Method for checking syntax

7stud2 · 4 December 2013 12:30

Is there any method to do syntax checking of a specific block but not
whole file?

···

--
Posted via http://www.ruby-forum.com/.

7stud2 · 4 December 2013 12:47

If the code allows it, you could isolate the block into a separate file
while checking.

Apart from that, I think you'd have to rely on options in your IDE.

···

--
Posted via http://www.ruby-forum.com/.

Tamara_Temple1 · 5 December 2013 00:25

Could you perhaps explain a little of why you want to do this? If you want
to check syntax programmatically, for example, you could eval the code as a
string, rescuing the result and checking for any syntax errors, etc. This
is what irb and pry are doing, effectively, at a very very basic level.

···

On Wed, Dec 4, 2013 at 6:30 AM, Asmita Chauhan <lists@ruby-forum.com> wrote:

Is there any method to do syntax checking of a specific block but not
whole file?

7stud2 · 5 December 2013 06:09

Actually, I want to separate out parsing(for syntax checking) and
execution.
In our Application, we are using eval, instace_eval, class_eval etc.
what i want to do is that parse code block for syntax checking at early
stage and defer the execution at later stage.

···

--
Posted via http://www.ruby-forum.com/.

7stud2 · 5 December 2013 11:08

Thanks Robert Klemme

I would try this in my application. Looks like this would be helpful.

···

--
Posted via http://www.ruby-forum.com/.

Stu1 · 6 December 2013 04:31

in your repl you can read in the current file and parse with regex. Pry has
it built in nowdays. I've used one of my own scripts for years which
defeats the repl -> editor -> run cycle. Ruby's ability to reopen classes
makes it ideal for this style of computation and experimentation.

···

On Wed, Dec 4, 2013 at 6:30 AM, Asmita Chauhan <lists@ruby-forum.com> wrote:

Is there any method to do syntax checking of a specific block but not
whole file?

--
Posted via http://www.ruby-forum.com/\.

7stud2 · 10 December 2013 22:44

begin; eval(code); rescue Object; $!; end }.value; p 42' "... blech"
#<SyntaxError: (eval):1: syntax error, unexpected tDOT3
... blech
^>
42

···

a:~ $ ruby -e 'code = ARGV.shift; p Thread.new(code){|code| $SAFE = 12;

--
Posted via http://www.ruby-forum.com/.

7stud2 · 12 December 2013 19:38

You can create a tempfile and then run

ruby -c filename # for syntax check
ruby -w filename # for warnings
ruby -wc filename # for both

I'd love to learn if there's a programmatic way to do this within Ruby,
but I haven't found it in the source code, and I'd rather than bring in
the rubinius melbourne parser.

This is how sandi_meter does it

github.com

makaroni4/sandi_meter/blob/15287d5/lib/sandi_meter/warning_scanner.rb#L24


                              else
                                validate(source)
                              end


  check_syntax(status)
  @indentation_warnings = parse_warnings
end


private
def validate(source)
  Open3.capture3('ruby -wc', stdin_data: source)
end


def check_syntax(status)
  raise SyntaxError, @warnings unless !!(status =~ /Syntax\sOK/)
end


def check_token_lines(token, line_num, end_line_num)
  raise 'No valid end line number' unless end_line_num =~ /^\d+$/
  raise 'No valid line number' unless line_num =~ /^\d+$/
  raise 'No valid token ("def" or "class")' unless token =~ /^def|class|module$/

Open3.capture3('ruby -wc', stdin_data: source)

But that's potentially pretty buggy on non *NIX OS's or non-mri rubies.

Does that possibly help? (Does anyone know how to do this within ruby?)

···

--
Posted via http://www.ruby-forum.com/.

7stud2 · 15 December 2013 17:31

referring to?

- JRuby bug Open3.capture3 error on Windows · Issue #1187 · jruby/jruby · GitHub
- Just anecdotal reports from talking to people. Back 1.8 days,
win32-open3 was required, but apparently no longer in 1.9+

Just the evidence of these bugs are why I'm not sure.

···

On Sat, Dec 14, 2013 at 11:01 PM, Stu <stu@rubyprogrammer.net> wrote:

Open3.capture3('ruby -wc', stdin_data: source)

But that's potentially pretty buggy on non *NIX OS's or non-mri rubies.

Why wouldn't that work on windows? Better yet which non-mri ruby are you

--
Posted via http://www.ruby-forum.com/\.

Ryan_Davis1 · 5 December 2013 01:18

That's a great idea. Especially if the user wants to verify system calls or FileUtils.rm_rf and the like.

