What would be the best way to simplify this foreach?

问题

I was testing an xml object to see how many levels deep it went and found that it goes 11 elements deep. I'm wondering how I could have done this simpler so that in the future I can save a few minutes.

$xml = simplexml_load_file(drupal_get_path('module', 'my_module') . '/test_file.xml');
  dpm($xml);
  foreach($xml->section as $section_l1) {
    dpm('L1-------------------------------');
    foreach($section_l1->attributes() as $a => $b) {
      dpm($a . ' = ' . $b);
    }
    dpm('-----:');
    foreach($section_l1->section as $section_l2) {
      dpm('---L2--------------------------');
      foreach($section_l2->attributes() as $a => $b) {
        dpm($a . ' = ' . $b);
      }
      dpm('-----:');
      foreach($section_l2->section as $section_l3) {
        dpm('------L3---------------------');
        foreach($section_l3->attributes() as $a => $b) {
          dpm($a . ' = ' . $b);
        }
        dpm('-----:');
        foreach($section_l3->section as $section_l4) {
          dpm('------L4---------------------');
          foreach($section_l4->attributes() as $a => $b) {
            dpm($a . ' = ' . $b);
          }
          dpm('-----:');
          foreach($section_l4->section as $section_l5) {
            dpm('------L5---------------------');
            foreach($section_l5->attributes() as $a => $b) {
              dpm($a . ' = ' . $b);
            }
            dpm('-----:');
            foreach($section_l5->section as $section_l6) {
              dpm('------L6---------------------');
              foreach($section_l6->attributes() as $a => $b) {
                dpm($a . ' = ' . $b);
              }
              dpm('-----:');
              foreach($section_l6->section as $section_l7) {
                dpm('------L7---------------------');
                foreach($section_l7->attributes() as $a => $b) {
                  dpm($a . ' = ' . $b);
                }
                dpm('-----:');
                foreach($section_l7->section as $section_l8) {
                  dpm('------L8---------------------');
                  foreach($section_l8->attributes() as $a => $b) {
                    dpm($a . ' = ' . $b);
                  }
                  dpm('-----:');
                  foreach($section_l8->section as $section_l9) {
                    dpm('------L9---------------------');
                    foreach($section_l9->attributes() as $a => $b) {
                      dpm($a . ' = ' . $b);
                    }
                    dpm('-----:');
                    foreach($section_l9->section as $section_l10) {
                      dpm('------L10---------------------');
                      foreach($section_l10->attributes() as $a => $b) {
                        dpm($a . ' = ' . $b);
                      }
                      dpm('-----:');
                      foreach($section_l10->section as $section_l11) {
                        dpm('------L11---------------------');
                        foreach($section_l11->attributes() as $a => $b) {
                          dpm($a . ' = ' . $b);
                        }
                        dpm('-----:');
                        foreach($section_l11->section as $section_l12) {
                          dpm('------L12---------------------');
                          foreach($section_l12->attributes() as $a => $b) {
                            dpm($a . ' = ' . $b);
                          }
                          dpm('-----:');
                          foreach($section_l12->section as $section_l13) {
                            dpm('------L13---------------------');
                            foreach($section_l13->attributes() as $a => $b) {
                              dpm($a . ' = ' . $b);
                            }
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }

Note: drupal_get_path and dpm are Drupal CMS functions and can be ignored here.

回答1:

This should work. Here is an example

function recurse($xml, $maxLevel = -1, $level = 0) {
    if ($maxLevel != -1 && $level > $maxLevel) {
        return;
    }

    if ($level == 0) {
        dpm($xml);
    }

    $string = '---------------------------------';
    $pos = $level * 3;
    $l = 'L'. ($level+1);
    $string = substr_replace($string, $l, $pos, strlen($l));
    foreach ($xml->section as $section) {
        dpm($string);
        foreach ($section->attributes() as $a=>$b) {
            dpm($a .' = '. $b);
        }
        dpm('-----:');
        recurse($section, $maxLevel, $level+1);
    }
}

$xml = simplexml_load_file(drupal_get_path('module', 'my_module') . '/test_file.xml');
recurse($xml);

You can specify the max level you want to go down using the second parameter, as I've done in the codepad example.

回答2:

Since you're doing a similar thing at each level you can put this logic into a function and call that logic at each level. An (untested) example would be something like:

$xml = simplexml_load_file(drupal_get_path('module', 'my_module') . '/test_file.xml');
function processXML($xml, $level = 1){
    dpm($xml);
    foreach($xml->section as $section_l1) {
         dpm('L'.$level.'-------------------------------');
         foreach($section_l1->attributes() as $a => $b) {
            dpm($a . ' = ' . $b);
         }
         dpm('-----:');
         processXML($section_l1,$level+1);
    }
}

回答3:

You could use a recursive function:

$xml = simplexml_load_file(drupal_get_path('module', 'my_module') . '/test_file.xml');
dpm($xml);
traverse($xml, 1);

private function traverse($section, $level) {
  dpm('L'.$level.'-------------------------------');

  foreach($section->attributes() as $a => $b) {
    dpm($a . ' = ' . $b);
  }

  dpm('-----:');

  traverse($section->section, $level+1)
}

回答4:

You need a recursive function:

$xml = simplexml_load_file(drupal_get_path('module', 'my_module') . '/test_file.xml');
dpm($xml);

$depth = $xml->section; // The array you want to find the depth
$iterator = 0; // The starting level
recurse_count($depth, $iterator); // Fire the function

function recurse_count($array, $iterator) {
    foreach($array->section as $children) {
        $iterator++; // Increment the iterator
        dpm('---L'.$iterator.'--------------------------');
        foreach($children->attributes() as $a => $b) {
            dpm($a . ' = ' . $b);
        }
        dpm('-----:');
    }
    recurse_count($children, $iterator); // Fire the function again
}

A recursive function is one that will call itself and is well suited for your issue. This example should work for your problem.

来源：https://stackoverflow.com/questions/19815824/what-would-be-the-best-way-to-simplify-this-foreach