Big-Data-HPC-Platform/ecl/hqlcpp/hqltcppc2.cpp

/*##############################################################################

    Copyright (C) 2011 HPCC Systems.

    All rights reserved. This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
############################################################################## */
#include "jliball.hpp"
#include "hql.hpp"

#include "platform.h"
#include "jlib.hpp"
#include "jexcept.hpp"
#include "jmisc.hpp"

#include "hql.hpp"
#include "hqlexpr.hpp"
#include "hqlfunc.hpp"
#include "hqlcpputil.hpp"
#include "hqlfold.hpp"
#include "hqlutil.hpp"

#include "hqlstmt.hpp"
#include "hqlwcpp.hpp"
#include "hqlcpp.ipp"
#include "hqltcppc.ipp"
#include "hqlhtcpp.ipp"
#include "hqlcerrors.hpp"
#include "hqlcatom.hpp"
#include "hqlpmap.hpp"
#include "hqlthql.hpp"
#include "hqlattr.hpp"

//#define TraceExprPrintLog(x, expr)                PrintLog(x ": %s", expr->toString(StringBuffer()).str());

//---------------------------------------------------------------------------
CChildSetColumnInfo::CChildSetColumnInfo(CContainerInfo * _container, CMemberInfo * _prior, IHqlExpression * _column) : CColumnInfo(_container, _prior, _column)
{
}

void CChildSetColumnInfo::buildColumnExpr(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, CHqlBoundExpr & bound)
{
    OwnedHqlExpr address = getColumnAddress(translator, ctx, selector, boolType, 0);
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, sizeof(bool));
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(bool)+sizeof(size32_t));

    bound.isAll.setown(convertAddressToValue(address, boolType));
    bound.length.setown(convertAddressToValue(addressSize, sizetType));
    bound.expr.setown(convertAddressToValue(addressData, queryType()));
}

void CChildSetColumnInfo::gatherSize(SizeStruct & target)
{
    addVariableSize(sizeof(bool) + sizeof(size32_t), target);
}


IHqlExpression * CChildSetColumnInfo::buildSizeOfUnbound(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector)
{
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, sizeof(bool));

    OwnedHqlExpr length = convertAddressToValue(addressSize, sizetType);
    OwnedHqlExpr boundSize = translator.getBoundSize(column->queryType(), length, NULL);
    return createValue(no_translated, LINK(sizetType), adjustValue(boundSize, sizeof(bool)+sizeof(size32_t)));
}

void CChildSetColumnInfo::buildDeserialize(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * helper)
{
    OwnedHqlExpr address = getColumnAddress(translator, ctx, selector, boolType, 0);
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, sizeof(bool));
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(bool)+sizeof(size32_t));

    size32_t sizeExtra = sizeof(bool)+sizeof(size32_t);

    //Read the all flag and the size
    OwnedHqlExpr sizeAllSizet = getSizetConstant(sizeExtra);
    callDeserializeGetN(translator, ctx, helper, sizeAllSizet, address);

    OwnedHqlExpr targetSize = convertAddressToValue(addressSize, sizetType);
    OwnedHqlExpr unboundSize = createTranslated(targetSize);
    checkAssignOk(translator, ctx, selector, unboundSize, sizeExtra);

    callDeserializeGetN(translator, ctx, helper, targetSize, addressData);

    OwnedHqlExpr sizeOfExpr = createValue(no_sizeof, LINK(sizetType), LINK(selector->queryExpr()));
    OwnedHqlExpr srcSize = adjustValue(targetSize, sizeExtra);
    ctx.associateExpr(sizeOfExpr, srcSize);
}

bool CChildSetColumnInfo::buildReadAhead(HqlCppTranslator & translator, BuildCtx & ctx, ReadAheadState & state)
{
    OwnedHqlExpr sizeAllFlag = getSizetConstant(1);
    callDeserializerSkipInputTranslatedSize(translator, ctx, state.helper, sizeAllFlag);
    OwnedHqlExpr sizeOfItems = callDeserializerGetSize(translator, ctx, state.helper);
    callDeserializerSkipInputTranslatedSize(translator, ctx, state.helper, sizeOfItems);
    return true;
}



void CChildSetColumnInfo::setColumn(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * _value)
{
    OwnedHqlExpr address = getColumnAddress(translator, ctx, selector, boolType, 0);
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, sizeof(bool));
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(bool)+sizeof(size32_t));

