Adding TabularDataReader::mapHeader method

CHANGELOG.md

@@ -9,6 +9,7 @@ All Notable changes to `Csv` will be documented in this file
 - `Statement::select`
 - `TabularDataReader::getRecordsAsObject`
 - `TabularDataReader::chunkBy`
+- `TabularDataReader::mapHeader`
 
 ### Deprecated
 

docs/9.0/reader/tabular-data-reader.md

@@ -452,6 +452,40 @@ $reader = Reader::createFromPath('/path/to/my/file.csv')
 <p class="message-notice">Added in version <code>9.12.0</code> for <code>Reader</code> and <code>ResultSet</code>.</p>
 <p class="message-info"> Wraps the functionality of <code>Statement::select</code>.</p>
 
+### mapHeader
+
+<p class="message-notice">Added in version <code>9.15.0</code> for <code>Reader</code> and <code>ResultSet</code>.</p>
+<p class="message-info"> Wraps the functionality of <code>Statement::process</code>.</p>
+
+Complementary to the `select` method, the `mapHeader` method allows you to redefine the column header 
+names and order and returns a new `TabularDataReader`. The submitted array argument act like the
+array from the `Statement::process` method but instead of returning a iterable structure of records
+it returns a new `TabularDataReader` with a new header.
+
+```php
+$tabularData = $reader
+    ->slice(0, 10)
+    ->mapHeader([
+        3 => 'Year',
+        2 => 'Gender',
+        0 => 'Firstname',
+        1 => 'Count',
+    ]);
+
+//is equivalent to
+
+$tabularData = Statement::create()
+    ->offset(0)
+    ->limit(10)
+    ->process($reader, [
+        3 => 'Year',
+        2 => 'Gender',
+        0 => 'Firstname',
+        1 => 'Count',
+    ]);
+$tabularData->getHeader(); // returns ['Year', 'Gender', 'Firstname', 'Count'];
+```
+
 ### matching, matchingFirst, matchingFirstOrFail
 
 The `matching` method allows selecting records, columns or cells from the tabular data reader that match the
@@ -487,6 +521,7 @@ use League\Csv\Reader;
 $reader = Reader::createFromString($csv);
 
 foreach ($reader->chunkBy(4) as $chunk) {
+    // $chunk is a TabularDataReader instance
     foreach ($chunk as $record) {
         //the actual record will be found here.
     }

src/Reader.php

@@ -331,6 +331,14 @@ public function chunkBy(int $length): Iterator
         return ResultSet::createFromTabularDataReader($this)->chunkBy($length);
     }
 
+    /**
+     * @param array<string> $header
+     */
+    public function mapHeader(array $headers): TabularDataReader
+    {
+        return Statement::create()->process($this, $headers);
+    }
+
     /**
      * @param Closure(array<mixed>, array-key): bool $closure
      *

src/ResultSet.php

@@ -190,6 +190,14 @@ public function chunkBy(int $length): Iterator
         }
     }
 
+    /**
+     * @param array<string> $headers
+     */
+    public function mapHeader(array $headers): TabularDataReader
+    {
+        return Statement::create()->process($this, $headers);
+    }
+
     public function filter(Closure $closure): TabularDataReader
     {
         return Statement::create()->where($closure)->process($this);

src/TabularDataReader.php

@@ -41,6 +41,7 @@
  * @method TabularDataReader|null matchingFirst(string $expression) extract the first found fragment identifier of the tabular data or return null if none is found
  * @method iterable<int, TabularDataReader> matching(string $expression) extract all found fragment identifiers for the tabular data
  * @method iterable<int, TabularDataReader> chunkBy(int $length) Chunk the TabulaDataReader into smaller TabularDataReader instance of the given size or less.
+ * @method TabularDataReader mapHeader(array $headers) Returns a new TabulaDataReader with a new set of headers.
  */
 interface TabularDataReader extends Countable, IteratorAggregate
 {