Spec Compliant Number.prototype.toString(), better Number object formating and -0

boa/src/builtins/number/mod.rs

@@ -361,18 +361,8 @@ impl Number {
 
     #[allow(clippy::wrong_self_convention)]
     pub(crate) fn to_native_string(x: f64) -> String {
-        if x == -0. {
-            return "0".to_owned();
-        } else if x.is_nan() {
-            return "NaN".to_owned();
-        } else if x.is_infinite() && x.is_sign_positive() {
-            return "Infinity".to_owned();
-        } else if x.is_infinite() && x.is_sign_negative() {
-            return "-Infinity".to_owned();
-        }
-
-        // FIXME: This is not spec compliant.
-        format!("{}", x)
+        let mut buffer = ryu_js::Buffer::new();
+        buffer.format(x).to_string()
     }
 
     /// `Number.prototype.toString( [radix] )`
@@ -400,6 +390,11 @@ impl Number {
                 .throw_range_error("radix must be an integer at least 2 and no greater than 36");
         }
 
+        // 5. If radixNumber = 10, return ! ToString(x).
+        if radix == 10 {
+            return Ok(Value::from(Self::to_native_string(x)));
+        }
+
         if x == -0. {
             return Ok(Value::from("0"));
         } else if x.is_nan() {
@@ -410,13 +405,6 @@ impl Number {
             return Ok(Value::from("-Infinity"));
         }
 
-        // 5. If radixNumber = 10, return ! ToString(x).
-        // This part should use exponential notations for long integer numbers commented tests
-        if radix == 10 {
-            // return Ok(to_value(format!("{}", Self::to_number(this).to_num())));
-            return Ok(Value::from(Self::to_native_string(x)));
-        }
-
         // This is a Optimization from the v8 source code to print values that can fit in a single character
         // Since the actual num_to_string allocates a 2200 bytes buffer for actual conversion
         // I am not sure if this part is effective as the v8 equivalent https://chromium.googlesource.com/v8/v8/+/refs/heads/master/src/builtins/number.tq#53

boa/src/builtins/number/tests.rs

@@ -328,49 +328,30 @@ fn to_string() {
 }
 
 #[test]
-#[ignore]
-// This tests fail for now since the Rust's default formatting for exponential format does not match the js spec.
-// https://github.com/jasonwilliams/boa/pull/381#discussion_r422458544
 fn num_to_string_exponential() {
     let realm = Realm::create();
     let mut engine = Interpreter::new(realm);
 
+    assert_eq!("0", forward(&mut engine, "(0).toString()"));
+    assert_eq!("0", forward(&mut engine, "(-0).toString()"));
     assert_eq!(
-        String::from("111111111111111110000"),
-        forward(&mut engine, "Number(111111111111111111111).toString()")
-    );
-    assert_eq!(
-        String::from("1.1111111111111111e+21"),
-        forward(&mut engine, "Number(1111111111111111111111).toString()")
-    );
-    assert_eq!(
-        String::from("1.1111111111111111e+22"),
-        forward(&mut engine, "Number(11111111111111111111111).toString()")
-    );
-    assert_eq!(
-        String::from("1e-7"),
-        forward(&mut engine, "Number(0.0000001).toString()")
-    );
-    assert_eq!(
-        String::from("1.2e-7"),
-        forward(&mut engine, "Number(0.00000012).toString()")
-    );
-    assert_eq!(
-        String::from("1.23e-7"),
-        forward(&mut engine, "Number(0.000000123).toString()")
-    );
-    assert_eq!(
-        String::from("1e-8"),
-        forward(&mut engine, "Number(0.00000001).toString()")
+        "111111111111111110000",
+        forward(&mut engine, "(111111111111111111111).toString()")
     );
     assert_eq!(
-        String::from("1.2e-8"),
-        forward(&mut engine, "Number(0.000000012).toString()")
+        "1.1111111111111111e+21",
+        forward(&mut engine, "(1111111111111111111111).toString()")
     );
     assert_eq!(
-        String::from("1.23e-8"),
-        forward(&mut engine, "Number(0.0000000123).toString()")
+        "1.1111111111111111e+22",
+        forward(&mut engine, "(11111111111111111111111).toString()")
     );
+    assert_eq!("1e-7", forward(&mut engine, "(0.0000001).toString()"));
+    assert_eq!("1.2e-7", forward(&mut engine, "(0.00000012).toString()"));
+    assert_eq!("1.23e-7", forward(&mut engine, "(0.000000123).toString()"));
+    assert_eq!("1e-8", forward(&mut engine, "(0.00000001).toString()"));
+    assert_eq!("1.2e-8", forward(&mut engine, "(0.000000012).toString()"));
+    assert_eq!("1.23e-8", forward(&mut engine, "(0.0000000123).toString()"));
 }
 
 #[test]

boa/src/builtins/value/display.rs

@@ -67,6 +67,14 @@ pub(crate) fn log_string_from(x: &Value, print_internals: bool, print_children:
             match v.borrow().data {
                 ObjectData::String(ref string) => format!("String {{ \"{}\" }}", string),
                 ObjectData::Boolean(boolean) => format!("Boolean {{ {} }}", boolean),
+                ObjectData::Number(rational) => {
+                    if rational.is_sign_negative() && rational == 0.0 {
+                        "Number { -0 }".to_string()
+                    } else {
+                        let mut buffer = ryu_js::Buffer::new();
+                        format!("Number {{ {} }}", buffer.format(rational))
+                    }
+                }
                 ObjectData::Array => {
                     let len = i32::from(
                         &v.borrow()
@@ -219,7 +227,16 @@ impl Display for Value {
     }
 }
 
+/// This is different from the ECMAScript compliant number to string, in the printing of `-0`.
+///
+/// This function prints `-0` as `-0` instead of pasitive `0` as the specification says.
+/// This is done to make it easer for the user of the REPL to identify what is a `-0` vs `0`,
+/// since the REPL is not bound to the ECMAScript specification we can do this.
 fn format_rational(v: f64, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-    let mut buffer = ryu_js::Buffer::new();
-    write!(f, "{}", buffer.format(v))
+    if v.is_sign_negative() && v == 0.0 {
+        f.write_str("-0")
+    } else {
+        let mut buffer = ryu_js::Buffer::new();
+        write!(f, "{}", buffer.format(v))
+    }
 }