From 740d864e678ab0c5518780afd906e2123d8a9d79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tu=E1=BA=A5n-Anh=20Nguy=E1=BB=85n?= <ubolonton@gmail.com>
Date: Sun, 19 Jul 2020 12:40:17 +0700
Subject: [PATCH] Add '.' as a valid start of a predicate, in addition to '#'

See https://github.com/ubolonton/emacs-tree-sitter/issues/38
---
 cli/src/tests/query_test.rs | 29 +++++++++++++++++++++++++++++
 lib/src/query.c             |  4 ++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/cli/src/tests/query_test.rs b/cli/src/tests/query_test.rs
index 06ecc42e..493bea8a 100644
--- a/cli/src/tests/query_test.rs
+++ b/cli/src/tests/query_test.rs
@@ -2087,6 +2087,35 @@ fn test_query_disable_pattern() {
     });
 }
 
+#[test]
+fn test_query_alternative_predicate_prefix() {
+    allocations::record(|| {
+        let language = get_language("c");
+        let query = Query::new(language, r#"
+            ((call_expression
+              function: (identifier) @keyword
+              arguments: (argument_list
+                          (string_literal) @function))
+             (.eq? @keyword "DEFUN"))
+        "#).unwrap();
+        let source = r#"
+            DEFUN ("identity", Fidentity, Sidentity, 1, 1, 0,
+                   doc: /* Return the argument unchanged.  */
+                   attributes: const)
+              (Lisp_Object arg)
+            {
+              return arg;
+            }
+        "#;
+        assert_query_matches(
+            language,
+            &query,
+            source,
+            &[(0, vec![("keyword", "DEFUN"), ("function", "\"identity\"")])],
+        );
+    });
+}
+
 fn assert_query_matches(
     language: Language,
     query: &Query,
diff --git a/lib/src/query.c b/lib/src/query.c
index b95ba057..acce2c72 100644
--- a/lib/src/query.c
+++ b/lib/src/query.c
@@ -805,8 +805,8 @@ static TSQueryError ts_query__parse_pattern(
       }
     }
 
-    // A pound character indicates the start of a predicate.
-    else if (stream->next == '#') {
+    // A dot/pound character indicates the start of a predicate.
+    else if (stream->next == '.' || stream->next == '#') {
       stream_advance(stream);
       return ts_query__parse_predicate(self, stream);
     }