symfony · fabpot · Apr 8, 2019 · Apr 7, 2019
diff --git a/src/Symfony/Component/Console/CHANGELOG.md b/src/Symfony/Component/Console/CHANGELOG.md
@@ -6,6 +6,8 @@ CHANGELOG
 
  * added support for hyperlinks
  * added `ProgressBar::iterate()` method that simplify updating the progress bar when iterating
+ * added `Question::setAutocompleterCallback()` to provide a callback function
+   that dynamically generates suggestions as the user types
 
 4.2.0
 -----

diff --git a/src/Symfony/Component/Console/Helper/QuestionHelper.php b/src/Symfony/Component/Console/Helper/QuestionHelper.php
@@ -115,7 +115,7 @@ private function doAsk(OutputInterface $output, Question $question)
         $this->writePrompt($output, $question);
 
         $inputStream = $this->inputStream ?: STDIN;
-        $autocomplete = $question->getAutocompleterValues();
+        $autocomplete = $question->getAutocompleterCallback();
 
         if (null === $autocomplete || !$this->hasSttyAvailable()) {
             $ret = false;
@@ -137,7 +137,7 @@ private function doAsk(OutputInterface $output, Question $question)
                 $ret = trim($ret);
             }
         } else {
-            $ret = trim($this->autocomplete($output, $question, $inputStream, \is_array($autocomplete) ? $autocomplete : iterator_to_array($autocomplete, false)));
+            $ret = trim($this->autocomplete($output, $question, $inputStream, $autocomplete));
         }
 
         if ($output instanceof ConsoleSectionOutput) {
@@ -194,17 +194,15 @@ protected function writeError(OutputInterface $output, \Exception $error)
     /**
      * Autocompletes a question.
      *
-     * @param OutputInterface $output
-     * @param Question        $question
-     * @param resource        $inputStream
+     * @param resource $inputStream
      */
-    private function autocomplete(OutputInterface $output, Question $question, $inputStream, array $autocomplete): string
+    private function autocomplete(OutputInterface $output, Question $question, $inputStream, callable $autocomplete): string
     {
         $ret = '';
 
         $i = 0;
         $ofs = -1;
-        $matches = $autocomplete;
+        $matches = $autocomplete($ret);
         $numMatches = \count($matches);
 
         $sttyMode = shell_exec('stty -g');
@@ -232,7 +230,7 @@ private function autocomplete(OutputInterface $output, Question $question, $inpu
 
                 if (0 === $i) {
                     $ofs = -1;
-                    $matches = $autocomplete;
+                    $matches = $autocomplete($ret);
                     $numMatches = \count($matches);
                 } else {
                     $numMatches = 0;
@@ -260,18 +258,25 @@ private function autocomplete(OutputInterface $output, Question $question, $inpu
             } elseif (\ord($c) < 32) {
                 if ("\t" === $c || "\n" === $c) {
                    if ($numMatches > 0 && -1 !== $ofs) {
-                        $ret = $matches[$ofs];
+                        $ret = (string) $matches[$ofs];
                         // Echo out remaining chars for current match
                         $output->write(substr($ret, $i));
                         $i = \strlen($ret);
+
+                        $matches = array_filter(
+                            $autocomplete($ret),
+                            function ($match) use ($ret) {
+                                return '' === $ret || 0 === strpos($match, $ret);
+                            }
+                        );
+                        $numMatches = \count($matches);
+                        $ofs = -1;
                     }
 
                     if ("\n" === $c) {
                         $output->write($c);
                         break;
                     }
-
-                    $numMatches = 0;
                 }
 
                 continue;
@@ -287,7 +292,7 @@ private function autocomplete(OutputInterface $output, Question $question, $inpu
                 $numMatches = 0;
                 $ofs = 0;
 
-                foreach ($autocomplete as $value) {
+                foreach ($autocomplete($ret) as $value) {
                     // If typed characters match the beginning chunk of value (e.g. [AcmeDe]moBundle)
                     if (0 === strpos($value, $ret)) {
                         $matches[$numMatches++] = $value;

diff --git a/src/Symfony/Component/Console/Question/Question.php b/src/Symfony/Component/Console/Question/Question.php
@@ -25,7 +25,7 @@ class Question
     private $attempts;
     private $hidden = false;
     private $hiddenFallback = true;
-    private $autocompleterValues;
+    private $autocompleterCallback;
     private $validator;
     private $default;
     private $normalizer;
@@ -81,7 +81,7 @@ public function isHidden()
      */
     public function setHidden($hidden)
     {
-        if ($this->autocompleterValues) {
+        if ($this->autocompleterCallback) {
             throw new LogicException('A hidden question cannot use the autocompleter.');
         }
 
