Yield from

src/main/jay/grammars/php.jay

@@ -76,11 +76,12 @@ use xp\compiler\ast\DynamicInstanceOfNode;
 use xp\compiler\ast\DynamicVariableReferenceNode;
 use xp\compiler\ast\NoopNode;
 use xp\compiler\ast\YieldNode;
+use xp\compiler\ast\YieldFromNode;
 %}
 
 %left ','
 %left '(' ')'
-%right T_YIELD
+%right T_YIELD T_YIELD_FROM
 %left T_BOOLEAN_OR
 %left T_BOOLEAN_AND
 %right '=' T_ADD_EQUAL T_SUB_EQUAL T_MUL_EQUAL T_DIV_EQUAL T_CONCAT_EQUAL T_MOD_EQUAL T_SHR T_SHL T_AND_EQUAL T_OR_EQUAL T_XOR_EQUAL
@@ -147,6 +148,7 @@ use xp\compiler\ast\YieldNode;
 %token T_BREAK 365
 %token T_CONTINUE 366
 %token T_YIELD 367
+%token T_YIELD_FROM 368
 
 %token T_IF 370
 %token T_ELSE 371
@@ -615,6 +617,9 @@ expression:
   | T_YIELD expression T_DOUBLE_ARROW expression {
       $$= $yyLex->create(new YieldNode($4, $2));
     }
+  | T_YIELD_FROM expression {
+      $$= $yyLex->create(new YieldFromNode($2));
+    }
   | assignment { 
       $$= $yyLex->create(new AssignmentNode($1)); 
     }

src/main/jay/grammars/xp.jay

@@ -71,11 +71,12 @@ use xp\compiler\ast\WithNode;
 use xp\compiler\ast\ArmNode;
 use xp\compiler\ast\BracedExpressionNode;
 use xp\compiler\ast\YieldNode;
+use xp\compiler\ast\YieldFromNode;
 %}
 
 %left ','
 %nonassoc T_ARROW
-%right T_YIELD
+%right T_YIELD T_YIELD_FROM
 %left T_BOOLEAN_OR
 %left T_BOOLEAN_AND
 %right '=' T_ADD_EQUAL T_SUB_EQUAL T_MUL_EQUAL T_DIV_EQUAL T_CONCAT_EQUAL T_MOD_EQUAL T_AND_EQUAL T_OR_EQUAL T_XOR_EQUAL
@@ -147,6 +148,7 @@ use xp\compiler\ast\YieldNode;
 %token T_BREAK 365
 %token T_CONTINUE 366
 %token T_YIELD 367
+%token T_YIELD_FROM 368
 
 %token T_IF 370
 %token T_ELSE 371
@@ -838,6 +840,9 @@ expression:
   | T_YIELD expression ':' expression {
       $$= $yyLex->create(new YieldNode($4, $2));
     }
+  | T_YIELD_FROM expression {
+      $$= $yyLex->create(new YieldFromNode($2));
+    }
   | expression T_AS paramtyperef { 
       $$= $yyLex->create(new CastNode(array_merge($3, array('expression' => $1)))); 
     }

src/main/php/xp/compiler/ast/Visitor.class.php

@@ -712,7 +712,28 @@ protected function visitBracedExpression(BracedExpressionNode $node) {
     $node->expression= $this->visitOne($node->expression);
     return $node;
   }
-
+
+  /**
+   * Visit a yield statement
+   *
+   * @param   xp.compiler.ast.Node node
+   */
+  protected function visitYield(YieldNode $node) {
+    $node->key && $node->key= $this->visitOne($node->key);
+    $node->value && $node->value= $this->visitOne($node->value);
+    return $node;
+  }
+
+  /**
+   * Visit a yield statement
+   *
+   * @param   xp.compiler.ast.Node node
+   */
+  protected function visitYieldFrom(YieldFromNode $node) {
+    $node->expr= $this->visitOne($node->expr);
+    return $node;
+  }
+
   /**
    * Visit a node. Delegates to visit*() methods
    *

