refactor: Move code out of Record [BC]

Breaking change:

- `Subject::getType()` now returns the tag number (like "650)" instead
  of a string representing the tag (like "topic"). Constants have been
  defined on `Subject` for comparison, so to check if a subject is a
  topical term, you can do `$subject->type == Subject::TOPICAL_TERM`.

Author: danmichaelo

src/Fields/ControlField.php

@@ -2,8 +2,15 @@
 
 namespace Scriptotek\Marc\Fields;
 
+use Scriptotek\Marc\Record;
+
 class ControlField extends Field implements FieldInterface
 {
+    public static function get(Record $record, $tag)
+    {
+        return parent::makeFieldObject($record, $tag);
+    }
+
     public function __toString()
     {
         return $this->field->getData();

src/Fields/Field.php

@@ -2,6 +2,8 @@
 
 namespace Scriptotek\Marc\Fields;
 
+use Scriptotek\Marc\Record;
+
 class Field
 {
     protected $field;
@@ -29,4 +31,20 @@ public function sf($code)
         $x = $this->getSubfield($code);
         return $x->getData();
     }
+
+    public static function makeFieldObject(Record $record, $tag, $pcre=false)
+    {
+        $field = $record->getField($tag, $pcre);
+
+        // Note: `new static()` is a way of creating a new instance of the
+        // called class using late static binding.
+        return isset($field) ? new static($field) : $field;
+    }
+
+    public static function makeFieldObjects(Record $record, $tag, $pcre=false)
+    {
+        return array_map(function($field) {
+            return new self($field);
+        }, $record->getFields($tag, $pcre));
+    }
 }

src/Fields/Isbn.php

@@ -2,6 +2,8 @@
 
 namespace Scriptotek\Marc\Fields;
 
+use Scriptotek\Marc\Record;
+
 class Isbn extends Field implements FieldInterface
 {
     public function __toString()
@@ -13,4 +15,9 @@ public function __toString()
 
         return $a->getData();
     }
+
+    public static function get(Record $record)
+    {
+        return parent::makeFieldObjects($record, '020');
+    }
 }

src/Fields/Subject.php

@@ -2,10 +2,28 @@
 
 namespace Scriptotek\Marc\Fields;
 
+use Scriptotek\Marc\Record;
+
 class Subject extends Field implements FieldInterface
 {
     public static $glue = ' : ';
 
+    const PERSONAL_NAME = '600';
+    const CORPORATION_NAME = '601';
+    const MEETING_NAME = '611';
+    const UNIFORM_TITLE = '630';
+    const NAMED_EVENT = '647';
+    const CHRONOLOGICAL_TERM = '648';
+    const TOPICAL_TERM = '650';
+    const GEOGRAPHIC_NAME = '651';
+    const UNCONTROLLED_INDEX_TERM = '653';
+    const FACETED_TOPICAL_TERM = '654';
+    const GENRE_FORM = '655';
+    const OCCUPATION = '656';
+    const FUNCTION_TERM = '657';
+    const CURRICULUM_OBJECTIVE = '658';
+    const HIERARCHICAL_PLACE_NAME = '662';
+
     protected $vocabularies = array(
         '0' => 'lcsh',  // 0: Library of Congress Subject Headings
         '1' => 'lccsh', // 1: LC subject headings for children's literature
@@ -17,6 +35,15 @@ class Subject extends Field implements FieldInterface
         // 7: Source specified in subfield $2
     );
 
+    public static function get(Record $record) {
+        return parent::makeFieldObjects($record, '6..', true);
+    }
+
+    public function getType()
+    {
+        return $this->getTag();
+    }
+
     public function getVocabulary()
     {
         $ind2 = $this->field->getIndicator(2);
@@ -28,7 +55,7 @@ public function getVocabulary()
             return $sf2->getData();
         }
 
-        return;
+        return null;
     }
 
     /**

src/Fields/Title.php

@@ -2,9 +2,16 @@
 
 namespace Scriptotek\Marc\Fields;
 
+use Scriptotek\Marc\Record;
+
 class Title extends Field implements FieldInterface
 {
 
+    public static function get(Record $record)
+    {
+        return parent::makeFieldObject($record, '245');
+    }
+
     /**
      * Returns the string representation $a, $b, $n and $p).
      *  - Joins the subfields by colon if no ISBD marker present at the end of $a

src/Record.php

@@ -6,6 +6,10 @@
 use File_MARC_Reference;
 use Scriptotek\Marc\Exceptions\RecordNotFound;
 use Scriptotek\Marc\Exceptions\UnknownRecordType;
+use Scriptotek\Marc\Fields\ControlField;
+use Scriptotek\Marc\Fields\Isbn;
+use Scriptotek\Marc\Fields\Subject;
+use Scriptotek\Marc\Fields\Title;
 
 class Record
 {
@@ -67,7 +71,7 @@ public static function fromString($data)
      * constants.
      *
      * @return string
-     * @throws ErrorException
+     * @throws UnknownRecordType
      */
     public function getType()
     {
@@ -107,64 +111,52 @@ public function getType()
      * a class in src/Fields/
      *************************************************************************/
 
-    public function getIsbns()
+    /**
+     * Get the value of the 001 field as a `ControlField` object.
+     *
+     * @return Title
+     */
+    public function getId()
     {
-        $fields = array();
-        foreach ($this->record->getFields('020') as $field) {
-            $fields[] = $this->makeField('Isbn', $field);
-        }
-
-        return $fields;
+        return ControlField::get($this, '001');
     }
 
