Class: Treequel::Filter

Inherits:

Object

Object
Treequel::Filter

show all

Extended by:: Loggability

Includes:: Constants::Patterns

Defined in:: lib/treequel/filter.rb

Overview

This is an object that is used to build an LDAP filter for Treequel::Branchsets.

Grammar (from RFC 2254) ==

filter     = "(" filtercomp ")"
filtercomp = and / or / not / item
and        = "&" filterlist
or         = "|" filterlist
not        = "!" filter
filterlist = 1*filter
item       = simple / present / substring / extensible
simple     = attr filtertype value
filtertype = equal / approx / greater / less
equal      = "="
approx     = "~="
greater    = ">="
less       = "<="
extensible = attr [":dn"] [":" matchingrule] ":=" value
             / [":dn"] ":" matchingrule ":=" value
present    = attr "=*"
substring  = attr "=" [initial] any [final]
initial    = value
any        = "*" *(value "*")
final      = value
attr       = AttributeDescription from Section 4.1.5 of [1]
matchingrule = MatchingRuleId from Section 4.1.9 of [1]
value      = AttributeValue from Section 4.1.6 of [1]

Defined Under Namespace

Classes: AndComponent, Component, FilterList, ItemComponent, NotComponent, OrComponent, PresentItemComponent, SimpleItemComponent, SubstringItemComponent

Constant Summary collapse

DEFAULT_EXPRESSION = The default filter expression to use when searching if none is specified

[ :objectClass ]

LOGICAL_COMPONENTS = The mapping of leftmost symbols in a boolean expression and the corresponding FilterComponent class.

{
	:or  => OrComponent,
	:|   => OrComponent,
	:and => AndComponent,
	:&   => AndComponent,
	:not => NotComponent,
	:"!" => NotComponent,
}

SEQUEL_FILTERTYPE_EQUIVALENTS = An equivalence mapping of operation names from Sequel expressions into Treequel equivalents

{
	:like => :equal,
	:>=   => :greater,
	:<=   => :less,
}

UNSUPPORTED_SEQUEL_FILTERTYPES = A list of filtertypes that come in as Sequel::Expressions; these generated nicer exception messages that just ‘unknown filtertype’

{
	:'~*' => %{LDAP doesn't support Regex filters},
	:'~'  => %{LDAP doesn't support Regex filters},
	:>    => %{LDAP doesn't support "greater-than"; use "greater-than-or-equal-to" (>=) instead},
	:<    => %{LDAP doesn't support "less-than"; use "less-than-or-equal-to" (<=) instead},
}

Constants included from Constants::Patterns

Instance Attribute Summary collapse

#component ⇒ Object

The filtercomp part of the filter.

Class Method Summary collapse

.parse_array_expression(expression) ⇒ Object

Turn the specified expression Array into a Treequel::Filter::Component object and return it.
.parse_expression(expression) ⇒ Object

Turn the specified filter expression into a Treequel::Filter::Component object and return it.
.parse_hash_expression(expression) ⇒ Object

Parse one or more tuples contained in a Hash into an ANDed set of Treequel::Filter::Components and return it.
.parse_item_component(attribute, value) ⇒ Object

Parse an item component from the specified attribute and value.
.parse_logical_array_expression(op, *components) ⇒ Object

Break down the given expression as a logical (AND, OR, or NOT) filter component and return it.
.parse_sequel_expression(expression) ⇒ Object

Parse a Sequel::SQL::Expression as a Treequel::Filter::Component and return it.
.parse_tuple_array_expression(expression) ⇒ Object

Parse a tuple of the form: [ Symbol, Object ] into a Treequel::Filter::Component and return it.

Instance Method Summary collapse

#&(other_filter) ⇒ Object (also: #+)

Return a new Filter that is the AND filter of the receiver with other_filter.
#==(other_filter) ⇒ Object

Equality operator – returns true if other_filter is equivalent to the receiver.
#initialize(*expression_parts) ⇒ Filter constructor

Create a new Treequel::Branchset::Filter with the specified expression.
#inspect ⇒ Object

Return a human-readable string representation of the filter suitable for debugging.
#promiscuous? ⇒ Boolean (also: #is_promiscuous?)

