/* -*- mode: c++; indent-tabs-mode: nil -*- */
/** @file QC_ListHashIterator.qpp ListHashIterator class definition */
/*
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*/

#include <qore/Qore.h>
#include "qore/intern/QoreListHashIterator.h"

//! This class an iterator class for lists of hashes as returned by Qore::SQL::Datasource::selectRows() and Qore::SQL::DatasourcePool::selectRows(), both of which return lists of columns where each list entry is a hash of the current column values
/** Call ListHashIterator::next() to iterate through the lists of column values; do not use the iterator if ListHashIterator::next() returns @ref False.
    A result list can be iterated in reverse order by calling ListHashIterator::prev() instead of ListHashIterator::next()

    @par Example: ListHashIterator basic usage
    @code{.py}
    list<auto> data = (
             {"column1": 1, "column2": "a"},
             {"column1": 2, "column2": "b"},
        );

    ListHashIterator it(data);
    while (it.next()) {
        printf("iter %d: %n\n", it.index(), it.getValue());
    }

    iter 0: hash: (column1: 1, column2: "a")
    iter 1: hash: (column1: 2, column2: "b")
    @endcode

    @note
    - In general, the ListHashIterator class is not designed to be accessed from multiple threads; it was created without locking for
      fast and efficient use when used from a single thread.  For methods that would be unsafe to use in another thread, any use of
      such methods in threads other than the thread where the constructor was called will cause an \c ITERATOR-THREAD-ERROR to be thrown.

    @see ListHashReverseIterator
 */
qclass ListHashIterator [arg=QoreListHashIterator* i; ns=Qore; vparent=AbstractQuantifiedBidirectionalIterator];

//! Creates the hash list iterator object
/** @param l the list of hashes to iterate

    @par Example:
    @code{.py}
ListHashIterator i(l);
    @endcode

    @note the constructor's argument is @ref softlist_type "softlist" so that it can also accept @ref nothing
*/
ListHashIterator::constructor(softlist<auto> l) {
    self->setPrivate(CID_LISTHASHITERATOR, new QoreListHashIterator(l));
}

//! Creates a copy of the ListHashIterator object, iterating the same object as the original and in the same position
/** @par Example:
    @code{.py}
ListHashIterator ni = i.copy();
    @endcode
*/
ListHashIterator::copy() {
    self->setPrivate(CID_LISTHASHITERATOR, new QoreListHashIterator(*i));
}

//! Moves the current position to the next element in the result list; returns @ref False if there are no more elements; if the iterator is not pointing at a valid element before this call, the iterator will be positioned on the first element in the list if the list is not empty
/** This method will return @ref True again after it returns @ref False once if list is not empty, otherwise it will always return @ref False.
    The iterator object should not be used after this method returns @ref False

    @return @ref False if there are no more elements in the result list (in which case the iterator object is invalid and should not be used); @ref True if successful (meaning that the iterator object is valid)

    @par Example:
    @code{.py}
while (i.next()) {
    printf(" + row %d: %y\n", i.index(), i.getValue());
}
    @endcode

    @throw ITERATOR-THREAD-ERROR this exception is thrown if this method is called from any thread other than the thread that created the object
*/
bool ListHashIterator::next() {
    if (i->check(xsink))
        return false;
    return i->next();
}

//! Moves the current position to the previous element in the result list; returns @ref False if there are no more elements; if the iterator is not pointing at a valid element before this call, the iterator will be positioned on the last element in the list if the list is not empty
/** This method will return @ref True again after it returns @ref False once if the list is not empty, otherwise it will always return @ref False.
    The iterator object should not be used after this method returns @ref False

    @return @ref False if there are no more elements in the result list (in which case the iterator object is invalid and should not be used); @ref True if successful (meaning that the iterator object is valid)

    @par Example:
    @code{.py}
while (i.prev()) {
    printf(" + row %d: %y\n", i.index(), i.getValue());
}
    @endcode

    @throw ITERATOR-THREAD-ERROR this exception is thrown if this method is called from any thread other than the thread that created the object
*/
bool ListHashIterator::prev() {
    if (i->check(xsink))
        return false;
    return i->prev();
}

//! returns @ref True if the result list is empty; @ref False if not
/** @return @ref True if the result list is empty; @ref False if not

    @par Example:
    @code{.py}
if (i.empty())
    printf("the result list is empty\n");
    @endcode
*/
bool ListHashIterator::empty() [flags=CONSTANT] {
    return i->empty();
}

//! returns @ref True if on the first element of the list
/** @return @ref True if on the first element of the list

    @par Example:
    @code{.py}
while (i.next()) {
    if (i.first())
        printf("START:\n");
}
    @endcode
*/
bool ListHashIterator::first() [flags=CONSTANT] {
   return i->first();
}

//! returns @ref True if on the last element of the list
/** @return @ref True if on the last element of the list

    @par Example:
    @code{.py}
while (i.next()) {
    if (i.last())
        printf("END.\n");
}
    @endcode
*/
bool ListHashIterator::last() [flags=CONSTANT] {
    return i->last();
}

//! returns the current row value as a hash or throws an \c INVALID-ITERATOR exception if the iterator is invalid
/** @return the current row value as a hash or throws an \c INVALID-ITERATOR exception if the iterator is invalid

    @par Example:
    @code{.py}
while (i.next()) {
    printf(" + row %d: %y\n", i.index(), i.getValue());
}
    @endcode