-    public function getSubjects($vocabulary = null, $type = null)
+    /**
+     * Get an array of the 020 fields as `Isbn` objects.
+     *
+     * @return Isbn[]
+     */
+    public function getIsbns()
     {
-        $fields = array();
-        $saf = array(
-            '600' => 'person',         # Subject Added Entry - Personal name
-            '610' => 'corporation',    # Subject Added Entry - Corporate name
-            '611' => 'meeting',        # Subject Added Entry - Meeting name
-            '630' => 'uniform-title',  # Subject Added Entry - Uniform title
-            '648' => 'time',           # Subject Added Entry - Chronological Term
-            '650' => 'topic',          # Subject Added Entry - Topical Term
-            '651' => 'place',          # Subject Added Entry - Geographic Name
-            '653' => 'uncontrolled',   # Index Term - Uncontrolled
-             // 654 :  Subject Added Entry - Faceted Topical Terms
-            '655' => 'form',           # Index Term - Genre/Form
-            '656' => 'occupation',     # Index Term - Occupation
-             // 657 - Index Term - Function
-             // 658 - Index Term - Curriculum Objective
-             // 662 - Subject Added Entry - Hierarchical Place Name
-             // 69X - Local Subject Access Fields
-        );
-        foreach ($saf as $k => $v) {
-            foreach ($this->record->getFields($k) as $field) { // or 655, 648, etc.
-                $f = $this->makeField('Subject', $field);
-                $f->type = $v;
-                $fields[] = $f;
-            }
-        }
-
-        return array_filter($fields, function ($s) use ($vocabulary, $type) {
-            $a = is_null($vocabulary) || $vocabulary == $s->vocabulary;
-            $b = is_null($type) || $type == $s->type;
-
-            return $a && $b;
-        });
+        return Isbn::get($this);
     }
 
+    /**
+     * Get the 245 field as a `Title` object. Returns null if no such field was found.
+     *
+     * @return Title
+     */
     public function getTitle()
     {
-        $field = $this->record->getField('245');
-
-        return $field ? $this->makeField('Title', $field) : null;
+        return Title::get($this);
     }
 
-    public function getId()
+    /**
+     * Get an array of the 6XX fields as `Subject` objects, optionally filtered by
+     * vocabulary and/or tag.
+     *
+     * @param string $vocabulary
+     * @param string $tag
+     * @return Subject[]
+     */
+    public function getSubjects($vocabulary = null, $tag = null)
     {
-        $field = $this->record->getField('001');
+        return array_filter(Subject::get($this), function ($field) use ($vocabulary, $tag) {
+            $a = is_null($vocabulary) || $vocabulary == $field->vocabulary;
+            $b = is_null($tag) || $tag == $field->type;
 
-        return $field ? $this->makeField('ControlField', $field) : null;
+            return $a && $b;
+        });
     }
 
     /*************************************************************************

tests/SubjectFieldTest.php

@@ -1,6 +1,7 @@
 <?php
 
 use Scriptotek\Marc\Collection;
+use Scriptotek\Marc\Fields\Subject;
 
 class SubjectFieldTest extends \PHPUnit_Framework_TestCase
 {
@@ -18,7 +19,7 @@ public function testSubjectString()
         # Vocabulary from indicator2
         $sub = $record->subjects[0];
         $this->assertEquals('lcsh', $sub->vocabulary);
-        $this->assertEquals('topic', $sub->type);
+        $this->assertEquals(Subject::TOPICAL_TERM, $sub->type);
         $this->assertEquals('Eightfold way (Nuclear physics) : Addresses, essays, lectures', strval($sub));
     }
 
@@ -31,24 +32,24 @@ public function testSubjects()
         $this->assertInstanceOf('Scriptotek\Marc\Fields\Subject', $subject);
         $this->assertEquals('noubomn', $subject->vocabulary);
         $this->assertEquals('Elementærpartikler', strval($subject));
-        $this->assertEquals('650', $subject->getTag('650'));
+        $this->assertEquals('650', $subject->getTag());
         $this->assertNull($subject->getControlNumber());
 
         $subject = $record->subjects[3];
         $this->assertInstanceOf('Scriptotek\Marc\Fields\Subject', $subject);
         $this->assertNull($subject->vocabulary);
         $this->assertEquals('elementærpartikler', strval($subject));
-        $this->assertEquals('653', $subject->getTag('650'));
+        $this->assertEquals('653', $subject->getTag());
     }
 
-    public function testGetSubjects()
+    public function testGetSubjectsFiltering()
     {
         $record = $this->getNthrecord(3);
 
         $lcsh = $record->getSubjects('lcsh');
         $noubomn = $record->getSubjects('noubomn');
-        $noubomn_topic = $record->getSubjects('noubomn', 'topic');
-        $noubomn_place = $record->getSubjects('noubomn', 'place');
+        $noubomn_topic = $record->getSubjects('noubomn', Subject::TOPICAL_TERM);
+        $noubomn_place = $record->getSubjects('noubomn', Subject::GEOGRAPHIC_NAME);
 
         $this->assertCount(1, $lcsh);
         $this->assertCount(2, $noubomn);