I've run syntax-cli and keep getting a error on the most simple parsing

user_11476714 0
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I've downloaded syntax-cli and ran the following command and get errors, could someone help?

npm install -g syntax-cli

I created a file call letter.bnf with the following content:

%lex

%%

\s+     /* do nothing */
\d+     return 'NUMBER'

/lex

%%

E
    : E '+' t
    | t
    ;

T
    : T '*' F
    | F
    ;
F
    : NUMBER
    ;

I then ran the command as follows:

syntax-cli --grammar letter.bnf --mode LALR1 --parse '2'

I keep getting the following error, what am I doing wrong?

Parsing mode: LALR1_BY_SLR(1).

Parsing:

2

SyntaxError:

2
^
Unexpected token: "2" at 1:0.
    at Tokenizer.throwUnexpectedToken (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/tokenizer.js:312:13)
    at LRParser._unexpectedToken (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/lr/lr-parser.js:224:23)
    at LRParser.parse (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/lr/lr-parser.js:163:16)
    at lrParse (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/bin/syntax.js:513:6)
    at parse (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/bin/syntax.js:488:45)
    at Object._genericLR (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/bin/syntax.js:372:7)
    at Object.LALR1_BY_SLR1 (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/bin/syntax.js:343:17)
    at Object.LALR1 (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/bin/syntax.js:340:17)
    at main (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/dist/bin/syntax.js:753:32)
    at Object.<anonymous> (/home/dancomp71/.nvm/versions/node/v16.16.0/lib/node_modules/syntax-cli/bin/syntax:5:30)

I've tried the command in a docker container, i've uploaded the code to my github, but I can't find the problem. I ran the command in wsl (windows/ubuntu) and in a ubuntu container with node, npm and syntax-cli installed.

bnf grammar compiler-construction
1 Answers

This probably has to do with using t instead of T in your rules for E.

I'm a little surprised that your parser generator didn't present you with an error or warning, since t is not defined anywhere, but perhaps the parser generator is designed to not require token declarations, in which case it would be hard to reliably detect the problem.

user_15662210
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