1 files changed, 87 insertions, 0 deletions
diff --git a/src/urubu/spec/tree.vartan b/src/urubu/spec/tree.vartan
new file mode 100644
index 0000000..aa8f733
--- /dev/null
+++ b/src/urubu/spec/tree.vartan
@@ -0,0 +1,87 @@
+#name tree;
+
+#prec (
+	#assign l_paren
+	#assign $empty_tree
+);
+
+tree
+	: l_paren identifier tree_list r_paren #ast identifier tree_list...
+	| l_paren identifier string r_paren    #ast identifier string
+	| l_paren error r_paren                #recover #ast error
+	;
+tree_list
+	: tree_list tree #ast tree_list... tree
+	| tree
+	|                #prec $empty_tree
+	;
+string
+	: raw_string
+	| interpreted_string
+	;
+raw_string
+	: raw_string_open opt_raw_string_body raw_string_close #ast opt_raw_string_body...
+	;
+opt_raw_string_body
+	: raw_string_body
+	|
+	;
+interpreted_string
+	: interpreted_string_open opt_interpreted_string_body interpreted_string_close #ast opt_interpreted_string_body...
+	| interpreted_string_open error interpreted_string_close #recover #ast error
+	;
+opt_interpreted_string_body
+	: interpreted_string_body #ast interpreted_string_body...
+	|
+	;
+interpreted_string_body
+	: interpreted_string_body interpreted_string_elem #ast interpreted_string_body... interpreted_string_elem...
+	| interpreted_string_elem                         #ast interpreted_string_elem...
+	;
+interpreted_string_elem
+	: interpreted_seq
+	| l_brace
+	| r_brace
+	| hex_digits
+	| escaped_seq
+	| escape_char
+	| codepoint_expr
+	;
+codepoint_expr
+	: codepoint_prefix l_brace hex_digits r_brace #ast hex_digits
+	;
+
+ws #skip
+	: "[\u{0009}\u{000A}\u{000D}\u{0020}]+";
+l_paren
+	: '(';
+r_paren
+	: ')';
+identifier
+	: "[0-9A-Za-z_]+";
+
+raw_string_open #push raw_string
+	: "'";
+raw_string_body #mode raw_string
+	: "[^']+";
+raw_string_close #mode raw_string #pop
+	: "'";
+
+interpreted_string_open #push interpreted_string
+	: '"';
+interpreted_seq #mode interpreted_string
+	: "[^\"\\{}0-9A-Fa-f]+";
+codepoint_prefix #mode interpreted_string
+	: '\u';
+l_brace #mode interpreted_string
+	: '{';
+r_brace #mode interpreted_string
+	: '}';
+hex_digits #mode interpreted_string
+	: "[0-9A-Fa-f]+";
+escaped_seq #mode interpreted_string
+	: "\\[\"\\]";
+escape_char #mode interpreted_string
+	: '\';
+interpreted_string_close #mode interpreted_string #pop
+	: '"';