    OwnedHqlExpr isAllTarget = convertAddressToValue(address, boolType);
    OwnedHqlExpr lengthTarget = convertAddressToValue(addressSize, sizetType);

    ITypeInfo * columnType = column->queryType();
    ITypeInfo * elementType = columnType->queryChildType();
    OwnedHqlExpr value = ensureExprType(_value, columnType);

    OwnedHqlExpr inlineSize;
    switch (value->getOperator())
    {
    case no_list:
        if ((value->numChildren() != 0) && ::isFixedSize(elementType))
            inlineSize.setown(getSizetConstant(value->numChildren() * elementType->getSize())); 
        break;
    }

    if (inlineSize)
    {
        checkAssignOk(translator, ctx, selector, inlineSize, sizeof(size32_t)+sizeof(bool));

        Owned<IHqlCppSetBuilder> builder = translator.createInlineSetBuilder(elementType, isAllTarget, inlineSize, addressData);
        builder->buildDeclare(ctx);

        translator.buildSetAssign(ctx, builder, value);

        CHqlBoundTarget boundTarget;
        boundTarget.length.set(lengthTarget);
        builder->buildFinish(ctx, boundTarget);
    }
    else
    {
        CHqlBoundExpr bound;
        if ((value->getOperator() == no_list) && value->numChildren())
        {
            CHqlBoundTarget tempTarget;
            translator.createTempFor(ctx, columnType, tempTarget, typemod_none, FormatNatural);
            translator.buildExprAssign(ctx, tempTarget, value);
            bound.setFromTarget(tempTarget);
        }
        else
            translator.buildExpr(ctx, value, bound);
        ensureSimpleLength(translator, ctx, bound);

        OwnedHqlExpr isAll = bound.getIsAll();
        OwnedHqlExpr length = translator.getBoundLength(bound);
        OwnedHqlExpr size = createValue(no_translated, LINK(sizetType), translator.getBoundSize(bound));
        checkAssignOk(translator, ctx, selector, size, sizeof(size32_t)+sizeof(bool));

        translator.assignBoundToTemp(ctx, isAllTarget, isAll);
        translator.assignBoundToTemp(ctx, lengthTarget, length);
        translator.buildBlockCopy(ctx, addressData, bound);

        ensureSimpleLength(translator, ctx, bound);
        OwnedHqlExpr boundSize = translator.getBoundSize(bound);
        associateSizeOf(ctx, selector, boundSize, sizeof(size32_t)+sizeof(bool));
    }
}

//---------------------------------------------------------------------------

IHqlExpression * CMemberInfo::addDatasetLimits(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * _value)
{
    LinkedHqlExpr value = _value;
    IHqlExpression * choosen = column->queryProperty(choosenAtom);
    if (choosen)
    {
        LinkedHqlExpr choosenValue = choosen->queryChild(0);
        if (!choosenValue->queryValue())
        {
            OwnedHqlExpr self = container->getRelativeSelf();
            OwnedHqlExpr absoluteExpr = replaceSelector(choosenValue, querySelfReference(), self);
            choosenValue.setown(selector->queryRootRow()->bindToRow(absoluteExpr, querySelfReference()));
        }
        else
        {
            if (hasNoMoreRowsThan(value, getIntValue(choosenValue)))
                choosenValue.clear();
        }

        if (choosenValue)
            value.setown(createDataset(no_choosen, LINK(value), LINK(choosenValue)));
    }