@@ -121,7 +121,9 @@ public function setHiddenFallback($fallback)
      */
     public function getAutocompleterValues()
     {
-        return $this->autocompleterValues;
+        $callback = $this->getAutocompleterCallback();
+
+        return $callback ? $callback('') : null;
     }
 
     /**
@@ -138,17 +140,46 @@ public function setAutocompleterValues($values)
     {
         if (\is_array($values)) {
             $values = $this->isAssoc($values) ? array_merge(array_keys($values), array_values($values)) : array_values($values);
-        }
 
-        if (null !== $values && !\is_array($values) && !$values instanceof \Traversable) {
+            $callback = static function () use ($values) {
+                return $values;
+            };
+        } elseif ($values instanceof \Traversable) {
+            $valueCache = null;
+            $callback = static function () use ($values, &$valueCache) {
+                return $valueCache ?? $valueCache = iterator_to_array($values, false);
+            };
+        } elseif (null === $values) {
+            $callback = null;
+        } else {
             throw new InvalidArgumentException('Autocompleter values can be either an array, "null" or a "Traversable" object.');
         }
 
-        if ($this->hidden) {
+        return $this->setAutocompleterCallback($callback);
+    }
+
+    /**
+     * Gets the callback function used for the autocompleter.
+     */
+    public function getAutocompleterCallback(): ?callable
+    {
+        return $this->autocompleterCallback;
+    }
+
+    /**
+     * Sets the callback function used for the autocompleter.
+     *
+     * The callback is passed the user input as argument and should return an iterable of corresponding suggestions.
+     *
+     * @return $this
+     */
+    public function setAutocompleterCallback(callable $callback = null): self
+    {
+        if ($this->hidden && null !== $callback) {
             throw new LogicException('A hidden question cannot use the autocompleter.');
         }
 
-        $this->autocompleterValues = $values;
+        $this->autocompleterCallback = $callback;
 
         return $this;
     }

diff --git a/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php b/src/Symfony/Component/Console/Tests/Helper/QuestionHelperTest.php
@@ -198,6 +198,67 @@ public function testAskWithAutocomplete()
         $this->assertEquals('FooBundle', $dialog->ask($this->createStreamableInputInterfaceMock($inputStream), $this->createOutputInterface(), $question));
     }
 
+    public function testAskWithAutocompleteCallback()
+    {
+        if (!$this->hasSttyAvailable()) {
+            $this->markTestSkipped('`stty` is required to test autocomplete functionality');
+        }
+
+        // Po<TAB>Cr<TAB>P<DOWN ARROW><DOWN ARROW><NEWLINE>
+        $inputStream = $this->getInputStream("Pa\177\177o\tCr\t\033[A\033[A\033[A\n");
+
+        $dialog = new QuestionHelper();
+        $helperSet = new HelperSet([new FormatterHelper()]);
+        $dialog->setHelperSet($helperSet);
+
+        $question = new Question('What\'s for dinner?');
+
+        // A simple test callback - return an array containing the words the
+        // user has already completed, suffixed with all known words.
+        //
+        // Eg: If the user inputs "Potato C", the return will be:
+        //
+        //     ["Potato Carrot ", "Potato Creme ", "Potato Curry ", ...]
+        //
+        // No effort is made to avoid irrelevant suggestions, as this is handled
+        // by the autocomplete function.
+        $callback = function ($input) {
+            $knownWords = [
+                'Carrot',
+                'Creme',
+                'Curry',
+                'Parsnip',
+                'Pie',
+                'Potato',
+                'Tart',
+            ];
+
+            $inputWords = explode(' ', $input);
+            $lastInputWord = array_pop($inputWords);
+            $suggestionBase = $inputWords
+                ? implode(' ', $inputWords).' '
+                : '';
+
+            return array_map(
+                function ($word) use ($suggestionBase) {
+                    return $suggestionBase.$word.' ';
+                },
+                $knownWords
+            );
+        };
+
+        $question->setAutocompleterCallback($callback);
+
+        $this->assertSame(
+            'Potato Creme Pie',
+            $dialog->ask(
+                $this->createStreamableInputInterfaceMock($inputStream),
+                $this->createOutputInterface(),
+                $question
+            )
+        );
+    }
+
     public function testAskWithAutocompleteWithNonSequentialKeys()
     {
         if (!$this->hasSttyAvailable()) {