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SLContext.cc

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/*
    File:           SLContext.cc

    Function:       See header file

    Author(s):      Andrew Willmott

    Copyright:      (c) 1995-2000, Andrew Willmott

    Notes:          

*/


#include "gcl/SLContext.h"

const UInt16 slc_EOL        = 0x8000;
const UInt16 slc_DaemonFlag = 0x4000;
const UInt16 slc_LevelMask  = 0x0FFF;


SLContext::SLContext(Int numAttrs) :
    attributeList(numAttrs),
    attributeStack()
{
    Clear();
}

AttrPtr SLContext::Get(AttrType attrType)
{
    if (attributeList[attrType].level & slc_DaemonFlag)
        return(attributeList[attrType].daemon->Get());
    else
        return(attributeList[attrType].data);       
}

Void SLContext::Set(AttrType attrType, AttrPtr attrPtr)
{
    Assert(attrType < attributeList.NumItems(),
            "(SLContext::Set) Unknown attribute type");
    AttrRec *pRec = &attributeList[attrType];
    AttrStackRec    sRec;
    Bool            isDaemon = (pRec->level & slc_DaemonFlag);
                
    // if the attribute exists and wasn't set this level, push it...

    if (pRec->data && (pRec->level & slc_LevelMask) < level)
    {
        sRec.attrRec = *pRec;
        sRec.attrType = attrType;
        
        if (isDaemon)
            pRec->daemon->Save();

        attributeStack.Push(sRec);
    }
    
    if (isDaemon)
        pRec->daemon->Set(attrPtr);
    else
        pRec->data = attrPtr;

    pRec->level = level;
}

Void SLContext::SetDaemon(AttrType attrType, AttrDaemon *daemon)
{
    Assert((attributeList[attrType].level & slc_DaemonFlag) == 0, "Daemon already set for this slot.");
    
    Set(attrType, daemon);

    if (daemon)
        attributeList[attrType].level |= slc_DaemonFlag;
}

Void SLContext::Push()
{
    AttrStackRec sRec;
    
    level++;
    sRec.attrRec.level = slc_EOL;   // mark pRec as a sentinel
    attributeStack.Push(sRec);      // Add to the stack
}

Void SLContext::Pop()
{
    Int i;
    
//  pop off all the attributes changed since the last push...

    Assert(level > 0, "(SLContext::Pop) Too many pops");
    
    while (!(attributeStack.Top().attrRec.level & slc_EOL)) 
    {
        if (attributeStack.Top().attrRec.level & slc_DaemonFlag)
            attributeStack.Top().attrRec.daemon->Restore();         

        attributeList[attributeStack.Top().attrType] =
            attributeStack.Top().attrRec;
        attributeStack.Pop();
    }

//  pop off the sentinel...

    attributeStack.Pop();
    level--;

// zero anything that wasn't previously set at this level.

    for (i = 0; i < attributeList.NumItems(); i++)
        if ((attributeList[i].level & slc_LevelMask) > level)
        {
            attributeList[i].data = 0;
            attributeList[i].level = 0;
        }
}

Bool SLContext::IsCurrent(AttrType attrType)
{
    return(attributeList[attrType].level == level);
}

Void SLContext::Clear()
{
    Int i;

    attributeStack.SetSize(0);
    level = 0;

    for (i = 0; i < attributeList.NumItems(); i++)
    {
        attributeList[i].level = 0; 
        attributeList[i].data = 0;
    }   
}

ostream &operator << (ostream &s, const AttrRec &ar)
{
    s << ar.data << "@" << ar.level;
    
    return(s);
}

ostream &operator << (ostream &s, const AttrStackRec &asr)
{
    s << asr.attrRec << ":" << asr.attrType;

    return(s);
}

ostream &operator << (ostream &s, const SLContext &ctx)
{
    s << "SLContext at level " << ctx.level << ". Current attributes: " << endl;
    s << (AttrList &) ctx.attributeList << endl;
    s << "Attribute stack: " << endl << (AttrStackList &) ctx.attributeStack << endl;
    
    return(s);
}

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