    IHqlExpression * maxCount = queryPropertyChild(column, maxCountAtom, 0);
    if (maxCount && !hasNoMoreRowsThan(value, getIntValue(maxCount)))
    {
        //Generate a limit test if there isn't a limit that ensures it is small enough
        StringBuffer failText, columnText;
        expandSelectPathText(columnText, true).toLowerCase();
        failText.appendf("Too many rows assigned to field %s", columnText.str());
        OwnedHqlExpr fail = translator.createFailAction(failText.str(), maxCount, NULL, translator.queryCurrentActivityId(ctx));
        value.setown(createDataset(no_limit, LINK(value), createComma(LINK(maxCount), LINK(fail))));
    }
    return value.getClear();
}


bool CMemberInfo::hasDatasetLimits() const
{
    if (column->queryProperty(choosenAtom))
        return true;

    if (queryPropertyChild(column, maxCountAtom, 0))
        return true;

    return false;
}

CChildDatasetColumnInfo::CChildDatasetColumnInfo(CContainerInfo * _container, CMemberInfo * _prior, IHqlExpression * _column, RecordOffsetMap & map, unsigned defaultMaxRecordSize) : CColumnInfo(_container, _prior, _column)
{
    ColumnToOffsetMap * offsetMap = map.queryMapping(column->queryRecord(), defaultMaxRecordSize);
    maxChildSize = offsetMap->getMaxSize();
#ifdef _DEBUG
    assertex(!recordRequiresSerialization(column->queryRecord()));
#endif
}

void CChildDatasetColumnInfo::buildColumnExpr(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, CHqlBoundExpr & bound)
{
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, 0);
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(size32_t));

    bound.length.setown(convertAddressToValue(addressSize, sizetType));
    bound.expr.setown(convertAddressToValue(addressData, queryType()));
}

void CChildDatasetColumnInfo::gatherSize(SizeStruct & target)
{
    addVariableSize(sizeof(size32_t), target);
}

void CColumnInfo::buildDeserializeChildLoop(HqlCppTranslator & translator, BuildCtx & loopctx, IReferenceSelector * selector, IHqlExpression * helper)
{
    OwnedHqlExpr endMarker = loopctx.getTempDeclare(sizetType, NULL);
    HqlExprArray args;
    args.append(*LINK(helper));
    OwnedHqlExpr beginCall = translator.bindTranslatedFunctionCall(deserializerBeginNestedAtom, args);
    loopctx.addAssign(endMarker, beginCall);

    args.append(*LINK(helper));
    args.append(*LINK(endMarker));
    OwnedHqlExpr loopCall = createBoolExpr(no_not, translator.bindTranslatedFunctionCall(deserializerFinishedNestedAtom, args));
    loopctx.addLoop(loopCall, NULL, false);
}

void CColumnInfo::buildDeserializeToBuilder(HqlCppTranslator & translator, BuildCtx & ctx, IHqlCppDatasetBuilder * builder, IReferenceSelector * selector, IHqlExpression * helper)
{
    BuildCtx loopctx(ctx);
    buildDeserializeChildLoop(translator, loopctx, selector, helper);

    BoundRow * selfRow = builder->buildDeserializeRow(loopctx, helper);
    builder->finishRow(loopctx, selfRow);
}


void CColumnInfo::buildDeserializeDatasetUsingBuilder(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * helper)
{
    Owned<IHqlCppDatasetBuilder> builder = translator.createBlockedDatasetBuilder(column->queryRecord());
    builder->buildDeclare(ctx);

    buildDeserializeToBuilder(translator, ctx, builder, selector, helper);

    CHqlBoundExpr bound;
    builder->buildFinish(ctx, bound);

