interpreter.java

一个简单的数据库

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package interpreterManager;
import apiManager.*;
import database.OperationInfo;
import database.*;
import fileManager.*;
import java.io.*;
import stringManager.*;
import java.lang.Exception;
import java.util.*;
import javax.swing.JOptionPane;
import bufferedManager.*;
import catalogManager.*;
/**
 *
 * @author outlaw
 */
public class Interpreter {
    public Interpreter(){
    }
    public static void createDataBase(String instr) throws Exception{
        try
        {
            String[] pathAndName=null;
            pathAndName=StringManager.operCreateDB(instr.substring( instr.indexOf("database")+8).trim());
            ArrayList<String> dbNames=CatalogManager.getAllDBName();
            for(int i=0;i<dbNames.size();i++)
            {
                if(dbNames.get(i).equals(pathAndName[1]))
                    throw new OperationInfo("Creating database error!:Creating a database with the same name:["+pathAndName[1]+"]");
            }
            APIManager.createDataBase(pathAndName[0], pathAndName[1]);    
        }catch(Exception ex)
        {
            throw ex;
        }
    }
    public static void createTable(String instr) throws Exception{
        ArrayList<String> attribNames=new ArrayList<String>();
        ArrayList<String> attribTypes=new ArrayList<String>();
        ArrayList<Integer>  features=new ArrayList<Integer>();
        StringBuilder tbName=new StringBuilder();
        StringManager.operCreateTB(instr.substring(instr.indexOf("table")+5).trim(),tbName,attribNames, attribTypes, features);
        if(attribNames.size()<1||attribNames.size()>32)
            throw new OperationInfo("Too few or too many attributes defined in the table :["+tbName+"]");
        TableData tb=CatalogManager.getTableByName(tbName.toString());
        if(tb!=null)
            throw new OperationInfo("Creating table["+tbName+"] error!You have a table with the same name!");
        APIManager.createTable(tbName.toString(),attribNames,attribTypes,features);
    }
    public static void insertTuple(String instr) throws Exception
    {
        //values的最后一个是它所在的table name
        //这个函数还可以改进，从而不需建立一个新的String的数组tempValues，减小开销。
        String[] tempValues=null,values=null;
        tempValues=StringManager.operInsertTuple(instr);
        values=new String[tempValues.length-1];
        int len=values.length;
        for(int i=0;i<len;i++)
        {
            values[i]=tempValues[i];
        }
        APIManager.insertTuple(values,tempValues[len]);
    }
    public static void execFile(String fullName) throws Exception
    {
        StringBuilder sb=new StringBuilder();
        String data=null;
        String[] instrs=null;
        FileInputStream fis=new FileInputStream(fullName);
        BufferedReader br=new BufferedReader(new InputStreamReader(fis));
        while((data=br.readLine())!=null)
        {
            sb.append(data);
        }
        instrs=sb.toString().split("create");
        for(int i=1;i<instrs.length;i++)
        {
            createTable("create "+instrs[i]);
        }
    }
    public static void quit() throws Exception
    {
        APIManager.quit();
    }
    public static void select(String instr) throws Exception
    {
        StringBuilder builder2=new StringBuilder();
        ArrayList<Integer> pos=new ArrayList<Integer>();
        ArrayList<Tuple> tuples=StringManager.operaSelect(instr,builder2,pos);
        if(tuples==null||tuples.size()==0)
            throw new Success("There are no tuples found!");
        String[] temp=builder2.toString().split(",");
        
        StringBuilder builder=new StringBuilder();
        for(int i=0;i<temp.length;i++)
        {
            String t=temp[i].trim();
            int len=t.length();
            builder.append(t);
            for(int j=0;j<15-len;j++)
                builder.append(" ");
        }
        builder.append("\n");
        int size=tuples.size();
        for(int i=0;i<size;i++)
        {
            String[] values=tuples.get(i).getValues();
            /*for(int j=0;j<values.length;j++)
            {
                String value=values[j];
                int len=value.length();
                builder.append(value);
                for(int k=0;k<15-len;k++)
                    builder.append(" ");
            }
            */
            for(int j=0;j<pos.size();j++)
            {
                String value=values[pos.get(j)];
                int len=value.length();
                builder.append(value);
                for(int k=0;k<15-len;k++)
                    builder.append(" ");
            }
            builder.append("\n");
        }
        throw new Success(builder.toString());
    }
    public static void createIndex(String instr) throws Exception
    {
        String[] params;
        params=StringManager.operCreateIndex(instr.substring(instr.indexOf("index")+5).trim());
        APIManager.createIndex(params,true);
    }
    public static void dropTable(String instr) throws Exception
    {
        String tbName;
        tbName=StringManager.operaDropTable(instr);
        APIManager.dropTable(tbName);
    }
    public static void dropIndex(String instr) throws Exception
    {
        String indName;
        StringManager.operaDropIndex(instr);
    }
    public static void deleteTuple(String instr) throws Exception
    {
        StringManager.operaDelete(instr.substring(0,instr.indexOf(";")).trim());
    }

