cannot parse words "start", "error", "atok" #3

#lang brag
foo   : "start"

.racket/6.12/pkgs/brag/brag/cfg-parser/cfg-parser.rkt:708:55: parser-non-terminals: start used as both token and non-terminal in: start

``` #lang brag foo : "start" ``` .racket/6.12/pkgs/brag/brag/cfg-parser/cfg-parser.rkt:708:55: parser-non-terminals: start used as both token and non-terminal in: start

I see what you mean. This is a bug in the underlying ragg code (which I didn’t write) so it will take me some time to figure it out. In the meantime, you can probably work around by specifying the rule like so?

#lang brag
foo : "star" "t"

I see what you mean. This is a bug in the underlying `ragg` code (which I didn’t write) so it will take me some time to figure it out. In the meantime, you can probably work around by specifying the rule like so? ```racket #lang brag foo : "star" "t" ```

Actually, that won’t work.

Here’s a better idea (this time I’m trying it before writing it). Instead of passing the raw string "start" (or "error" or "atok") as a token, edit your lexer to package each into a named token structure, e.g., (token 'START "start"). Then you can change the grammar to refer to this named token:

;; parse.rkt
#lang brag
foo   : START

This will parse the same way, and the underlying string will end up the parse tree:

#lang br
(require "parse.rkt" brag/support)
(parse-to-datum (list (token 'START "start")))

'(foo "start")

Actually, that won’t work. Here’s a better idea (this time I’m trying it before writing it). Instead of passing the raw string `"start"` (or `"error"` or `"atok"`) as a token, edit your lexer to package each into a named token structure, e.g., `(token 'START "start")`. Then you can change the grammar to refer to this named token: ``` ;; parse.rkt #lang brag foo : START ``` This will parse the same way, and the underlying string will end up the parse tree: ```racket #lang br (require "parse.rkt" brag/support) (parse-to-datum (list (token 'START "start"))) ``` ``` '(foo "start") ```

Note to self: check if this is an insurmountable restriction of the underlying cfg-parser function. If so, the only “fix” is to amend the docs with a list of reserved words.

Note to self: check if this is an insurmountable restriction of the underlying `cfg-parser` function. If so, the only “fix” is to amend the docs with a list of reserved words.

I was able to rehabilitate "start" and "atok" as literal tokens. But according to the br-parser-tools docs, “A token cannot be named error, since error it has special use in the parser.” I’ve also updated the brag docs to note this.

I was able to rehabilitate `"start"` and `"atok"` as literal tokens. But [according to the `br-parser-tools` docs]( https://docs.racket-lang.org/br-parser-tools/Lexers.html?q=cfg-parser#%28form._%28%28lib._br-parser-tools%2Flex..rkt%29._define-tokens%29%29), “A token cannot be named `error`, since `error` it has special use in the parser.” I’ve also updated the `brag` docs to note this.

Thanks for looking into this.

I git cloned the latest and tried cd brag ; raco pkg install but I got a lot of errors. If I cd brag and do raco test . i get some files running then brag/brag/brag.scrbl:6:21: cannot open module file module path: brag/support failure.

How should I test this latest commit?

raco setup: error: during making for <pkgs>/brag/brag/brag/test
raco setup:   brag/brag/test/test-parser.rkt:6:9: collection not found
raco setup:     for module path: brag/rules/parser
raco setup:     collection: "brag/rules"

standard-module-name-resolver: collection not found
  for module path: brag/rules/rule-structs
  collection: "brag/rules"
  in collection directories:
   /home/ivy/.racket/6.12/collects
   /usr/share/racket/collects

Thanks for looking into this. I git cloned the latest and tried cd brag ; raco pkg install but I got a lot of errors. If I cd brag and do raco test . i get some files running then `brag/brag/brag.scrbl:6:21: cannot open module file module path: brag/support` failure. How should I test this latest commit? -------------- ``` raco setup: error: during making for <pkgs>/brag/brag/brag/test raco setup: brag/brag/test/test-parser.rkt:6:9: collection not found raco setup: for module path: brag/rules/parser raco setup: collection: "brag/rules" standard-module-name-resolver: collection not found for module path: brag/rules/rule-structs collection: "brag/rules" in collection directories: /home/ivy/.racket/6.12/collects /usr/share/racket/collects ```

I’m not sure a direct git clone will work, because this repo holds a multi-collection package. Better to use raco pkg update brag.

I’m not sure a direct `git clone` will work, because this repo holds a multi-collection package. Better to use `raco pkg update brag`.

(BTW I can’t reproduce these errors locally, nor do they show up on Travis, which heightens my suspicion that the git clone technique is the problem)

(BTW I can’t reproduce these errors locally, nor do they show up on Travis, which heightens my suspicion that the `git clone` technique is the problem)

I tried raco pkg update brag but it got me the latest release from racket pkgs which seems to be before this latest git commit with the "start" fix.

I tried `raco pkg update brag` but it got me the latest release from racket pkgs which seems to be before this latest git commit with the "start" fix.

You can also do raco pkg install https://github.com/mbutterick/brag.git?path=brag if the package server isn’t going fast enough

You can also do `raco pkg install https://github.com/mbutterick/brag.git?path=brag` if the package server isn’t going fast enough

thanks a lot that worked, I see that I can use "start" now but not "%start".

OK, fixed that

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cannot parse words "start", "error", "atok" #3