    OwnedHqlExpr translated = bound.getTranslatedExpr();
    setColumn(translator, ctx, selector, translated);
}


void CChildDatasetColumnInfo::buildDeserialize(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * helper)
{
    IHqlExpression * record = column->queryRecord();

    if (recordRequiresSerialization(record))
    {
        buildDeserializeDatasetUsingBuilder(translator, ctx, selector, helper);
        return;
    }

    if (isConditional())
        checkAssignOk(translator, ctx, selector, queryZero(), sizeof(size32_t));

    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, 0);
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(size32_t));

    //Read the all flag and the size
    OwnedHqlExpr sizeSizet = getSizetConstant(sizeof(size32_t));
    callDeserializeGetN(translator, ctx, helper, sizeSizet, addressSize);

    OwnedHqlExpr targetSize = convertAddressToValue(addressSize, sizetType);
    OwnedHqlExpr simpleSize = translator.ensureSimpleTranslatedExpr(ctx, targetSize);
    OwnedHqlExpr unboundSize = createTranslated(simpleSize);
    checkAssignOk(translator, ctx, selector, unboundSize, sizeof(size32_t));

    callDeserializeGetN(translator, ctx, helper, simpleSize, addressData);

    OwnedHqlExpr sizeOfExpr = createValue(no_sizeof, LINK(sizetType), LINK(selector->queryExpr()));
    OwnedHqlExpr srcSize = adjustValue(simpleSize, sizeof(size32_t));
    ctx.associateExpr(sizeOfExpr, srcSize);
}


bool CChildDatasetColumnInfo::buildReadAhead(HqlCppTranslator & translator, BuildCtx & ctx, ReadAheadState & state)
{
    OwnedHqlExpr sizeOfDataset = callDeserializerGetSize(translator, ctx, state.helper);
    callDeserializerSkipInputTranslatedSize(translator, ctx, state.helper, sizeOfDataset);
    return true;
}


IHqlExpression * CChildDatasetColumnInfo::buildSizeOfUnbound(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector)
{
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, 0);
    OwnedHqlExpr length = convertAddressToValue(addressSize, sizetType);
    OwnedHqlExpr boundSize = translator.getBoundSize(column->queryType(), length, NULL);
    return createValue(no_translated, LINK(sizetType), adjustValue(boundSize, sizeof(size32_t)));
}

void CChildDatasetColumnInfo::setColumn(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * _value)
{
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, 0);
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(size32_t));

    OwnedHqlExpr lengthTarget = convertAddressToValue(addressSize, sizetType);

    ITypeInfo * columnType = column->queryType();
    OwnedHqlExpr value = LINK(_value); //ensureExprType(_value, columnType);
    ITypeInfo * valueType = value->queryType();

    assertex(recordTypesMatch(valueType, columnType));

    bool assignInline = false;  // canEvaluateInline(value);   // MORE: What is the test
//  bool assignInline = canAssignInline(&ctx, value) && !canEvaluateInline(&ctx, value);
    value.setown(addDatasetLimits(translator, ctx, selector, value));

    IHqlExpression * record = column->queryRecord();
    if (assignInline)
    {
        OwnedHqlExpr inlineSize = getSizetConstant(0);
        checkAssignOk(translator, ctx, selector, inlineSize, sizeof(size32_t));

        //Can only assign inline if we know the maximum length that will be assigned is 0.
        Owned<IHqlCppDatasetBuilder> builder = translator.createInlineDatasetBuilder(record, inlineSize, addressData);
        builder->buildDeclare(ctx);

        translator.buildDatasetAssign(ctx, builder, value);

        CHqlBoundTarget boundTarget;
        boundTarget.length.set(lengthTarget);
        builder->buildFinish(ctx, boundTarget);
    }
    else
    {
        CHqlBoundExpr bound;
        translator.buildDataset(ctx, value, bound, FormatBlockedDataset);
        translator.normalizeBoundExpr(ctx, bound);
        ensureSimpleLength(translator, ctx, bound);

