非常教程

Ruby 2.4参考手册

DBM

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'

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'] ConstantsNEWDB指示dbm_open()应该以读/写模式打开数据库,如果数据库尚不存在则创建该数据库,如果已存在,则删除所有内容。READER指示dbm_open()应该打开该数据库处于只读模式VERSION标识ndbm库的版本。

示例:

  • “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;
}
DBM
Ruby 2.4

Ruby 是一种面向对象、命令式、函数式、动态的通用编程语言,是世界上最优美而巧妙的语言。

主页 https://www.ruby-lang.org/
源码 https://github.com/ruby/ruby
版本 2.4
发布版本 2.4.1

Ruby 2.4目录

1.缩略 | Abbrev
2.ARGF
3.数组 | Array
4.Base64
5.基本对象 | BasicObject
6.基准测试 | Benchmark
7.BigDecimal
8.绑定 | Binding
9.CGI
10.类 | Class
11.比较 | Comparable
12.负责 | Complex
13.计算续体 | Continuation
14.覆盖 | Coverage
15.CSV
16.日期 | Date
17.日期时间 | DateTime
18.DBM
19.代理 | Delegator
20.摘要 | Digest
21.Dir
22.DRb
23.编码 | Encoding
24.枚举 | Enumerable
25.枚举 | Enumerator
26.ENV
27.ERB
28.错误 | Errors
29.Etc
30.期望值 | Exception
31.错误类 | FalseClass
32.Fiber
33.Fiddle
34.文件 | File
35.文件实用程序 | FileUtils
36.查找 | Find
37.浮点 | Float
38.Forwardable
39.GC
40.GDBM
41.GetoptLong
42.Hash
43.Integer
44.IO
45.IPAddr
46.JSON
47.Kernel
48.语言 | 3Language
49.记录 | Logger
50.编排 | Marshal
51.MatchData
52.数学 | Math
53.矩阵 | Matrix
54.方法 | Method
55.模型 | Module
56.监控 | Monitor
57. 互斥 | Mutex
58.Net
59.Net::FTP
60.Net::HTTP
61.Net::IMAP
62.Net::SMTP
63.NilClass
64.数字 | Numeric
65.对象 | Object
66.ObjectSpace
67.Observable
68.Open3
69.OpenSSL
70.OpenStruct
71.OpenURI
72.OptionParser
73.路径名 | Pathname
74.完整输出 | PrettyPrint
75.Prime
76.Proc
77.过程 | Process
78.PStore
79.PTY
80.队列 | Queue
81.随机 | Random
82.范围 | Range
83.合理的 | Rational
84.Readline
85.Regexp
86.Resolv
87.Ripper
88.RubyVM
89.Scanf
90.SDBM
91.SecureRandom
92.Set
93.Shell
94.信号 | Signal
95.Singleton
96.套接字 | Socket
97.字符串 | String
98.StringIO
99.StringScanner
100.结构 | Struct