Support for the Ruby 2.4 series has ended. See here for reference.
Object
SDBM
provides a simple file-based key-value store, which can only store String keys and values.
Note that Ruby comes with the source code for SDBM
, while the DBM and GDBM standard libraries rely on external libraries and headers.
Insert values:
require 'sdbm' SDBM.open 'my_database' do |db| db['apple'] = 'fruit' db['pear'] = 'fruit' db['carrot'] = 'vegetable' db['tomato'] = 'vegetable' end
Bulk update:
require 'sdbm' SDBM.open 'my_database' do |db| db.update('peach' => 'fruit', 'tomato' => 'fruit') end
Retrieve values:
require 'sdbm' SDBM.open 'my_database' do |db| db.each do |key, value| puts "Key: #{key}, Value: #{value}" end end
Outputs:
Key: apple, Value: fruit Key: pear, Value: fruit Key: carrot, Value: vegetable Key: peach, Value: fruit Key: tomato, Value: fruit
Creates a new database handle by opening the given filename
. SDBM
actually uses two physical files, with extensions '.dir' and '.pag'. These extensions will automatically be appended to the filename
.
If the file does not exist, a new file will be created using the given mode
, unless mode
is explicitly set to nil. In the latter case, no database will be created.
If the file exists, it will be opened in read/write mode. If this fails, it will be opened in read-only mode.
static VALUE fsdbm_initialize(int argc, VALUE *argv, VALUE obj) { VALUE file, vmode; DBM *dbm; struct dbmdata *dbmp; int mode; if (rb_scan_args(argc, argv, "11", &file, &vmode) == 1) { mode = 0666; /* default value */ } else if (NIL_P(vmode)) { mode = -1; /* return nil if DB not exist */ } else { mode = NUM2INT(vmode); } FilePathValue(file); dbm = 0; if (mode >= 0) dbm = sdbm_open(RSTRING_PTR(file), O_RDWR|O_CREAT, mode); if (!dbm) dbm = sdbm_open(RSTRING_PTR(file), O_RDWR, 0); if (!dbm) dbm = sdbm_open(RSTRING_PTR(file), O_RDONLY, 0); 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; }
If called without a block, this is the same as SDBM.new
.
If a block is given, the new database will be passed to the block and will be safely closed after the block has executed.
Example:
require 'sdbm' SDBM.open('my_database') do |db| db['hello'] = 'world' end
static VALUE fsdbm_s_open(int argc, VALUE *argv, VALUE klass) { VALUE obj = fsdbm_alloc(klass); if (NIL_P(fsdbm_initialize(argc, argv, obj))) { return Qnil; } if (rb_block_given_p()) { return rb_ensure(rb_yield, obj, fsdbm_close, obj); } return obj; }
Returns the value
in the database associated with the given key
string.
If no value is found, returns nil
.
static VALUE fsdbm_aref(VALUE obj, VALUE keystr) { return fsdbm_fetch(obj, keystr, Qnil); }
Stores a new value
in the database with the given key
as an index.
If the key
already exists, this will update the value
associated with the key
.
Returns the given value
.
static VALUE fsdbm_store(VALUE obj, VALUE keystr, VALUE valstr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; if (valstr == Qnil) { fsdbm_delete(obj, keystr); return Qnil; } fdbm_modify(obj); ExportStringValue(keystr); ExportStringValue(valstr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); val.dptr = RSTRING_PTR(valstr); val.dsize = RSTRING_LENINT(valstr); GetDBM2(obj, dbmp, dbm); dbmp->di_size = -1; if (sdbm_store(dbm, key, val, DBM_REPLACE)) { #ifdef HAVE_DBM_CLAERERR sdbm_clearerr(dbm); #endif if (errno == EPERM) rb_sys_fail(0); rb_raise(rb_eDBMError, "sdbm_store failed"); } return valstr; }
Deletes all data from the database.
static VALUE fsdbm_clear(VALUE obj) { datum key; struct dbmdata *dbmp; DBM *dbm; fdbm_modify(obj); GetDBM2(obj, dbmp, dbm); dbmp->di_size = -1; while (key = sdbm_firstkey(dbm), key.dptr) { if (sdbm_delete(dbm, key)) { rb_raise(rb_eDBMError, "sdbm_delete failed"); } } dbmp->di_size = 0; return obj; }
Closes the database file.