        OwnedHqlExpr length = translator.getBoundLength(bound);
        OwnedHqlExpr size = createValue(no_translated, LINK(sizetType), translator.getBoundSize(bound));
        checkAssignOk(translator, ctx, selector, size, sizeof(size32_t));

        translator.assignBoundToTemp(ctx, lengthTarget, length);
        translator.buildBlockCopy(ctx, addressData, bound);

        //Use the size just calculated for the field
        OwnedHqlExpr sizeOfExpr = createValue(no_sizeof, LINK(sizetType), LINK(selector->queryExpr()));
        OwnedHqlExpr boundSize = translator.getBoundSize(bound);
        OwnedHqlExpr srcSize = adjustValue(boundSize, sizeof(size32_t));
        ctx.associateExpr(sizeOfExpr, srcSize);
    }
}

AColumnInfo * CChildDatasetColumnInfo::lookupColumn(IHqlExpression * search)
{
    throwError1(HQLERR_LookupNotActiveDataset, search->queryName()->str());
    return NULL;
}


//---------------------------------------------------------------------------

CChildLimitedDatasetColumnInfo::CChildLimitedDatasetColumnInfo(CContainerInfo * _container, CMemberInfo * _prior, IHqlExpression * _column, RecordOffsetMap & map, unsigned defaultMaxRecordSize) : CColumnInfo(_container, _prior, _column)
{
    IHqlExpression * count = column->queryProperty(countAtom);
    if (count)
        countField.setown(foldHqlExpression(column->queryProperty(countAtom)->queryChild(0)));
    else
    {
        IHqlExpression * size = column->queryProperty(sizeofAtom);
        if (size)
            sizeField.setown(foldHqlExpression(size->queryChild(0)));
        else
            countField.setown(createConstantOne());
    }
    if (countField)
        countField.setown(ensureExprType(countField, sizetType));
    if (sizeField)
        sizeField.setown(ensureExprType(sizeField, sizetType));
    ColumnToOffsetMap * offsetMap = map.queryMapping(column->queryRecord(), defaultMaxRecordSize);
    maxChildSize = offsetMap->getMaxSize();
    fixedChildSize = offsetMap->isFixedWidth() ? maxChildSize : UNKNOWN_LENGTH;
}

void CChildLimitedDatasetColumnInfo::buildColumnExpr(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, CHqlBoundExpr & bound)
{
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), 0);

    if (countField)
    {
        OwnedHqlExpr mappedCount = replaceSelector(countField, querySelfReference(), selector->queryExpr()->queryChild(0));
        CHqlBoundExpr boundCount;
        translator.buildExpr(ctx, mappedCount, boundCount);
        bound.count.set(boundCount.expr);
    }
    else
    {
        OwnedHqlExpr mappedSize = replaceSelector(sizeField, querySelfReference(), selector->queryExpr()->queryChild(0));
        CHqlBoundExpr boundSize;
        translator.buildExpr(ctx, mappedSize, boundSize);
        bound.length.set(boundSize.expr);
    }

    bound.expr.setown(convertAddressToValue(addressData, queryType()));
}

void CChildLimitedDatasetColumnInfo::gatherSize(SizeStruct & target)
{
    if (isFixedSize())
    {
        unsigned fixedSize;
        if (sizeField && sizeField->queryValue())
            fixedSize = (unsigned)getIntValue(sizeField);
        else
        {
            fixedSize = (unsigned)getIntValue(countField) * fixedChildSize;
        }

        if (isConditional())
            addVariableSize(fixedSize, target);
        else
            target.addFixed(fixedSize);
    }
    else
    {
        addVariableSize(0, target);
    }
}