···

On Dec 4, 2013, at 16:25, tamouse pontiki <tamouse.lists@gmail.com> wrote:

On Wed, Dec 4, 2013 at 6:30 AM, Asmita Chauhan <lists@ruby-forum.com> wrote:
Is there any method to do syntax checking of a specific block but not
whole file?

Could you perhaps explain a little of why you want to do this? If you want to check syntax programmatically, for example, you could eval the code as a string, rescuing the result and checking for any syntax errors, etc. This is what irb and pry are doing, effectively, at a very very basic level.

Tamara_Temple1 · 5 December 2013 04:52

Sure, just like you can do with irb and pry.

···

On Wed, Dec 4, 2013 at 7:18 PM, Ryan Davis <ryand-ruby@zenspider.com> wrote:

On Dec 4, 2013, at 16:25, tamouse pontiki <tamouse.lists@gmail.com> wrote:

> On Wed, Dec 4, 2013 at 6:30 AM, Asmita Chauhan <lists@ruby-forum.com> > wrote:
> Is there any method to do syntax checking of a specific block but not
> whole file?
>
> Could you perhaps explain a little of why you want to do this? If you
want to check syntax programmatically, for example, you could eval the code
as a string, rescuing the result and checking for any syntax errors, etc.
This is what irb and pry are doing, effectively, at a very very basic level.

That's a great idea. Especially if the user wants to verify system calls
or FileUtils.rm_rf and the like.

Robert_K1 · 5 December 2013 09:14

Just wrap the piece of code:

irb(main):007:0> code = '1 + 2'
=> "1 + 2"
irb(main):008:0> compiled = eval("lambda { #{code} }")
=> #<Proc:0x0000060036f988@(eval):1 (lambda)>
irb(main):009:0> compiled.call
=> 3

Now with a broken piece:

irb(main):010:0> code = '1 + '
=> "1 + "
irb(main):011:0> compiled = eval("lambda { #{code} }")
SyntaxError: (eval):1: syntax error, unexpected '}'
lambda { 1 + }
               ^
        from (irb):11:in `eval'
        from (irb):11
        from /usr/bin/irb:12:in `<main>'

Cheers

robert

···

On Thu, Dec 5, 2013 at 7:09 AM, Asmita Chauhan <lists@ruby-forum.com> wrote:

Actually, I want to separate out parsing(for syntax checking) and
execution.
In our Application, we are using eval, instace_eval, class_eval etc.
what i want to do is that parse code block for syntax checking at early
stage and defer the execution at later stage.

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

Joel_VanderWerf · 11 December 2013 05:28

Watch out for #eval; this never finishes:

ruby -e 'code = ARGV.shift; p Thread.new(code){|code| $SAFE = 12;
begin; eval(code); rescue Object; $!; end }.value; p 42' 'loop {}'

···

On 12/10/2013 02:44 PM, dojo 4. wrote:

a:~ $ ruby -e 'code = ARGV.shift; p Thread.new(code){|code| $SAFE = 12;
begin; eval(code); rescue Object; $!; end }.value; p 42' "... blech"
#<SyntaxError: (eval):1: syntax error, unexpected tDOT3
... blech
^>
42

Thyago_Barbosa_Rodri · 11 December 2013 10:08

I'm sorry, guys, this wrapped around my brain and I couldn't unwrap it so
far:

In

def check_syntax src
  catch(:good) do
    eval("throw :good; #{src}")
  end
  true
rescue SyntaxError
  false
end

Why insert the *throw* before the code to be checked? If *throw* comes
first, shouldn't it always jump out of the *eval* before checking *src*?
Sorry for slowing the conversation down, just seeing an opportunity to
learn =]

···

2013/12/11 Joel VanderWerf <joelvanderwerf@gmail.com>

On 12/10/2013 02:44 PM, dojo 4. wrote:

a:~ $ ruby -e 'code = ARGV.shift; p Thread.new(code){|code| $SAFE = 12;
begin; eval(code); rescue Object; $!; end }.value; p 42' "... blech"
#<SyntaxError: (eval):1: syntax error, unexpected tDOT3
... blech
^>
42

Watch out for #eval; this never finishes:

ruby -e 'code = ARGV.shift; p Thread.new(code){|code| $SAFE = 12;
begin; eval(code); rescue Object; $!; end }.value; p 42' 'loop {}'

--
Thyago Barbosa Rodrigues [Natal-RN/Brasil]

"Who loves not wine, women and song,
remains a fool his whole life long"
(Martin Luther [Martinho Lutero], Teólogo Alemão)

"Phantasie ist wichtiger als Wissen, denn Wissen ist begrenzt." (Albert
Einstein)

Stu1 · 15 December 2013 05:01

Why wouldn't that work on windows? Better yet which non-mri ruby are you
referring to?

