Rewrite double.parse.

runtime/lib/double.cc

Index: runtime/lib/double.cc
diff --git a/runtime/lib/double.cc b/runtime/lib/double.cc
index dbc6886960bf4729f78af7d97b373d90030c7ac4..62411a967fb408cb127320d7a32215d820a0e101 100644
--- a/runtime/lib/double.cc
+++ b/runtime/lib/double.cc
@@ -198,90 +198,24 @@ DEFINE_NATIVE_ENTRY(Double_toInt, 1) {
 
 DEFINE_NATIVE_ENTRY(Double_parse, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(String, value, arguments->NativeArgAt(0));
-  if (value.IsOneByteString()) {
-    // Quick conversion for unpadded doubles in strings.
-    const intptr_t len = value.Length();
-    if (len > 0) {
-      const char* cstr = value.ToCString();
-      ASSERT(cstr != NULL);
-      // Dart differences from strtod:
-      // a) '5.' is not a valid double (no digit after period).
-      // b) '+5.0' is not a valid double (leading plus).
-      if (cstr[0] != '+') {
-        bool dot_ok = true;
-        const char* tmp = cstr;
-        while (*tmp != '\0') {
-          const char ch = *tmp++;
-          if (ch == '.') {
-            const char nextCh = *tmp;
-            dot_ok = ('0' <= nextCh) && (nextCh <= '9');
-            break;
-          }
-        }
-        if (dot_ok) {
-          double double_value;
-          if (CStringToDouble(cstr, len, &double_value)) {
-            return Double::New(double_value);
-          }
-        }
-      }
-    }
-  }
-  Scanner scanner(value, Symbols::Empty());
-  const Scanner::GrowableTokenStream& tokens = scanner.GetStream();
-  String* number_string;
-  bool is_positive;
-  if (Scanner::IsValidLiteral(tokens,
-                              Token::kDOUBLE,
-                              &is_positive,
-                              &number_string)) {
-    // Even if original string was two byte string the scanner should produce
-    // literal value that is represented as a one byte string because all
-    // characters in the double literal are Latin-1.
-    ASSERT(number_string->IsOneByteString());
-    const char* cstr = number_string->ToCString();
-
-    double double_value;
-    bool ok = CStringToDouble(cstr, number_string->Length(), &double_value);
-    ASSERT(ok);
-
-    if (!is_positive) {
-      double_value = -double_value;
-    }
-    return Double::New(double_value);
-  }
 
-  if (Scanner::IsValidLiteral(tokens,
-                              Token::kINTEGER,
-                              &is_positive,
-                              &number_string)) {
-    Integer& res = Integer::Handle(Integer::New(*number_string));
-    if (is_positive) {
-      return Double::New(res.AsDoubleValue());
-    }
-    return Double::New(-res.AsDoubleValue());
-  }
+  const intptr_t len = value.Length();
 
-  // Infinity and nan.
-  if (Scanner::IsValidLiteral(tokens,
-                              Token::kIDENT,
-                              &is_positive,
-                              &number_string)) {
-    if (number_string->Equals("NaN")) {
-      return Double::New(NAN);
-    }
-    if (number_string->Equals("Infinity")) {
-      if (is_positive) {
-        return Double::New(INFINITY);
-      }
-      return Double::New(-INFINITY);
-    }
+  // The native function only accepts one-byte strings. The Dart side converts
+  // other types of strings to one-byte strings, if necessary.
+  if ((!value.IsOneByteString() && !value.IsExternalOneByteString())
+      || (len == 0)) {
+    return Object::null();
   }
 
-  const Array& args = Array::Handle(Array::New(1));
-  args.SetAt(0, value);
-  Exceptions::ThrowByType(Exceptions::kFormat, args);
-  return Object::null();
+  double double_value;
+  const char* cstr = value.ToCString();
+  ASSERT(cstr != NULL);
+  if (CStringToDouble(cstr, len, &double_value)) {
+    return Double::New(double_value);
+  } else {
+    return Object::null();
+  }
 }