744 lines
26 KiB
Ruby
744 lines
26 KiB
Ruby
#--
|
|
# =============================================================================
|
|
# Copyright (c) 2004, Jamis Buck (jgb3@email.byu.edu)
|
|
# All rights reserved.
|
|
#
|
|
# Redistribution and use in source and binary forms, with or without
|
|
# modification, are permitted provided that the following conditions are met:
|
|
#
|
|
# * Redistributions of source code must retain the above copyright notice,
|
|
# this list of conditions and the following disclaimer.
|
|
#
|
|
# * Redistributions in binary form must reproduce the above copyright
|
|
# notice, this list of conditions and the following disclaimer in the
|
|
# documentation and/or other materials provided with the distribution.
|
|
#
|
|
# * The names of its contributors may not be used to endorse or promote
|
|
# products derived from this software without specific prior written
|
|
# permission.
|
|
#
|
|
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
|
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
|
|
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
|
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
# =============================================================================
|
|
#++
|
|
|
|
require 'base64'
|
|
require 'sqlite3/constants'
|
|
require 'sqlite3/errors'
|
|
require 'sqlite3/pragmas'
|
|
require 'sqlite3/statement'
|
|
require 'sqlite3/translator'
|
|
require 'sqlite3/value'
|
|
|
|
module SQLite3
|
|
|
|
# The Database class encapsulates a single connection to a SQLite3 database.
|
|
# Its usage is very straightforward:
|
|
#
|
|
# require 'sqlite3'
|
|
#
|
|
# db = SQLite3::Database.new( "data.db" )
|
|
#
|
|
# db.execute( "select * from table" ) do |row|
|
|
# p row
|
|
# end
|
|
#
|
|
# db.close
|
|
#
|
|
# It wraps the lower-level methods provides by the selected driver, and
|
|
# includes the Pragmas module for access to various pragma convenience
|
|
# methods.
|
|
#
|
|
# The Database class provides type translation services as well, by which
|
|
# the SQLite3 data types (which are all represented as strings) may be
|
|
# converted into their corresponding types (as defined in the schemas
|
|
# for their tables). This translation only occurs when querying data from
|
|
# the database--insertions and updates are all still typeless.
|
|
#
|
|
# Furthermore, the Database class has been designed to work well with the
|
|
# ArrayFields module from Ara Howard. If you require the ArrayFields
|
|
# module before performing a query, and if you have not enabled results as
|
|
# hashes, then the results will all be indexible by field name.
|
|
class Database
|
|
include Pragmas
|
|
|
|
class <<self
|
|
|
|
alias :open :new
|
|
|
|
# Quotes the given string, making it safe to use in an SQL statement.
|
|
# It replaces all instances of the single-quote character with two
|
|
# single-quote characters. The modified string is returned.
|
|
def quote( string )
|
|
string.gsub( /'/, "''" )