IHqlExpression * CChildLimitedDatasetColumnInfo::buildSizeOfUnbound(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector)
{
    CHqlBoundExpr bound;
    buildColumnExpr(translator, ctx, selector, bound);
    OwnedHqlExpr length = translator.getBoundLength(bound);
    return createTranslated(length);
}

bool CChildLimitedDatasetColumnInfo::isFixedSize()
{
    if (sizeField && sizeField->queryValue())
        return true;
    if (countField && countField->queryValue() && (fixedChildSize != UNKNOWN_LENGTH))
        return true;
    return false;   //MORE:
}

void CChildLimitedDatasetColumnInfo::buildDeserializeChildLoop(HqlCppTranslator & translator, BuildCtx & loopctx, IReferenceSelector * selector, IHqlExpression * helper)
{
    OwnedHqlExpr mappedCount = replaceSelector(countField, querySelfReference(), selector->queryExpr()->queryChild(0));
    CHqlBoundExpr bound;
    translator.buildTempExpr(loopctx, mappedCount, bound);

    OwnedHqlExpr test = createValue(no_postdec, LINK(bound.expr));
    loopctx.addLoop(test, NULL, false);
}

bool CChildLimitedDatasetColumnInfo::prepareReadAhead(HqlCppTranslator & translator, ReadAheadState & state)
{
    OwnedHqlExpr self = container->getRelativeSelf();
    if (sizeField)
    {
        OwnedHqlExpr mappedSize = replaceSelector(sizeField, querySelfReference(), self);
        gatherSelectExprs(state.requiredValues, mappedSize);
    }
    else if (countField)
    {
        OwnedHqlExpr mappedCount = replaceSelector(countField, querySelfReference(), self);
        gatherSelectExprs(state.requiredValues, mappedCount);
    }
    return true;
}


bool CChildLimitedDatasetColumnInfo::buildReadAhead(HqlCppTranslator & translator, BuildCtx & ctx, ReadAheadState & state)
{
    try
    {
        OwnedHqlExpr self = container->getRelativeSelf();
        if (sizeField)
        {
            OwnedHqlExpr mappedSize = replaceSelector(sizeField, querySelfReference(), self);
            OwnedHqlExpr replacedSize = quickFullReplaceExpressions(mappedSize, state.requiredValues, state.mappedValues);
            if (containsSelector(replacedSize, queryRootSelf()))
                return false;
            callDeserializerSkipInputSize(translator, ctx, state. helper, replacedSize);
            return true;
        }
        else
        {
            OwnedHqlExpr mappedCount = replaceSelector(countField, querySelfReference(), self);
            OwnedHqlExpr replacedCount = quickFullReplaceExpressions(mappedCount, state.requiredValues, state.mappedValues);
            if (containsSelector(replacedCount, queryRootSelf()))
                return false;
            if (fixedChildSize != UNKNOWN_LENGTH)
            {
                OwnedHqlExpr scaledSize = multiplyValue(replacedCount, fixedChildSize);
                callDeserializerSkipInputSize(translator, ctx, state. helper, scaledSize);
                return true;
            }

            BuildCtx loopctx(ctx);
            CHqlBoundExpr bound;
            translator.buildTempExpr(loopctx, replacedCount, bound);

            OwnedHqlExpr test = createValue(no_postdec, LINK(bound.expr));
            loopctx.addLoop(test, NULL, false);

            StringBuffer prefetcherInstanceName;
            translator.ensureRowPrefetcher(prefetcherInstanceName, ctx, column->queryRecord());
            
            StringBuffer s;
            s.append(prefetcherInstanceName).append("->readAhead(");
            translator.generateExprCpp(s, state.helper).append(");");
            loopctx.addQuoted(s);
            return true;
        }
    }
    catch (IException * e)
    {
        //yuk yuk yuk!!  Couldn't resolve the dataset count/size for some strange reason
        e->Release();
    }
    return false;
}


void CChildLimitedDatasetColumnInfo::buildDeserialize(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * helper)
{
    if (sizeField || !countField)
    {
        ctx.addQuoted("rtlFailUnexpected();");
        return;
    }