src/main/php/xp/compiler/ast/YieldFromNode.class.php

@@ -0,0 +1,21 @@
+<?php namespace xp\compiler\ast;
+
+/**
+ * The "yield from" statement
+ */
+class YieldFromNode extends Node {
+  public $expr;
+
+  public function __construct($expr) {
+    $this->expr= $expr;
+  }
+
+  /**
+   * Returns a hashcode
+   *
+   * @return  string
+   */
+  public function hashCode() {
+    return 'yield from '.$this->expr->hashCode();
+  }
+}

src/main/php/xp/compiler/emit/Emitter.class.php

@@ -697,7 +697,15 @@ protected abstract function emitSilenceOperator($b, $silenced);
    * @param   xp.compiler.ast.YieldNode yield
    */
   protected abstract function emitYield($b, $yield);
-
+
+  /**
+   * Emit a yield node
+   *
+   * @param   xp.compiler.emit.Buffer b
+   * @param   xp.compiler.ast.YieldFromNode yield
+   */
+  protected abstract function emitYieldFrom($b, $yield);
+
   /**
    * Emit a single node
    *

src/main/php/xp/compiler/emit/php/Emitter.class.php

@@ -2327,6 +2327,16 @@ protected function emitYield($b, $yield) {
     $this->error('V505', 'Yield not supported in '.$this->getClassName());
   }
 
+  /**
+   * Emit a yield from node
+   *
+   * @param   xp.compiler.emit.Buffer b
+   * @param   xp.compiler.ast.YieldFromNode yield
+   */
+  protected function emitYieldFrom($b, $yield) {
+    $this->error('V505', 'Yield not supported in '.$this->getClassName());
+  }
+
   /**
    * Emit all given nodes
    *
@@ -2450,6 +2460,8 @@ protected function emitTry($b, $try) {
           V54Emitter::emitTry($b, $try);
         }
       }');
+    } else if (version_compare(PHP_VERSION, '7.0.0', 'gt')) {
+      return new V70Emitter();
     } else if (version_compare(PHP_VERSION, '5.5.0', 'gt')) {
       return new V55Emitter();
     } else {

src/main/php/xp/compiler/emit/php/V55Emitter.class.php

@@ -26,6 +26,52 @@ protected function emitYield($b, $yield) {
     }
   }
 
+  /**
+   * Emit a yield from node
+   *
+   * @param   xp.compiler.emit.Buffer b
+   * @param   xp.compiler.ast.YieldFromNode yield
+   */
+  protected function emitYieldFrom($b, $yield) {
+    static $shim= '
+      if ($iter instanceof \\Generator) {
+        defined(\'HHVM_VERSION\') && $iter->next();
+        $send= eval(\'return function() use($iter) {
+          $recv= null;
+          $send= true;
+          while ($iter->valid()) {
+            $next= $iter->current();
+            $send ? $iter->send($recv) : $iter->throw($recv);
+            try {
+              $recv= \'.(defined(\'HHVM_VERSION\') ? \'yield $next\' : \'(yield $next)\').\';
+              $send= true;
+            } catch (\\Exception $e) {
+              $recv= $e;
+              $send= false;
+            }
+          }
+        };\');
+        foreach ($send() as $next) { yield $next; }
+      } else {
+        foreach ($iter as $next) { yield $next; }
+      }
+    ';
+
+    $iter= $this->tempVar();
+    $b->append($iter)->append('=');
+    $this->emitOne($b, $yield->expr);
+    $b->append(';');
+
+    $b->append(strtr($shim, [
+      "\n"    => '',
+      '  '    => '',
+      '$iter' => $iter,
+      '$recv' => $this->tempVar(),
+      '$send' => $this->tempVar(),
+      '$next' => $this->tempVar()
+    ]));
+  }
+
   /**
    * Emit a try / catch block
    *

