109 lines
3.7 KiB
Ruby
109 lines
3.7 KiB
Ruby
require 'time'
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require 'date'
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module SQLite3
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# The Translator class encapsulates the logic and callbacks necessary for
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# converting string data to a value of some specified type. Every Database
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# instance may have a Translator instance, in order to assist in type
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# translation (Database#type_translation).
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#
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# Further, applications may define their own custom type translation logic
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# by registering translator blocks with the corresponding database's
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# translator instance (Database#translator).
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class Translator
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# Create a new Translator instance. It will be preinitialized with default
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# translators for most SQL data types.
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def initialize
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@translators = Hash.new( proc { |type,value| value } )
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@type_name_cache = {}
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register_default_translators
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end
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# Add a new translator block, which will be invoked to process type
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# translations to the given type. The type should be an SQL datatype, and
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# may include parentheses (i.e., "VARCHAR(30)"). However, any parenthetical
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# information is stripped off and discarded, so type translation decisions
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# are made solely on the "base" type name.
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#
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# The translator block itself should accept two parameters, "type" and
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# "value". In this case, the "type" is the full type name (including
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# parentheses), so the block itself may include logic for changing how a
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# type is translated based on the additional data. The "value" parameter
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# is the (string) data to convert.
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#
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# The block should return the translated value.
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def add_translator( type, &block ) # :yields: type, value
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@translators[ type_name( type ) ] = block
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end
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# Translate the given string value to a value of the given type. In the
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# absense of an installed translator block for the given type, the value
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# itself is always returned. Further, +nil+ values are never translated,
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# and are always passed straight through regardless of the type parameter.
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def translate( type, value )
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unless value.nil?
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@translators[ type_name( type ) ].call( type, value )
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end
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end
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# A convenience method for working with type names. This returns the "base"
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# type name, without any parenthetical data.
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def type_name( type )
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@type_name_cache[type] ||= begin
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type = "" if type.nil?
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type = $1 if type =~ /^(.*?)\(/
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type.upcase
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end
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end
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private :type_name
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# Register the default translators for the current Translator instance.
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# This includes translators for most major SQL data types.
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def register_default_translators
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[ "time",
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"timestamp" ].each { |type| add_translator( type ) { |t, v| Time.parse( v ) } }
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add_translator( "date" ) { |t,v| Date.parse(v) }
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add_translator( "datetime" ) { |t,v| DateTime.parse(v) }
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[ "decimal",
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"float",
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"numeric",
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"double",
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"real",
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"dec",
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"fixed" ].each { |type| add_translator( type ) { |t,v| v.to_f } }
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[ "integer",
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"smallint",
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"mediumint",
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"int",
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"bigint" ].each { |type| add_translator( type ) { |t,v| v.to_i } }
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[ "bit",
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"bool",
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"boolean" ].each do |type|
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add_translator( type ) do |t,v|
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!( v.strip.gsub(/00+/,"0") == "0" ||
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v.downcase == "false" ||
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v.downcase == "f" ||
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v.downcase == "no" ||
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v.downcase == "n" )
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end
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end
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add_translator( "tinyint" ) do |type, value|
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if type =~ /\(\s*1\s*\)/
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value.to_i == 1
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else
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value.to_i
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end
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end
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end
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private :register_default_translators
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end
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end
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