Template namespaces

src/main/php/web/frontend/TemplatesFrom.class.php

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+<?php namespace web\frontend;
+
+use com\github\mustache\templates\Templates;
+use com\handlebarsjs\FilesIn;
+use util\NoSuchElementException;
+
+/**
+ * Loads templates from a given path by default, supporting namespaced
+ * templates (`namespace:name`) from a given map of namespaces and paths
+ * or loaders.
+ *
+ * @test  web.frontend.unittest.TemplatesFromTest
+ */
+class TemplatesFrom extends Templates {
+  private $default;
+  private $namespaced= [];
+
+  /**
+   * Creates a new instance
+   *
+   * @param string|io.Path|io.Folder|parent $default
+   * @param [:string|io.Path|io.Folder|parent] $namespaced
+   */
+  public function __construct($default, array $namespaced= []) {
+    $this->default= $this->asTemplates($default);
+    foreach ($namespaced as $ns => $t) {
+      $this->namespaced[$ns]= $this->asTemplates($t);
+    }
+  }
+
+  /**
+   * Casts given argument to a `Templates` instance.
+   *
+   * @param  string|io.Path|io.Folder|parent $arg
+   * @return parent
+   */
+  private function asTemplates($arg) {
+    return $arg instanceof parent ? $arg : new FilesIn($arg);
+  }
+
+  /**
+   * Load a template by a given name
+   *
+   * @param  string $name The template name, not including the file extension
+   * @return com.github.mustache.templates.Input
+   * @throws util.NoSuchElementException
+   */
+  public function source($name) {
+    if (false === ($p= strpos($name, ':'))) return $this->default->source($name);
+
+    $ns= substr($name, 0, $p);
+    if ($t= ($this->namespaced[$ns] ?? null)) return $t->source(substr($name, $p + 1));
+
+    throw new NoSuchElementException('Unknown namespace "'.$ns.'"');
+  }
+
+  /**
+   * Returns available templates
+   *
+   * @return com.github.mustache.TemplateListing
+   */
+  public function listing() {
+    return $this->default->listing(); // FIXME
+  }
+}

src/test/php/web/frontend/unittest/TemplatesFromTest.class.php

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+<?php namespace web\frontend\unittest;
+
+use com\github\mustache\InMemory;
+use test\{Assert, Expect, Test, Values};
+use util\NoSuchElementException;
+use web\frontend\{Handlebars, TemplatesFrom};
+
+class TemplatesFromTest extends HandlebarsTest {
+
+  #[Test]
+  public function can_create_with_templates() {
+    new TemplatesFrom($this->templates);
+  }
+
+  #[Test]
+  public function can_create_with_path() {
+    new TemplatesFrom('src/main/handlebars');
+  }
+
+  #[Test, Expect(class: NoSuchElementException::class, message: 'Unknown namespace "nonexistant"')]
+  public function errors_for_non_existant_namespaces() {
+    (new TemplatesFrom($this->templates))->source('nonexistant:name');
+  }
+
+  #[Test]
+  public function render_directly() {
+    $fixture= new Handlebars(new TemplatesFrom(
+      $this->templates,
+      ['layout' => (new InMemory())->add('content', '<h1>{{title}}</h1>')]
+    ));
+
+    Assert::equals('<h1>Test</h1>', $fixture->render('layout:content', ['title' => 'Test']));
+  }
+
+  #[Test]
+  public function referenced_as_partial() {
+    $fixture= new Handlebars(new TemplatesFrom(
+      $this->templates->add('fixture', '{{> layout:content}}'),
+      ['layout' => (new InMemory())->add('content', '<h1>{{title}}</h1>')]
+    ));
+
+    Assert::equals('<h1>Test</h1>', $fixture->render('fixture', ['title' => 'Test']));
+  }
+
+  #[Test]
+  public function passing_variables_to_partial() {
+    $fixture= new Handlebars(new TemplatesFrom(
+      $this->templates->add('fixture', '{{> layout:content title="Test"}}'),
+      ['layout' => (new InMemory())->add('content', '<h1>{{title}}</h1>')]
+    ));
+
+    Assert::equals('<h1>Test</h1>', $fixture->render('fixture', []));
+  }
+
+  #[Test, Values(['layout', 'example/layout-lib'])]
+  public function partial_blocks($ns) {
+    $template= "{{#> {$ns}:content}}{{#*inline 'title'}}Test{{/inline}}{{/{$ns}:content}}";
+    $fixture= new Handlebars(new TemplatesFrom(
+      $this->templates->add('fixture', $template),
+      [$ns => (new InMemory())->add('content', '<h1>{{> title}}</h1>')]
+    ));
+
+    Assert::equals('<h1>Test</h1>', $fixture->render('fixture', []));
+  }
+}