tweak: Add code comment (#4722)

Author: max-sixty

prqlc/prqlc-parser/src/lexer/mod.rs

@@ -10,11 +10,6 @@ pub mod lr;
 #[cfg(test)]
 mod test;
 
-// TODO: we have `lex_source` and `lex_source_recovery` and don't have the same
-// structure for PR. Probably we should have a single approach to the inclusion
-// and naming of a function which returns both the tokens & errors, and a
-// function that returns both.
-
 /// Lex PRQL into LR, returning both the LR and any errors encountered
 pub fn lex_source_recovery(source: &str, source_id: u16) -> (Option<Vec<Token>>, Vec<Error>) {
     let (tokens, lex_errors) = lexer().parse_recovery(source);

prqlc/prqlc-parser/src/parser/mod.rs

@@ -14,13 +14,14 @@ pub(crate) mod stmt;
 mod test;
 mod types;
 
+// Note that `parse_source` is in `prqlc` crate, not in `prqlc-parser` crate,
+// because it logs using the logging framework in `prqlc`.
+
 pub fn parse_lr_to_pr(
     source: &str,
     source_id: u16,
     lr: Vec<lr::Token>,
 ) -> (Option<Vec<pr::Stmt>>, Vec<Error>) {
-    // We don't want comments in the AST (but we do intend to use them as part of
-    // formatting)
     let stream = prepare_stream(lr.into_iter(), source, source_id);
     let (pr, parse_errors) = stmt::source().parse_recovery(stream);
 

prqlc/prqlc/src/parser.rs

@@ -53,6 +53,10 @@ pub fn parse(file_tree: &SourceTree) -> Result<pr::ModuleDef, Errors> {
 }
 
 /// Build PR AST from a PRQL query string.
+// We have this function in `prqlc` rather than in `prqlc-parser` crate since
+// our logging is in `prqlc` and we want to log the LR. (We could split the logging
+// out into a separate crate, but it has dependencies on `prqlc` internals and
+// would be an effort)
 pub(crate) fn parse_source(source: &str, source_id: u16) -> Result<Vec<pr::Stmt>, Vec<Error>> {
     let (tokens, mut errors) = prqlc_parser::lexer::lex_source_recovery(source, source_id);