|
|
end
|
|
|
|
end
|
|
|
|
# The low-level opaque database handle that this object wraps.
|
|
attr_reader :handle
|
|
|
|
# A reference to the underlying SQLite3 driver used by this database.
|
|
attr_reader :driver
|
|
|
|
# A boolean that indicates whether rows in result sets should be returned
|
|
# as hashes or not. By default, rows are returned as arrays.
|
|
attr_accessor :results_as_hash
|
|
|
|
# A boolean indicating whether or not type translation is enabled for this
|
|
# database.
|
|
attr_accessor :type_translation
|
|
|
|
# Create a new Database object that opens the given file. If utf16
|
|
# is +true+, the filename is interpreted as a UTF-16 encoded string.
|
|
#
|
|
# By default, the new database will return result rows as arrays
|
|
# (#results_as_hash) and has type translation disabled (#type_translation=).
|
|
def initialize( file_name, options={} )
|
|
utf16 = options.fetch(:utf16, false)
|
|
load_driver( options[:driver] )
|
|
|
|
@statement_factory = options[:statement_factory] || Statement
|
|
|
|
result, @handle = @driver.open( file_name, utf16 )
|
|
Error.check( result, nil, "could not open database" )
|
|
|
|
@closed = false
|
|
@results_as_hash = options.fetch(:results_as_hash,false)
|
|
@type_translation = options.fetch(:type_translation,false)
|
|
@translator = nil
|
|
end
|
|
|
|
# Return +true+ if the string is a valid (ie, parsable) SQL statement, and
|
|
# +false+ otherwise. If +utf16+ is +true+, then the string is a UTF-16
|
|
# character string.
|
|
def complete?( string, utf16=false )
|
|
@driver.complete?( string, utf16 )
|
|
end
|
|
|
|
# Return a string describing the last error to have occurred with this
|
|
# database.
|
|
def errmsg( utf16=false )
|
|
@driver.errmsg( @handle, utf16 )
|
|
end
|
|
|
|
# Return an integer representing the last error to have occurred with this
|
|
# database.
|
|
def errcode
|
|
@driver.errcode( @handle )
|
|
end
|
|
|
|
# Return the type translator employed by this database instance. Each
|
|
# database instance has its own type translator; this allows for different
|
|
# type handlers to be installed in each instance without affecting other
|
|
# instances. Furthermore, the translators are instantiated lazily, so that
|
|
# if a database does not use type translation, it will not be burdened by
|
|
# the overhead of a useless type translator. (See the Translator class.)
|
|
def translator
|
|
@translator ||= Translator.new
|
|
end
|
|
|
|
# Closes this database.
|
|
def close
|
|
unless @closed
|
|
result = @driver.close( @handle )
|
|
Error.check( result, self )
|
|
end
|
|
@closed = true
|
|
end
|
|
|
|
# Returns +true+ if this database instance has been closed (see #close).
|
|
def closed?
|
|
@closed
|
|
end
|
|
|
|
# Installs (or removes) a block that will be invoked for every SQL
|
|
# statement executed. The block receives a two parameters: the +data+
|
|
# argument, and the SQL statement executed. If the block is +nil+,
|
|
# any existing tracer will be uninstalled.
|
|
def trace( data=nil, &block )
|
|
@driver.trace( @handle, data, &block )
|
|
end
|
|
|
|
# Installs (or removes) a block that will be invoked for every access
|
|
# to the database. If the block returns 0 (or +nil+), the statement
|
|
# is allowed to proceed. Returning 1 causes an authorization error to
|
|
# occur, and returning 2 causes the access to be silently denied.
|
|
def authorizer( data=nil, &block )
|
|
result = @driver.set_authorizer( @handle, data, &block )
|
|
Error.check( result, self )
|
|
end
|
|
|
|
# Returns a Statement object representing the given SQL. This does not
|
|
# execute the statement; it merely prepares the statement for execution.
|
|
def prepare( sql )
|
|
stmt = @statement_factory.new( self, sql )
|
|
if block_given?
|
|
begin
|
|
yield stmt
|
|
ensure
|
|
stmt.close
|
|
end
|
|
else
|
|
return stmt
|
|
end
|
|
end
|
|
|
|
# Executes the given SQL statement. If additional parameters are given,
|
|
# they are treated as bind variables, and are bound to the placeholders in
|
|
# the query.
|
|
#
|
|
# Note that if any of the values passed to this are hashes, then the
|
|
# key/value pairs are each bound separately, with the key being used as
|
|
# the name of the placeholder to bind the value to.
|
|
#
|
|
# The block is optional. If given, it will be invoked for each row returned
|
|
# by the query. Otherwise, any results are accumulated into an array and
|
|
# returned wholesale.
|
|
#
|
|
# See also #execute2, #query, and #execute_batch for additional ways of
|
|
# executing statements.
|
|
def execute( sql, *bind_vars )
|
|
prepare( sql ) do |stmt|
|
|
result = stmt.execute( *bind_vars )
|
|
if block_given?