    /*public static ArrayList<String>  engine(String instr) throws Exception
    {
        String[] keyWord={"create","insert","select","delete","drop"};
        int[] len={6,6,6,6,4};
        instr=instr.trim();
        int id;
        String command=null;
        ArrayList<String> commands=new ArrayList<String>();
        int smallIndex;
        while(instr.length()!=0)
        {
            instr=instr.trim();
            int i;
            smallIndex=10000;
            for(i=0;i<keyWord.length;i++)
            {
                String keyword=keyWord[i];
                int index=instr.indexOf(keyword,1);
                if(index!=-1&&index!=0&&index<smallIndex)
                {
                    smallIndex=index;
                }
            }
            if(smallIndex==10000)
            {
                commands.add(instr);
                break;
            }
            else
            {
                command=instr.substring(0,smallIndex);
                commands.add(command);
                instr=instr.substring(smallIndex);
            }
        }
        return commands;
    }*/
    
    public static ArrayList<String>  engine(String instr) throws Exception
    {
        instr=instr.trim();
        ArrayList<String> commands=new ArrayList<String>();
        if(instr.indexOf(";")==-1)
        {
            commands.add(instr);
            return commands;
        }
        String[] temp=instr.split(";");
        boolean isLeft=false;
        String t=instr.substring(instr.lastIndexOf(";")+1);
        if(t.trim().length()!=0)
            isLeft=true;
        if(isLeft)
        {
            for(int i=0;i<temp.length-2;i++)
            {
                temp[i]+=";";
                commands.add(temp[i]);
            }
            commands.add(temp[temp.length-2]+";"+temp[temp.length-1]);
        }
        else
        {
            for(int i=0;i<temp.length;i++)
            {
                temp[i]+=";";
                commands.add(temp[i]);
            }
        }
           
        return commands;
    }
    public static void dispatchInstr(String instr) throws Exception
    {
        instr=instr.trim();
        String instr_case_no_sense=instr;
        instr=instr.toLowerCase();
        
        if(!StringManager.verifySemicolon(instr))
            throw new OperationInfo("SQL syntax error!\nSemicolon not satisfied!" +
                    "\n");
        if(!StringManager.verifyBracket(instr))
            throw new OperationInfo("The bracket of this command:["+instr+"]is not balanced!");
        
        if(instr.indexOf("create")!=-1&&instr.substring(0,6).equals("create"))
        {
            String TblOrInd;
            try
            {
                TblOrInd=instr.substring(6).trim().substring(0,5);
            }catch(Exception ex)
            {
                throw new OperationInfo("Syntax error!");
            }
            if(instr.substring(6).trim().substring(0,8).equals("database"))
            {
                try
                {
                    createDataBase(instr);
                }catch(Exception ex)
                {
                    throw ex;
                }
            }else if(TblOrInd.equals("table"))
            {
                createTable(instr);
            }else if(TblOrInd.equals("index"))
            {
                createIndex(instr);
            }else 
                throw new OperationInfo("Create instruction sytax error!");
        }
        else if(instr.indexOf("drop")!=-1&&instr.substring(0,4).equals("drop"))
        {
            String TblOrInd;
            try
            {
                TblOrInd=instr.substring(4).trim().substring(0,5);
            }catch(Exception ex)
            {
                throw new OperationInfo("Syntax error!");
            }
            if(TblOrInd.equals("table"))
            {
                dropTable(instr);
            }
            else if(TblOrInd.equals("index"))
            {
                dropIndex(instr);
            }
            else 
                throw new OperationInfo("Drop instruction syntax error!");
        }
        else if(instr.indexOf("select")!=-1&&instr.substring(0,6).equals("select"))
        { 
            select(instr_case_no_sense);
        }
        else if(instr.indexOf("insert")!=-1&&instr.substring(0,6).equals("insert"))
        {
            insertTuple(instr_case_no_sense);
        }
        else if(instr.indexOf("delete")!=-1&&instr.substring(0,6).equals("delete"))
        {
            if(instr.substring(6).indexOf("from")!=-1)
                deleteTuple(instr_case_no_sense);
            else
                throw new OperationInfo("Delete syntax error!No 'from' in this instruction");
        }
        else if(instr.indexOf("execfile")!=-1)
        {
            execFile(instr.substring(instr.indexOf("execfile")+8,instr.indexOf(";")).trim());
        }
        else if(instr.indexOf("quit")!=-1&&instr.substring(0,instr.indexOf(";")).trim().equals("quit"))
        {
            quit();
        }
        else
            throw new OperationInfo("Instruction syntax error!");
    }
}