Merge pull request #52 from xp-framework/feature/pipelines

Add syntactical support for pipelines with `|>` and `?|>`

Author: thekid

src/main/php/lang/ast/Tokens.class.php

@@ -17,15 +17,15 @@ class Tokens {
     '=' => ['===', '=>', '=='],
     '!' => ['!==', '!='],
     '&' => ['&&=', '&&', '&='],
-    '|' => ['||=', '||', '|='],
+    '|' => ['||=', '||', '|=', '|>'],
     '^' => ['^='],
     '+' => ['+=', '++'],
     '-' => ['-=', '--', '->'],
     '*' => ['**=', '*=', '**'],
     '/' => ['/=', '//', '/*'],
     '~' => ['~='],
     '%' => ['%='],
-    '?' => ['?->', '??=', '?:', '??'],
+    '?' => ['?->', '?|>', '??=', '?:', '??'],
     '.' => ['...', '.='],
     ':' => ['::'],
     '[' => [],

src/main/php/lang/ast/nodes/PipeExpression.class.php

@@ -0,0 +1,19 @@
+<?php namespace lang\ast\nodes;
+
+use lang\ast\Node;
+
+class PipeExpression extends Node {
+  public $kind= 'pipe';
+  public $expression, $target;
+
+  public function __construct($expression, $target, $line= -1) {
+    $this->expression= $expression;
+    $this->target= $target;
+    $this->line= $line;
+  }
+
+  /** @return iterable */
+  public function children() {
+    return [$this->expression, $this->target];
+  }
+}

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

@@ -43,6 +43,7 @@
   NullSafeInstanceExpression,
   OffsetExpression,
   Parameter,
+  PipeExpression,
   Property,
   ReturnStatement,
   ScopeExpression,
@@ -174,6 +175,16 @@ public function __construct() {
       return new ScopeExpression($scope, $expr, $token->line);
     });
 
+    $this->infix('|>', 40, function($parse, $token, $left) {
+      return new PipeExpression($left, $this->expression($parse, 40), $left->line);
+    });
+
+    $this->infix('?|>', 40, function($parse, $node, $left) {
+      $value= new PipeExpression($left, $this->expression($parse, 40), $left->line);
+      $value->kind= 'nullsafepipe';
+      return $value;
+    });
+
     $this->infix('(', 100, function($parse, $token, $left) {
 
       // Resolve ambiguity by looking ahead: `func(...)` which is a first-class
@@ -207,7 +218,7 @@ public function __construct() {
       return new OffsetExpression($left, $expr, $left->line);
     });
 
-    $this->infix('?', 80, function($parse, $token, $left) {
+    $this->infix('?', 30, function($parse, $token, $left) {
       $when= $this->expression($parse, 0);
       $parse->expecting(':', 'ternary');
       $else= $this->expression($parse, 0);