Add TernaryToSpaceshipRector

config/level/php/php70.yml

@@ -16,3 +16,4 @@ services:
     Rector\Php\Rector\FuncCall\CallUserMethodRector : ~
     Rector\Php\Rector\FuncCall\EregToPregMatchRector: ~
     Rector\Php\Rector\Switch_\ReduceMultipleDefaultSwitchRector: ~
+    Rector\Php\Rector\Ternary\TernaryToSpaceshipRector: ~

packages/Php/src/Rector/Ternary/TernaryToSpaceshipRector.php

@@ -0,0 +1,125 @@
+<?php declare(strict_types=1);
+
+namespace Rector\Php\Rector\Ternary;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\BinaryOp;
+use PhpParser\Node\Expr\BinaryOp\Greater;
+use PhpParser\Node\Expr\BinaryOp\Smaller;
+use PhpParser\Node\Expr\BinaryOp\Spaceship;
+use PhpParser\Node\Expr\Ternary;
+use Rector\Rector\AbstractRector;
+use Rector\RectorDefinition\CodeSample;
+use Rector\RectorDefinition\RectorDefinition;
+
+/**
+ * @see https://wiki.php.net/rfc/combined-comparison-operator
+ */
+final class TernaryToSpaceshipRector extends AbstractRector
+{
+    public function getDefinition(): RectorDefinition
+    {
+        return new RectorDefinition('Use <=> spaceship instead of ternary with same effect', [
+            new CodeSample(
+                <<<'CODE_SAMPLE'
+function order_func($a, $b) {
+    return ($a < $b) ? -1 : (($a > $b) ? 1 : 0);
+}
+CODE_SAMPLE
+                ,
+                <<<'CODE_SAMPLE'
+function order_func($a, $b) {
+    return $a <=> $b;
+}
+CODE_SAMPLE
+            ),
+        ]);
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getNodeTypes(): array
+    {
+        return [Ternary::class];
+    }
+
+    /**
+     * @param Ternary $node
+     */
+    public function refactor(Node $node): ?Node
+    {
+        if ($this->shouldSkip($node)) {
+            return null;
+        }
+
+        /** @var Ternary $nestedTernary */
+        $nestedTernary = $node->else;
+
+        $spaceshipNode = $this->processSmallerThanTernary($node, $nestedTernary);
+        if ($spaceshipNode !== null) {
+            return $spaceshipNode;
+        }
+
+        return $this->processGreaterThanTernary($node, $nestedTernary);
+    }
+
+    private function shouldSkip(Ternary $ternaryNode): bool
+    {
+        if (! $ternaryNode->cond instanceof BinaryOp) {
+            return true;
+        }
+
+        if (! $ternaryNode->else instanceof Ternary) {
+            return true;
+        }
+
+        $nestedTernary = $ternaryNode->else;
+
+        // $a X $b ? . : ($a X $b ? . : .)
+        if (! $this->areNodesEqual($ternaryNode->cond->left, $nestedTernary->cond->left)) {
+            return true;
+        }
+
+        // $a X $b ? . : ($a X $b ? . : .)
+        if (! $this->areNodesEqual($ternaryNode->cond->right, $nestedTernary->cond->right)) {
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Matches "$a < $b ? -1 : ($a > $b ? 1 : 0)"
+     */
+    private function processSmallerThanTernary(Ternary $node, Ternary $nestedTernary): ?Spaceship
+    {
+        if ($node->cond instanceof Smaller && $nestedTernary->cond instanceof Greater) {
+            if ($this->isValue($node->if, -1) && $this->isValue($nestedTernary->if, 1) && $this->isValue(
+                $nestedTernary->else,
+                0
+            )) {
+                return new Spaceship($node->cond->left, $node->cond->right);
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Matches "$a > $b ? -1 : ($a < $b ? 1 : 0)"
+     */
+    private function processGreaterThanTernary(Ternary $node, Ternary $nestedTernary): ?Spaceship
+    {
+        if ($node->cond instanceof Greater && $nestedTernary->cond instanceof Smaller) {
+            if ($this->isValue($node->if, -1) && $this->isValue($nestedTernary->if, 1) && $this->isValue(
+                $nestedTernary->else,
+                0
+            )) {
+                return new Spaceship($node->cond->right, $node->cond->left);
+            }
+        }
+
+        return null;
+    }
+}

packages/Php/tests/Rector/Ternary/TernaryToSpaceshipRector/Fixture/fixture.php.inc

