Files
bison/examples/c/bistromathic
Akim Demaille cb9f4cb543 examples: fix handling of syntax errors
The shell grammar does not allow empty statements in then/else part of
an if, but examples/test failed to catch the syntax errors from the
script it ran.  So exited with success anyway.

You would expect 'set -e' to suffice, but with bash 3.2 actually it
does not.  As a matter of fact, I could find a way to have this behave
properly:

    $ cat test.sh
    set -e
    cleanup ()
    {
      status=$?
      echo "cleanup: $status"
      exit $status
    }
    trap cleanup 0 1 2 13 15
    . $1
    s=$?
    echo "test.sh: $s"
    exit $s

    $ cat bistro.test
    if true; then
    fi

    $ /bin/sh ./test.sh ./bistro.test
    ./bistro.test: line 2: syntax error near unexpected token `fi'
    cleanup: 0
    $ echo $?
    0

Remove the set -e (or the trap), and tada, it works...  So we have to
deal with the error by hand.

* examples/test ($exit): Replace with...
($status): this.
Preserve the exit status of the test case.
* examples/c/bistromathic/bistromathic.test: Fix syntax error.
2020-05-05 08:21:12 +02:00
..

bistromathic - all the bells and whistles

This example demonstrates best practices when using Bison.

  • Its hand-written scanner tracks locations.
  • Its interface is pure.
  • It uses the error token to get error recovery.
  • Its interface is "incremental", well suited for interaction: it uses the push-parser API to feed the parser with the incoming tokens.
  • It features an interactive command line with completion based on the parser state, based on yyexpected_tokens.
  • It uses Bison's standard catalogue for internationalization of generated messages.
  • It uses a custom syntax error with location, lookahead correction and token internationalization.
  • It supports debug traces with semantic values.
  • It uses named references instead of the traditional $1, $2, etc.