    @note
    - equivalent to ListHashIterator::getRow()

    @throw ITERATOR-THREAD-ERROR this exception is thrown if this method is called from any thread other than the thread that created the object
    @throw INVALID-ITERATOR the iterator is not pointing at a valid element or the list being iterated does not contain a hash element at the current iterator position
*/
hash<auto> ListHashIterator::getValue() [flags=RET_VALUE_ONLY] {
    if (i->check(xsink))
        return QoreValue();
    return i->getRow(xsink);
}

//! returns the current row value as a hash or throws an \c INVALID-ITERATOR exception if the iterator is invalid
/** @return the current row value as a hash or throws an \c INVALID-ITERATOR exception if the iterator is invalid

    @par Example:
    @code{.py}
while (i.next()) {
    printf(" + row %d: %y\n", i.index(), i.getValue());
}
    @endcode

    @note equivalent to ListHashIterator::getValue()

    @throw ITERATOR-THREAD-ERROR this exception is thrown if this method is called from any thread other than the thread that created the object
    @throw INVALID-ITERATOR the iterator is not pointing at a valid element or the list being iterated does not contain a hash element at the current iterator position
*/
hash<auto> ListHashIterator::getRow() [flags=RET_VALUE_ONLY] {
    if (i->check(xsink))
        return QoreValue();
    return i->getRow(xsink);
}

//! returns the current iterator position in the list or -1 if not pointing at a valid element
/** @return the current iterator position in the list or -1 if not pointing at a valid element

    @par Example:
    @code{.py}
while (i.next()) {
    printf("+ %d/%d: %y\n", i.index(), i.max(), i.getValue());
}
    @endcode
*/
int ListHashIterator::index() [flags=CONSTANT] {
    return i->index();
}

//! returns the number of elements in the list
/** @return the number of elements in the list

    @par Example:
    @code{.py}
while (i.next()) {
    printf("+ %d/%d: %y\n", i.index(), i.max(), i.getValue());
}
    @endcode
*/
int ListHashIterator::max() [flags=CONSTANT] {
    return i->max();
}

//! sets the new position in the result list; if the position is invalid then the method returns @ref False, meaning the iterator is not valid, otherwise it returns @ref True
/** @param pos the new position for the iterator with 0 as the first element

    @return @ref False, meaning the iterator is not valid, otherwise it returns @ref True

    @par Example:
    @code{.py}
if (!i.set(pos))
    throw "INVALID-POSITION", sprintf("%d is an invalid position", pos);
    @endcode

    @throw ITERATOR-THREAD-ERROR this exception is thrown if this method is called from any thread other than the thread that created the object
*/
bool ListHashIterator::set(int pos) {
    if (i->check(xsink))
        return false;
    return !i->set(pos);
}

//! This method allows the iterator to be dereferenced directly as a hash for the current row being iterated, as memberGate methods are called implicitly when an unknown member is accessed from outside the class.
/** @param key the column name for the value to retrieve

    @return the current column value of the given row

    @par Example:
    @code{.py}
while (i.next()) {
    printf("%d: value: %y", i.index(), i.value);
}
    @endcode

    @throw ITERATOR-THREAD-ERROR this exception is thrown if this method is called from any thread other than the thread that created the object
    @throw INVALID-ITERATOR the iterator is not pointing at a valid element or the list being iterated does not contain a hash element at the current iterator position or the given hash key does not exist

    @note equivalent to ListHashIterator::getKeyValue() when called explicitly
*/
auto ListHashIterator::memberGate(string key) [flags=RET_VALUE_ONLY] {
    if (i->check(xsink))
        return QoreValue();

    return i->getReferencedKeyValue(key->getBuffer(), xsink);
}

//! Returns the current value for the column given as an argument
/** @param key the column name for the value to retrieve

    @return the current column value of the given row

    @par Example:
    @code{.py}
while (i.next()) {
    printf("%d: value: %y", i.index(), i.getKeyValue("value"));
}
    @endcode

    @throw ITERATOR-THREAD-ERROR this exception is thrown if this method is called from any thread other than the thread that created the object
    @throw INVALID-ITERATOR the iterator is not pointing at a valid element or the list being iterated does not contain a hash element at the current iterator position or the given hash key does not exist

    @note ListHashIterator::memberGate() allows for the iterator to act as if it is a hash with members equal to the current row being iterated
*/
auto ListHashIterator::getKeyValue(string key) [flags=RET_VALUE_ONLY] {
    if (i->check(xsink))
        return QoreValue();

    return i->getReferencedKeyValue(key->getBuffer(), xsink);
}

//! returns @ref True "True" if the iterator is currently pointing at a valid element, @ref False "False" if not
/** @return @ref True "True" if the iterator is currently pointing at a valid element, @ref False "False" if not

    @par Example:
    @code{.py}
if (i.valid())
    printf("current value: %y\n", i.getValue());
    @endcode
*/
bool ListHashIterator::valid() [flags=CONSTANT] {
    return i->valid();
}

//! Reset the iterator instance to its initial state
/** Reset the iterator instance to its initial state

   @par Example
   @code{.py}
i.reset();
   @endcode

    @throw ITERATOR-THREAD-ERROR this exception is thrown if this method is called from any thread other than the thread that created the object
*/
ListHashIterator::reset() {
    if (i->check(xsink))
        return QoreValue();
    i->reset();
}
