Preserve old DataPack behavior when overwriting data (#848)

* Match old DataPack behavior when overwriting data

* Make RemoveItem more flexible

* Ditch implied RemoveItem behavior & asher fixes

* KyleS nits - but fixed before he says them

* Add back implicit behavior

* Update CDataPack.cpp

Committing to the spec.

* Update CDataPack.h

* fixup removing last item if explicitly requested

* Fix logic for accepting pack pos, rather than index

* Fixup IsReadable

* headache is over now

core/logic/CDataPack.cpp

@@ -223,3 +223,24 @@ void *CDataPack::ReadMemory(size_t *size) const
 
 	return ptr;
 }
+
+bool CDataPack::RemoveItem(size_t pos)
+{
+	if (!elements.length())
+	{
+		return false;
+	}
+
+	if (pos == static_cast<size_t>(-1))
+	{
+		pos = position;
+	}
+	if (pos >= elements.length())
+	{
+		return false;
+	}
+
+	elements.remove(pos);
+	--position;
+	return true;
+}

core/logic/CDataPack.h

@@ -76,6 +76,7 @@ public:
 	void Initialize();
 	inline size_t GetCapacity() const { return this->elements.length(); };
 	inline CDataPackType GetCurrentType(void) const { return this->elements[this->position].type; };
+	bool RemoveItem(size_t pos = -1);
 private:
 
 	typedef union {

core/logic/smn_datapacks.cpp

@@ -99,6 +99,12 @@ static cell_t smn_WritePackCell(IPluginContext *pContext, const cell_t *params)
 		return pContext->ThrowNativeError("Invalid data pack handle %x (error %d).", hndl, herr);
 	}
 
+	bool insert = (params[0] >= 3) ? params[3] : false;
+	if (!insert)
+	{
+		pDataPack->RemoveItem();
+	}
+
 	pDataPack->PackCell(params[2]);
 
 	return 1;
@@ -120,6 +126,12 @@ static cell_t smn_WritePackFloat(IPluginContext *pContext, const cell_t *params)
 		return pContext->ThrowNativeError("Invalid data pack handle %x (error %d).", hndl, herr);
 	}
 
+	bool insert = (params[0] >= 3) ? params[3] : false;
+	if (!insert)
+	{
+		pDataPack->RemoveItem();
+	}
+
 	pDataPack->PackFloat(sp_ctof(params[2]));
 
 	return 1;
@@ -141,6 +153,12 @@ static cell_t smn_WritePackString(IPluginContext *pContext, const cell_t *params
 		return pContext->ThrowNativeError("Invalid data pack handle %x (error %d).", hndl, herr);
 	}
 
+	bool insert = (params[0] >= 3) ? params[3] : false;
+	if (!insert)
+	{
+		pDataPack->RemoveItem();
+	}
+
 	char *str;
 	pContext->LocalToString(params[2], &str);
 	pDataPack->PackString(str);
@@ -164,6 +182,12 @@ static cell_t smn_WritePackFunction(IPluginContext *pContext, const cell_t *para
 		return pContext->ThrowNativeError("Invalid data pack handle %x (error %d).", hndl, herr);
 	}
 
+	bool insert = (params[0] >= 3) ? params[3] : false;
+	if (!insert)
+	{
+		pDataPack->RemoveItem();
+	}
+
 	pDataPack->PackFunction(params[2]);
 
 	return 1;

plugins/include/datapack.inc

@@ -50,22 +50,26 @@ methodmap DataPack < Handle
 	// Packs a normal cell into a data pack.
 	//
 	// @param cell		Cell to add.
-	public native void WriteCell(any cell);
+	// @param insert	Determines whether mid-pack writes will insert instead of overwrite.
+	public native void WriteCell(any cell, bool insert = false);
 
 	// Packs a float into a data pack.
 	//
 	// @param val		Float to add.
-	public native void WriteFloat(float val);
+	// @param insert	Determines whether mid-pack writes will insert instead of overwrite.
+	public native void WriteFloat(float val, bool insert = false);
 
 	// Packs a string into a data pack.
 	//
 	// @param str		String to add.
-	public native void WriteString(const char[] str);
+	// @param insert	Determines whether mid-pack writes will insert instead of overwrite.
+	public native void WriteString(const char[] str, bool insert = false);
 
 	// Packs a function pointer into a data pack.
 	//
 	// @param fktptr	Function pointer to add.
-	public native void WriteFunction(Function fktptr);
+	// @param insert	Determines whether mid-pack writes will insert instead of overwrite.
+	public native void WriteFunction(Function fktptr, bool insert = false);
 
 	// Reads a cell from a data pack.
 	//
@@ -96,8 +100,8 @@ methodmap DataPack < Handle
 	// Returns whether or not a specified number of bytes from the data pack
 	//  position to the end can be read.
 	//
-	// @param bytes		Number of bytes to simulate reading.
+	// @param unused	Unused variable. Exists for backwards compatability.
-	public native bool IsReadable(int bytes);
+	public native bool IsReadable(int unused = 0);
 	
 	// The read or write position in a data pack.
 	property DataPackPos Position {