Filter Class Reference

Track data filter. More...

#include <filter.h>

Inheritance diagram for Filter:

Collaboration diagram for Filter:

Classes
class	DisallowedOperator
	Error for filter expressions trying to use a relational operation incorrectly. More...
class	InvalidValue
	Error for filter expression containing an invalid value. More...
class	Operation
	Nodes for the filter parse tree. More...
class	ParseError
	Error for generic filter syntax/parse errors. More...

Public Types
enum class	Field {   Invalid = 0 , Id , Artist , Album ,   Type , Genre , Playlist , Title ,   Search , Name , Year , Duration ,   Lastplay , Track , Rating , Played ,   Heard , Rated , UserRating , False ,   Compilation , Count }
	Fields on which comparisons can be done by the filter. More...
enum class	Action {   Noop , And , Or , LessThan ,   LessEqual , Equal , NotEqual , GreaterThan ,   GreaterEqual , Match }
	Filter operations; each node in the parse tree has one action indicating how to proceed. More...
using	DuplicationFlags = EnumeratedArray< Field, bool >
using	FilterRating = float

Public Member Functions
	Filter (void)
	Filter (const Filter &)=default
	Filter (Filter &&from_filter)=default
	Filter (const std::string &expression)
	Create a new filter from an expression. More...
	Filter (const MusicThingie *thing, const MusicThingie::Type type=MusicThingie::Type(0), const DuplicationFlags &manner=DuplicationFlags(true))
	Create a new filter. More...
Filter &	operator= (const std::string &expression)
	Assign a new expression to a filter. More...
Filter &	operator= (const Filter &filter)=default
Filter &	operator= (Filter &&from_filter)=default
virtual	~Filter ()
	Destroy a filter. More...
template<typename MusicThing >
bool	matches (const MusicThing *thing) const
	Check if a filter matches a song, album, artist or playlist. More...
bool	canPersist (void) const
std::string	toString () const
	Get a filter's expression. More...
template<>
bool	matches (const MusicThingie *thing) const
	Specialization for matching to determine the type of thing being tested by the filter expression at run-time. More...
template<>
bool	matches (const MusicThingie *thing) const

Static Public Attributes
static const unsigned	FieldCount = static_cast <unsigned> (Field::Count)
static const Filter	All
	Selects all tracks. More...
static const Filter	None
	Selects nothing. More...

Protected Types
using	Op = std::unique_ptr< Operation >
	Container for Operation, to ensure instances are cleaned up. More...

Protected Member Functions
const char *	skipWhitespace (const char **const command)
std::string	gatherString (const char **const command, const char *error_reason)
	Gather a string, either quoted or not, processing quote characters. More...
Op	parseParenthesis (const char **const command)
	Handle (parenthesis in an expression). More...
Op	parseComparison (const char **const command)
	Handle comparison or other base operator in expression. More...
Op	parseSearch (const char **const command)
	Handle bare search term in expression. More...
Op	parseNegation (const char **const command)
	Handle negation operator, then choose parenthesis or a comparison. More...
Op	parseOr (const char **const command)
	Handle binary OR, either as | or ||. More...
Op	parseAnd (const char **const command)
	Handle binary AND, either as & or &&. More...

Protected Attributes
std::shared_ptr< Operation >	parsetree
bool	persistable = true
	Not true if user referenced or other problematic expressions. More...

Friends
class	Constraints
class	Query::Details
class	Query::List

Detailed Description

Track data filter.

Created from a logical statement describing match criteria, the track filter can then be used to test if a track/song, album, artist or playlist matches the criteria.

Member Typedef Documentation

DuplicationFlags

using Filter::DuplicationFlags = EnumeratedArray<Field, bool>

FilterRating

using Filter::FilterRating = float

Op

using Filter::Op = std::unique_ptr<Operation>

protected

Container for Operation, to ensure instances are cleaned up.

Member Enumeration Documentation

Action

enum Filter::Action

strong

Filter operations; each node in the parse tree has one action indicating how to proceed.

Enumerator
Noop
And
Or
LessThan
LessEqual
Equal
NotEqual
GreaterThan
GreaterEqual
Match

Field

enum Filter::Field

strong

Fields on which comparisons can be done by the filter.

Enumerator
Invalid
Id
Artist
Album
Type
Genre
Playlist
Title	Song name.
Search
Name
Year
Duration
Lastplay
Track	Track number.
Rating
Played
Heard
Rated
UserRating
False
Compilation
Count

Constructor & Destructor Documentation

Filter() [1/5]

Filter::Filter ( void  )

inline

Filter() [2/5]

Filter::Filter ( const Filter &  )

default

Filter() [3/5]

Filter::Filter ( Filter &&  from_filter )

default

Filter() [4/5]

Filter::Filter

(

const std::string &

expr

)

Create a new filter from an expression.