|
|
result.each { |row| yield row }
|
|
else
|
|
return result.inject( [] ) { |arr,row| arr << row; arr }
|
|
end
|
|
end
|
|
end
|
|
|
|
# Executes the given SQL statement, exactly as with #execute. However, the
|
|
# first row returned (either via the block, or in the returned array) is
|
|
# always the names of the columns. Subsequent rows correspond to the data
|
|
# from the result set.
|
|
#
|
|
# Thus, even if the query itself returns no rows, this method will always
|
|
# return at least one row--the names of the columns.
|
|
#
|
|
# See also #execute, #query, and #execute_batch for additional ways of
|
|
# executing statements.
|
|
def execute2( sql, *bind_vars )
|
|
prepare( sql ) do |stmt|
|
|
result = stmt.execute( *bind_vars )
|
|
if block_given?
|
|
yield result.columns
|
|
result.each { |row| yield row }
|
|
else
|
|
return result.inject( [ result.columns ] ) { |arr,row|
|
|
arr << row; arr }
|
|
end
|
|
end
|
|
end
|
|
|
|
# Executes all SQL statements in the given string. By contrast, the other
|
|
# means of executing queries will only execute the first statement in the
|
|
# string, ignoring all subsequent statements. This will execute each one
|
|
# in turn. The same bind parameters, if given, will be applied to each
|
|
# statement.
|
|
#
|
|
# This always returns +nil+, making it unsuitable for queries that return
|
|
# rows.
|
|
def execute_batch( sql, *bind_vars )
|
|
sql = sql.strip
|
|
until sql.empty? do
|
|
prepare( sql ) do |stmt|
|
|
stmt.execute( *bind_vars )
|
|
sql = stmt.remainder.strip
|
|
end
|
|
end
|
|
nil
|
|
end
|
|
|
|
# This is a convenience method for creating a statement, binding
|
|
# paramters to it, and calling execute:
|
|
#
|
|
# result = db.query( "select * from foo where a=?", 5 )
|
|
# # is the same as
|
|
# result = db.prepare( "select * from foo where a=?" ).execute( 5 )
|
|
#
|
|
# You must be sure to call +close+ on the ResultSet instance that is
|
|
# returned, or you could have problems with locks on the table. If called
|
|
# with a block, +close+ will be invoked implicitly when the block
|
|
# terminates.
|
|
def query( sql, *bind_vars )
|
|
result = prepare( sql ).execute( *bind_vars )
|
|
if block_given?
|
|
begin
|
|
yield result
|
|
ensure
|
|
result.close
|
|
end
|
|
else
|
|
return result
|
|
end
|
|
end
|
|
|
|
# A convenience method for obtaining the first row of a result set, and
|
|
# discarding all others. It is otherwise identical to #execute.
|
|
#
|
|
# See also #get_first_value.
|
|
def get_first_row( sql, *bind_vars )
|
|
execute( sql, *bind_vars ) { |row| return row }
|
|
nil
|
|
end
|
|
|
|
# A convenience method for obtaining the first value of the first row of a
|
|
# result set, and discarding all other values and rows. It is otherwise
|
|
# identical to #execute.
|
|
#
|
|
# See also #get_first_row.
|
|
def get_first_value( sql, *bind_vars )
|
|
execute( sql, *bind_vars ) { |row| return row[0] }
|
|
nil
|
|
end
|
|
|
|
# Obtains the unique row ID of the last row to be inserted by this Database
|
|
# instance.
|
|
def last_insert_row_id
|
|
@driver.last_insert_rowid( @handle )
|
|
end
|
|
|
|
# Returns the number of changes made to this database instance by the last
|
|
# operation performed. Note that a "delete from table" without a where
|
|
# clause will not affect this value.
|
|
def changes
|
|
@driver.changes( @handle )
|
|
end
|
|
|
|
# Returns the total number of changes made to this database instance
|
|
# since it was opened.
|
|
def total_changes
|
|
@driver.total_changes( @handle )