@@ -0,0 +1,19 @@
+<?php
+
+function order_func($a, $b) {
+    return ($a < $b) ? -1 : (($a > $b) ? 1 : 0);
+
+    return ($a > $b) ? -1 : (($a < $b) ? 1 : 0);
+}
+
+?>
+-----
+<?php
+
+function order_func($a, $b) {
+    return $a <=> $b;
+
+    return $b <=> $a;
+}
+
+?>

packages/Php/tests/Rector/Ternary/TernaryToSpaceshipRector/TernaryToSpaceshipRectorTest.php

@@ -0,0 +1,19 @@
+<?php declare(strict_types=1);
+
+namespace Rector\Php\Tests\Rector\Ternary\TernaryToSpaceshipRector;
+
+use Rector\Php\Rector\Ternary\TernaryToSpaceshipRector;
+use Rector\Testing\PHPUnit\AbstractRectorTestCase;
+
+final class TernaryToSpaceshipRectorTest extends AbstractRectorTestCase
+{
+    public function test(): void
+    {
+        $this->doTestFiles([__DIR__ . '/Fixture/fixture.php.inc']);
+    }
+
+    protected function getRectorClass(): string
+    {
+        return TernaryToSpaceshipRector::class;
+    }
+}

packages/Php/tests/Rector/Ternary/TernaryToSpaceshipRector/config.yml

@@ -0,0 +1,2 @@
+services:
+    Rector\Php\Rector\Ternary\TernaryToSpaceshipRector: ~

src/Rector/AbstractRector.php

@@ -2,6 +2,7 @@
 
 namespace Rector\Rector;
 
+use PhpParser\ConstExprEvaluator;
 use PhpParser\Node;
 use PhpParser\Node\Expr;
 use PhpParser\Node\Stmt;
@@ -34,15 +35,22 @@ abstract class AbstractRector extends NodeVisitorAbstract implements PhpRectorIn
      */
     private $symfonyStyle;
 
+    /**
+     * @var ConstExprEvaluator
+     */
+    private $constExprEvaluator;
+
     /**
      * @required
      */
     public function setAbstractRectorDependencies(
         AppliedRectorCollector $appliedRectorCollector,
-        SymfonyStyle $symfonyStyle
+        SymfonyStyle $symfonyStyle,
+        ConstExprEvaluator $constExprEvaluator
     ): void {
         $this->appliedRectorCollector = $appliedRectorCollector;
         $this->symfonyStyle = $symfonyStyle;
+        $this->constExprEvaluator = $constExprEvaluator;
     }
 
     /**
@@ -101,6 +109,30 @@ abstract class AbstractRector extends NodeVisitorAbstract implements PhpRectorIn
         return $nodes;
     }
 
+    /**
+     * @return mixed
+     */
+    protected function getValue(Node $node)
+    {
+        if (! $node instanceof Expr) {
+            return null;
+        }
+        return $this->constExprEvaluator->evaluateSilently($node);
+    }
+
+    /**
+     * @param mixed $expectedValue
+     */
+    protected function isValue(Node $node, $expectedValue): bool
+    {
+        $nodeValue = $this->getValue($node);
+        if ($nodeValue === null) {
+            return false;
+        }
+
+        return $nodeValue === $expectedValue;
+    }
+
     protected function notifyNodeChangeFileInfo(Node $node): void
     {
         /** @var SmartFileInfo|null $fileInfo */