Raises SDBMError
if the database is already closed.
static VALUE fsdbm_close(VALUE obj) { struct dbmdata *dbmp; GetDBM(obj, dbmp); sdbm_close(dbmp->di_dbm); dbmp->di_dbm = 0; return Qnil; }
Returns true
if the database is closed.
static VALUE fsdbm_closed(VALUE obj) { struct dbmdata *dbmp; TypedData_Get_Struct(obj, struct dbmdata, &sdbm_type, dbmp); if (dbmp == 0) return Qtrue; if (dbmp->di_dbm == 0) return Qtrue; return Qfalse; }
Deletes the key-value pair corresponding to the given key
. If the key
exists, the deleted value will be returned, otherwise nil
.
If a block is provided, the deleted key
and value
will be passed to the block as arguments. If the key
does not exist in the database, the value will be nil
.
static VALUE fsdbm_delete(VALUE obj, VALUE keystr) { datum key, value; struct dbmdata *dbmp; DBM *dbm; VALUE valstr; fdbm_modify(obj); ExportStringValue(keystr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); GetDBM2(obj, dbmp, dbm); dbmp->di_size = -1; value = sdbm_fetch(dbm, key); if (value.dptr == 0) { if (rb_block_given_p()) return rb_yield(keystr); return Qnil; } /* need to save value before sdbm_delete() */ valstr = rb_external_str_new(value.dptr, value.dsize); if (sdbm_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; }
Iterates over the key-value pairs in the database, deleting those for which the block returns true
.
static VALUE fsdbm_delete_if(VALUE obj) { datum key, val; struct dbmdata *dbmp; DBM *dbm; VALUE keystr, valstr; VALUE ret, ary = rb_ary_new(); long i; int status = 0, n; fdbm_modify(obj); GetDBM2(obj, dbmp, dbm); n = dbmp->di_size; dbmp->di_size = -1; for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); keystr = rb_external_str_new(key.dptr, key.dsize); valstr = rb_external_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); ExportStringValue(keystr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); if (sdbm_delete(dbm, key)) { rb_raise(rb_eDBMError, "sdbm_delete failed"); } } if (status) rb_jump_tag(status); if (n > 0) dbmp->di_size = n - RARRAY_LENINT(ary); return obj; }
Iterates over each key-value pair in the database.
If no block is given, returns an Enumerator.
static VALUE fsdbm_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 = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); keystr = rb_external_str_new(key.dptr, key.dsize); valstr = rb_external_str_new(val.dptr, val.dsize); rb_yield(rb_assoc_new(keystr, valstr)); GetDBM2(obj, dbmp, dbm); } return obj; }
Iterates over each key
in the database.
If no block is given, returns an Enumerator.
static VALUE fsdbm_each_key(VALUE obj) { datum key; struct dbmdata *dbmp; DBM *dbm; RETURN_ENUMERATOR(obj, 0, 0); GetDBM2(obj, dbmp, dbm); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { rb_yield(rb_external_str_new(key.dptr, key.dsize)); GetDBM2(obj, dbmp, dbm); } return obj; }
Iterates over each key-value pair in the database.
If no block is given, returns an Enumerator.
static VALUE fsdbm_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 = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); keystr = rb_external_str_new(key.dptr, key.dsize); valstr = rb_external_str_new(val.dptr, val.dsize); rb_yield(rb_assoc_new(keystr, valstr)); GetDBM2(obj, dbmp, dbm); } return obj; }
Iterates over each value
in the database.
