rowsubst.java

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package MyNa.utils;

import java.io.BufferedReader;
import java.io.PrintWriter;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Hashtable;
import java.util.Enumeration;

/* given a template file, a resultset, and prior name->value pairs,
 we want to substitute values for names, at least supporting:
$$SUBSTD:$:  $FieldName1$ for $Parameter1$ is $FieldValue1$
$$SUBSTDERR:$: There was no $FieldName1$ for $Parameter1$.

in this line, the "D" stands for Data, indicating that there
has to be actual query-result data (or update-data, in which
case only NumberAffected will be defined by the query.) Here,
when we look up JoeSchmoe's number 123-4567, the SUBSTD line
will be sent to the browser as a line reading

   THENUMBER for JoeSchmoe is 123-4567

 For SELECT * FROM PHONEBOOK we probably want

<TABLE BORDER=1>
$$SUBST:$: <TR><TH>$FieldName1$</TH><TH>$FieldName2$</TH></TR>
$$SUBSTD*:$:<TR><TD>$FieldValue1$</TH><TH>$FieldValue2$</TH></TR>
</TABLE>

*/


public class RowSubst {
  RowSequence theRows; Env theInitEnv; Logger lg;
  String theFileName;   BufferedReader theInput; 
  PrintWriter theOutput; boolean dataFailed;
  String theCommandPrefix="$$SUBST";
  String SUBST="";
  String SUBSTD="D";
  String SUBSTDERR="DERR";
  String SUBSTDSTAR="D*";

public RowSubst(String fName,RowSequence rows,PrintWriter out) {
  this(newReader(fName),rows,out);
  theFileName=fName;
}
public static BufferedReader newReader(String fName){
  BufferedReader bR; 
  try{bR=new BufferedReader(new FileReader(fName));}
  catch(FileNotFoundException Ex){return null;}
  return bR;
}
public RowSubst(BufferedReader brin,RowSequence rows,PrintWriter out) {
  theInput=brin; theOutput=out; theRows=rows;
  theInitEnv=rows.getRow(); 
//  lg=new Logger("C:\\MyNa\\rs.log"); lg.clearLog();
  dataFailed=false; 
  }
  
public String interpretLine(String L){
  if(L==null)return "";
  if(!L.startsWith(theCommandPrefix))return L;
  try{
    int cmdBegin=theCommandPrefix.length();
    int cmdEnd=L.indexOf(':');
    int delimEnd=L.indexOf(':',1+cmdEnd);
    String cmd=L.substring(cmdBegin,cmdEnd);
    String delim=L.substring(1+cmdEnd,delimEnd);
    L=L.substring(1+delimEnd,L.length());
    if(SUBST.equals(cmd)){
      return Misc.stringDelimSubst(L,delim,theInitEnv);
    } else if (SUBSTD.equals(cmd)){
      if(theRows.next())
         return Misc.stringDelimSubst(L,delim,theRows.getRow());
      else {dataFailed=true; return "";}
    } else if (SUBSTDERR.equals(cmd)){
      if(!dataFailed)return "";
      else return Misc.stringDelimSubst(L,delim,theInitEnv);
    }else if (SUBSTDSTAR.equals(cmd)){
      String S="";
      while(theRows.next())
         S+=Misc.stringDelimSubst(L,delim,theRows.getRow())+"\n";
      return S;
    } else return L;
    }catch(Exception E){}
  return L;
}

public void interpret(){
  String nextLine;
  if(theInput==null)return;
  try{
  while(null!=(nextLine=theInput.readLine()))
    theOutput.println(interpretLine(nextLine));
  theInput.close();
  // note that theOutput _may_ continue with other stuff.
  }catch(IOException e)
       {try{theInput.close();}catch(IOException ex){}}
}

}