Function expand

src/engine/function.cpp:1262–1327

} expansion_item;

static LIST * expand( expansion_item * items, int32_t const length )
{
    LIST * result = L0;
    string buf[ 1 ];
    int32_t size = 0;
    int32_t i;

    assert( length > 0 );
    for ( i = 0; i < length; ++i )
    {
        LISTITER iter = list_begin( items[ i ].values );
        LISTITER const end = list_end( items[ i ].values );

        /* If any of the items has no values - the result is an empty list. */
        if ( iter == end ) return L0;

        /* Set each item's 'current' to its first listed value. This indicates
         * each item's next value to be used when constructing the list of all
         * possible concatenated values.
         */
        items[ i ].current = iter;

        /* Calculate the longest concatenated string length - to know how much
         * memory we need to allocate as a buffer for holding the concatenated
         * strings.
         */
        {
            int32_t max = 0;
            for ( ; iter != end; iter = list_next( iter ) )
            {
                int32_t const len = int32_t(strlen( object_str( list_item( iter ) ) ));
                if ( len > max ) max = len;
            }
            size += max;
        }
    }

    string_new( buf );
    string_reserve( buf, size );

    i = 0;
    while ( i >= 0 )
    {
        for ( ; i < length; ++i )
        {
            items[ i ].size = buf->size;
            string_append( buf, object_str( list_item( items[ i ].current ) ) );
        }
        result = list_push_back( result, object_new( buf->value ) );
        while ( --i >= 0 )
        {
            if ( list_next( items[ i ].current ) != list_end( items[ i ].values
                ) )
            {
                items[ i ].current = list_next( items[ i ].current );
                string_truncate( buf, items[ i ].size );
                break;
            }