Add basic wp-bind code

phpunit/directives/wp-bind.php

@@ -0,0 +1,33 @@
+<?php
+/**
+ * wp-bind directive test.
+ */
+
+require_once __DIR__ . '/../../src/directives/wp-bind.php';
+
+require_once __DIR__ . '/../../src/html/index.php';
+
+/**
+ * Tests for the wp-bind directive.
+ *
+ * @group  directives
+ * @covers process_wp_bind
+ */
+class Tests_Directives_WpBind extends WP_UnitTestCase {
+	public function test_directive() {
+		$markup = '<img wp-bind:src="context.myblock.imageSource" />';
+		$tags = new WP_HTML_Processor( $markup );
+		$tags->next_tag();
+
+		$context_before = array( 'myblock' => array( 'imageSource' => './wordpress.png' ) );
+		$context = $context_before;
+		process_wp_bind( $tags, $context );
+
+		$this->assertSame(
+			'<img src="./wordpress.png" wp-bind:src="context.myblock.imageSource" />',
+			$tags->get_updated_html()
+		);
+		// $this->assertSame( './wordpress.png', $tags->get_attribute( 'src' ) ); // FIXME: Doesn't currently work.
+		$this->assertSame( $context_before, $context, 'wp-bind directive changed context' );
+	}
+}

src/directives/wp-bind.php

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+<?php
+
+require_once __DIR__ . '/utils.php';
+
+function process_wp_bind( &$tags, &$context ) {
+	$prefixed_attributes = $tags->get_attributes_by_prefix( 'wp-bind:' );
+
+	foreach( $prefixed_attributes as $name => $expr ) {
+		$attr_parts = explode( ':', $name );
+		if ( count( $attr_parts ) < 2 ) {
+			continue;
+		}
+		$bound_attr = $attr_parts[1];
+
+		// TODO: Properly parse $value.
+		$value = get_from_context( $expr, $context );
+		$tags->set_attribute( $bound_attr, $value );
+	}
+}