DBM

Class

Introduction

The DBM class provides a wrapper to a Unix-style dbm or Database Manager library.

Dbm databases do not have tables or columns; they are simple key-value data stores, like a Ruby Hash except not resident in RAM. Keys and values must be strings.

The exact library used depends on how Ruby was compiled. It could be any of the following:

The original ndbm library is released in 4.3BSD. It is based on dbm library in Unix Version 7 but has different API to support multiple databases in a process.
Berkeley DB versions 1 thru 6, also known as BDB and Sleepycat DB, now owned by Oracle Corporation.
Berkeley DB 1.x, still found in 4.4BSD derivatives (FreeBSD, OpenBSD, etc).
gdbm, the GNU implementation of dbm.
qdbm, another open source reimplementation of dbm.

All of these dbm implementations have their own Ruby interfaces available, which provide richer (but varying) APIs.

Cautions

Before you decide to use DBM, there are some issues you should consider:

Each implementation of dbm has its own file format. Generally, dbm libraries will not read each other’s files. This makes dbm files a bad choice for data exchange.
Even running the same OS and the same dbm implementation, the database file format may depend on the CPU architecture. For example, files may not be portable between PowerPC and 386, or between 32 and 64 bit Linux.
Different versions of Berkeley DB use different file formats. A change to the OS may therefore break DBM access to existing files.
Data size limits vary between implementations. Original Berkeley DB was limited to 2GB of data. Dbm libraries also sometimes limit the total size of a key/value pair, and the total size of all the keys that hash to the same value. These limits can be as little as 512 bytes. That said, gdbm and recent versions of Berkeley DB do away with these limits.

Given the above cautions, DBM is not a good choice for long term storage of important data. It is probably best used as a fast and easy alternative to a Hash for processing large amounts of data.

Example

require 'dbm'
db = DBM.open('rfcs', 0666, DBM::WRCREAT)
db['822'] = 'Standard for the Format of ARPA Internet Text Messages'
db['1123'] = 'Requirements for Internet Hosts - Application and Support'
db['3068'] = 'An Anycast Prefix for 6to4 Relay Routers'
puts db['822']

Constants

READER

Indicates that dbm_open() should open the database in read-only mode

WRITER

Indicates that dbm_open() should open the database in read/write mode

WRCREAT

Indicates that dbm_open() should open the database in read/write mode, and create it if it does not already exist

NEWDB

Indicates that dbm_open() should open the database in read/write mode, create it if it does not already exist, and delete all contents if it does already exist.

VERSION

Identifies ndbm library version.

Examples:

“ndbm (4.3BSD)”
“Berkeley DB 4.8.30: (April 9, 2010)”
“Berkeley DB (unknown)” (4.4BSD, maybe)
“GDBM version 1.8.3. 10/15/2002 (built Jul 1 2011 12:32:45)”
“QDBM 1.8.78”

Class Methods

DBM.new(filename[, mode[, flags]]) → dbm

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_initialize(int argc, VALUE *argv, VALUE obj)
{
    VALUE file, vmode, vflags;
    DBM *dbm;
    struct dbmdata *dbmp;
    int mode, flags = 0;

    TypedData_Get_Struct(obj, struct dbmdata, &dbm_type, dbmp);
    if (rb_scan_args(argc, argv, "12", &file, &vmode, &vflags) == 1) {
        mode = 0666;           /* default value */
    }
    else if (NIL_P(vmode)) {
        mode = -1;             /* return nil if DB not exist */
    }
    else {
        mode = NUM2INT(vmode);
    }

    if (!NIL_P(vflags))
        flags = NUM2INT(vflags);

    FilePathValue(file);

