query.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2005
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: query.c,v 1.12 2005/10/14 12:53:07 bostic Exp $
 */

#include "csv.h"
#include "csv_local.h"
#include "csv_extern.h"

static int query_by_field(char *);
static int query_fieldlist(char *);
static int query_help(char *);
static int query_usage(void);

typedef struct _cmdtab {
        char    *cmd;                   /* Command name */
        int     (*f)(char *);           /* Underlying function. */
        char    *help;                  /* Help message. */
} CMDTAB;

static CMDTAB cmdtab[] = {
        { "?",
                query_help,
                "?\t\tDisplay help screen" },
        { "exit",
                NULL,
                "exit\t\tExit program" },
        { "fields",
                query_fieldlist,
                "fields\t\tDisplay list of field names" },
        { "help",
                query_help,
                "help\t\tDisplay help screen" },
        { "quit",
                NULL,
                "quit\t\tExit program" },
        { NULL,
                query_by_field,
    "field[op]value\tDisplay fields by value (=, !=, <, <=, >, >=, ~, !~)" },
        { NULL,         NULL,           NULL }
};

/*
 * query_interactive --
 *      Allow the user to interactively query the database.
 */
int
query_interactive()
{
        int done;
        char *p, input[256];

        for (;;) {
                printf("Query: ");
                (void)fflush(stdout);
                if (fgets(input, sizeof(input), stdin) == NULL) {
                        printf("\n");
                        if (ferror(stdin)) {
                                dbenv->err(dbenv, errno,
                                    "error occurred reading from stdin");
                                return (1);
                        }
                        break;
                }
                if ((p = strchr(input, '\n')) == NULL) {
                        dbenv->errx(dbenv, "input buffer too small");
                        return (1);
                }
                *p = '\0';
                if (query(input, &done) != 0)
                        return (1);
                if (done != 0)
                        break;
        }
        return (0);
}

/*
 * query --
 *      Process a query.
 */
int
query(char *cmd, int *donep)
{
        CMDTAB *p;

        if (donep != NULL)
                *donep = 0;

        for (p = cmdtab; p->cmd != NULL; ++p)
                if (p->cmd != NULL &&
                    strncasecmp(cmd, p->cmd, strlen(p->cmd)) == 0)
                        break;

        if (p->cmd == NULL)
                return (query_by_field(cmd));

        if (p->f == NULL) {
                if (donep != NULL)
                        *donep = 1;
                return (0);
        }

        return (p->f(cmd));
}

/*
 * query_by_field --
 *      Query the primary database by field.
 */
static int
query_by_field(char *input)
{
        OPERATOR operator;
        size_t len;
        char *field, *op, *value;

        /*
         * We expect to see "field [op] value" -- figure it out.
         *
         * Skip leading whitespace.
         */
        while (isspace(*input))
                ++input;

        /*
         * Find an operator, and it better not start the string.
         */
        if ((len = strcspn(field = input, "<>!=~")) == 0)
                return (query_usage());
        op = field + len;

        /* Figure out the operator, and find the start of the value. */
        switch (op[0]) {
        case '~':
                operator = WC;
                value = op + 1;
                break;
        case '!':
                if (op[1] == '=') {
                        operator = NEQ;
                        value = op + 2;
                        break;
                }
                if (op[1] == '~') {
                        operator = NWC;
                        value = op + 2;
                        break;
                }
                return (query_usage());
        case '<':
                if (op[1] == '=') {
                        operator = LTEQ;
                        value = op + 2;
                } else {
                        operator = LT;
                        value = op + 1;
                }
                break;
        case '=':
                operator = EQ;
                if (op[1] == '=')
                        value = op + 2;
                else
                        value = op + 1;
                break;
        case '>':
                if (op[1] == '=') {
                        operator = GTEQ;
                        value = op + 2;
                } else {
                        operator = GT;
                        value = op + 1;
                }
                break;
        default:
                return (query_usage());
        }

        /* Terminate the field name, and there better be a field name. */
        while (--op > input && isspace(*op))
                ;
        if (op == input)
                return (query_usage());
        op[1] = '\0';

        /* Make sure there is a value field. */
        while (isspace(*value))
                ++value;
        if (*value == '\0')
                return (query_usage());

        return (DbRecord_search_field_name(field, value, operator));
}

/*
 * query_fieldlist --
 *      Display list of field names.
 */
static int
query_fieldlist(char *input)
{
        DbField *f;

        input = input;                          /* Quiet compiler. */

        for (f = fieldlist; f->name != NULL; ++f)
                printf("field %3d: %s\n", f->fieldno, f->name);
        return (0);
}

/*
 * query_help --
 *      Query command list.
 */
static int
query_help(char *input)
{
        CMDTAB *p;

        input = input;                          /* Quiet compiler. */

        printf("Query commands:\n");
        for (p = cmdtab; p->help != NULL; ++p)
                printf("\t%s\n", p->help);
        return (0);
}

/*
 * query_usage --
 *      Query usage message.
 */
static int
query_usage(void)
{
        fprintf(stderr, "%s: query syntax error\n", progname);
        return (query_help(NULL));
}

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