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require 'sqlite3/constants'
require 'sqlite3/errors'
module SQLite3
# The ResultSet object encapsulates the enumerability of a query's output.
# It is a simple cursor over the data that the query returns. It will
# very rarely (if ever) be instantiated directly. Instead, client's should
# obtain a ResultSet instance via Statement#execute.
class ResultSet
include Enumerable
# A trivial module for adding a +types+ accessor to an object.
module TypesContainer
attr_accessor :types
end
# A trivial module for adding a +fields+ accessor to an object.
module FieldsContainer
attr_accessor :fields
end
# Create a new ResultSet attached to the given database, using the
# given sql text.
def initialize( db, stmt )
@db = db
@driver = @db.driver
@stmt = stmt
commence
end
# A convenience method for compiling the virtual machine and stepping
# to the first row of the result set.
def commence
result = @driver.step( @stmt.handle )
if result == Constants::ErrorCode::ERROR
@driver.reset( @stmt.handle )
end
check result
@first_row = true
end
private :commence
def check( result )
@eof = ( result == Constants::ErrorCode::DONE )
found = ( result == Constants::ErrorCode::ROW )
Error.check( result, @db ) unless @eof || found
end
private :check
# Reset the cursor, so that a result set which has reached end-of-file
# can be rewound and reiterated.
def reset( *bind_params )
@stmt.must_be_open!
@stmt.reset!(false)
@driver.reset( @stmt.handle )
@stmt.bind_params( *bind_params )
@eof = false
commence
end
# Query whether the cursor has reached the end of the result set or not.
def eof?
@eof
end
# Obtain the next row from the cursor. If there are no more rows to be
# had, this will return +nil+. If type translation is active on the
# corresponding database, the values in the row will be translated
# according to their types.
#
# The returned value will be an array, unless Database#results_as_hash has
# been set to +true+, in which case the returned value will be a hash.
#
# For arrays, the column names are accessible via the +fields+ property,
# and the column types are accessible via the +types+ property.
#
# For hashes, the column names are the keys of the hash, and the column
# types are accessible via the +types+ property.
def next
return nil if @eof
@stmt.must_be_open!
unless @first_row
result = @driver.step( @stmt.handle )
check result
end
@first_row = false
unless @eof
row = []
@driver.data_count( @stmt.handle ).times do |column|
type = @driver.column_type( @stmt.handle, column )
if type == Constants::ColumnType::TEXT
row << @driver.column_text( @stmt.handle, column )
elsif type == Constants::ColumnType::NULL
row << nil
elsif type == Constants::ColumnType::BLOB
row << @driver.column_blob( @stmt.handle, column )
else
row << @driver.column_text( @stmt.handle, column )
end
end
if @db.type_translation
row = @stmt.types.zip( row ).map do |type, value|
@db.translator.translate( type, value )
end
end
if @db.results_as_hash
new_row = Hash[ *( @stmt.columns.zip( row ).flatten ) ]
row.each_with_index { |value,idx| new_row[idx] = value }
row = new_row
else
row.extend FieldsContainer unless row.respond_to?(:fields)
row.fields = @stmt.columns
end
row.extend TypesContainer
row.types = @stmt.types
return row
end
nil
end
# Required by the Enumerable mixin. Provides an internal iterator over the
# rows of the result set.
def each
while row=self.next
yield row
end
end
# Closes the statement that spawned this result set.
# <em>Use with caution!</em> Closing a result set will automatically
# close any other result sets that were spawned from the same statement.
def close
@stmt.close
end
# Queries whether the underlying statement has been closed or not.
def closed?
@stmt.closed?
end
# Returns the types of the columns returned by this result set.
def types
@stmt.types
end
# Returns the names of the columns returned by this result set.
def columns
@stmt.columns
end
end
end
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