DBM

class DBM

Parent:ObjectIncluded modules:Enumerable

介绍

DBM类为Unix风格的dbm或数据库管理器库提供封装。

Dbm数据库没有表或列; 它们是简单的键值数据存储，就像Ruby Hash，除了不驻留在RAM中。键和值必须是字符串。

所使用的确切库取决于Ruby是如何编译的。它可以是以下任何一种：

最初的ndbm库在4.3BSD中发布。它基于Unix版本7中的dbm库，但具有不同的API以支持进程中的多个数据库。

Berkeley DB版本1至5，也被称为BDB和Sleepycat DB，现在归甲骨文公司所有。

Berkeley DB 1.x，仍然可以在4.4BSD衍生产品（FreeBSD，OpenBSD等）中找到。

gdbm，dbm的GNU实现。

QDBM，这些 DBM 实现的 dbm.All 的另一个开源重新实现有可用自己的 Ruby 接口，提供更丰富（但不同）APIs.CautionsBefore 您决定使用 DBM，也有一些问题，你应该考虑：

每个dbm的实现都有自己的文件格式。通常，dbm库不会读取彼此的文件。这使得dbm文件成为数据交换的不错的选择。

即使运行相同的操作系统和相同的dbm实现，数据库文件格式也可能取决于CPU体系结构。例如，文件可能不能在PowerPC和386之间，或在32和64位Linux之间移植。

不同版本的Berkeley DB使用不同的文件格式。因此，对操作系统的更改可能会破坏对现有文件的DBM访问。

数据大小限制因实现而异。原始的Berkeley DB仅限于2GB的数据。 Dbm库有时还会限制键/值对的总大小，以及散列为相同值的所有键的总大小。这些限制可能只有512个字节。也就是说，gdbm和Berkeley DB的最新版本取消了这些限制。鉴于上述注意事项，DBM不是长期存储重要数据的好选择。它可能最适合用作处理大量数据的Hash的快速和简单替代。示例 'dbm'

“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”

WRCREAT

指示dbm_open（）应以读取/写入模式打开数据库，如果数据库尚不存在，则创建该数据库

WRITER

指示dbm_open（）应以读/写模式打开数据库

公共类方法

new(filename[, mode, flags]) → dbm Show source

用指定名称打开一个dbm数据库，该名称可以包含一个目录路径。任何需要的文件扩展名都将由dbm库自动提供。例如，Berkeley DB追加'.db'，而GNU gdbm使用两个扩展名为'.dir'和'.pag'的物理文件。

该模式应该是一个整数，如Unix chmod。

标志应该是READER，WRITER，WRCREAT或NEWDB之一。

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

    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
    }

    dbmp = ALLOC(struct dbmdata
    DATA_PTR(obj) = dbmp;
    dbmp->di_dbm = dbm;
    dbmp->di_size = -1;

    return obj;
}

open(filename[, mode, flags]) → dbm Show source

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

打开一个dbm数据库并在给定块的情况下产生它。另见DBM.new。

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;
}

公共实例方法

dbmkey→字符串值或零显示源

通过查找提供的密钥字符串，从数据库中返回一个值。如果找不到密钥，则返回nil。

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

dbmkey = value Show source

将指定的字符串值存储在数据库中，通过提供的字符串键进行索引。

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;
}

clear Show source

从数据库中删除所有数据。

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;
}

close Show source

关闭数据库。

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

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

    return Qnil;
}

closed? → true or false Show source

如果数据库关闭，则返回true，否则返回false。

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

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

    return Qfalse;
}

delete(key) Show source

从数据库中删除一个条目。

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_tainted_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;
}

delete_if {|key, value| block} → self Show source

删除代码块返回true的所有条目。返回自身。

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_tainted_str_new(key.dptr, key.dsize
        OBJ_FREEZE(keystr
        valstr = rb_tainted_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;
}

each_pair {|key,value| block} → self Show source

为数据库中的每个键值对调用一次块。返回自身。

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_tainted_str_new(key.dptr, key.dsize
        valstr = rb_tainted_str_new(val.dptr, val.dsize
        rb_yield(rb_assoc_new(keystr, valstr)
        GetDBM2(obj, dbmp, dbm
    }

    return obj;
}

each_key {|key| block} → self Show source

为数据库中的每个键字符串调用一次块。返回自身。

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_tainted_str_new(key.dptr, key.dsize)
        GetDBM2(obj, dbmp, dbm
    }
    return obj;
}

each_pair {|key,value| block} → self Show source

为数据库中的每个键值对调用一次块。返回自身。

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_tainted_str_new(key.dptr, key.dsize
        valstr = rb_tainted_str_new(val.dptr, val.dsize
        rb_yield(rb_assoc_new(keystr, valstr)
        GetDBM2(obj, dbmp, dbm
    }

