
                         if cnt > 0 { try!(write!(self.writer, ", ")); }
                         try!(self.emit_node(x));
                     }
-                    self.level -= 1;
                     try!(write!(self.writer, "]"));
                     Ok(())
             },
@@ -181,8 +178,7 @@ impl<'a> YamlEmitter<'a> {
             Yaml::String(ref v) => {
                 if need_quotes(v) {
                     try!(escape_str(self.writer, v));
-                }
+                } else {
-                else {
                     try!(write!(self.writer, "{}", v));
                 }
                 Ok(())
@@ -306,10 +302,13 @@ fn need_quotes(string: &str) -> bool {
             _ => false,
         }
     })
-    || string == "true"
+    || [// http://yaml.org/type/bool.html
-    || string == "false"
+        "y","Y","yes","Yes","YES","n","N","no","No","NO",
-    || string == "null"
+        "True", "TRUE", "true", "False", "FALSE", "false",
-    || string == "~"
+        "on","On","ON","off","Off","OFF",
+        // http://yaml.org/type/null.html
+        "null","Null","NULL", "~"
+    ].contains(&string)
     || string.starts_with('.')
     || string.parse::<i64>().is_ok()
     || string.parse::<f64>().is_ok()
@@ -421,7 +420,8 @@ products:
   "true": bool key
   "{}": empty hash key
 x: test
-y: string with spaces"#;
+"y": "can't avoid quoting here"
+z: string with spaces"#;
 
         let docs = YamlLoader::load_from_str(&s).unwrap();
         let doc = &docs[0];
@@ -434,6 +434,42 @@ y: string with spaces"#;
         assert_eq!(s, writer, "actual:\n\n{}\n", writer);
     }
 
+    #[test]
+    fn emit_quoted_bools() {
+        let input = r#"---
+string0: yes
+string1: no
+string2: "true"
+string3: "false"
+string4: "~"
+null0: ~
+[true, false]: real_bools
+[True, TRUE, False, FALSE, y,Y,yes,Yes,YES,n,N,no,No,NO,on,On,ON,off,Off,OFF]: false_bools
+bool0: true
+bool1: false"#;
+        let expected = r#"---
+string0: "yes"
+string1: "no"
+string2: "true"
+string3: "false"
+string4: "~"
+null0: ~
+[true, false]: real_bools
+["True", "TRUE", "False", "FALSE", "y", "Y", "yes", "Yes", "YES", "n", "N", "no", "No", "NO", "on", "On", "ON", "off", "Off", "OFF"]: false_bools
+bool0: true
+bool1: false"#;
+
+        let docs = YamlLoader::load_from_str(&input).unwrap();
+        let doc = &docs[0];
+        let mut writer = String::new();
+        {
+            let mut emitter = YamlEmitter::new(&mut writer);
+            emitter.dump(doc).unwrap();
+        }
+
+        assert_eq!(expected, writer, "actual:\n\n{}\n", writer);
+    }
+
     #[test]
     fn test_empty_and_nested() {
         let s = r#"---