|
|
end
|
|
|
|
# Interrupts the currently executing operation, causing it to abort.
|
|
def interrupt
|
|
@driver.interrupt( @handle )
|
|
end
|
|
|
|
# Register a busy handler with this database instance. When a requested
|
|
# resource is busy, this handler will be invoked. If the handler returns
|
|
# +false+, the operation will be aborted; otherwise, the resource will
|
|
# be requested again.
|
|
#
|
|
# The handler will be invoked with the name of the resource that was
|
|
# busy, and the number of times it has been retried.
|
|
#
|
|
# See also #busy_timeout.
|
|
def busy_handler( data=nil, &block ) # :yields: data, retries
|
|
result = @driver.busy_handler( @handle, data, &block )
|
|
Error.check( result, self )
|
|
end
|
|
|
|
# Indicates that if a request for a resource terminates because that
|
|
# resource is busy, SQLite should wait for the indicated number of
|
|
# milliseconds before trying again. By default, SQLite does not retry
|
|
# busy resources. To restore the default behavior, send 0 as the
|
|
# +ms+ parameter.
|
|
#
|
|
# See also #busy_handler.
|
|
def busy_timeout( ms )
|
|
result = @driver.busy_timeout( @handle, ms )
|
|
Error.check( result, self )
|
|
end
|
|
|
|
# Creates a new function for use in SQL statements. It will be added as
|
|
# +name+, with the given +arity+. (For variable arity functions, use
|
|
# -1 for the arity.)
|
|
#
|
|
# The block should accept at least one parameter--the FunctionProxy
|
|
# instance that wraps this function invocation--and any other
|
|
# arguments it needs (up to its arity).
|
|
#
|
|
# The block does not return a value directly. Instead, it will invoke
|
|
# the FunctionProxy#set_result method on the +func+ parameter and
|
|
# indicate the return value that way.
|
|
#
|
|
# Example:
|
|
#
|
|
# db.create_function( "maim", 1 ) do |func, value|
|
|
# if value.nil?
|
|
# func.result = nil
|
|
# else
|
|
# func.result = value.split(//).sort.join
|
|
# end
|
|
# end
|
|
#
|
|
# puts db.get_first_value( "select maim(name) from table" )
|
|
def create_function( name, arity, text_rep=Constants::TextRep::ANY,
|
|
&block ) # :yields: func, *args
|
|
# begin
|
|
callback = proc do |func,*args|
|
|
begin
|
|
block.call( FunctionProxy.new( @driver, func ),
|
|
*args.map{|v| Value.new(self,v)} )
|
|
rescue StandardError, Exception => e
|
|
@driver.result_error( func,
|
|
"#{e.message} (#{e.class})", -1 )
|
|
end
|
|
end
|
|
|
|
result = @driver.create_function( @handle, name, arity, text_rep, nil,
|
|
callback, nil, nil )
|
|
Error.check( result, self )
