Rereorganize grammar for better feedback

notcl.js

@@ -10,9 +10,11 @@ var Notcl = (() => {
 
   const InterCommandWhitespace = Regex(/\s+/y).expects("whitespace");
 
-  const Comment = Regex(/#[^\n]*/y).expects("#");
+  const Comment = Regex(/#[^\n]*/y)
+    .expects("#")
+    .map(() => []);
 
-  const PreCommand = AtLeast(0, Choose(InterCommandWhitespace, Comment));
+  const PreCommand = AtLeast(0, InterCommandWhitespace);
 
   const PreWordWhitespace = Regex(/[^\S\n;]+/y).expects("whitespace");
 
@@ -28,8 +30,12 @@ var Notcl = (() => {
     AtLeast(
       0,
       Choose(
-        Use(() => Brace).map((text) => `{${text}}`),
-        Regex(/[^{}]+/y).map(([text]) => text)
+        Use(() => Brace)
+          .expects("{")
+          .map((text) => `{${text}}`),
+        Regex(/[^{}]+/y)
+          .expects("text")
+          .map(([text]) => text)
       )
     ),
     Regex(/\}/y).expects("}")
@@ -40,7 +46,9 @@ var Notcl = (() => {
     Brace.map((text) => ({ text }))
   );
 
-  const CommandTerminator = Regex(/[\n;]/y).expects("NEWLINE | ;");
+  const CommandTerminator = Regex(/[\n;]/y)
+    .expects("NEWLINE | ;")
+    .map(() => true);
 
   /** @type {Peg.Pattern<Notcl.Command>} */
   const Command = Sequence(
@@ -54,17 +62,19 @@ var Notcl = (() => {
 
   /** @type {Peg.Pattern<Notcl.Script>} */
   const Script = Sequence(
-    PreCommand,
-    AtLeast(0, Command),
     AtLeast(
       0,
-      Sequence(CommandTerminator, PreCommand, Command).map(
-        ([, , command]) => command
+      Choose(
+        PreWordWhitespace.map(() => []),
+        CommandTerminator.map(() => []),
+        Sequence(Comment, Choose(CommandTerminator, End())).map(() => []),
+        Sequence(Command, Choose(CommandTerminator, End())).map(
+          ([words]) => words
+        )
       )
     ),
-    AtLeast(0, PreCommand),
     End()
-  ).map(([, command, moreCommands]) => command.concat(moreCommands));
+  ).map(([commands]) => commands.filter((command) => command.length > 0));
 
   const ERROR_CONTEXT = /(?<=([^\n]{0,50}))([^\n]{0,50})/y;