If no block is given, returns an Enumerator.
static VALUE fsdbm_each_value(VALUE obj) { datum key, val; struct dbmdata *dbmp; DBM *dbm; RETURN_ENUMERATOR(obj, 0, 0); GetDBM2(obj, dbmp, dbm); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); rb_yield(rb_external_str_new(val.dptr, val.dsize)); GetDBM2(obj, dbmp, dbm); } return obj; }
Returns true
if the database is empty.
static VALUE fsdbm_empty_p(VALUE obj) { datum key; struct dbmdata *dbmp; DBM *dbm; GetDBM(obj, dbmp); if (dbmp->di_size < 0) { dbm = dbmp->di_dbm; for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { return Qfalse; } } else { if (dbmp->di_size) return Qfalse; } return Qtrue; }
Returns the value
in the database associated with the given key
string.
If a block is provided, the block will be called when there is no value
associated with the given key
. The key
will be passed in as an argument to the block.
If no block is provided and no value is associated with the given key
, then an IndexError will be raised.
static VALUE fsdbm_fetch_m(int argc, VALUE *argv, VALUE obj) { VALUE keystr, valstr, ifnone; rb_scan_args(argc, argv, "11", &keystr, &ifnone); valstr = fsdbm_fetch(obj, keystr, ifnone); if (argc == 1 && !rb_block_given_p() && NIL_P(valstr)) rb_raise(rb_eIndexError, "key not found"); return valstr; }
Returns true
if the database contains the given key
.
static VALUE fsdbm_has_key(VALUE obj, VALUE keystr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; ExportStringValue(keystr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); GetDBM2(obj, dbmp, dbm); val = sdbm_fetch(dbm, key); if (val.dptr) return Qtrue; return Qfalse; }
Returns true
if the database contains the given value
.
static VALUE fsdbm_has_value(VALUE obj, VALUE valstr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; ExportStringValue(valstr); val.dptr = RSTRING_PTR(valstr); val.dsize = RSTRING_LENINT(valstr); GetDBM2(obj, dbmp, dbm); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); if (val.dsize == RSTRING_LENINT(valstr) && memcmp(val.dptr, RSTRING_PTR(valstr), val.dsize) == 0) return Qtrue; } return Qfalse; }
Returns true
if the database contains the given key
.
static VALUE fsdbm_has_key(VALUE obj, VALUE keystr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; ExportStringValue(keystr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); GetDBM2(obj, dbmp, dbm); val = sdbm_fetch(dbm, key); if (val.dptr) return Qtrue; return Qfalse; }
Returns a Hash in which the key-value pairs have been inverted.
Example:
require 'sdbm' SDBM.open 'my_database' do |db| db.update('apple' => 'fruit', 'spinach' => 'vegetable') db.invert #=> {"fruit" => "apple", "vegetable" => "spinach"} end
static VALUE fsdbm_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 = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); keystr = rb_external_str_new(key.dptr, key.dsize); valstr = rb_external_str_new(val.dptr, val.dsize); rb_hash_aset(hash, valstr, keystr); } return hash; }
Returns the key
associated with the given value
. If more than one key
corresponds to the given value
, then the first key to be found will be returned. If no keys are found, nil
will be returned.
static VALUE fsdbm_key(VALUE obj, VALUE valstr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; ExportStringValue(valstr); val.dptr = RSTRING_PTR(valstr); val.dsize = RSTRING_LENINT(valstr); GetDBM2(obj, dbmp, dbm); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); if (val.dsize == RSTRING_LEN(valstr) && memcmp(val.dptr, RSTRING_PTR(valstr), val.dsize) == 0) return rb_external_str_new(key.dptr, key.dsize); } return Qnil; }
Returns true
if the database contains the given key
.
