From 686c1fb522761d8ae2573560ca52297226e0b7da Mon Sep 17 00:00:00 2001
From: Yuya Nishihara <yuya@tcha.org>
Date: Tue, 7 Feb 2023 18:33:26 +0900
Subject: [PATCH] templater: allow trailing comma

While rewriting the default log template, I find it's annoying that I have
to remove "," from the last line.
---
 src/commands/mod.rs    |  2 +-
 src/template.pest      |  2 +-
 src/template_parser.rs | 18 ++++++++++++++++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/commands/mod.rs b/src/commands/mod.rs
index 6b67b7c4d..660ffc30f 100644
--- a/src/commands/mod.rs
+++ b/src/commands/mod.rs
@@ -1449,7 +1449,7 @@ fn log_template(settings: &UserSettings) -> String {
                 working_copies,
                 git_head,
                 commit_id.{prefix_format},
-                if(conflict, label("conflict", "conflict"))
+                if(conflict, label("conflict", "conflict")),
               )
               "\n"
               if(empty, label("empty", "(empty)") " ")
diff --git a/src/template.pest b/src/template.pest
index 1d0c82d7c..a18e3d2c5 100644
--- a/src/template.pest
+++ b/src/template.pest
@@ -33,7 +33,7 @@ identifier = @{ (ASCII_ALPHA | "_") ~ (ASCII_ALPHANUMERIC | "_")* }
 
 function = { identifier ~ "(" ~ function_arguments ~ ")" }
 function_arguments = {
-  template ~ ("," ~ template)*
+  template ~ ("," ~ template)* ~ ("," ~ whitespace*)?
   | whitespace*
 }
 
diff --git a/src/template_parser.rs b/src/template_parser.rs
index 3d0ebcf52..466f3fe05 100644
--- a/src/template_parser.rs
+++ b/src/template_parser.rs
@@ -789,6 +789,24 @@ mod tests {
         })
     }
 
+    #[test]
+    fn test_function_call_syntax() {
+        // Trailing comma isn't allowed for empty argument
+        assert!(parse(r#" "".first_line() "#).is_ok());
+        assert!(parse(r#" "".first_line(,) "#).is_err());
+
+        // Trailing comma is allowed for the last argument
+        assert!(parse(r#" "".contains("") "#).is_ok());
+        assert!(parse(r#" "".contains("",) "#).is_ok());
+        assert!(parse(r#" "".contains("" ,  ) "#).is_ok());
+        assert!(parse(r#" "".contains(,"") "#).is_err());
+        assert!(parse(r#" "".contains("",,) "#).is_err());
+        assert!(parse(r#" "".contains("" , , ) "#).is_err());
+        assert!(parse(r#" label("","") "#).is_ok());
+        assert!(parse(r#" label("","",) "#).is_ok());
+        assert!(parse(r#" label("",,"") "#).is_err());
+    }
+
     #[test]
     fn test_integer_literal() {
         let extract = |x: Expression<()>| x.try_into_integer().unwrap().extract(&());