feat: add eq / in processors and make WhenRenderer whitespace-tolerant (#31)

blocks/_shared/processor-suggestions.js

@@ -44,6 +44,18 @@ const PROCESSORS = [
 		takesArg: true,
 		argHint: '99',
 	},
+	{
+		name: 'eq',
+		label: __( 'eq — keep value when it equals the argument, else empty', 'feedwright' ),
+		takesArg: true,
+		argHint: 'trash',
+	},
+	{
+		name: 'in',
+		label: __( 'in — keep value when it appears in the comma-separated list, else empty', 'feedwright' ),
+		takesArg: true,
+		argHint: 'trash,draft',
+	},
 ];
 
 /**

docs/requirements.md

@@ -1254,7 +1254,9 @@ public function render( array $block, Context $ctx ): array {
     $negate     = ! empty( $block['attrs']['negate'] );
 
     $value = '' === $expression ? '' : $this->resolver->resolve( $expression, $ctx );
-    $gate  = '' !== $value;
+    // Whitespace-only counts as empty so a stray trailing space doesn't
+    // flip the gate to always-true.
+    $gate  = '' !== trim( $value );
     if ( $negate ) $gate = ! $gate;
 
     if ( ! $gate ) return [];
@@ -1269,7 +1271,7 @@ public function render( array $block, Context $ctx ): array {
 }
 ```
 
-The "non-empty string" truthiness rule is intentional and works well with the existing processor chain — `map`, `default`, `first` all produce strings. For more elaborate predicates (numeric comparisons etc.), users compose them via processors rather than introducing a new condition DSL.
+The "non-empty string" truthiness rule is intentional and works well with the existing processor chain — `map`, `default`, `first`, `eq`, `in` all produce strings. For more elaborate predicates (numeric comparisons etc.), users compose them via processors rather than introducing a new condition DSL. The check uses `trim()` so whitespace-only output is treated as empty (a common typo class — trailing space on the expression).
 
 `feedwright/when` does not switch context; it inherits the current item / sub-item / channel scope from its position in the block tree. Item-level expressions inside a channel-scoped `when` will resolve to empty because there is no current post — that is the correct degraded behavior, not an error.
 
@@ -1597,6 +1599,8 @@ You can append `|name:arg` to the end of a binding to apply transforms to the re
 | `map` | `key=val,*=fallback` | If the input matches `key`, return that line's `val`. `*` is the fallback if no key matches. If neither matches nor `*` exists, returns empty string. The first `=` separates key and val, so `=` may appear in val. Useful for conditionals such as mapping `post_status` to a numeric `<media:status>` flag (publish=1 / removed=0): `{{post_raw.post_status\|map:publish=1,*=0}}` |
 | `first` | separator (default `, `) | Returns the first segment of a separator-joined string. Pairs naturally with `post_term.{taxonomy}` (which joins multi-term posts with `", "`) before piping into `map`. Example: `{{post_term.category\|first\|map:Tech=10,News=20}}`. The separator argument cannot contain `\|` (pipe-syntax conflict) or `}`; to split on `\|`, change the upstream binding to emit a different separator via its modifier first |
 | `default` | replacement value | Returns the literal argument when the input is the empty string; otherwise passes the input through unchanged. Differs from `map`'s `*` in that it triggers only on empty input — `"0"` and other falsy-looking strings pass through. Idiomatic with `post_term_meta`: `{{post_term_meta.category._mediba_category_id\|default:99}}` |
