command.cpp

FastDb是高效的内存数据库系统

// -*- Mode: C++ -*-

//         command.cpp
//
// Copyright (c) 1996, Regents of the University of California
// $Header: /cvsroot/fastdb/fastdb/GiST/BTree/command.cpp,v 1.1 2007/07/18 20:45:46 knizhnik Exp $

#include <stdio.h>
#include <fstream.h>
#ifdef UNIX
#include <unistd.h>
#endif

#include "BT.h"
#include "command.h"


struct Table
{
    char *name;
    GiST *gist;
};

#define MAX_TABLES 10
#define NOT_FOUND (-1)

dbDatabase db;

REGISTER(Record);

Table tables[MAX_TABLES];
int numTables = 0;
int debug = 0;

int GetTable(const char *name)
{
    int i;

    for (i=0; i<numTables; i++)
	if (!strcmp(tables[i].name, name))
	    break;
    return i == numTables ? NOT_FOUND : i;
}

void CommandCreate(const char *method,
		   const char *table)
{
    if (numTables == MAX_TABLES) {
	cout << "This progam can only handle "<<MAX_TABLES<<" open tables.\n";
	return;
    }

    if (GetTable(table) != NOT_FOUND) {
	cerr << "Table already open!\n";
	return;
    }

    if (strcmp(method, "btree")) {
	cerr << "The only supported method is btree.\n";
	return;
    }

    GiST *gist = new BT(db);

    gist->Create(table);
    if (!gist->IsOpen()) {
	cout << "Error opening table.\n";
	delete gist;
	return;
    }

    cout << "Table " << table << " created as type " << method << ".\n";

    tables[numTables].name = strdup(table);
    tables[numTables].gist = gist;
    numTables++;
}

void CommandDrop(const char *table)
{
    if (GetTable(table) != NOT_FOUND) {
	cerr << "Cannot drop an open table.\n";
	return;
    }
    cout << "Table " << table << " dropped.\n";
}

void CommandOpen(const char *method, const char *table)
{
    if (numTables == MAX_TABLES) {
	cout << "This progam can only handle "<<MAX_TABLES<<" open tables.\n";
	return;
    }

    if (GetTable(table) != NOT_FOUND) {
	cout << "Table already open!\n";
	return;
    }

	if (strcmp(method, "btree")) {
	cerr << "The only supported method is btree.\n";
	return;
    }

    GiST *gist = new BT(db);

    gist->Open(table);

    if (!gist->IsOpen()) {
	delete gist;
	cout << "Error opening table.\n";
	return;
    }

    cout << "Table " << table << " opened.\n";

    tables[numTables].gist = gist;
    tables[numTables].name = strdup(table);
    numTables++;
}

void CommandClose(const char *table)
{
    int i;

    i = GetTable(table);
    if (i == NOT_FOUND) {
	cerr << "Table is not open.\n";
	return;
    }

    cout << "Table " << table << " closed.\n";
    delete tables[i].gist;

    for ( ; i < numTables-1; i++)
	tables[i] = tables[i+1];
    numTables--;
}

void CommandSelect(const char *table,
		   const GiSTpredicate& pred)
{
    int i;

    i = GetTable(table);
    if (i == NOT_FOUND) {
	cerr << "Table is not open!\n";
	return;
    }

    GiST *gist = tables[i].gist;

    GiSTcursor *c = gist->Search(pred);
    GiSTentry *e;
    dbCursor<Record> cursor;
    while ((e = c->Next()) != NULL) {
	dbReference<Record> ref(e->Ptr());
	cursor.at(ref);
	cout << cursor->value << "\n";
	delete e;
    }
    delete c;
}

void CommandDelete(const char *table,
		   const GiSTpredicate &pred)
{
    int i;

    if ((i = GetTable(table)) == NOT_FOUND) {
	cerr << "Table not open!\n";
	return;
    }

    if (i != NOT_FOUND)
	tables[i].gist->Delete(pred);
}

void CommandInsert(const char  *table,
		   const BTkey& key,
		   int          value)
{
    int i;

    if ((i = GetTable(table)) == NOT_FOUND) {
	cerr << "Table not open!\n";
	return;
    }

    Record rec;
    rec.value = value;
    dbReference<Record> ref = insert(rec);
    GiST *gist = tables[i].gist;
    gist->Insert(BTentry(key, ref.getOid()));
    cout << "(" << key << ", " << value << ") inserted into " << table << ".\n";
}

void CommandQuit()
{
    for (int i=0; i<numTables; i++)
	delete tables[i].gist;
    cout << "Goodbye.\n";
    db.close();
    exit(0);
}

void CommandPrompt()
{
    cout << "BTree> ";
	cout.flush();
}

void CommandDebug()
{
    debug = !debug;
    cout << "Debugging Output ";
    cout << (debug ? "ON\n" : "OFF\n");
}

void CommandHelp()
{
    ifstream is("BTree.help");
    char c;

    while (is.get(c)) cout << c;
}

void CommandDump(const char *table, GiSTpage page)
{
    int i;

    if ((i = GetTable(table)) == NOT_FOUND) {
	cout << "No such table is open.\n";
	return;
    }

    GiSTpath path;
    path.MakeRoot();
#ifdef PRINTING_OBJECTS
    tables[i].gist->DumpNode(cout, path);
#endif
}

int yyparse();

int main()
{
    cout << "**  BTree: A B+-tree implementation based on Generalized Search Trees\n";
    cout << "Type \"help\" for a list of commands.\n\n";
    if (db.open("tstbtree")) { 
	CommandPrompt();
	yyparse();
	return 0;
    } else { 
	return 1;
    }
}