CRM-13580 - crmScope - Add support for "dynamic variable scopes" in Smarty

This allows one to temporarily a set variable for a brief duration -- and
restore the variable's original value afterward.

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* CRM-13580: Set translation domain implicitly in extensions
  http://issues.civicrm.org/jira/browse/CRM-13580

CRM/Core/Smarty/plugins/block.crmScope.php

+<?php
+
+/**
+ * Smarty block function to temporarily define variables.
+ *
+ * Example:
+ *
+ * @code
+ * {tsScope x=1}
+ *   Expect {$x}==1
+ *   {tsScope x=2}
+ *     Expect {$x}==2
+ *   {/tsScope}
+ *   Expect {$x}==1
+ * {/tsScope}
+ * @endcode
+ *
+ * @param array $params   must define 'name'
+ * @param string $content    Default content
+ * @param object $smarty  the Smarty object
+ *
+ * @return string
+ */
+function smarty_block_crmScope($params, $content, &$smarty, &$repeat) {
+  // A list of variables/values to save temporarily
+  static $backupFrames = array();
+
+  if ($repeat) {
+    // open crmScope
+    $vars = $smarty->get_template_vars();
+    $backupFrame = array();
+    foreach ($params as $key => $value) {
+      $backupFrame[$key] = isset($vars[$key]) ? $vars[$key] : NULL;
+    }
+    $backupFrames[] = $backupFrame;
+    _smarty_block_crmScope_applyFrame($smarty, $params);
+  }
+  else {
+    // close crmScope
+    _smarty_block_crmScope_applyFrame($smarty, array_pop($backupFrames));
+  }
+
+  return $content;
+}
+
+function _smarty_block_crmScope_applyFrame(&$smarty, $frame) {
+  foreach ($frame as $key => $value) {
+    $smarty->assign($key, $value);
+  }
+}
\ No newline at end of file

tests/phpunit/CRM/Core/Smarty/plugins/CrmScopeTest.php

+<?php
+
+require_once 'CiviTest/CiviUnitTestCase.php';
+
+class CRM_Core_Smarty_plugins_CrmScopeTest extends CiviUnitTestCase {
+  function setUp() {
+    parent::setUp();
+    require_once 'CRM/Core/Smarty.php';
+
+    // Templates should normally be file names, but for unit-testing it's handy to use "string:" notation
+    require_once 'CRM/Core/Smarty/resources/String.php';
+    civicrm_smarty_register_string_resource();
+  }
+
+  function scopeCases() {
+    $cases = array();
+    $cases[] = array('', '{crmScope}{/crmScope}');
+    $cases[] = array('', '{crmScope x=1}{/crmScope}');
+    $cases[] = array('x=', 'x={$x}');
+    $cases[] = array('x=1', '{crmScope x=1}x={$x}{/crmScope}');
+    $cases[] = array('x=1', '{$x}{crmScope x=1}x={$x}{/crmScope}{$x}');
+    $cases[] = array('x=1 x=2 x=1', '{crmScope x=1}x={$x} {crmScope x=2}x={$x}{/crmScope} x={$x}{/crmScope}');
+    $cases[] = array('x=1 x=2 x=3 x=2 x=1', '{crmScope x=1}x={$x} {crmScope x=2}x={$x} {crmScope x=3}x={$x}{/crmScope} x={$x}{/crmScope} x={$x}{/crmScope}');
+    $cases[] = array('x=1,y=9', '{crmScope x=1 y=9}x={$x},y={$y}{/crmScope}');
+    $cases[] = array('x=1,y=9 x=1,y=8 x=1,y=9', '{crmScope x=1 y=9}x={$x},y={$y} {crmScope y=8}x={$x},y={$y}{/crmScope} x={$x},y={$y}{/crmScope}');
+    $cases[] = array('x=', 'x={$x}');
+    return $cases;
+  }
+
+  /**
+   * @dataProvider scopeCases
+   */
+  function testBlank($expected, $input) {
+    $smarty = CRM_Core_Smarty::singleton();
+    $actual = $smarty->fetch('string:' . $input);
+    $this->assertEquals($expected, $actual, "Process input=[$input]");
+  }
+
+}