+| `eq` | comparison value | Equality gate: returns the input unchanged when it equals the argument, empty string otherwise. Argument is trimmed. Composes naturally with `feedwright/when` (which treats non-empty as truthy). Example: `{{post_raw.post_status\|eq:trash}}` |
+| `in` | comma-separated list | Multi-value equality gate: returns the input when it appears in the list, empty string otherwise. Each list entry is trimmed. Example: `{{post_raw.post_status\|in:trash,draft}}` |
 
 Unknown processor names log a warning and pass the input through unchanged.
 

languages/feedwright-ja-093f72868b125390d00428ed7df28073.json

@@ -27,6 +27,12 @@
             ],
             "default \u2014 replace empty input with a literal value": [
                 "default \u2014 \u5165\u529b\u304c\u7a7a\u306e\u3068\u304d\u306b literal \u3067\u5024\u3092\u7f6e\u304d\u63db\u3048\u308b"
+            ],
+            "eq \u2014 keep value when it equals the argument, else empty": [
+                "eq \u2014 \u5f15\u6570\u3068\u4e00\u81f4\u3059\u308b\u3068\u304d\u3060\u3051\u5024\u3092\u6b8b\u3059\u3001\u9055\u3048\u3070\u7a7a"
+            ],
+            "in \u2014 keep value when it appears in the comma-separated list, else empty": [
+                "in \u2014 \u30ab\u30f3\u30de\u533a\u5207\u308a\u30ea\u30b9\u30c8\u306e\u3044\u305a\u308c\u304b\u3068\u4e00\u81f4\u3059\u308b\u3068\u304d\u3060\u3051\u5024\u3092\u6b8b\u3059\u3001\u9055\u3048\u3070\u7a7a"
             ]
         }
     }

languages/feedwright-ja.po

@@ -1051,3 +1051,11 @@ msgstr "条件"
 msgctxt "block keyword"
 msgid "filter"
 msgstr "フィルタ"
+
+#: blocks/_shared/processor-suggestions.js:49
+msgid "eq — keep value when it equals the argument, else empty"
+msgstr "eq — 引数と一致するときだけ値を残す、違えば空"
+
+#: blocks/_shared/processor-suggestions.js:55
+msgid "in — keep value when it appears in the comma-separated list, else empty"
+msgstr "in — カンマ区切りリストのいずれかと一致するときだけ値を残す、違えば空"

languages/feedwright.pot

@@ -9,7 +9,7 @@ msgstr ""
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
-"POT-Creation-Date: 2026-04-28T10:39:48+00:00\n"
+"POT-Creation-Date: 2026-04-28T10:55:40+00:00\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "X-Generator: WP-CLI 2.12.0\n"
 "X-Domain: feedwright\n"
@@ -820,6 +820,14 @@ msgstr ""
 msgid "default — replace empty input with a literal value"
 msgstr ""
 
+#: blocks/_shared/processor-suggestions.js:49
+msgid "eq — keep value when it equals the argument, else empty"
+msgstr ""
+
+#: blocks/_shared/processor-suggestions.js:55
+msgid "in — keep value when it appears in the comma-separated list, else empty"
+msgstr ""
+
 #: blocks/channel/block.json
 msgctxt "block title"
 msgid "<channel>"

src/Bindings/Resolver.php

@@ -46,6 +46,8 @@ public function __construct() {
 			'map'        => array( self::class, 'process_map' ),
 			'first'      => array( self::class, 'process_first' ),
 			'default'    => array( self::class, 'process_default' ),
+			'eq'         => array( self::class, 'process_eq' ),
+			'in'         => array( self::class, 'process_in' ),
 		);
 
 		if ( function_exists( 'apply_filters' ) ) {
@@ -248,6 +250,42 @@ public static function process_first( string $value, string $arg ): string {
 		return false === $pos ? $value : substr( $value, 0, $pos );
 	}
 
+	/**
+	 * Equality gate: return the input unchanged when it equals the argument,
+	 * empty string otherwise. Combines naturally with `feedwright/when`,