    return obj;
}

each_value {|value| block} → self Show source

为数据库中的每个值字符串调用一次块。返回自身。

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_tainted_str_new(val.dptr, val.dsize)
        GetDBM2(obj, dbmp, dbm
    }
    return obj;
}

empty? Show source

如果数据库为空，则返回true，否则返回false。

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;
}

fetch(key, ifnone) → value Show source

通过查找提供的密钥字符串，从数据库中返回一个值。如果找不到密钥，则返回ifnone。如果ifnone没有给出，则引发IndexError。

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;
}

has_key?(key) → boolean Show source

如果数据库包含指定的键，则返回true，否则返回false。

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;
}

has_value?(value) → boolean Show source

如果数据库包含指定的字符串值，则返回true，否则返回false。

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;
}

include?(key) → boolean Show source

如果数据库包含指定的键，则返回true，否则返回false。

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;
}

invert → hash Show source

通过使用数据库中的每个值作为关键字创建一个哈希（不是DBM数据库），并将相应的键用作其值。

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_tainted_str_new(key.dptr, key.dsize
        valstr = rb_tainted_str_new(val.dptr, val.dsize
        rb_hash_aset(hash, valstr, keystr
    }
    return hash;
}

key(value) → string Show source

返回指定值的键。

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;
    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 ((long)val.dsize == RSTRING_LEN(valstr) &&
            memcmp(val.dptr, RSTRING_PTR(valstr), val.dsize) == 0) {
            return rb_tainted_str_new(key.dptr, key.dsize
        }
    }
    return Qnil;
}

key?(key) → boolean Show source

如果数据库包含指定的键，则返回true，否则返回false。

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;
}

keys → array Show source

返回数据库中所有字符串键的数组。

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_tainted_str_new(key.dptr, key.dsize)
    }

    return ary;
}

length → integer Show source

返回数据库中条目的数量。

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
}

member?(key) → boolean Show source

如果数据库包含指定的键，则返回true，否则返回false。

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;
}

reject {|key,value| block} → Hash Show source

将数据库的内容转换为内存中的哈希，然后使用指定的代码块调用Hash#reject，返回一个新的哈希。

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

reject! {|key, value| block} → self Show source

删除代码块返回true的所有条目。返回自身。

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_tainted_str_new(key.dptr, key.dsize
        OBJ_FREEZE(keystr
        valstr = rb_tainted_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;
}

replace(obj) Show source

用指定对象的内容替换数据库的内容。接受实现#each_pair方法的任何对象，包括Hash和DBM对象。

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;
}

select {|key, value| block} → array Show source

返回由代码块返回true的键值对组成的新数组。

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_tainted_str_new(key.dptr, key.dsize),
                             rb_tainted_str_new(val.dptr, val.dsize)
        v = rb_yield(assoc
        if (RTEST(v)) {
            rb_ary_push(new, assoc
        }
        GetDBM2(obj, dbmp, dbm
    }

    return new;
}

shift() → key, value()

从数据库中删除一个键值对，并返回它。如果数据库为空，则返回nil。无法保证值的排除/返回顺序。

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_tainted_str_new(key.dptr, key.dsize
    valstr = rb_tainted_str_new(val.dptr, val.dsize
    dbm_delete(dbm, key

    return rb_assoc_new(keystr, valstr
}

size → integer Show source

返回数据库中条目的数量。

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
}

store(key, value) → value Show source

将指定的字符串值存储在数据库中，通过提供的字符串键进行索引。

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;
}

to_a → array Show source

将数据库的内容转换为一个包含键值数组的数组，并将其返回。

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_tainted_str_new(key.dptr, key.dsize),
                                      rb_tainted_str_new(val.dptr, val.dsize))
    }

    return ary;
}

to_hash → hash Show source

将数据库的内容转换为内存中的哈希对象，并将其返回。

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_tainted_str_new(key.dptr, key.dsize),
                           rb_tainted_str_new(val.dptr, val.dsize)
    }

    return hash;
}

update(obj) Show source

使用指定对象的多个值更新数据库。接受实现#each_pair方法的任何对象，包括Hash和DBM对象。

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

value?(value) → boolean Show source

如果数据库包含指定的字符串值，则返回true，否则返回false。

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;
}

values → array Show source

返回数据库中所有字符串值的数组。

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_tainted_str_new(val.dptr, val.dsize)
    }

    return ary;
}

values_at(key, ...) → Array Show source

返回包含与给定键相关的值的数组。

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;
}