static VALUE fsdbm_has_key(VALUE obj, VALUE keystr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; ExportStringValue(keystr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); GetDBM2(obj, dbmp, dbm); val = sdbm_fetch(dbm, key); if (val.dptr) return Qtrue; return Qfalse; }
Returns a new Array containing the keys in the database.
static VALUE fsdbm_keys(VALUE obj) { datum key; struct dbmdata *dbmp; DBM *dbm; VALUE ary; GetDBM2(obj, dbmp, dbm); ary = rb_ary_new(); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { rb_ary_push(ary, rb_external_str_new(key.dptr, key.dsize)); } return ary; }
Returns the number of keys in the database.
static VALUE fsdbm_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 = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { i++; } dbmp->di_size = i; return INT2FIX(i); }
Returns true
if the database contains the given key
.
static VALUE fsdbm_has_key(VALUE obj, VALUE keystr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; ExportStringValue(keystr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); GetDBM2(obj, dbmp, dbm); val = sdbm_fetch(dbm, key); if (val.dptr) return Qtrue; return Qfalse; }
Creates a new Hash using the key-value pairs from the database, then calls Hash#reject with the given block, which returns a Hash with only the key-value pairs for which the block returns false
.
static VALUE fsdbm_reject(VALUE obj) { return rb_hash_delete_if(fsdbm_to_hash(obj)); }
Iterates over the key-value pairs in the database, deleting those for which the block returns true
.
static VALUE fsdbm_delete_if(VALUE obj) { datum key, val; struct dbmdata *dbmp; DBM *dbm; VALUE keystr, valstr; VALUE ret, ary = rb_ary_new(); long i; int status = 0, n; fdbm_modify(obj); GetDBM2(obj, dbmp, dbm); n = dbmp->di_size; dbmp->di_size = -1; for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); keystr = rb_external_str_new(key.dptr, key.dsize); valstr = rb_external_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); ExportStringValue(keystr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); if (sdbm_delete(dbm, key)) { rb_raise(rb_eDBMError, "sdbm_delete failed"); } } if (status) rb_jump_tag(status); if (n > 0) dbmp->di_size = n - RARRAY_LENINT(ary); return obj; }
Empties the database, then inserts the given key-value pairs.
This method will work with any object which implements an each_pair
method, such as a Hash.
static VALUE fsdbm_replace(VALUE obj, VALUE other) { fsdbm_clear(obj); rb_block_call(other, rb_intern("each_pair"), 0, 0, update_i, obj); return obj; }
Returns a new Array of key-value pairs for which the block returns true
.
Example:
require 'sdbm' SDBM.open 'my_database' do |db| db['apple'] = 'fruit' db['pear'] = 'fruit' db['spinach'] = 'vegetable' veggies = db.select do |key, value| value == 'vegetable' end #=> [["apple", "fruit"], ["pear", "fruit"]] end
static VALUE fsdbm_select(VALUE obj) { VALUE new = rb_ary_new(); datum key, val; DBM *dbm; struct dbmdata *dbmp; GetDBM2(obj, dbmp, dbm); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { VALUE assoc, v; val = sdbm_fetch(dbm, key); assoc = rb_assoc_new(rb_external_str_new(key.dptr, key.dsize), rb_external_str_new(val.dptr, val.dsize)); v = rb_yield(assoc); if (RTEST(v)) { rb_ary_push(new, assoc); } GetDBM2(obj, dbmp, dbm); } return new; }
Removes a key-value pair from the database and returns them as an Array. If the database is empty, returns nil
.
static VALUE fsdbm_shift(VALUE obj) { datum key, val; struct dbmdata *dbmp; DBM *dbm; VALUE keystr, valstr; fdbm_modify(obj); GetDBM2(obj, dbmp, dbm); key = sdbm_firstkey(dbm); if (!key.dptr) return Qnil; val = sdbm_fetch(dbm, key); keystr = rb_external_str_new(key.dptr, key.dsize); valstr = rb_external_str_new(val.dptr, val.dsize); sdbm_delete(dbm, key); if (dbmp->di_size >= 0) { dbmp->di_size--; } return rb_assoc_new(keystr, valstr); }
Returns the number of keys in the database.
static VALUE fsdbm_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 = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { i++; } dbmp->di_size = i; return INT2FIX(i); }
Stores a new value
in the database with the given key
as an index.