+	 * which treats any non-empty value as a truthy gate.
+	 *
+	 * Argument leading / trailing whitespace is trimmed (parity with `map`).
+	 *
+	 * Example:
+	 *   {{post_raw.post_status|eq:trash}}  -> "trash" when status is trash, else ""
+	 *
+	 * @param string $value Input value.
+	 * @param string $arg   Value to compare against.
+	 */
+	public static function process_eq( string $value, string $arg ): string {
+		return trim( $arg ) === $value ? $value : '';
+	}
+
+	/**
+	 * Multi-value equality gate: return the input unchanged when it appears
+	 * in the comma-separated argument list, empty string otherwise. Each list
+	 * entry is trimmed.
+	 *
+	 * Example:
+	 *   {{post_raw.post_status|in:trash,draft}}  -> "trash" or "draft", else ""
+	 *
+	 * @param string $value Input value.
+	 * @param string $arg   Comma-separated list of accepted values.
+	 */
+	public static function process_in( string $value, string $arg ): string {
+		if ( '' === $arg ) {
+			return '';
+		}
+		$candidates = array_map( 'trim', explode( ',', $arg ) );
+		return in_array( $value, $candidates, true ) ? $value : '';
+	}
+
 	/**
 	 * Replace an empty string input with the literal argument.
 	 *

src/Renderer/WhenRenderer.php

@@ -63,8 +63,10 @@ public function render( array $block, Context $ctx ): array {
 		$expression = (string) ( $attrs['expression'] ?? '' );
 		$negate     = ! empty( $attrs['negate'] );
 
-		$value     = '' === $expression ? '' : $this->resolver->resolve( $expression, $ctx );
-		$matches   = '' !== $value;
+		$value = '' === $expression ? '' : $this->resolver->resolve( $expression, $ctx );
+		// Whitespace-only resolution counts as empty: a stray trailing space
+		// in the expression must not flip the gate to always-true.
+		$matches   = '' !== trim( $value );
 		$gate_open = $negate ? ! $matches : $matches;
 
 		if ( ! $gate_open ) {

tests/Integration/RenderTest.php

@@ -942,6 +942,52 @@ public function test_when_block_works_at_channel_scope(): void {
 		$this->assertStringContainsString( '<hint>channel-only</hint>', $xml );
 	}
 
+	public function test_when_block_treats_whitespace_only_value_as_empty(): void {
+		// Stray trailing space in the expression used to flip the gate to
+		// always-true: '{{...|eq:trash}} ' resolved to ' ' (a space) for
+		// non-trash posts, which was non-empty. Ensure trim() makes it empty.
+		self::factory()->post->create( array( 'post_status' => 'publish', 'post_title' => 'Live Post' ) );
+
+		$inner      = '<!-- wp:feedwright/element {"tagName":"deleted","contentMode":"empty"} /-->';
+		$when_attrs = wp_json_encode(
+			// Expression resolves to "" + " " for publish; whitespace-only.
+			array( 'expression' => '{{post_raw.post_status|eq:trash}} ' )
+		);
+		$content = '<!-- wp:feedwright/rss --><!-- wp:feedwright/channel -->'
+			. '<!-- wp:feedwright/item-query {"postsPerPage":1} --><!-- wp:feedwright/item -->'
+			. "<!-- wp:feedwright/when {$when_attrs} -->{$inner}<!-- /wp:feedwright/when -->"
+			. '<!-- /wp:feedwright/item --><!-- /wp:feedwright/item-query -->'
+			. '<!-- /wp:feedwright/channel --><!-- /wp:feedwright/rss -->';
+
+		$feed_post = $this->make_feed_post( $content );
+		$xml       = ( new Renderer( Plugin::build_resolver() ) )->render( $feed_post )['xml'];
+
+		$this->assertStringNotContainsString( '<deleted/>', $xml );
+	}
+
+	public function test_when_block_uses_eq_processor_for_status_match(): void {
+		// Sanity: the recommended idiom `{{post_raw.post_status|eq:trash}}`