    //NB: The serialized form of a dataset with an external count is not the same as a normal dataset
    IHqlExpression * record = column->queryRecord();
    if (recordRequiresSerialization(record) || !translator.isFixedRecordSize(record))
    {
        Owned<IHqlCppDatasetBuilder> builder = translator.createBlockedDatasetBuilder(column->queryRecord());
        builder->buildDeclare(ctx);

        buildDeserializeToBuilder(translator, ctx, builder, selector, helper);

        CHqlBoundExpr bound;
        builder->buildFinish(ctx, bound);

        setColumnFromBuilder(translator, ctx, selector, builder);
    }
    else
        CColumnInfo::buildDeserialize(translator, ctx, selector, helper);
}



void CChildLimitedDatasetColumnInfo::setColumn(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * value)
{
    if (sizeField)
        translator.throwError(HQLERR_CannotCreateSizedChildDataset);

    if (countField)
    {
        IHqlExpression * record = column->queryRecord();

        OwnedHqlExpr mappedCount = replaceSelector(countField, querySelfReference(), selector->queryExpr()->queryChild(0));
        Owned<IHqlCppDatasetBuilder> builder = translator.createLimitedDatasetBuilder(record, mappedCount);
        builder->buildDeclare(ctx);
        translator.buildDatasetAssign(ctx, builder, value);

        setColumnFromBuilder(translator, ctx, selector, builder);
    }
}

void CChildLimitedDatasetColumnInfo::setColumnFromBuilder(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlCppDatasetBuilder * builder)
{
    CHqlBoundExpr bound;
    builder->buildFinish(ctx, bound);
    if (bound.length)
        bound.length.setown(translator.ensureSimpleTranslatedExpr(ctx, bound.length));

    OwnedHqlExpr size = createValue(no_translated, LINK(sizetType), translator.getBoundSize(bound));
    checkAssignOk(translator, ctx, selector, size, 0);

    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), 0);
    translator.buildBlockCopy(ctx, addressData, bound);

    //Use the size just calculated for the field
    OwnedHqlExpr sizeOfExpr = createValue(no_sizeof, LINK(sizetType), LINK(selector->queryExpr()));
    OwnedHqlExpr srcSize = translator.getBoundSize(bound);
    ctx.associateExpr(sizeOfExpr, srcSize);
}

AColumnInfo * CChildLimitedDatasetColumnInfo::lookupColumn(IHqlExpression * search)
{
    throwError1(HQLERR_LookupNotActiveDataset, search->queryName()->str());
    return NULL;
}

//--------------------------------------------------------------------------------------------

CChildLinkedDatasetColumnInfo::CChildLinkedDatasetColumnInfo(CContainerInfo * _container, CMemberInfo * _prior, IHqlExpression * _column, RecordOffsetMap & map, unsigned defaultMaxRecordSize) : CColumnInfo(_container, _prior, _column)
{
    ColumnToOffsetMap * offsetMap = map.queryMapping(column->queryRecord(), defaultMaxRecordSize);
    maxChildSize = offsetMap->getMaxSize();
}

void CChildLinkedDatasetColumnInfo::buildColumnExpr(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, CHqlBoundExpr & bound)
{
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, 0);
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(size32_t));

    bound.count.setown(convertAddressToValue(addressSize, sizetType));
    bound.expr.setown(convertAddressToValue(addressData, queryType()));
}

void CChildLinkedDatasetColumnInfo::gatherSize(SizeStruct & target)
{
    unsigned thisSize = sizeof(size32_t) + sizeof(byte * *);
    if (isConditional())
        addVariableSize(thisSize, target);      // the size is used for ensure if condition is true
    else
        target.addFixed(thisSize);
}


