#ifndef __GET_DRVS_H
#define __GET_DRVS_H

#include <string>
#include <map>

#include "eval.hh"


struct DrvInfo
{
private:
    string drvPath;
    string outPath;
    
public:
    string name;
    string system;

    ATermMap attrs;

    string queryDrvPath(EvalState & state) const
    {
        if (drvPath == "") {
            Expr a = attrs.get("drvPath");
            (string &) drvPath = a ? evalPath(state, a) : "";
        }
        return drvPath;
    }
    
    string queryOutPath(EvalState & state) const
    {
        if (outPath == "") {
            Expr a = attrs.get("outPath");
            if (!a) throw Error("output path missing");
            (string &) outPath = evalPath(state, a);
        }
        return outPath;
    }

    void setDrvPath(const string & s)
    {
        drvPath = s;
    }
    
    void setOutPath(const string & s)
    {
        outPath = s;
    }
};


typedef list<DrvInfo> DrvInfos;


/* Evaluate expression `e'.  If it evaluates to a derivation, store
   information about the derivation in `drv' and return true.
   Otherwise, return false. */
bool getDerivation(EvalState & state, Expr e, DrvInfo & drv);

void getDerivations(EvalState & state, Expr e, DrvInfos & drvs);


#endif /* !__GET_DRVS_H */