+		// gates correctly on a single trashed post amid live ones.
+		self::factory()->post->create( array( 'post_status' => 'publish', 'post_title' => 'Live' ) );
+		$dead = self::factory()->post->create( array( 'post_status' => 'publish', 'post_title' => 'Dead' ) );
+		wp_trash_post( $dead );
+
+		$inner      = '<!-- wp:feedwright/element {"tagName":"deleted","contentMode":"empty"} /-->';
+		$when_attrs = wp_json_encode( array( 'expression' => '{{post_raw.post_status|eq:trash}}' ) );
+		$query_attrs = wp_json_encode( array( 'postsPerPage' => 10, 'postStatus' => array( 'publish', 'trash' ) ) );
+		$content     = '<!-- wp:feedwright/rss --><!-- wp:feedwright/channel -->'
+			. "<!-- wp:feedwright/item-query {$query_attrs} --><!-- wp:feedwright/item -->"
+			. "<!-- wp:feedwright/when {$when_attrs} -->{$inner}<!-- /wp:feedwright/when -->"
+			. '<!-- /wp:feedwright/item --><!-- /wp:feedwright/item-query -->'
+			. '<!-- /wp:feedwright/channel --><!-- /wp:feedwright/rss -->';
+
+		$feed_post = $this->make_feed_post( $content );
+		$xml       = ( new Renderer( Plugin::build_resolver() ) )->render( $feed_post )['xml'];
+
+		// Exactly one <deleted/> for the trashed post; live post gets none.
+		$this->assertSame( 1, substr_count( $xml, '<deleted/>' ) );
+	}
+
 	public function test_when_blocks_can_nest(): void {
 		self::factory()->post->create( array( 'post_status' => 'publish', 'post_title' => 'Nested' ) );
 

tests/Unit/BindingResolverTest.php

@@ -270,4 +270,46 @@ public function test_chain_falls_through_to_default_when_map_missing(): void {
 			$r->resolve( '{{foo.k|first|map:お役立ち=91,芸能=92|default:99}}', $this->ctx() )
 		);
 	}
+
+	public function test_eq_processor_returns_value_when_equal(): void {
+		$r = new Resolver();
+		$r->add( new FakeProvider( 'foo', array( 'k' => 'trash' ) ) );
+		$this->assertSame( 'trash', $r->resolve( '{{foo.k|eq:trash}}', $this->ctx() ) );
+	}
+
+	public function test_eq_processor_returns_empty_when_not_equal(): void {
+		$r = new Resolver();
+		$r->add( new FakeProvider( 'foo', array( 'k' => 'publish' ) ) );
+		$this->assertSame( '', $r->resolve( '{{foo.k|eq:trash}}', $this->ctx() ) );
+	}
+
+	public function test_eq_processor_trims_argument_whitespace(): void {
+		$r = new Resolver();
+		$r->add( new FakeProvider( 'foo', array( 'k' => 'trash' ) ) );
+		$this->assertSame( 'trash', $r->resolve( '{{foo.k|eq: trash }}', $this->ctx() ) );
+	}
+
+	public function test_in_processor_returns_value_when_in_list(): void {
+		$r = new Resolver();
+		$r->add( new FakeProvider( 'foo', array( 'k' => 'draft' ) ) );
+		$this->assertSame( 'draft', $r->resolve( '{{foo.k|in:trash,draft,pending}}', $this->ctx() ) );
+	}
+
+	public function test_in_processor_returns_empty_when_not_in_list(): void {
+		$r = new Resolver();
+		$r->add( new FakeProvider( 'foo', array( 'k' => 'publish' ) ) );
+		$this->assertSame( '', $r->resolve( '{{foo.k|in:trash,draft}}', $this->ctx() ) );
+	}
+
+	public function test_in_processor_trims_each_list_entry(): void {
+		$r = new Resolver();
+		$r->add( new FakeProvider( 'foo', array( 'k' => 'draft' ) ) );
+		$this->assertSame( 'draft', $r->resolve( '{{foo.k|in: trash , draft , pending }}', $this->ctx() ) );
+	}
+
+	public function test_in_processor_with_empty_list_returns_empty(): void {
+		$r = new Resolver();
+		$r->add( new FakeProvider( 'foo', array( 'k' => 'anything' ) ) );
+		$this->assertSame( '', $r->resolve( '{{foo.k|in:}}', $this->ctx() ) );
+	}
 }