|
|
|
|
self
|
|
end
|
|
|
|
# Creates a new aggregate function for use in SQL statements. Aggregate
|
|
# functions are functions that apply over every row in the result set,
|
|
# instead of over just a single row. (A very common aggregate function
|
|
# is the "count" function, for determining the number of rows that match
|
|
# a query.)
|
|
#
|
|
# The new function will be added as +name+, with the given +arity+. (For
|
|
# variable arity functions, use -1 for the arity.)
|
|
#
|
|
# The +step+ parameter must be a proc object that accepts as its first
|
|
# parameter a FunctionProxy instance (representing the function
|
|
# invocation), with any subsequent parameters (up to the function's arity).
|
|
# The +step+ callback will be invoked once for each row of the result set.
|
|
#
|
|
# The +finalize+ parameter must be a +proc+ object that accepts only a
|
|
# single parameter, the FunctionProxy instance representing the current
|
|
# function invocation. It should invoke FunctionProxy#set_result to
|
|
# store the result of the function.
|
|
#
|
|
# Example:
|
|
#
|
|
# db.create_aggregate( "lengths", 1 ) do
|
|
# step do |func, value|
|
|
# func[ :total ] ||= 0
|
|
# func[ :total ] += ( value ? value.length : 0 )
|
|
# end
|
|
#
|
|
# finalize do |func|
|
|
# func.set_result( func[ :total ] || 0 )
|
|
# end
|
|
# end
|
|
#
|
|
# puts db.get_first_value( "select lengths(name) from table" )
|
|
#
|
|
# See also #create_aggregate_handler for a more object-oriented approach to
|
|
# aggregate functions.
|
|
def create_aggregate( name, arity, step=nil, finalize=nil,
|
|
text_rep=Constants::TextRep::ANY, &block )
|
|
# begin
|
|
if block
|
|
proxy = AggregateDefinitionProxy.new
|
|
proxy.instance_eval &block
|
|
step ||= proxy.step_callback
|
|
finalize ||= proxy.finalize_callback
|
|
end
|
|
|
|
step_callback = proc do |func,*args|
|
|
ctx = @driver.aggregate_context( func )
|
|
unless ctx[:__error]
|
|
begin
|
|
step.call( FunctionProxy.new( @driver, func, ctx ),
|
|
*args.map{|v| Value.new(self,v)} )
|
|
rescue Exception => e
|
|
ctx[:__error] = e
|
|
end
|
|
end
|
|
end
|
|
|
|
finalize_callback = proc do |func|
|
|
ctx = @driver.aggregate_context( func )
|
|
unless ctx[:__error]
|
|
begin
|
|
finalize.call( FunctionProxy.new( @driver, func, ctx ) )
|
|
rescue Exception => e
|
|
@driver.result_error( func,
|
|
"#{e.message} (#{e.class})", -1 )
|
|
end
|
|
else
|
|
e = ctx[:__error]
|
|
@driver.result_error( func,
|
|
"#{e.message} (#{e.class})", -1 )
|
|
end
|
|
end
|
|
|
|
result = @driver.create_function( @handle, name, arity, text_rep, nil,
|
|
nil, step_callback, finalize_callback )
|
|
Error.check( result, self )
