vtab< Derived >::cursor Class Reference

Base class for cursors. More...

Inheritance diagram for vtab< Derived >::cursor:

Public Member Functions
	cursor (cursor &)=delete
cursor &	operator= (cursor &)=delete
sqlite3_vtab_cursor *	c_ptr () const noexcept
	Access the underlying sqlite3_vtab_cursor struct.
template<class D = Derived>
void	filter (int idx, typename D::index_data_type idx_data, int argc, value **argv)
	Begins a search of a virtual table.
template<class D = Derived>
void	filter (int idx, int argc, value **argv)
	Begins a search of a virtual table.
bool	eof () const noexcept
	Whether the cursor reached the end.
void	next ()
	Advances the cursor.
void	column (context &ctxt, int idx) const
	Retrieves the value of the virtual table column in a row cursor is currently pointing at.
sqlite_int64	rowid () const
	Retrieves the rowid of the row cursor is currently pointing at.

Protected Member Functions
	cursor (Derived *owner)
	Constructs an instance with a given owner.
Derived *	owner () const noexcept
	Returns the owning vtab - derived class.

Detailed Description

template<class Derived>
class thinsqlitepp::vtab< Derived >::cursor

Base class for cursors.

It wraps sqlite3_vtab_cursor and provides default implementation of the required methods. The default implementation returns no rows. Re-define various methods in your derived classes.

Member Function Documentation

filter() [1/2]

template<class Derived >

template<class D = Derived>

void filter ( int idx, typename D::index_data_type idx_data, int argc, value ** argv )

inline

Begins a search of a virtual table.

Equivalent to xFilter

This method is called if index_data_type is defined as a pointer.

Re-define this method as a non-templated function in your derived class. Your implementation can throw exceptions to indicate errors.

This method can be called multiple times and should initialize cursor internals to start cursor iteration anew (do not rely on constructor to do that).

The default implementation does nothing.

Template Parameters

D	Defers resolution of nested data types declared in derived class. This is an internal implementation detail - your re-defined implementations do not need to be templated.

Parameters

idx	value passed to index_info::set_index_number in best_index. Its significance is entirely up to you
idx_data	pointer passed to index_info::set_index_data. Its significance is entirely up to you
argc	count of items in argv array
argv	requested values of certain expressions from index_info::constraint_usage

filter() [2/2]

template<class Derived >

template<class D = Derived>

void filter ( int idx, int argc, value ** argv )

inline

Begins a search of a virtual table.

Equivalent to xFilter

This method is called if index_data_type is void.

Re-define this method as a non-templated function in your derived class. Your implementation can throw exceptions to indicate errors.

This method can be called multiple times and should initialize cursor internals to start cursor iteration anew (do not rely on constructor to do that).

The default implementation does nothing.

Template Parameters

D	Defers resolution of nested data types declared in derived class. This is an internal implementation detail - your re-defined implementations do not need to be templated.

Parameters

idx	value passed to index_info::set_index_number in best_index. Its significance is entirely up to you
argc	count of items in argv array
argv	requested values of certain expressions from index_info::constraint_usage

eof()

template<class Derived >

bool eof ( ) const

inlinenoexcept

Whether the cursor reached the end.

Equivalent to xEof

Re-define this method together with next() in your derived class. Your implementation must also be noexcept.

This default implementation always returns true

next()

template<class Derived >

void next ( )

inline

Advances the cursor.

Equivalent to xNext

Re-define this method together with eof() in your derived class. Your implementation can throw exceptions to indicate errors.

This default implementation should never be called since default eof() always returns true. If called it will report an error.

column()

template<class Derived >

void column ( context & ctxt, int idx ) const

inline

Retrieves the value of the virtual table column in a row cursor is currently pointing at.

Equivalent to xColumn

Re-define this method in your derived class. Your implementation can throw exceptions to indicate errors.

This default implementation always return null

Parameters

ctxt	the context to set the column value on
idx	column index

rowid()

template<class Derived >

sqlite_int64 rowid ( ) const

inline

Retrieves the rowid of the row cursor is currently pointing at.

Equivalent to xRowid

Re-define this method in your derived class. Your implementation can throw exceptions to indicate errors.

This default implementation always reports an error

owner()

template<class Derived >

Derived * owner ( ) const

inlineprotectednoexcept

Returns the owning vtab - derived class.

Equivalent to accessing the pVtab field of sqlite3_vtab_cursor

Note

this is safe to call from your derived class constructor