Checkout of Instiki Trunk 1/21/2007.

vendor/plugins/sqlite3-ruby/sqlite3/translator.rb

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