fix(es/lexer): Fix lexing of numbers with large exponent (#3061)

swc_ecma_parser: - Fix lexing of numbers where exponents are large enough to be parsed as `Infinity`. (Closes #3060)
swc-project · Dec 18, 2021 · 0c813ae · 0c813ae
1 parent 8c16c2b
commit 0c813ae
Showing 1 changed file with 59 additions and 5 deletions.
diff --git a/crates/swc_ecma_parser/src/lexer/number.rs b/crates/swc_ecma_parser/src/lexer/number.rs
@@ -137,13 +137,22 @@ impl<'a, I: Input> Lexer<'a, I> {
             };
 
             let exp = self.read_number_no_dot(10)?;
-            let flag = if positive { '+' } else { '-' };
 
-            raw_val.push(flag);
-            write!(raw_val, "{}", exp).unwrap();
+            val = if exp == f64::INFINITY {
+                if positive && val != 0.0 {
+                    f64::INFINITY
+                } else {
+                    0.0
+                }
+            } else {
+                let flag = if positive { '+' } else { '-' };
+
+                raw_val.push(flag);
+                write!(raw_val, "{}", exp).unwrap();
 
-            // TODO:
-            val = raw_val.parse().expect("failed to parse float literal");
+                // TODO:
+                raw_val.parse().expect("failed to parse float literal")
+            }
         }
 
         self.ensure_not_ident()?;
@@ -478,6 +487,51 @@ mod tests {
         assert_eq!(1e30, num("1e30"));
     }
 
+    #[test]
+    fn num_very_big_exp() {
+        const LARGE_POSITIVE_EXP: &str =
+            "1e100000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000";
+        const LARGE_NEGATIVE_EXP: &str =
+            "1e-10000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             000000000000000000000000000000000000000000000000000000";
+        const ZERO_WITH_LARGE_POSITIVE_EXP: &str =
+            "0e100000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000";
+        const ZERO_WITH_LARGE_NEGATIVE_EXP: &str =
+            "0e-10000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             000000000000000000000000000000000000000000000000000000";
+        const LARGE_MANTISSA_WITH_LARGE_NEGATIVE_EXP: &str =
+            "10000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             000000000000000000000000000000000000000000000000000000\
+             e-100000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             00000000000000000000000000000000000000000000000000000000000000000\
+             000000000000000000000000000000000000000000000000000000";
+
+        assert_eq!(num(LARGE_POSITIVE_EXP), INFINITY);
+        assert_eq!(num(LARGE_NEGATIVE_EXP), 0.0);
+        assert_eq!(num(ZERO_WITH_LARGE_POSITIVE_EXP), 0.0);
+        assert_eq!(num(ZERO_WITH_LARGE_NEGATIVE_EXP), 0.0);
+        assert_eq!(num(LARGE_MANTISSA_WITH_LARGE_NEGATIVE_EXP), 0.0);
+    }
+
     #[test]
     fn num_big_many_zero() {
         assert_eq!(