Parameters

expr	The expression for the filter.

Exceptions

CommandError

indicating nature of syntax or semantic errors. bad_alloc may also be thrown.

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Filter() [5/5]

Filter::Filter	(	const MusicThingie *	thing,
		const MusicThingie::Type	type = MusicThingie::Type (0),
		const DuplicationFlags &	manner = DuplicationFlags (true)
	)

Create a new filter.

Parameters

thing	Criteria for the new filter.
type	The type of filter to create. Songs can create song, album, or artist filters; albums can create album or artist filters.
manner	Flags indicating what criteria to include in the filter.

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~Filter()

Filter::~Filter ( )

virtual

Destroy a filter.

Member Function Documentation

canPersist()

bool Filter::canPersist ( void  ) const

inline

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gatherString()

std::string Filter::gatherString ( const char **const  command, const char *  error_reason  )

protected

Gather a string, either quoted or not, processing quote characters.

Parameters

command	The point in the command being parsed at which to gather.
error_reason	A message to include in a ParseError should there be no string to gather.

Returns

String found, with quoted characters adapted.

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matches() [1/3]

template<typename MusicThing >

bool Filter::matches ( const MusicThing *  thing ) const

inline

Check if a filter matches a song, album, artist or playlist.

Parameters

thing

The item to compare.

Returns

True if it matches, false otherwise.

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matches() [2/3]

template<>

bool Filter::matches

(

const MusicThingie *

thing

)

const

Specialization for matching to determine the type of thing being tested by the filter expression at run-time.

Parameters

thing

A thing to compare.

Returns

true if the thing matches, false if not.

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matches() [3/3]

template<>

bool Filter::matches

(

const MusicThingie *

thing

)

const

operator=() [1/3]

Filter& Filter::operator= ( const Filter &  filter )

default

operator=() [2/3]

Filter & Filter::operator=

(

const std::string &

expr

)

Assign a new expression to a filter.

Parameters

expr	The new expression.

operator=() [3/3]

Filter& Filter::operator= ( Filter &&  from_filter )

default

parseAnd()

Filter::Op Filter::parseAnd ( const char **const  command )

protected

Handle binary AND, either as & or &&.

Parameters

command

The point in the command being parsed. On return, updated to reflect expression portions consumed.

Returns

parse tree representing expression parsed.

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parseComparison()

Filter::Op Filter::parseComparison ( const char **const  command )

protected

Handle comparison or other base operator in expression.

Parameters

command

The point in the command being parsed. On return, updated to reflect expression portions consumed.

Returns

Operation representing comparison or operator parsed.

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parseNegation()

Filter::Op Filter::parseNegation ( const char **const  command )

protected

Handle negation operator, then choose parenthesis or a comparison.

Parameters

command

The point in the command being parsed. On return, updated to reflect expression portions consumed.

Returns

parse tree representing expression parsed.

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parseOr()

Filter::Op Filter::parseOr ( const char **const  command )

protected

Handle binary OR, either as | or ||.

Parameters

command

The point in the command being parsed. On return, updated to reflect expression portions consumed.

Returns

parse tree representing expression parsed.

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parseParenthesis()

Filter::Op Filter::parseParenthesis ( const char **const  command )

protected

Handle (parenthesis in an expression).

Parameters

command

The point in the command being parsed. On return, updated to reflect expression portions consumed.

Returns

Operation tree representing expression parsed.

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parseSearch()

Filter::Op Filter::parseSearch ( const char **const  command )

protected

Handle bare search term in expression.

This is identified by a quote (either ' or ") where we expect a comparison term in the expression.

Parameters

command

The point in the command being parsed. On return, updated to reflect expression portions consumed.

Returns

Operation representing search term.

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skipWhitespace()

const char* Filter::skipWhitespace ( const char **const  command )

inlineprotected

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toString()

std::string Filter::toString

(

)

const

Get a filter's expression.

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Friends And Related Function Documentation

Constraints

friend class Constraints

friend

Query::Details

friend class Query::Details

friend

Query::List

friend class Query::List

friend

Member Data Documentation

All

const Filter Filter::All

static

Selects all tracks.

FieldCount

const unsigned Filter::FieldCount = static_cast <unsigned> (Field::Count)

static

None

const Filter Filter::None

static

Selects nothing.

parsetree

std::shared_ptr<Operation> Filter::parsetree

protected

persistable

bool Filter::persistable = true

protected

Not true if user referenced or other problematic expressions.

---

The documentation for this class was generated from the following files:

• songs/filter.h
• songs/filter.cpp