    /*
     * Note:
     * gdbm 1.10 works with O_CLOEXEC.  gdbm 1.9.1 silently ignore it.
     */
#ifndef O_CLOEXEC
#   define O_CLOEXEC 0
#endif

    if (flags & RUBY_DBM_RW_BIT) {
        flags &= ~RUBY_DBM_RW_BIT;
        dbm = dbm_open(RSTRING_PTR(file), flags|O_CLOEXEC, mode);
    }
    else {
        dbm = 0;
        if (mode >= 0) {
            dbm = dbm_open(RSTRING_PTR(file), O_RDWR|O_CREAT|O_CLOEXEC, mode);
        }
        if (!dbm) {
            dbm = dbm_open(RSTRING_PTR(file), O_RDWR|O_CLOEXEC, 0);
        }
        if (!dbm) {
            dbm = dbm_open(RSTRING_PTR(file), O_RDONLY|O_CLOEXEC, 0);
        }
    }

    if (dbm) {
        /*
         * History of dbm_pagfno() and dbm_dirfno() in ndbm and its compatibles.
         * (dbm_pagfno() and dbm_dirfno() is not standardized.)
         *
         * 1986: 4.3BSD provides ndbm.
         *       It provides dbm_pagfno() and dbm_dirfno() as macros.
         * 1991: gdbm-1.5 provides them as functions.
         *       They returns a same descriptor.
         *       (Earlier releases may have the functions too.)
         * 1991: Net/2 provides Berkeley DB.
         *       It doesn't provide dbm_pagfno() and dbm_dirfno().
         * 1992: 4.4BSD Alpha provides Berkeley DB with dbm_dirfno() as a function.
         *       dbm_pagfno() is a macro as DBM_PAGFNO_NOT_AVAILABLE.
         * 1997: Berkeley DB 2.0 is released by Sleepycat Software, Inc.
         *       It defines dbm_pagfno() and dbm_dirfno() as macros.
         * 2011: gdbm-1.9 creates a separate dir file.
         *       dbm_pagfno() and dbm_dirfno() returns different descriptors.
         */
#if defined(HAVE_DBM_PAGFNO)
        rb_fd_fix_cloexec(dbm_pagfno(dbm));
#endif
#if defined(HAVE_DBM_DIRFNO)
        rb_fd_fix_cloexec(dbm_dirfno(dbm));
#endif

#if defined(RUBYDBM_DB_HEADER) && defined(HAVE_TYPE_DBC)
        /* Disable Berkeley DB error messages such as:
         * DB->put: attempt to modify a read-only database */
        ((DBC*)dbm)->dbp->set_errfile(((DBC*)dbm)->dbp, NULL);
#endif
    }

    if (!dbm) {
        if (mode == -1) return Qnil;
        rb_sys_fail_str(file);
    }

    if (dbmp->di_dbm)
        dbm_close(dbmp->di_dbm);
    dbmp->di_dbm = dbm;
    dbmp->di_size = -1;

    return obj;
}

Open a dbm database with the specified name, which can include a directory path. Any file extensions needed will be supplied automatically by the dbm library. For example, Berkeley DB appends ‘.db’, and GNU gdbm uses two physical files with extensions ‘.dir’ and ‘.pag’.

The mode should be an integer, as for Unix chmod.

Flags should be one of READER, WRITER, WRCREAT or NEWDB.

DBM.open(filename[, mode[, flags]]) → dbm

DBM.open(filename[, mode[, flags]]) {|dbm| block}

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_s_open(int argc, VALUE *argv, VALUE klass)
{
    VALUE obj = fdbm_alloc(klass);

    if (NIL_P(fdbm_initialize(argc, argv, obj))) {
        return Qnil;
    }

    if (rb_block_given_p()) {
        return rb_ensure(rb_yield, obj, fdbm_close, obj);
    }

    return obj;
}

Open a dbm database and yields it if a block is given. See also DBM.new.