|
|
|
|
self
|
|
end
|
|
|
|
# This is another approach to creating an aggregate function (see
|
|
# #create_aggregate). Instead of explicitly specifying the name,
|
|
# callbacks, arity, and type, you specify a factory object
|
|
# (the "handler") that knows how to obtain all of that information. The
|
|
# handler should respond to the following messages:
|
|
#
|
|
# +arity+:: corresponds to the +arity+ parameter of #create_aggregate. This
|
|
# message is optional, and if the handler does not respond to it,
|
|
# the function will have an arity of -1.
|
|
# +name+:: this is the name of the function. The handler _must_ implement
|
|
# this message.
|
|
# +new+:: this must be implemented by the handler. It should return a new
|
|
# instance of the object that will handle a specific invocation of
|
|
# the function.
|
|
#
|
|
# The handler instance (the object returned by the +new+ message, described
|
|
# above), must respond to the following messages:
|
|
#
|
|
# +step+:: this is the method that will be called for each step of the
|
|
# aggregate function's evaluation. It should implement the same
|
|
# signature as the +step+ callback for #create_aggregate.
|
|
# +finalize+:: this is the method that will be called to finalize the
|
|
# aggregate function's evaluation. It should implement the
|
|
# same signature as the +finalize+ callback for
|
|
# #create_aggregate.
|
|
#
|
|
# Example:
|
|
#
|
|
# class LengthsAggregateHandler
|
|
# def self.arity; 1; end
|
|
#
|
|
# def initialize
|
|
# @total = 0
|
|
# end
|
|
#
|
|
# def step( ctx, name )
|
|
# @total += ( name ? name.length : 0 )
|
|
# end
|
|
#
|
|
# def finalize( ctx )
|
|
# ctx.set_result( @total )
|
|
# end
|
|
# end
|
|
#
|
|
# db.create_aggregate_handler( LengthsAggregateHandler )
|
|
# puts db.get_first_value( "select lengths(name) from A" )
|
|
def create_aggregate_handler( handler )
|
|
arity = -1
|
|
text_rep = Constants::TextRep::ANY
|
|
|
|
arity = handler.arity if handler.respond_to?(:arity)
|
|
text_rep = handler.text_rep if handler.respond_to?(:text_rep)
|
|
name = handler.name
|
|
|
|
step = proc do |func,*args|
|
|
ctx = @driver.aggregate_context( func )
|
|
unless ctx[ :__error ]
|
|
ctx[ :handler ] ||= handler.new
|
|
begin
|
|
ctx[ :handler ].step( FunctionProxy.new( @driver, func, ctx ),
|
|
*args.map{|v| Value.new(self,v)} )
|
|
rescue Exception, StandardError => e
|
|
ctx[ :__error ] = e
|
|
end
|
|
end
|
|
end
|
|
|
|
finalize = proc do |func|
|
|
ctx = @driver.aggregate_context( func )
|
|
unless ctx[ :__error ]
|
|
ctx[ :handler ] ||= handler.new
|
|
begin
|
|
ctx[ :handler ].finalize( FunctionProxy.new( @driver, func, ctx ) )
|
|
rescue Exception => e
|
|
ctx[ :__error ] = e
|
|
end
|
|
end
|
|
|
|
if ctx[ :__error ]
|
|
e = ctx[ :__error ]
|
|
@driver.sqlite3_result_error( func, "#{e.message} (#{e.class})", -1 )
|
|
end
|
|
end
|
|
|
|
result = @driver.create_function( @handle, name, arity, text_rep, nil,
|
|
nil, step, finalize )
|
|
Error.check( result, self )
|
|
|
|
self
|
|
end
|
|
|
|
# Begins a new transaction. Note that nested transactions are not allowed
|
|
# by SQLite, so attempting to nest a transaction will result in a runtime
|
|
# exception.
|
|
#
|
|
# The +mode+ parameter may be either <tt>:deferred</tt> (the default),
|
|
# <tt>:immediate</tt>, or <tt>:exclusive</tt>.
|
|
#
|
|
# If a block is given, the database instance is yielded to it, and the
|
|
# transaction is committed when the block terminates. If the block
|
|
# raises an exception, a rollback will be performed instead. Note that if
|
|
# a block is given, #commit and #rollback should never be called
|
|
# explicitly or you'll get an error when the block terminates.
|
|
#
|
|
# If a block is not given, it is the caller's responsibility to end the
|
|
# transaction explicitly, either by calling #commit, or by calling
|
|
# #rollback.
|
|
def transaction( mode = :deferred )
|
|
execute "begin #{mode.to_s} transaction"
|
|
@transaction_active = true
|
|
|
|
if block_given?
|
|
abort = false
|
|
begin
|
|
yield self
|
|
rescue Exception
|
|
abort = true
|
|
raise
|
|
ensure
|
|
abort and rollback or commit
|
|
end
|
|
end
|
|
|
|
true
|
|
end
|
|
|
|
# Commits the current transaction. If there is no current transaction,
|
|
# this will cause an error to be raised. This returns +true+, in order
|
|
# to allow it to be used in idioms like
|
|
# <tt>abort? and rollback or commit</tt>.
|
|
def commit
|
|
execute "commit transaction"
|
|
@transaction_active = false
|
|
true
|
|
end
|
|
|
|
# Rolls the current transaction back. If there is no current transaction,
|
|
# this will cause an error to be raised. This returns +true+, in order
|
|
# to allow it to be used in idioms like
|
|
# <tt>abort? and rollback or commit</tt>.
|
|
def rollback
|
|
execute "rollback transaction"
|
|
@transaction_active = false
|
|
true
|
|
end
|
|
|
|
# Returns +true+ if there is a transaction active, and +false+ otherwise.
|
|
def transaction_active?
