Fix a major plStringStream bug, and add an SSO-like optimization to it

Sources/Plasma/CoreLib/plString.cpp

@@ -800,14 +800,25 @@ plString operator+(const char *left, const plString &right)
 
 plStringStream &plStringStream::append(const char *data, size_t length)
 {
-    if (fLength + length > fBufSize) {
-        char *bigger = new char[fBufSize * 2];
-        memcpy(bigger, fBuffer, fBufSize);
-        delete [] fBuffer;
-        fBuffer = bigger;
-        fBufSize *= 2;
+    size_t bufSize = ICanHasHeap() ? fBufSize : 256;
+    char *bufp = ICanHasHeap() ? fBuffer : fShort;
+
+    if (fLength + length > bufSize) {
+        size_t bigSize = bufSize;
+        do {
+            hsAssert(bigSize * 2, "plStringStream buffer too large");
+            bigSize *= 2;
+        } while (fLength + length > bigSize);
+
+        char *bigger = new char[bigSize];
+        memcpy(bigger, GetRawBuffer(), bufSize);
+        if (ICanHasHeap())
+            delete [] fBuffer;
+        fBuffer = bufp = bigger;
+        fBufSize = bigSize;
     }
-    memcpy(fBuffer + fLength, data, length);
+
+    memcpy(bufp + fLength, data, length);
     fLength += length;
     return *this;
 }
@@ -832,6 +843,13 @@ plStringStream &plStringStream::operator<<(unsigned int num)
     return operator<<(buffer);
 }
 
+plStringStream &plStringStream::operator<<(double num)
+{
+    char buffer[64];
+    snprintf(buffer, 64, "%f", num);
+    return operator<<(buffer);
+}
+
 size_t ustrlen(const UniChar *ustr, size_t max)
 {
     size_t length = 0;

Sources/Plasma/CoreLib/plString.h

@@ -341,17 +341,19 @@ plString operator+(const char *left, const plString &right);
 class plStringStream
 {
 public:
-    plStringStream() : fBufSize(256), fLength(0)
+    plStringStream() : fLength(0)
     {
-        fBuffer = new char[fBufSize];
+        fShort[0] = 0;
     }
-    ~plStringStream() { delete [] fBuffer; }
+    ~plStringStream() { if (ICanHasHeap()) delete [] fBuffer; }
 
     plStringStream &append(const char *data, size_t length);
 
     plStringStream &operator<<(const char *text);
     plStringStream &operator<<(int num);
     plStringStream &operator<<(unsigned int num);
+    plStringStream &operator<<(float num) { return operator<<(static_cast<double>(num)); }
+    plStringStream &operator<<(double num);
     plStringStream &operator<<(char ch) { return append(&ch, 1); }
 
     plStringStream &operator<<(const plString &text)
@@ -359,13 +361,25 @@ public:
         return append(text.c_str(), text.GetSize());
     }
 
+    const char *GetRawBuffer() const // WARNING:  Not null-terminated!
+    {
+        return ICanHasHeap() ? fBuffer : fShort;
+    }
+
     size_t GetLength() const { return fLength; }
-    plString GetString() { return plString::FromUtf8(fBuffer, fLength); }
+    plString GetString() { return plString::FromUtf8(GetRawBuffer(), fLength); }
 
 private:
-    char *fBuffer;
-    size_t fBufSize;
+    union {
+        struct {
+            char *fBuffer;
+            size_t fBufSize;
+        };
+        char fShort[256];
+    };
     size_t fLength;
+
+    bool ICanHasHeap() const { return fLength > 256; }
 };
 
 size_t ustrlen(const UniChar *ustr, size_t max = plString::kSizeAuto);