TemplateStream.h

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/****
 * Sming Framework Project - Open Source framework for high efficiency native ESP8266 development.
 * Created 2015 by Skurydin Alexey
 * http://github.com/SmingHub/Sming
 * All files of the Sming Core are provided under the LGPL v3 license.
 *
 * TemplateStream.h
 *
 ****/

#pragma once

#include "DataSourceStream.h"
#include "WHashMap.h"
#include "WString.h"

#ifndef TEMPLATE_MAX_VAR_NAME_LEN

#define TEMPLATE_MAX_VAR_NAME_LEN 32
#endif

class TemplateStream : public IDataSourceStream
{
public:
    using Variables = HashMap<String, String>;

    using GetValueDelegate = Delegate<String(const char* name)>;

    TemplateStream(IDataSourceStream* stream, bool owned = true)
        : stream(stream), streamOwned(owned), doubleBraces(false)

    {
        reset();
    }

    ~TemplateStream()
    {
        if(streamOwned) {
            delete stream;
        }
    }

    StreamType getStreamType() const override
    {
        return stream ? eSST_Template : eSST_Invalid;
    }

    uint16_t readMemoryBlock(char* data, int bufSize) override;

    int seekFrom(int offset, SeekOrigin origin) override;

    bool isFinished() override
    {
        return stream ? stream->isFinished() : true;
    }

    void setVar(const String& name, const String& value)
    {
        templateData[name] = value;
    }

    void setVars(const Variables& vars)
    {
        templateData.setMultiple(vars);
    }

    Variables& variables()
    {
        return templateData;
    }

    String getName() const override
    {
        return stream ? stream->getName() : nullptr;
    }

    void onGetValue(GetValueDelegate callback)
    {
        getValueCallback = callback;
    }

    void enableOutput(bool enable)
    {
        enableNextState = enable;
    }

    bool isOutputEnabled() const
    {
        return outputEnabled;
    }

    void setDoubleBraces(bool enable)
    {
        doubleBraces = enable;
    }

    virtual String evaluate(char*& expr);

    String eval(String expr)
    {
        char* p = expr.begin();
        return evaluate(p);
    }

    virtual String getValue(const char* name);

private:
    void reset()
    {
        value = nullptr;
        streamPos = 0;
        valuePos = 0;
        valueWaitSize = 0;
        tagLength = 0;
        sendingValue = false;
        outputEnabled = true;
        enableNextState = true;
    }

    IDataSourceStream* stream;
    Variables templateData;
    GetValueDelegate getValueCallback;
    String value;
    uint32_t streamPos;     
    uint16_t valuePos;      
    uint16_t valueWaitSize; 
    uint8_t tagLength;
    bool streamOwned : 1;
    bool sendingValue : 1;
    bool outputEnabled : 1;
    bool enableNextState : 1;
    bool doubleBraces : 1;
};