Add support for the match expression

thekid · thekid · commit b6d0269899e9 · 2020-07-20T00:38:42.000+02:00
See xp-framework/ast#8
diff --git a/src/main/php/lang/ast/emit/PHP.class.php b/src/main/php/lang/ast/emit/PHP.class.php
@@ -545,6 +545,34 @@ protected function emitSwitch($result, $switch) {
     $result->out->write('}');
   }
 
+  protected function emitMatch($result, $match) {
+    $t= $result->temp();
+    $result->out->write('('.$t.'=');
+    $this->emitOne($result, $match->expression);
+    $result->out->write(')');
+
+    $b= 0;
+    foreach ($match->cases as $case) {
+      foreach ($case->expressions as $expression) {
+        $b && $result->out->write($t);
+        $result->out->write('===');
+        $this->emitOne($result, $expression);
+        $result->out->write('?');
+        $this->emitOne($result, $case->body[0]);
+        $result->out->write(':(');
+        $b++;
+      }
+    }
+
+    // Emit IIFE for raising an error until we have throw expressions
+    if (null === $match->default) {
+      $result->out->write('function() use('.$t.') { throw new \\Error("Unhandled match value of type ".gettype('.$t.')); })(');
+    } else {
+      $this->emitOne($result, $match->default[0]);
+    }
+    $result->out->write(str_repeat(')', $b));
+  }
+
   protected function emitCatch($result, $catch) {
     if (empty($catch->types)) {
       $result->out->write('catch(\\Throwable $'.$catch->variable.') {');
diff --git a/src/test/php/lang/ast/unittest/emit/ControlStructuresTest.class.php b/src/test/php/lang/ast/unittest/emit/ControlStructuresTest.class.php
@@ -1,5 +1,6 @@
 <?php namespace lang\ast\unittest\emit;
 
+use lang\Throwable;
 use unittest\Assert;
 
 class ControlStructuresTest extends EmittingTest {
@@ -61,4 +62,50 @@ public function run($arg) {
 
     Assert::equals($expected, $r);
   }
+
+  #[@test, @values([[SEEK_SET, 10], [SEEK_CUR, 11], [SEEK_END, 6100]])]
+  public function match($whence, $expected) {
+    $r= $this->run('class <T> {
+      public function run($arg) {
+        $position= 1;
+        $size= 6100;
+        return match ($arg) {
+          SEEK_SET => 10,
+          SEEK_CUR => $position + 10,
+          SEEK_END => min($size + $position, $size),
+        };
+      }
+    }', $whence);
+
+    Assert::equals($expected, $r);
+  }
+
+  #[@test, @values([[SEEK_SET, 10], [SEEK_CUR, 11], [SEEK_END, 6100]])]
+  public function match_with_default($whence, $expected) {
+    $r= $this->run('class <T> {
+      public function run($arg) {
+        $position= 1;
+        $size= 6100;
+        return match ($arg) {
+          SEEK_SET => 10,
+          SEEK_CUR => $position + 10,
+          default  => min($size + $position, $size),
+        };
+      }
+    }', $whence);
+
+    Assert::equals($expected, $r);
+  }
+
+  #[@test, @expect(['class' => Throwable::class, 'withMessage' => '/Unhandled match value of type .+/'])]
+  public function unhandled_match() {
+    $this->run('class <T> {
+      public function run($arg) {
+        return match ($arg) {
+          SEEK_SET => 10,
+          SEEK_CUR => $position + 10,
+        };
+      }
+    }', SEEK_END);
+  }
 }