Returns true if the filter contains a single ‘present’ component for the objectClass attribute (which will match every entry).
#to_s ⇒ Object

Return the Treequel::Branchset::Filter as a String.
#|(other_filter) ⇒ Object

Return a new Filter that is the OR filter of the receiver with other_filter.

Constructor Details

#initialize(*expression_parts) ⇒ `Filter`

Create a new Treequel::Branchset::Filter with the specified expression.

# File 'lib/treequel/filter.rb', line 675

def initialize( *expression_parts )
	self.log.debug "New filter for expression: %p" % [ expression_parts ]
	@component = self.class.parse_expression( expression_parts )
	self.log.debug "  expression parsed into component: %p" % [ @component ]

	super()
end

Instance Attribute Details

#component ⇒ `Object`

The filtercomp part of the filter



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# File 'lib/treequel/filter.rb', line 689

def component
  @component
end

Class Method Details

.parse_array_expression(expression) ⇒ `Object`

Turn the specified expression Array into a Treequel::Filter::Component object and return it.

# File 'lib/treequel/filter.rb', line 462

def self::parse_array_expression( expression )
	self.log.debug "Parsing Array expression %p" % [ expression ]

	case

	# [ ] := '(objectClass=*)'
	when expression.empty?
		self.log.debug "  empty expression -> objectClass presence item component"
		return Treequel::Filter::PresentItemComponent.new

	# Collection of subfilters
	# [ [:uid, 'mahlon'], [:employeeNumber, 20202] ]
	when expression.all? {|elem| elem.is_a?(Array) }
		self.log.debug "  parsing array of subfilters"
		filters = expression.collect {|exp| Treequel::Filter.new(exp) }
		if filters.length > 1
			return Treequel::Filter::AndComponent.new( filters )
		else
			return filters.first
		end

	# Literal filters [ 'uid~=gung', 'l=bangkok' ]  := '(uid~=gung)(l=bangkok)'
	when expression.all? {|item| item.is_a?(String) }
		filters = expression.collect {|item| Treequel::Filter.new(item) }
		return Treequel::Filter::FilterList.new( filters )

	# Collection of subfilter objects
	when expression.all? {|elem| elem.is_a?(Treequel::Filter) }
		return Treequel::Filter::FilterList.new( expression )

	# [ :attribute ] := '(attribute=*)'
	when expression.length == 1
		return self.parse_expression( expression[0] )

	when expression[0].is_a?( Symbol )
		return self.parse_tuple_array_expression( expression )

	else
		raise Treequel::ExpressionError,
			"don't know how to turn %p into a filter component" % [ expression ]
	end

end

.parse_expression(expression) ⇒ `Object`

Turn the specified filter expression into a Treequel::Filter::Component object and return it.

# File 'lib/treequel/filter.rb', line 423

def self::parse_expression( expression )
	self.log.debug "Parsing expression %p" % [ expression ]
	expression = expression[0] if expression.is_a?( Array ) && expression.length == 1

	case expression

	# String-literal filters
	when String
		return expression

	# 'Item' components
	when Array
		return self.parse_array_expression( expression )

	# Composite item components
	when Hash
		return self.parse_hash_expression( expression )

	# Unwrapped presence item filter
	when Symbol
		return Treequel::Filter::PresentItemComponent.new( expression )

	# Support Sequel expressions
	when Sequel::SQL::Expression
		return self.parse_sequel_expression( expression )

	# Filters and components can already act as components of other filters
	when Treequel::Filter, Treequel::Filter::Component
		return expression

	else
		raise Treequel::ExpressionError,
			"don't know how to turn %p into an filter component" % [ expression ]
	end
end

.parse_hash_expression(expression) ⇒ `Object`

Parse one or more tuples contained in a Hash into an ANDed set of Treequel::Filter::Components and return it.