src/main/php/xp/compiler/emit/php/V70Emitter.class.php

@@ -0,0 +1,18 @@
+<?php namespace xp\compiler\emit\php;
+
+/**
+* Emits sourcecode using PHP 7.0 sourcecode
+ */
+class V70Emitter extends V55Emitter {
+
+  /**
+   * Emit a yield from node
+   *
+   * @param   xp.compiler.emit.Buffer b
+   * @param   xp.compiler.ast.YieldFromNode yield
+   */
+  protected function emitYieldFrom($b, $yield) {
+    $b->append('yield from ');
+    $this->emitOne($b, $yield->expr);
+  }
+}

src/main/php/xp/compiler/syntax/php/Lexer.class.php

@@ -49,7 +49,6 @@ class Lexer extends \text\parser\generic\AbstractLexer {
       'while'         => Parser::T_WHILE,
       'break'         => Parser::T_BREAK,
       'continue'      => Parser::T_CONTINUE,
-      'yield'         => Parser::T_YIELD,
 
       'if'            => Parser::T_IF,
       'else'          => Parser::T_ELSE,
@@ -66,15 +65,15 @@ class Lexer extends \text\parser\generic\AbstractLexer {
       '.' => array('.=' => Parser::T_CONCAT_EQUAL),
       '+' => array('+=' => Parser::T_ADD_EQUAL, '++' => Parser::T_INC),
       '*' => array('*=' => Parser::T_MUL_EQUAL),
-      '/' => array('/=' => Parser::T_DIV_EQUAL),
       '%' => array('%=' => Parser::T_MOD_EQUAL),
       '=' => array('==' => Parser::T_EQUALS, '=>' => Parser::T_DOUBLE_ARROW),
       '!' => array('!=' => Parser::T_NOT_EQUALS),
       ':' => array('::' => Parser::T_DOUBLE_COLON),
       '|' => array('||' => Parser::T_BOOLEAN_OR, '|=' => Parser::T_OR_EQUAL),
       '&' => array('&&' => Parser::T_BOOLEAN_AND, '&=' => Parser::T_AND_EQUAL),
       '^' => array('^=' => Parser::T_XOR_EQUAL),
-      '?' => array('?>' => -1)
+      '?' => array('?>' => -1),
+      'yield' => array('yield from' => Parser::T_YIELD_FROM, 'yield' => Parser::T_YIELD)
     );
 
   const 
@@ -212,6 +211,28 @@ public function advance() {
       } else if ('$' === $token{0}) {
         $this->token= Parser::T_VARIABLE;
         $this->value= substr($token, 1);
+      } else if (isset(self::$lookahead[$token])) {
+        $ahead= $token;
+        $p= true;
+        foreach (self::$lookahead[$token] as $candidate => $id) {
+          $l= strlen($candidate);
+          while (strlen($ahead) < $l && $this->tokenizer->hasMoreTokens()) {
+            $ahead.= $this->nextToken();
+          }
+          if (0 === strncmp($candidate, $ahead, $l)) {
+            if (0 === $id) break;
+            $this->token= $id;
+            $this->value= $candidate;
+            $this->pushBack(substr($ahead, $l));
+            $p= false;
+            break;
+          }
+        }
+        if ($p) {
+          $this->pushBack(substr($ahead, 1));
+          $this->token= ord($token);
+          $this->value= $token;
+        }
       } else if (isset(self::$keywords[$token])) {
         $this->token= self::$keywords[$token];
         $this->value= $token;
@@ -241,17 +262,6 @@ public function advance() {
           $this->value= $token;
           $this->pushBack($ahead);
         }
-      } else if (isset(self::$lookahead[$token])) {
-        $ahead= $this->nextToken();
-        $combined= $token.$ahead;
-        if (isset(self::$lookahead[$token][$combined])) {
-          $this->token= self::$lookahead[$token][$combined];
-          $this->value= $combined;
-        } else {
-          $this->token= ord($token);
-          $this->value= $token;
-          $this->pushBack($ahead);
-        }
       } else if (false !== strpos(self::DELIMITERS, $token) && 1 == strlen($token)) {
         $this->token= ord($token);
         $this->value= $token;