Instance Methods

dbm[key] → string value or nil

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_aref(VALUE obj, VALUE keystr)
{
    return fdbm_fetch(obj, keystr, Qnil);
}

Return a value from the database by locating the key string provided. If the key is not found, returns nil.

dbm[key] = value

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_store(VALUE obj, VALUE keystr, VALUE valstr)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;

    fdbm_modify(obj);
    keystr = rb_obj_as_string(keystr);
    valstr = rb_obj_as_string(valstr);

    key.dptr = RSTRING_PTR(keystr);
    key.dsize = RSTRING_DSIZE(keystr);

    val.dptr = RSTRING_PTR(valstr);
    val.dsize = RSTRING_DSIZE(valstr);

    GetDBM2(obj, dbmp, dbm);
    dbmp->di_size = -1;
    if (dbm_store(dbm, key, val, DBM_REPLACE)) {
        dbm_clearerr(dbm);
        if (errno == EPERM) rb_sys_fail(0);
        rb_raise(rb_eDBMError, "dbm_store failed");
    }

    return valstr;
}

Stores the specified string value in the database, indexed via the string key provided.

dbm.clear

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_clear(VALUE obj)
{
    datum key;
    struct dbmdata *dbmp;
    DBM *dbm;

    fdbm_modify(obj);
    GetDBM2(obj, dbmp, dbm);
    dbmp->di_size = -1;
    while (key = dbm_firstkey(dbm), key.dptr) {
        if (dbm_delete(dbm, key)) {
            rb_raise(rb_eDBMError, "dbm_delete failed");
        }
    }
    dbmp->di_size = 0;

    return obj;
}

Deletes all data from the database.

dbm.close

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_close(VALUE obj)
{
    struct dbmdata *dbmp;

    GetDBM(obj, dbmp);
    dbm_close(dbmp->di_dbm);
    dbmp->di_dbm = 0;

    return Qnil;
}

Closes the database.

dbm.closed? → true or false

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_closed(VALUE obj)
{
    struct dbmdata *dbmp;

    TypedData_Get_Struct(obj, struct dbmdata, &dbm_type, dbmp);
    if (dbmp->di_dbm == 0)
        return Qtrue;

    return Qfalse;
}

Returns true if the database is closed, false otherwise.

dbm.delete(key)

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_delete(VALUE obj, VALUE keystr)
{
    datum key, value;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE valstr;
    long len;

    fdbm_modify(obj);
    ExportStringValue(keystr);
    len = RSTRING_LEN(keystr);
    if (TOO_LONG(len)) goto not_found;
    key.dptr = RSTRING_PTR(keystr);
    key.dsize = (DSIZE_TYPE)len;

    GetDBM2(obj, dbmp, dbm);

    value = dbm_fetch(dbm, key);
    if (value.dptr == 0) {
      not_found:
        if (rb_block_given_p()) return rb_yield(keystr);
        return Qnil;
    }

    /* need to save value before dbm_delete() */
    valstr = rb_str_new(value.dptr, value.dsize);

    if (dbm_delete(dbm, key)) {
        dbmp->di_size = -1;
        rb_raise(rb_eDBMError, "dbm_delete failed");
    }
    else if (dbmp->di_size >= 0) {
        dbmp->di_size--;
    }
    return valstr;
}

Deletes an entry from the database.

dbm.delete_if {|key, value| block} → self

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_delete_if(VALUE obj)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE keystr, valstr;
    VALUE ret, ary = rb_ary_tmp_new(0);
    int status = 0;
    long i, n;

    fdbm_modify(obj);
    GetDBM2(obj, dbmp, dbm);
    n = dbmp->di_size;
    dbmp->di_size = -1;

    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        keystr = rb_str_new(key.dptr, key.dsize);
        OBJ_FREEZE(keystr);
        valstr = rb_str_new(val.dptr, val.dsize);
        ret = rb_protect(rb_yield, rb_assoc_new(rb_str_dup(keystr), valstr), &status);
        if (status != 0) break;
        if (RTEST(ret)) rb_ary_push(ary, keystr);
        GetDBM2(obj, dbmp, dbm);
    }

    for (i = 0; i < RARRAY_LEN(ary); i++) {
        keystr = RARRAY_AREF(ary, i);
        key.dptr = RSTRING_PTR(keystr);
        key.dsize = (DSIZE_TYPE)RSTRING_LEN(keystr);
        if (dbm_delete(dbm, key)) {
            rb_raise(rb_eDBMError, "dbm_delete failed");
        }
    }
    if (status) rb_jump_tag(status);
    if (n > 0) dbmp->di_size = n - RARRAY_LEN(ary);
    rb_ary_clear(ary);

    return obj;
}

Deletes all entries for which the code block returns true. Returns self.

