Issue 4125 - [emscripten] Convert filter classes to C++

compiled/String.h

 #pragma once
 
 #include <cstddef>
 #include <cstring>
 #include <algorithm>
 
 #include <emscripten.h>
 
 #include "debug.h"
 
@@ skipping 16 matching lines @@
 
   static constexpr size_type FLAGS_MASK = 0xC0000000;
   static constexpr size_type LENGTH_MASK = 0x3FFFFFFF;
 
   static constexpr size_type npos = -1;
 
 protected:
   value_type* mBuf;
   size_type mLen;
 
-  String(value_type* buf, size_type len, size_type flags)
+  explicit String(value_type* buf, size_type len, size_type flags)
       : mBuf(buf), mLen((len & LENGTH_MASK) | flags)
   {
   }
 
   ~String()
   {
   }
 
   void reset(value_type* buf, size_type len, size_type flags)
   {
@@ skipping 92 matching lines @@
   bool is_invalid() const
   {
     return (mLen & FLAGS_MASK) == INVALID;
   }
 
   bool is_deleted() const
   {
     return (mLen & FLAGS_MASK) == DELETED;
   }
 
-  void tolower()

[sergei, 2017/01/10 15:58:02]

it seems to be consistent it should be to_lower or toLower.

[Wladimir Palant, 2017/03/13 17:42:15]

Done.

+  void toLower()
   {
     size_type len = length();
     for (size_type i = 0; i < len; ++i)
     {
       value_type currChar = mBuf[i];
 
       // This should be more efficient with a lookup table but I couldn't measure
       // any performance difference.
       if (currChar >= u'A' && currChar <= u'Z')
         mBuf[i] = currChar + u'a' - u'A';
       else if (currChar >= 128)
       {
-        // It seems that calling JS it the easiest solution for lowercasing

[sergei, 2017/01/10 15:57:54]

typo: it -> is

[Wladimir Palant, 2017/03/13 17:42:20]

Done.

+        // It seems that calling JS is the easiest solution for lowercasing
         // Unicode characters.
         mBuf[i] = EM_ASM_INT({
           return String.fromCharCode($0).toLowerCase().charCodeAt(0);
         }, currChar);
       }
     }
   }
 };
 
 class DependentString : public String
 {
 public:
-  DependentString()
+  explicit DependentString()
       : String(nullptr, 0, INVALID)
   {
   }
 
-  DependentString(value_type* buf, size_type len)
+  explicit DependentString(value_type* buf, size_type len)
       : String(buf, len, READ_WRITE)
   {
   }
 
-  DependentString(const value_type* buf, size_type len)
+  explicit DependentString(const value_type* buf, size_type len)
       : String(const_cast<value_type*>(buf), len, READ_ONLY)
   {
   }
 
   explicit DependentString(String& str, size_type pos = 0, size_type len = npos)
       : String(
           str.mBuf + std::min(pos, str.length()),
           std::min(len, str.length() - std::min(pos, str.length())),
           str.is_readOnly() ? READ_ONLY : READ_WRITE
         )
@@ skipping 44 matching lines @@
 }
 
 inline void String_assert_readonly(bool readOnly)
 {
   assert(!readOnly, u"Writing access to a read-only string"_str);
 }
 
 class OwnedString : public String
 {
 private:
-  value_type* allocate(size_type len)
+  void grow(size_type additionalSize)
+  {
+    OwnedString newValue(length() + additionalSize);
+    if (length() > 0)
+      std::memcpy(newValue.mBuf, mBuf, sizeof(value_type) * length());
+    *this = std::move(newValue);
+  }
+
+public:
+  explicit OwnedString(size_type len = 0)
+      : String(nullptr, len, READ_WRITE)
   {
     if (len)
-      return new value_type[len];
+    {
+      mBuf = new value_type[length()];
+      annotate_address(mBuf, "String");
+    }
     else
-      return nullptr;
-  }
-
-  void grow(size_type additionalSize)
-  {
-    size_type oldLength = length();

[sergei, 2017/01/10 15:57:56]

It seems it can be simplified to

auto newValue = OwnedString(length() + additionalSize);
if (length() > 0)
  std::memcpy(mBuf, oldBuffer, sizeof(value_type) * oldLength);
*this = std::move(newValue);

[Wladimir Palant, 2017/03/13 17:42:18]

Done.

-    size_type newLength = oldLength + additionalSize;
-    value_type* oldBuffer = mBuf;
-
-    reset(nullptr, newLength, READ_WRITE);
-    newLength = length();
-    mBuf = allocate(newLength);
-    annotate_address(mBuf, "String");
-
-    if (oldLength)
-      std::memcpy(mBuf, oldBuffer, sizeof(value_type) * oldLength);
-    if (oldBuffer)
-      delete[] oldBuffer;
-  }
-
-public:
-  OwnedString(size_type len = 0)
-      : String(nullptr, len, READ_WRITE)
-  {
-    mBuf = allocate(length());
-    annotate_address(mBuf, "String");
-  }
-
-  OwnedString(const String& str)
+      mBuf = nullptr;
+  }
+
+  explicit OwnedString(const String& str)
       : OwnedString(str.length())
   {
     if (length())
       std::memcpy(mBuf, str.mBuf, sizeof(value_type) * length());
   }
 
   OwnedString(const OwnedString& str)
       : OwnedString(static_cast<const String&>(str))
   {
   }
 
-  OwnedString(const value_type* str, size_type len)
+  explicit OwnedString(const value_type* str, size_type len)
       : OwnedString(DependentString(str, len))
   {
   }
 
-  OwnedString(OwnedString&& str)
+  explicit OwnedString(OwnedString&& str)
       : OwnedString(0)
   {
     mBuf = str.mBuf;
     mLen = str.mLen;
     str.mBuf = nullptr;
     str.mLen = READ_WRITE | 0;
   }
 
   ~OwnedString()
   {
     if (mBuf)
       delete[] mBuf;
   }
 
   OwnedString& operator=(const String& str)
   {
     *this = std::move(OwnedString(str));
     return *this;
   }
 
   OwnedString& operator=(const OwnedString& str)
   {
     *this = std::move(OwnedString(str));
     return *this;
   }
 
   OwnedString& operator=(OwnedString&& str)

[sergei, 2017/01/10 15:57:52]

I don't know how I missed it before but it's incorrect.
Let's say we have
OwnedString value = u"abc"_str; // it allocates memory (mBuf).
value = std::move(u"new value"_str); // who will delete old mBuf pointing to
"abc"?

I would simply swap members of this and str.

[Wladimir Palant, 2017/03/13 17:42:13]

Done.

   {
-    mBuf = str.mBuf;
-    mLen = str.mLen;
-    str.mBuf = nullptr;
-    str.mLen = READ_WRITE | 0;
+    std::swap(mBuf, str.mBuf);
+    std::swap(mLen, str.mLen);
     return *this;
   }
 
   void append(const value_type* source, size_type sourceLen)
   {
     if (!sourceLen)
       return;
 
     assert(source, u"Null buffer passed to OwnedString.append()"_str);
     size_t oldLength = length();
     grow(sourceLen);
     std::memcpy(mBuf + oldLength, source, sizeof(value_type) * sourceLen);
   }
 
   void append(const String& str)
   {
     append(str.mBuf, str.length());
   }
 
   void append(value_type c)
   {
     append(&c, 1);
   }
 };