streams.php

<?php

// A "stream" represents a CSV file or another data source.
// "streams" exist on different levels. And a higher-level stream can use a lower-level stream as a data source.
// Problem: Find better nomenclature.
// Currently: RowStream, (AssocRowStream), AssocStream, ObjectStream.

assert($rowStream instanceof RowStreamInterface);
$rows = [];
while (false !== $row = $rowStream->fetchRow()) {
  assert(is_array($row));
  // Keys are column indices, so they are integers, properly ordered.
  assert(array_values($row) === $row);
  foreach ($row as $iColumn => $cell) {
    // Values are string cell contents.
    assert(is_string($cell));
  }
  $rows[] = $row;
}

assert($assocStream insteancof AssocStreamInterface);
$entries = [];
while (false !== $entry = $assocStream->fetchAssoc()) {
  assert(is_array($row));
  // Keys are column names, so they are generally strings.
  # assert(array_values($row) === $row);
  foreach ($entry as $colName => $cellValue) {
    // $cellValue can have any type whatsoever.
    # assert(is_string($cellValue));
  }
  $entries[] = $entry;
}

// Between these two:
assert($assocRowStream insteancof AssocRowStreamInterface);
$entries = [];
while (false !== $entry = $assocRowStream->fetchAssocRow()) {
  assert(is_array($row));
  // Keys are column names, so they are generally strings.
  # assert(array_values($entry) === $entry);
  foreach ($entry as $colName => $cell) {
    // Values are string cell contents.
    assert(is_string($cell));
  }
  $entries[] = $entry;
}

assert($objectStream instanceof ObjectStreamInterface);
$objects = [];
while (false !== $object = $objectStream->fetchObject()) {
  assert(is_object($object));
  $objects[] = $object;
}