templater: extract stub function that resolves method name

We'll probably add "Did you mean?" hint there.

cli/src/commit_templater.rs

@@ -71,12 +71,9 @@ impl<'repo> TemplateLanguage<'repo> for CommitTemplateLanguage<'repo> {
                 template_builder::build_core_method(self, build_ctx, property, function)
             }
             CommitTemplatePropertyKind::Commit(property) => {
-                // TODO: add name resolution helper that provides typo hint
-                if let Some(build) = self.build_fn_table.commit_methods.get(function.name) {
-                    build(self, build_ctx, property, function)
-                } else {
-                    Err(TemplateParseError::no_such_method("Commit", function))
-                }
+                let table = &self.build_fn_table.commit_methods;
+                let build = template_parser::lookup_method("Commit", table, function)?;
+                build(self, build_ctx, property, function)
             }
             CommitTemplatePropertyKind::CommitList(property) => {
                 template_builder::build_unformattable_list_method(

cli/src/template_parser.rs

@@ -855,6 +855,20 @@ pub fn expect_lambda_with<'a, 'i, T>(
     }
 }
 
+/// Looks up `table` by the given method name.
+pub fn lookup_method<'a, V>(
+    type_name: impl Into<String>,
+    table: &'a HashMap<&str, V>,
+    function: &FunctionCallNode,
+) -> TemplateParseResult<&'a V> {
+    if let Some(value) = table.get(function.name) {
+        Ok(value)
+    } else {
+        // TODO: provide typo hint
+        Err(TemplateParseError::no_such_method(type_name, function))
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use assert_matches::assert_matches;