Use specialized Node subclasses instead of misusing the CaseLabel

Author: thekid

ChangeLog.md

@@ -3,6 +3,12 @@ Switch expression for PHP - ChangeLog
 
 ## ?.?.? / ????-??-??
 
+## 0.3.0 / 2019-09-22
+
+* Refactored code to use specialized `lang.ast.Node` subclasses instead of
+  misusing the `CaseLabel` class from the `lang.ast` package.
+  (@thekid)
+
 ## 0.2.0 / 2019-09-09
 
 * Updated dependency to newest version of `xp-framework/compiler`, see

src/main/php/lang/ast/syntax/php/CaseBlock.class.php

@@ -0,0 +1,36 @@
+<?php namespace lang\ast\syntax\php;
+
+use lang\ast\Node;
+use lang\ast\nodes\Braced;
+use lang\ast\nodes\InvokeExpression;
+use lang\ast\nodes\LambdaExpression;
+use lang\ast\nodes\Signature;
+
+class CaseBlock extends Node {
+  public $kind= 'caseblock';
+  public $conditions, $statements;
+
+  public function __construct($conditions, $statements) {
+    $this->conditions= $conditions;
+    $this->statements= $statements;
+  }
+
+  /**
+   * Transforms case body into an expression by turning statement lists into an IIFE.
+   *
+   * @return lang.ast.Node
+   */
+  public function expression() {
+    return new InvokeExpression(new Braced(new LambdaExpression(new Signature([], null), $this->statements)), []);
+  }
+
+  /** @return iterable */
+  public function children() {
+    foreach ((array)$this->conditions as $node) {
+      yield $node;
+    }
+    foreach ($this->statements as $node) {
+      yield $node;
+    }
+  }
+}

src/main/php/lang/ast/syntax/php/CaseExpression.class.php

@@ -0,0 +1,28 @@
+<?php namespace lang\ast\syntax\php;
+
+use lang\ast\Node;
+
+class CaseExpression extends Node {
+  public $kind= 'caseexpr';
+  public $conditions, $expression;
+
+  public function __construct($conditions, $expression) {
+    $this->conditions= $conditions;
+    $this->expression= $expression;
+  }
+
+  /** @return lang.ast.Node */
+  public function expression() {
+    return $this->expression;
+  }
+
+  /** @return iterable */
+  public function children() {
+    foreach ((array)$this->conditions as $node) {
+      yield $node;
+    }
+    if (null !== $this->expression) {
+      yield $this->expression;
+    }
+  }
+}

src/main/php/lang/ast/syntax/php/SwitchExpression.class.php

@@ -57,14 +57,12 @@ public function setup($language, $emitter) {
         $parse->expecting('=>', 'switch');
         if ('{' === $parse->token->value) {
           $parse->forward();
-          $return= $this->statements($parse);
+          $cases[]= new CaseBlock($expr, $this->statements($parse));
           $parse->expecting('}', 'switch');
         } else {
-          $return= $this->expression($parse, 0);
+          $cases[]= new CaseExpression($expr, $this->expression($parse, 0));
           $parse->expecting(';', 'switch');
         }
-
-        $cases[]= new CaseLabel($expr, $return);
       }
       $parse->forward();
 
@@ -77,17 +75,7 @@ public function setup($language, $emitter) {
       return $stmt;
     });
 
-    // Transforms case body into an expression by turning statement lists into an IIFE,
-    // should that be necessary.
-    $asExpr= function($body) {
-      if ($body instanceof Node) {
-        return $body;
-      } else {
-        return new InvokeExpression(new Braced(new LambdaExpression(new Signature([], null), $body)), []);
-      }
-    };
-
-    $emitter->transform('switchexpr', function($codegen, $node) use($asExpr) {
+    $emitter->transform('switchexpr', function($codegen, $node) {
       static $is= [
         'string'   => true,
         'int'      => true,
@@ -104,9 +92,9 @@ public function setup($language, $emitter) {
       $ternary= new TernaryExpression(null, null, null);
       $ptr= &$ternary;
       foreach ($node->cases as $case) {
-        if (null === $case->expression) {
-          $ptr->otherwise= $asExpr($case->body);
-        } else foreach ($case->expression as $i => $expr) {
+        if (null === $case->conditions) {
+          $ptr->otherwise= $case->expression();
+        } else foreach ($case->conditions as $i => $expr) {
           if ($expr instanceof FunctionType || $expr instanceof ArrayType || $expr instanceof MapType) {
             $cond= new InvokeExpression(new Literal('is'), [new Literal('"'.$expr->name().'"'), $t]);
           } else if ($expr instanceof Type) {
@@ -120,7 +108,7 @@ public function setup($language, $emitter) {
             $cond= new BinaryExpression($t, '===', $expr);
           }
 
-          $ptr->otherwise= new Braced(new TernaryExpression($cond, $asExpr($case->body), null));
+          $ptr->otherwise= new Braced(new TernaryExpression($cond, $case->expression(), null));
           $ptr= &$ptr->otherwise->expression;
         }
       }