parser comments

Author: jbclements

src/libsyntax/parse/classify.rs

@@ -15,6 +15,13 @@
 use ast;
 use codemap;
 
+// does this expression require a semicolon to be treated
+// as a statement? The negation of this: 'can this expression
+// be used as a statement without a semicolon' -- is used
+// as an early-bail-out in the parser so that, for instance,
+// 'if true {...} else {...}
+//  |x| 5 '
+// isn't parsed as (if true {...} else {...} | x) | 5
 pub fn expr_requires_semi_to_be_stmt(e: @ast::expr) -> bool {
     match e.node {
       ast::expr_if(*)
@@ -40,6 +47,9 @@ pub fn expr_is_simple_block(e: @ast::expr) -> bool {
     }
 }
 
+// this statement requires a semicolon after it.
+// note that in one case (stmt_semi), we've already
+// seen the semicolon, and thus don't need another.
 pub fn stmt_ends_with_semi(stmt: &ast::stmt) -> bool {
     return match stmt.node {
         ast::stmt_decl(d, _) => {

src/libsyntax/parse/comments.rs

@@ -309,6 +309,8 @@ pub struct lit {
     pos: BytePos
 }
 
+// it appears this function is called only from pprust... that's
+// probably not a good thing.
 pub fn gather_comments_and_literals(span_diagnostic:
                                     @diagnostic::span_handler,
                                     path: ~str,

src/libsyntax/parse/lexer.rs

@@ -286,6 +286,8 @@ fn consume_any_line_comment(rdr: @mut StringReader)
         }
     } else if rdr.curr == '#' {
         if nextch(rdr) == '!' {
+            // I guess this is the only way to figure out if
+            // we're at the beginning of the file...
             let cmap = @CodeMap::new();
             (*cmap).files.push(rdr.filemap);
             let loc = cmap.lookup_char_pos_adj(rdr.last_pos);