If the key
already exists, this will update the value
associated with the key
.
Returns the given value
.
static VALUE fsdbm_store(VALUE obj, VALUE keystr, VALUE valstr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; if (valstr == Qnil) { fsdbm_delete(obj, keystr); return Qnil; } fdbm_modify(obj); ExportStringValue(keystr); ExportStringValue(valstr); key.dptr = RSTRING_PTR(keystr); key.dsize = RSTRING_LENINT(keystr); val.dptr = RSTRING_PTR(valstr); val.dsize = RSTRING_LENINT(valstr); GetDBM2(obj, dbmp, dbm); dbmp->di_size = -1; if (sdbm_store(dbm, key, val, DBM_REPLACE)) { #ifdef HAVE_DBM_CLAERERR sdbm_clearerr(dbm); #endif if (errno == EPERM) rb_sys_fail(0); rb_raise(rb_eDBMError, "sdbm_store failed"); } return valstr; }
Returns a new Array containing each key-value pair in the database.
Example:
require 'sdbm' SDBM.open 'my_database' do |db| db.update('apple' => 'fruit', 'spinach' => 'vegetable') db.to_a #=> [["apple", "fruit"], ["spinach", "vegetable"]] end
static VALUE fsdbm_to_a(VALUE obj) { datum key, val; struct dbmdata *dbmp; DBM *dbm; VALUE ary; GetDBM2(obj, dbmp, dbm); ary = rb_ary_new(); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); rb_ary_push(ary, rb_assoc_new(rb_external_str_new(key.dptr, key.dsize), rb_external_str_new(val.dptr, val.dsize))); } return ary; }
Returns a new Hash containing each key-value pair in the database.
static VALUE fsdbm_to_hash(VALUE obj) { datum key, val; struct dbmdata *dbmp; DBM *dbm; VALUE hash; GetDBM2(obj, dbmp, dbm); hash = rb_hash_new(); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); rb_hash_aset(hash, rb_external_str_new(key.dptr, key.dsize), rb_external_str_new(val.dptr, val.dsize)); } return hash; }
Insert or update key-value pairs.
This method will work with any object which implements an each_pair
method, such as a Hash.
static VALUE fsdbm_update(VALUE obj, VALUE other) { rb_block_call(other, rb_intern("each_pair"), 0, 0, update_i, obj); return obj; }
Returns true
if the database contains the given value
.
static VALUE fsdbm_has_value(VALUE obj, VALUE valstr) { datum key, val; struct dbmdata *dbmp; DBM *dbm; ExportStringValue(valstr); val.dptr = RSTRING_PTR(valstr); val.dsize = RSTRING_LENINT(valstr); GetDBM2(obj, dbmp, dbm); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); if (val.dsize == RSTRING_LENINT(valstr) && memcmp(val.dptr, RSTRING_PTR(valstr), val.dsize) == 0) return Qtrue; } return Qfalse; }
Returns a new Array containing the values in the database.
static VALUE fsdbm_values(VALUE obj) { datum key, val; struct dbmdata *dbmp; DBM *dbm; VALUE ary; GetDBM2(obj, dbmp, dbm); ary = rb_ary_new(); for (key = sdbm_firstkey(dbm); key.dptr; key = sdbm_nextkey(dbm)) { val = sdbm_fetch(dbm, key); rb_ary_push(ary, rb_external_str_new(val.dptr, val.dsize)); } return ary; }
Returns an Array of values corresponding to the given keys.
static VALUE fsdbm_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, fsdbm_fetch(obj, argv[i], Qnil)); } return new; }