# File 'lib/treequel/filter.rb', line 509

def self::parse_hash_expression( expression )
	self.log.debug "Parsing Hash expression %p" % [ expression ]

	filterlist = expression.collect do |key, expr|
		self.log.debug "  adding %p => %p to the filter list" % [ key, expr ]
		if expr.respond_to?( :fetch )
			if expr.respond_to?( :length ) && expr.length > 1
				self.log.debug "    ORing together %d subfilters since %p has indices" %
					[ expr.length, expr ]
				subfilters = expr.collect {|val| Treequel::Filter.new(key, val) }
				Treequel::Filter.new( :or, subfilters )
			else
				self.log.debug "    unwrapping singular subfilter"
				Treequel::Filter.new([ key.to_sym, expr.first ])
			end
		else
			self.log.debug "    value is a scalar; creating a single filter"
			Treequel::Filter.new( key.to_sym, expr )
		end
	end

	if filterlist.length > 1
		return Treequel::Filter::AndComponent.new( *filterlist )
	else
		return filterlist.first
	end
end

.parse_item_component(attribute, value) ⇒ `Object`

Parse an item component from the specified attribute and value

# File 'lib/treequel/filter.rb', line 587

def self::parse_item_component( attribute, value )
	self.log.debug "  tuple expression (%p=%p)-> item component" %
		[ attribute, value ]

	case
	when attribute.to_s.index( ':' )
		raise NotImplementedError, "extensible filters are not yet supported"
	when value == '*'
		return Treequel::Filter::PresentItemComponent.new( attribute )
	when value =~ LDAP_SUBSTRING_FILTER_VALUE
		return Treequel::Filter::SubstringItemComponent.new( attribute, value )
	else
		return Treequel::Filter::SimpleItemComponent.new( attribute, value )
	end
end

.parse_logical_array_expression(op, *components) ⇒ `Object`

Break down the given expression as a logical (AND, OR, or NOT) filter component and return it.

# File 'lib/treequel/filter.rb', line 569

def self::parse_logical_array_expression( op, *components )
	self.log.debug "Parsing logical %p expression with components: %p" %
		[ op, components ]

	compclass = LOGICAL_COMPONENTS[ op ] or
		raise "don't know what a %p condition is. I only know about: %p" %
			[ op, LOGICAL_COMPONENTS.keys ]

	filterlist = components.collect do |filterexp|
		self.log.debug "  making %p into a component" % [ filterexp ]
		Treequel::Filter.new( filterexp )
	end.flatten

	return compclass.new( *filterlist )
end

.parse_sequel_expression(expression) ⇒ `Object`

Parse a Sequel::SQL::Expression as a Treequel::Filter::Component and return it.

# File 'lib/treequel/filter.rb', line 605

def self::parse_sequel_expression( expression )
	self.log.debug "  parsing Sequel expression: %p" % [ expression ]

	if expression.respond_to?( :op )
		op = expression.op.to_s.downcase.to_sym

		if equivalent = SEQUEL_FILTERTYPE_EQUIVALENTS[ op ]
			attribute, value = *expression.args

			# Turn :sn.like( 'bob' ) into (cn~=bob) 'cause it has no asterisks
			if op == :like
				if value.index( '*' )
					self.log.debug \
						"    turning a LIKE expression with an asterisk into a substring filter"
					return Treequel::Filter::SubstringItemComponent.new( attribute, value )
				else
					self.log.debug \
						"    turning a LIKE expression with no wildcards into an 'approx' filter"
					equivalent = :approx
				end
			end

			return Treequel::Filter::SimpleItemComponent.new( attribute, value, equivalent )

		elsif op == :'!='
			contents = Treequel::Filter.new( expression.args )
			return Treequel::Filter::NotComponent.new( contents )

		elsif op == :'not like'
			self.log.debug "  making a NOT LIKE expression out of: %p" % [ expression ]
			attribute, value = *expression.args
			component = nil

			if value.index( '*' )
				component = Treequel::Filter::SubstringItemComponent.new( attribute, value )
			else
				component = Treequel::Filter::SimpleItemComponent.new( attribute, value, :approx )
			end

			filter = Treequel::Filter.new( component )
			return Treequel::Filter::NotComponent.new( filter )

		elsif LOGICAL_COMPONENTS.key?( op )
			components = expression.args.collect do |comp|
				Treequel::Filter.new( comp )
			end

			return self.parse_logical_array_expression( op, components )

		elsif msg = UNSUPPORTED_SEQUEL_FILTERTYPES[ op ]
			raise Treequel::ExpressionError,
				"unsupported Sequel filter syntax %p: %s" %
				[ expression, msg ]
		else
			raise ScriptError,
				"  unhandled Sequel BooleanExpression: add handling for %p: %p" % [ op, expression ]
		end

	else
		raise Treequel::ExpressionError,
			"don't know how to turn %p into a component" % [ expression ]
	end
end

.parse_tuple_array_expression(expression) ⇒ `Object`

Parse a tuple of the form: [ Symbol, Object ] into a Treequel::Filter::Component and return it.