···

On Thu, Dec 12, 2013 at 1:38 PM, Benjamin F. <lists@ruby-forum.com> wrote:

You can create a tempfile and then run

ruby -c filename # for syntax check
ruby -w filename # for warnings
ruby -wc filename # for both

I'd love to learn if there's a programmatic way to do this within Ruby,
but I haven't found it in the source code, and I'd rather than bring in
the rubinius melbourne parser.

This is how sandi_meter does it

sandi_meter/lib/sandi_meter/warning_scanner.rb at 15287d5b74bcd94711fc5deaf75780b29e3a50a1 · makaroni4/sandi_meter · GitHub

Open3.capture3('ruby -wc', stdin_data: source)

But that's potentially pretty buggy on non *NIX OS's or non-mri rubies.

Does that possibly help? (Does anyone know how to do this within ruby?)

--
Posted via http://www.ruby-forum.com/\.

Ryan_Davis1 · 6 December 2013 21:36

Except that's not what they do. If they evaled, then they'd delete all your files before you got to type "if false".

···

On Dec 4, 2013, at 20:52, tamouse pontiki <tamouse.lists@gmail.com> wrote:

Sure, just like you can do with irb and pry.

Ryan_Davis1 · 6 December 2013 21:49

The other one I've seen looks like:

def check_syntax src
  catch(:good) do
    eval("throw :good; #{src}")
  end
  true
rescue SyntaxError
  false
end

and you can, of course, use RubyParser.new.parse(src).

···

On Dec 5, 2013, at 1:14, Robert Klemme <shortcutter@googlemail.com> wrote:

On Thu, Dec 5, 2013 at 7:09 AM, Asmita Chauhan <lists@ruby-forum.com> wrote:

Actually, I want to separate out parsing(for syntax checking) and
execution.
In our Application, we are using eval, instace_eval, class_eval etc.
what i want to do is that parse code block for syntax checking at early
stage and defer the execution at later stage.

Just wrap the piece of code:

irb(main):007:0> code = '1 + 2'
=> "1 + 2"
irb(main):008:0> compiled = eval("lambda { #{code} }")
=> #<Proc:0x0000060036f988@(eval):1 (lambda)>
irb(main):009:0> compiled.call
=> 3

Jesus_Gabriel_y_Gala · 11 December 2013 10:30

It is to ensure that you don't execute the code just yet. You want
only to check the syntax, not execute it.
eval will parse the code, raising a SyntaxError if something is
syntactically wrong, then start executing it. First thing is the
throw, so it throws, skipping all the rest.

Jesus.

···

On Wed, Dec 11, 2013 at 11:08 AM, Thyago Barbosa Rodrigues <thyagobr@gmail.com> wrote:

I'm sorry, guys, this wrapped around my brain and I couldn't unwrap it so
far:

In

def check_syntax src
  catch(:good) do
    eval("throw :good; #{src}")
  end
  true
rescue SyntaxError
  false
end

Why insert the throw before the code to be checked? If throw comes first,
shouldn't it always jump out of the eval before checking src?
Sorry for slowing the conversation down, just seeing an opportunity to learn

Joel_VanderWerf · 8 December 2013 19:57

Use BEGIN to be a bit safer:

def check_syntax_unsafe src
   catch(:good) do
     eval("throw :good; #{src}")
   end
   true
rescue SyntaxError
   false
end

def check_syntax_safe src
   catch(:good) do
     eval("BEGIN {throw :good}; #{src}")
   end
   true
rescue SyntaxError
   false
end

puts "UNSAFE"
p check_syntax_unsafe %{
BEGIN {puts "haha"}
}

puts

puts "SAFE"
p check_syntax_safe %{
BEGIN {puts "haha"}
}

__END__

Output:

UNSAFE
haha
true

SAFE
true

···

On 12/06/2013 01:49 PM, Ryan Davis wrote:

def check_syntax src
   catch(:good) do
     eval("throw :good; #{src}")
   end
   true
rescue SyntaxError
   false
end

Robert_K1 · 8 December 2013 18:45

This is nice! Thank you for that.

Kind regards

robert

···

On Fri, Dec 6, 2013 at 10:49 PM, Ryan Davis <ryand-ruby@zenspider.com> wrote:

The other one I've seen looks like:

def check_syntax src
  catch(:good) do
    eval("throw :good; #{src}")
  end
  true
rescue SyntaxError
  false
end

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

Topic		Replies	Views
Dynamic syntax check ruby-talk	6	80	8 November 2007
Syntax checker? ruby-talk	21	99	13 December 2005
Ruby syntax ruby-talk	1	84	31 March 2006
[QUIZ] Code Heuristics (#172) ruby-talk	5	89	8 August 2008
Checking File for a line ruby-talk	8	99	25 November 2007

Method for checking syntax

Related topics