dbm.each_pair {|key,value| block} -> self

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_each_pair(VALUE obj)
{
    datum key, val;
    DBM *dbm;
    struct dbmdata *dbmp;
    VALUE keystr, valstr;

    RETURN_ENUMERATOR(obj, 0, 0);

    GetDBM2(obj, dbmp, dbm);

    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        keystr = rb_str_new(key.dptr, key.dsize);
        valstr = rb_str_new(val.dptr, val.dsize);
        rb_yield(rb_assoc_new(keystr, valstr));
        GetDBM2(obj, dbmp, dbm);
    }

    return obj;
}

Calls the block once for each [key, value] pair in the database. Returns self.

dbm.each_key {|key| block} → self

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_each_key(VALUE obj)
{
    datum key;
    struct dbmdata *dbmp;
    DBM *dbm;

    RETURN_ENUMERATOR(obj, 0, 0);

    GetDBM2(obj, dbmp, dbm);
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        rb_yield(rb_str_new(key.dptr, key.dsize));
        GetDBM2(obj, dbmp, dbm);
    }
    return obj;
}

Calls the block once for each key string in the database. Returns self.

dbm.each_pair {|key,value| block} → self

ext/dbm/dbm.c View on GitHub

An alias for each

dbm.each_value {|value| block} → self

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_each_value(VALUE obj)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;

    RETURN_ENUMERATOR(obj, 0, 0);

    GetDBM2(obj, dbmp, dbm);
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        rb_yield(rb_str_new(val.dptr, val.dsize));
        GetDBM2(obj, dbmp, dbm);
    }
    return obj;
}

Calls the block once for each value string in the database. Returns self.

dbm.empty?

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_empty_p(VALUE obj)
{
    datum key;
    struct dbmdata *dbmp;
    DBM *dbm;

    GetDBM2(obj, dbmp, dbm);
    if (dbmp->di_size < 0) {
        dbm = dbmp->di_dbm;

        for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
            return Qfalse;
        }
    }
    else {
        if (dbmp->di_size)
            return Qfalse;
    }
    return Qtrue;
}

Returns true if the database is empty, false otherwise.

dbm.fetch(key[, ifnone]) → value

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_fetch_m(int argc, VALUE *argv, VALUE obj)
{
    VALUE keystr, valstr, ifnone;

    rb_scan_args(argc, argv, "11", &keystr, &ifnone);
    valstr = fdbm_fetch(obj, keystr, ifnone);
    if (argc == 1 && !rb_block_given_p() && NIL_P(valstr))
        rb_raise(rb_eIndexError, "key not found");

    return valstr;
}

Return a value from the database by locating the key string provided. If the key is not found, returns ifnone. If ifnone is not given, raises IndexError.

dbm.has_key?(key) → boolean

ext/dbm/dbm.c View on GitHub

An alias for include?

dbm.has_value?(value) → boolean

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_has_value(VALUE obj, VALUE valstr)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    long len;

    ExportStringValue(valstr);
    len = RSTRING_LEN(valstr);
    if (TOO_LONG(len)) return Qfalse;
    val.dptr = RSTRING_PTR(valstr);
    val.dsize = (DSIZE_TYPE)len;

    GetDBM2(obj, dbmp, dbm);
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        if ((DSIZE_TYPE)val.dsize == (DSIZE_TYPE)RSTRING_LEN(valstr) &&
            memcmp(val.dptr, RSTRING_PTR(valstr), val.dsize) == 0)
            return Qtrue;
    }
    return Qfalse;
}

Returns true if the database contains the specified string value, false otherwise.

dbm.include?(key) → boolean

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_has_key(VALUE obj, VALUE keystr)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    long len;