# File 'lib/treequel/filter.rb', line 540

def self::parse_tuple_array_expression( expression )
	self.log.debug "Parsing tuple Array expression %p" % [ expression ]

	case expression[1]

	# [ :and/:or/:not, [:uid, 1] ]      := (&/|/!(uid=1))
	# [ :and/:or/:not, {:uid => 1} ]    := (&/|/!(uid=1))
	when Array, Hash
		return self.parse_logical_array_expression( *expression )

	when Range
		self.log.debug "  two ANDed item expressions from a Range"
		attribute = expression[0]
		range = expression[1]
		left = "#{attribute}>=#{range.begin}"
		right = "#{attribute}<=#{range.exclude_end? ? range.max : range.end}"
		return self.parse_logical_array_expression( :and, [left, right] )

	# [ :attribute, 'value' ]  := '(attribute=value)'
	# when String, Symbol, Numeric, Time
	else
		self.log.debug "  item expression from a %p" % [ expression[1].class ]
		return self.parse_item_component( *expression )
	end
end

Instance Method Details

#&(other_filter) ⇒ `Object` Also known as: +

Return a new Filter that is the AND filter of the receiver with other_filter.

# File 'lib/treequel/filter.rb', line 731

def &( other_filter )
	return other_filter if self.promiscuous?
	return self.dup if other_filter.promiscuous?
	return self.class.new( :and, [self, other_filter] )
end

#==(other_filter) ⇒ `Object`

Equality operator – returns true if other_filter is equivalent to the receiver.



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# File 'lib/treequel/filter.rb', line 725

def ==( other_filter )
	return ( self.component == other_filter.component )
end

#inspect ⇒ `Object`

Return a human-readable string representation of the filter suitable for debugging.

# File 'lib/treequel/filter.rb', line 706

def inspect
	return %{#<%s:0x%0x (%s)>} % [
		self.class.name,
		self.object_id * 2,
		self.component,
	]
end

#promiscuous? ⇒ `Boolean` Also known as: is_promiscuous?

Returns true if the filter contains a single ‘present’ component for the objectClass attribute (which will match every entry)

Returns:

(Boolean)



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# File 'lib/treequel/filter.rb', line 717

def promiscuous?
	return self.component.promiscuous?
end

#to_s ⇒ `Object`

Return the Treequel::Branchset::Filter as a String.

# File 'lib/treequel/filter.rb', line 693

def to_s
	# self.log.debug "stringifying filter %p" % [ self ]
	filtercomp = self.component.to_s
	if filtercomp[0] == ?(
		return filtercomp
	else
		return '(' + filtercomp + ')'
	end
end

#|(other_filter) ⇒ `Object`

Return a new Filter that is the OR filter of the receiver with other_filter.

# File 'lib/treequel/filter.rb', line 740

def |( other_filter )
	return other_filter if self.promiscuous?
	return self.dup if other_filter.promiscuous?

	# Collapse nested ORs into a single one with an additional alternation
	# if possible.
	if self.component.respond_to?( :add_alternation )
		self.log.debug "collapsing nested ORs..."
		newcomp = self.component.dup
		newcomp.add_alternation( other_filter )
		return self.class.new( newcomp )
	else
		return self.class.new( :or, [self, other_filter] )
	end
end

Class: Treequel::Filter

Overview

Grammar (from RFC 2254) ==

Defined Under Namespace

Constant Summary collapse

Constants included from Constants::Patterns

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*expression_parts) ⇒ Filter

Instance Attribute Details

#component ⇒ Object

Class Method Details

.parse_array_expression(expression) ⇒ Object

.parse_expression(expression) ⇒ Object

.parse_hash_expression(expression) ⇒ Object

.parse_item_component(attribute, value) ⇒ Object

.parse_logical_array_expression(op, *components) ⇒ Object

.parse_sequel_expression(expression) ⇒ Object

.parse_tuple_array_expression(expression) ⇒ Object