Class: Amalgalite::Requires

Inherits:
Object
  • Object
show all
Defined in:
lib/amalgalite/requires.rb,
ext/amalgalite/c/amalgalite_requires_bootstrap.c

Overview

Requires encapsulates requiring items from the database

Defined Under Namespace

Classes: Bootstrap

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ Requires

Returns a new instance of Requires.



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# File 'lib/amalgalite/requires.rb', line 74

def initialize( opts = {} )
  @dbfile_name       = opts[:dbfile_name]       || Bootstrap::DEFAULT_DB
  @table_name        = opts[:table_name]        || Bootstrap::DEFAULT_TABLE
  @filename_column   = opts[:filename_column]   || Bootstrap::DEFAULT_FILENAME_COLUMN
  @contents_column   = opts[:contents_column]   || Bootstrap::DEFAULT_CONTENTS_COLUMN
  @compressed_column = opts[:compressed_column] || Bootstrap::DEFAULT_COMPRESSED_COLUMN
  @db_connection   = Requires.db_connection_to( dbfile_name )
  Requires.load_path << self
end

Instance Attribute Details

#compressed_column ⇒ Object (readonly)

Returns the value of attribute compressed_column.



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# File 'lib/amalgalite/requires.rb', line 71

def compressed_column
  @compressed_column
end

#contents_column ⇒ Object (readonly)

Returns the value of attribute contents_column.



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# File 'lib/amalgalite/requires.rb', line 70

def contents_column
  @contents_column
end

#db_connection ⇒ Object (readonly)

Returns the value of attribute db_connection.



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# File 'lib/amalgalite/requires.rb', line 72

def db_connection
  @db_connection
end

#dbfile_name ⇒ Object (readonly)

Returns the value of attribute dbfile_name.



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# File 'lib/amalgalite/requires.rb', line 67

def dbfile_name
  @dbfile_name
end

#filename_column ⇒ Object (readonly)

Returns the value of attribute filename_column.



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# File 'lib/amalgalite/requires.rb', line 69

def filename_column
  @filename_column
end

#table_name ⇒ Object (readonly)

Returns the value of attribute table_name.



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# File 'lib/amalgalite/requires.rb', line 68

def table_name
  @table_name
end

Class Method Details

.db_connection_to(dbfile_name) ⇒ Object

Allocate a database connection to the given filename. For file databases, this means giving the same connection back if you ask for a connection to the same file. For in-memory databases, you get a new one each time.



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# File 'lib/amalgalite/requires.rb', line 26

def db_connection_to( dbfile_name )
  if dbfile_name == ":memory:"
    return ::Amalgalite::Database.new( dbfile_name )
  else
    unless connection = load_path_db_connections[ dbfile_name ] 
      connection = ::Amalgalite::Database.new( dbfile_name )
      load_path_db_connections[dbfile_name] = connection
    end
    return connection
  end
end

.load_path ⇒ Object 



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# File 'lib/amalgalite/requires.rb', line 16

def load_path
  @load_path ||= []
end

.load_path_db_connections ⇒ Object 



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# File 'lib/amalgalite/requires.rb', line 12

def load_path_db_connections
  @load_path_db_connections ||= {}
end

.require(filename) ⇒ Object 



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# File 'lib/amalgalite/requires.rb', line 46

def require( filename )
  if load_path.empty? then
    raise ::LoadError, "Amalgalite load path is empty -- #{filename}"
  elsif $LOADED_FEATURES.include?( filename ) then
    return false
  elsif Requires.requiring.include?( filename ) then 
    return false
  else
    Requires.requiring << filename
    load_path.each do |lp|
      if lp.require( filename ) then
        Requires.requiring.delete( filename )
        return true
      end
    end
    Requires.requiring.delete( filename )
    raise ::LoadError, "amalgalite has no such file to load -- #{filename}"
  end
end

.requiring ⇒ Object

Setting a class level variable as a flag to know what we are currently in the middle of requiring



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# File 'lib/amalgalite/requires.rb', line 42

def requiring
  @requiring ||= []
end

Instance Method Details

#file_contents(filename) ⇒ Object

Return the contents of the named file.



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# File 'lib/amalgalite/requires.rb', line 125

def file_contents(filename)
  rows = db_connection.execute(sql, filename)
  if rows.size > 0 then
    row = rows.first

    contents = row[contents_column].to_s
    if row[compressed_column] then 
      contents = ::Amalgalite::Packer.gunzip( contents )
    end
    
    return contents
  else
    return nil
  end
end

#import(sql) ⇒ Object

Import an SQL dump into the fake file system.



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# File 'lib/amalgalite/requires.rb', line 145

def import(sql)
  db_connection.import(sql)
end

#require(filename) ⇒ Object

load a file in this database table. This will check and see if the file is already required. If it isn’t it will select the contents associated with the row identified by the filename and eval those contents within the context of TOPLEVEL_BINDING. The filename is then appended to $LOADED_FEATURES.

if the file was required then true is returned, otherwise false



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# File 'lib/amalgalite/requires.rb', line 100

def require( filename )
  if $LOADED_FEATURES.include?( filename ) then
    return false
  else
    begin
      filename = filename.gsub(/\.rb\Z/,'')

      contents = file_contents(filename)

      if contents
        eval( contents, TOPLEVEL_BINDING, filename )
        $LOADED_FEATURES << filename
        return true
      else
        return false
      end
    rescue => e
      raise ::LoadError, "Failure loading #{filename} from #{dbfile_name} : #{e}"
    end
  end
end

#sql ⇒ Object

return the sql to find the file contents for a file in this requires



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# File 'lib/amalgalite/requires.rb', line 87

def sql
  @sql ||= "SELECT #{filename_column}, #{compressed_column}, #{contents_column} FROM #{table_name} WHERE #{filename_column} = ?"
end