    ExportStringValue(keystr);
    len = RSTRING_LEN(keystr);
    if (TOO_LONG(len)) return Qfalse;
    key.dptr = RSTRING_PTR(keystr);
    key.dsize = (DSIZE_TYPE)len;

    GetDBM2(obj, dbmp, dbm);
    val = dbm_fetch(dbm, key);
    if (val.dptr) return Qtrue;
    return Qfalse;
}

Returns true if the database contains the specified key, false otherwise.

dbm.invert → hash

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_invert(VALUE obj)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE keystr, valstr;
    VALUE hash = rb_hash_new();

    GetDBM2(obj, dbmp, dbm);
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        keystr = rb_str_new(key.dptr, key.dsize);
        valstr = rb_str_new(val.dptr, val.dsize);
        rb_hash_aset(hash, valstr, keystr);
    }
    return hash;
}

Returns a Hash (not a DBM database) created by using each value in the database as a key, with the corresponding key as its value.

dbm.key(value) → string

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_key(VALUE obj, VALUE valstr)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    long len;

    ExportStringValue(valstr);
    len = RSTRING_LEN(valstr);
    if (TOO_LONG(len)) return Qnil;

    GetDBM2(obj, dbmp, dbm);
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        if ((long)val.dsize == RSTRING_LEN(valstr) &&
            memcmp(val.dptr, RSTRING_PTR(valstr), val.dsize) == 0) {
            return rb_str_new(key.dptr, key.dsize);
        }
    }
    return Qnil;
}

Returns the key for the specified value.

dbm.key?(key) → boolean

ext/dbm/dbm.c View on GitHub

An alias for include?

dbm.keys → array

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_keys(VALUE obj)
{
    datum key;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE ary;

    GetDBM2(obj, dbmp, dbm);

    ary = rb_ary_new();
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        rb_ary_push(ary, rb_str_new(key.dptr, key.dsize));
    }

    return ary;
}

Returns an array of all the string keys in the database.

dbm.length → integer

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_length(VALUE obj)
{
    datum key;
    struct dbmdata *dbmp;
    DBM *dbm;
    int i = 0;

    GetDBM2(obj, dbmp, dbm);
    if (dbmp->di_size > 0) return INT2FIX(dbmp->di_size);

    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        i++;
    }
    dbmp->di_size = i;

    return INT2FIX(i);
}

Returns the number of entries in the database.

dbm.member?(key) → boolean

ext/dbm/dbm.c View on GitHub

An alias for include?

dbm.reject {|key,value| block} → Hash

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_reject(VALUE obj)
{
    return rb_hash_delete_if(fdbm_to_hash(obj));
}

Converts the contents of the database to an in-memory Hash, then calls Hash#reject with the specified code block, returning a new Hash.

dbm.reject! {|key, value| block} → self

ext/dbm/dbm.c View on GitHub

An alias for delete_if

dbm.replace(obj)

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_replace(VALUE obj, VALUE other)
{
    fdbm_clear(obj);
    rb_block_call(other, rb_intern("each_pair"), 0, 0, update_i, obj);
    return obj;
}

Replaces the contents of the database with the contents of the specified object. Takes any object which implements the each_pair method, including Hash and DBM objects.

dbm.select {|key, value| block} → array

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_select(VALUE obj)
{
    VALUE new = rb_ary_new();
    datum key, val;
    DBM *dbm;
    struct dbmdata *dbmp;

    GetDBM2(obj, dbmp, dbm);
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        VALUE assoc, v;
        val = dbm_fetch(dbm, key);
        assoc = rb_assoc_new(rb_str_new(key.dptr, key.dsize),
                             rb_str_new(val.dptr, val.dsize));
        v = rb_yield(assoc);
        if (RTEST(v)) {
            rb_ary_push(new, assoc);
        }
        GetDBM2(obj, dbmp, dbm);
    }

    return new;
}

Returns a new array consisting of the [key, value] pairs for which the code block returns true.

dbm.shift() → [key, value]