|
|
@transaction_active
|
|
end
|
|
|
|
# Loads the corresponding driver, or if it is nil, attempts to locate a
|
|
# suitable driver.
|
|
def load_driver( driver )
|
|
case driver
|
|
when Class
|
|
# do nothing--use what was given
|
|
when Symbol, String
|
|
require "sqlite3/driver/#{driver.to_s.downcase}/driver"
|
|
driver = SQLite3::Driver.const_get( driver )::Driver
|
|
else
|
|
[ "Native", "DL" ].each do |d|
|
|
begin
|
|
require "sqlite3/driver/#{d.downcase}/driver"
|
|
driver = SQLite3::Driver.const_get( d )::Driver
|
|
break
|
|
rescue SyntaxError
|
|
raise
|
|
rescue ScriptError, Exception, NameError
|
|
end
|
|
end
|
|
raise "no driver for sqlite3 found" unless driver
|
|
end
|
|
|
|
@driver = driver.new
|
|
end
|
|
private :load_driver
|
|
|
|
# A helper class for dealing with custom functions (see #create_function,
|
|
# #create_aggregate, and #create_aggregate_handler). It encapsulates the
|
|
# opaque function object that represents the current invocation. It also
|
|
# provides more convenient access to the API functions that operate on
|
|
# the function object.
|
|
#
|
|
# This class will almost _always_ be instantiated indirectly, by working
|
|
# with the create methods mentioned above.
|
|
class FunctionProxy
|
|
|
|
# Create a new FunctionProxy that encapsulates the given +func+ object.
|
|
# If context is non-nil, the functions context will be set to that. If
|
|
# it is non-nil, it must quack like a Hash. If it is nil, then none of
|
|
# the context functions will be available.
|
|
def initialize( driver, func, context=nil )
|
|
@driver = driver
|
|
@func = func
|
|
@context = context
|
|
end
|
|
|
|
# Calls #set_result to set the result of this function.
|
|
def result=( result )
|
|
set_result( result )
|
|
end
|
|
|
|
# Set the result of the function to the given value. The function will
|
|
# then return this value.
|
|
def set_result( result, utf16=false )
|
|
@driver.result_text( @func, result, utf16 )
|
|
end
|
|
|
|
# Set the result of the function to the given error message.
|
|
# The function will then return that error.
|
|
def set_error( error )
|
|
@driver.result_error( @func, error.to_s, -1 )
|
|
end
|
|
|
|
# (Only available to aggregate functions.) Returns the number of rows
|
|
# that the aggregate has processed so far. This will include the current
|
|
# row, and so will always return at least 1.
|
|
def count
|
|
ensure_aggregate!
|
|
@driver.aggregate_count( @func )
|
|
end
|
|
|
|
# Returns the value with the given key from the context. This is only
|
|
# available to aggregate functions.
|
|
def []( key )
|
|
ensure_aggregate!
|
|
@context[ key ]
|
|
end
|
|
|
|
# Sets the value with the given key in the context. This is only
|
|
# available to aggregate functions.
|
|
def []=( key, value )
|
|
ensure_aggregate!
|
|
@context[ key ] = value
|
|
end
|
|
|
|
# A function for performing a sanity check, to ensure that the function
|
|
# being invoked is an aggregate function. This is implied by the
|
|
# existence of the context variable.
|
|
def ensure_aggregate!
|
|
unless @context
|
|
raise MisuseException, "function is not an aggregate"
|
|
end
|
|
end
|
|
private :ensure_aggregate!
|
|
|
|
end
|
|
|
|
# A proxy used for defining the callbacks to an aggregate function.
|
|
class AggregateDefinitionProxy # :nodoc:
|
|
attr_reader :step_callback, :finalize_callback
|
|
|
|
def step( &block )
|
|
@step_callback = block
|
|
end
|
|
|
|
def finalize( &block )
|
|
@finalize_callback = block
|
|
end
|
|
end
|
|
|
|
end
|
|
|
|
end
|
|
|