IHqlExpression * CChildLinkedDatasetColumnInfo::buildSizeOfUnbound(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector)
{
    return getSizetConstant(sizeof(size32_t) + sizeof(byte * *));
}

void CChildLinkedDatasetColumnInfo::buildDeserialize(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * helper)
{
    if (isConditional())
        checkAssignOk(translator, ctx, selector, queryZero(), sizeof(size32_t) + sizeof(byte * *));

    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, 0);
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(size32_t));

    IHqlExpression * record = column->queryRecord();
    CHqlBoundTarget boundTarget;
    boundTarget.count.setown(convertAddressToValue(addressSize, sizetType));
    boundTarget.expr.setown(convertAddressToValue(addressData, queryType()));

    HqlExprArray args;
    args.append(*translator.createRowSerializer(ctx, record, deserializerAtom));
    args.append(*LINK(helper));
    OwnedHqlExpr call = translator.bindFunctionCall(deserializerRowsetHelperAtom, args, queryType());
    translator.buildExprAssign(ctx, boundTarget, call);
}


bool CChildLinkedDatasetColumnInfo::buildReadAhead(HqlCppTranslator & translator, BuildCtx & ctx, ReadAheadState & state)
{
    OwnedHqlExpr sizeOfDataset = callDeserializerGetSize(translator, ctx, state.helper);
    callDeserializerSkipInputTranslatedSize(translator, ctx, state.helper, sizeOfDataset);
    return true;
}



void CChildLinkedDatasetColumnInfo::buildSerialize(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * helper)
{
    IHqlExpression * record = column->queryRecord();

    HqlExprArray args;
    args.append(*LINK(helper));
    args.append(*translator.createRowSerializer(ctx, record, serializerAtom));
    args.append(*LINK(selector->queryExpr()));
    OwnedHqlExpr call = translator.bindTranslatedFunctionCall(serializerRowsetHelperAtom, args);
    translator.buildStmt(ctx, call);
}



bool CChildLinkedDatasetColumnInfo::modifyColumn(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * value, node_operator op)
{
    if (hasDatasetLimits() || (op != no_assign_addfiles))
        return false;

    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, 0);
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(size32_t));

    ITypeInfo * resultType = queryType();
    ITypeInfo * valueType = value->queryType();
    assertex(recordTypesMatch(valueType, resultType));

    CHqlBoundTarget boundTarget;
    boundTarget.count.setown(convertAddressToValue(addressSize, sizetType));
    boundTarget.expr.setown(convertAddressToValue(addressData, queryType()));

    HqlExprArray args;
    args.append(*LINK(value));
    OwnedHqlExpr call = translator.bindFunctionCall(appendRowsToRowsetAtom, args, resultType);
    translator.buildDatasetAssign(ctx, boundTarget, call);
    return true;
}


void CChildLinkedDatasetColumnInfo::setColumn(HqlCppTranslator & translator, BuildCtx & ctx, IReferenceSelector * selector, IHqlExpression * _value)
{
    OwnedHqlExpr addressSize = getColumnAddress(translator, ctx, selector, sizetType, 0);
    OwnedHqlExpr addressData = getColumnAddress(translator, ctx, selector, queryType(), sizeof(size32_t));

    ITypeInfo * resultType = queryType();
    LinkedHqlExpr value = _value;
    ITypeInfo * valueType = value->queryType();

    assertex(recordTypesMatch(valueType, resultType));

    value.setown(addDatasetLimits(translator, ctx, selector, value));

    CHqlBoundTarget boundTarget;
    boundTarget.count.setown(convertAddressToValue(addressSize, sizetType));
    boundTarget.expr.setown(convertAddressToValue(addressData, queryType()));

    if (value->getOperator() == no_null)
        value.setown(createNullExpr(resultType));
    
    translator.buildDatasetAssign(ctx, boundTarget, value);
}

AColumnInfo * CChildLinkedDatasetColumnInfo::lookupColumn(IHqlExpression * search)
{
    throwError1(HQLERR_LookupNotActiveDataset, search->queryName()->str());
    return NULL;
}