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_shift(VALUE obj)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE keystr, valstr;

    fdbm_modify(obj);
    GetDBM2(obj, dbmp, dbm);
    dbmp->di_size = -1;

    key = dbm_firstkey(dbm);
    if (!key.dptr) return Qnil;
    val = dbm_fetch(dbm, key);
    keystr = rb_str_new(key.dptr, key.dsize);
    valstr = rb_str_new(val.dptr, val.dsize);
    dbm_delete(dbm, key);

    return rb_assoc_new(keystr, valstr);
}

Removes a [key, value] pair from the database, and returns it. If the database is empty, returns nil. The order in which values are removed/returned is not guaranteed.

          
            static VALUE
fdbm_to_a(VALUE obj)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE ary;

    GetDBM2(obj, dbmp, dbm);
    ary = rb_ary_new();
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        rb_ary_push(ary, rb_assoc_new(rb_str_new(key.dptr, key.dsize),
                                      rb_str_new(val.dptr, val.dsize)));
    }

    return ary;
}

Converts the contents of the database to an array of [key, value] arrays, and returns it.

dbm.to_hash → hash

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_to_hash(VALUE obj)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE hash;

    GetDBM2(obj, dbmp, dbm);
    hash = rb_hash_new();
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        rb_hash_aset(hash, rb_str_new(key.dptr, key.dsize),
                           rb_str_new(val.dptr, val.dsize));
    }

    return hash;
}

Converts the contents of the database to an in-memory Hash object, and returns it.

dbm.update(obj)

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_update(VALUE obj, VALUE other)
{
    rb_block_call(other, rb_intern("each_pair"), 0, 0, update_i, obj);
    return obj;
}

Updates the database with multiple values from the specified object. Takes any object which implements the each_pair method, including Hash and DBM objects.

dbm.value?(value) → boolean

ext/dbm/dbm.c View on GitHub

An alias for has_value?

dbm.values → array

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_values(VALUE obj)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE ary;

    GetDBM2(obj, dbmp, dbm);
    ary = rb_ary_new();
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        rb_ary_push(ary, rb_str_new(val.dptr, val.dsize));
    }

    return ary;
}

Returns an array of all the string values in the database.

dbm.values_at(key, ...) → Array

ext/dbm/dbm.c View on GitHub

          
            static VALUE
fdbm_values_at(int argc, VALUE *argv, VALUE obj)
{
    VALUE new = rb_ary_new2(argc);
    int i;

    for (i=0; i<argc; i++) {
        rb_ary_push(new, fdbm_fetch(obj, argv[i], Qnil));
    }

    return new;
}

Returns an array containing the values associated with the given keys.

DBM

Introduction

Cautions

Example

READER

WRITER

WRCREAT

NEWDB

VERSION

DBM.new(filename[, mode[, flags]]) → dbm

DBM.open(filename[, mode[, flags]]) → dbm

DBM.open(filename[, mode[, flags]]) {|dbm| block}

dbm[key] → string value or nil

dbm[key] = value

dbm.clear

dbm.close

dbm.closed? → true or false

dbm.delete(key)

dbm.delete_if {|key, value| block} → self

dbm.each_pair {|key,value| block} -> self

dbm.each_key {|key| block} → self

dbm.each_pair {|key,value| block} → self

dbm.each_value {|value| block} → self

dbm.empty?

dbm.fetch(key[, ifnone]) → value

dbm.has_key?(key) → boolean

dbm.has_value?(value) → boolean

dbm.include?(key) → boolean

dbm.invert → hash

dbm.key(value) → string

dbm.key?(key) → boolean

dbm.keys → array

dbm.length → integer

dbm.member?(key) → boolean

dbm.reject {|key,value| block} → Hash

dbm.reject! {|key, value| block} → self

dbm.replace(obj)

dbm.select {|key, value| block} → array

dbm.shift() → [key, value]

dbm.size → integer

dbm.store(key, value) → value

dbm.to_a → array

dbm.to_hash → hash

dbm.update(obj)

dbm.value?(value) → boolean

dbm.values → array

dbm.values_at(key, ...) → Array