templater: relax whitespace requirement by leveraging implicit whitespace rule

This means `f ()`, `x . f()`, etc. are now allowed. Before, `x\n.f()` was syntax
error, which seemed unintuitive in multi-line expression.

This also means that whitespace around alias declaration is ignored.
tempalte-aliases.' foo ' is identical to tempalte-aliases.foo.

https://pest.rs/book/grammars/syntax.html#implicit-whitespace

Closes #7378

Author: yuja

CHANGELOG.md

@@ -73,6 +73,8 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 * `jj file show` now accepts `-T`/`--template` option to insert file metadata.
 
+* The template language now allows arbitrary whitespace between any operators.
+
 * The new configuration option `git.colocate=boolean` controls whether or not
   Git repositories are colocated by default.
 

cli/src/template.pest

@@ -20,7 +20,7 @@
 // If making significant changes to this grammar, consider also updating the
 // tree-sitter grammar: https://github.com/bryceberger/tree-sitter-jjtemplate
 
-whitespace = _{ " " | "\t" | "\r" | "\n" | "\x0c" }
+WHITESPACE = _{ " " | "\t" | "\r" | "\n" | "\x0c" }
 
 string_escape = @{
   "\\"
@@ -73,24 +73,23 @@ infix_ops = _{
   | rem_op
 }
 
-function = { identifier ~ "(" ~ whitespace* ~ function_arguments ~ whitespace* ~ ")" }
-keyword_argument = { identifier ~ whitespace* ~ "=" ~ whitespace* ~ template }
+function = { identifier ~ "(" ~ function_arguments ~ ")" }
+keyword_argument = { identifier ~ "=" ~ template }
 argument = _{ keyword_argument | template }
 function_arguments = {
-  argument ~ (whitespace* ~ "," ~ whitespace* ~ argument)* ~ (whitespace* ~ ",")?
+  argument ~ ("," ~ argument)* ~ ","?
   | ""
 }
 lambda = {
-  "|" ~ whitespace* ~ formal_parameters ~ whitespace* ~ "|"
-  ~ whitespace* ~ template
+  "|" ~ formal_parameters ~ "|" ~ template
 }
 formal_parameters = {
-  identifier ~ (whitespace* ~ "," ~ whitespace* ~ identifier)* ~ (whitespace* ~ ",")?
+  identifier ~ ("," ~ identifier)* ~ ","?
   | ""
 }
 
 primary = _{
-  ("(" ~ whitespace* ~ template ~ whitespace* ~ ")")
+  ("(" ~ template ~ ")")
   | function
   | lambda
   | identifier
@@ -104,18 +103,17 @@ term = {
 }
 
 expression = {
-  (prefix_ops ~ whitespace*)* ~ term
-  ~ (whitespace* ~ infix_ops ~ whitespace* ~ (prefix_ops ~ whitespace*)* ~ term)*
+  prefix_ops* ~ term ~ (infix_ops ~ prefix_ops* ~ term)*
 }
 
 template = {
-  expression ~ (whitespace* ~ concat_op ~ whitespace* ~ expression)*
+  expression ~ (concat_op ~ expression)*
 }
 
-program = _{ SOI ~ whitespace* ~ template? ~ whitespace* ~ EOI }
+program = _{ SOI ~ template? ~ EOI }
 
 function_alias_declaration = {
-  identifier ~ "(" ~ whitespace* ~ formal_parameters ~ whitespace* ~ ")"
+  identifier ~ "(" ~ formal_parameters ~ ")"
 }
 alias_declaration = _{
   SOI ~ (function_alias_declaration | identifier) ~ EOI

cli/src/template_builder.rs

@@ -2295,6 +2295,9 @@ mod tests {
 
         // Parenthesized method chaining
         insta::assert_snapshot!(env.render_ok(r#"(hello).upper()"#), @"HELLO");
+
+        // Multi-line method chaining
+        insta::assert_snapshot!(env.render_ok("hello\n  .upper()"), @"HELLO");
     }
 
     #[test]
@@ -2303,11 +2306,11 @@ mod tests {
         env.add_keyword("description", || literal("".to_owned()));
         env.add_keyword("empty", || literal(true));
 
-        insta::assert_snapshot!(env.parse_err(r#"description ()"#), @r"
-         --> 1:13
+        insta::assert_snapshot!(env.parse_err(r#"foo bar"#), @r"
+         --> 1:5
           |
-        1 | description ()
-          |             ^---
+        1 | foo bar
+          |     ^---
           |
           = expected <EOI>, `++`, `||`, `&&`, `==`, `!=`, `>=`, `>`, `<=`, `<`, `+`, `-`, `*`, `/`, or `%`
         ");

cli/src/template_parser.rs

@@ -62,7 +62,7 @@ impl Rule {
     fn to_symbol(self) -> Option<&'static str> {
         match self {
             Self::EOI => None,
-            Self::whitespace => None,
+            Self::WHITESPACE => None,
             Self::string_escape => None,
             Self::string_content_char => None,
             Self::string_content => None,
@@ -1076,6 +1076,16 @@ mod tests {
 
     #[test]
     fn test_string_literal() {
+        // Whitespace in string literal should be preserved
+        assert_eq!(
+            parse_into_kind(r#" " " "#),
+            Ok(ExpressionKind::String(" ".to_owned())),
+        );
+        assert_eq!(
+            parse_into_kind(r#" ' ' "#),
+            Ok(ExpressionKind::String(" ".to_owned())),
+        );
+
         // "\<char>" escapes
         assert_eq!(
             parse_into_kind(r#" "\t\r\n\"\\\0\e" "#),

cli/tests/test_templater.rs

@@ -23,19 +23,6 @@ fn test_templater_parse_error() {
     let work_dir = test_env.work_dir("repo");
     let render = |template| get_template_output(&work_dir, "@-", template);
 
-    insta::assert_snapshot!(render(r#"description ()"#), @r"
-    ------- stderr -------
-    Error: Failed to parse template: Syntax error
-    Caused by:  --> 1:13
-      |
-    1 | description ()
-      |             ^---
-      |
-      = expected <EOI>, `++`, `||`, `&&`, `==`, `!=`, `>=`, `>`, `<=`, `<`, `+`, `-`, `*`, `/`, or `%`
-    [EOF]
-    [exit status: 1]
-    ");
-
     // Typo
     test_env.add_config(
         r###"