NoMethodError: undefined method `charpos' for "+":String

[ravinggenius]

I'm getting a NoMethodError when calling Parslet::Slice#offset. The error only happens in 1.6.1, not 1.6.0. I'm using Ruby 2.1.2, but the issue also happens in Ruby 2.1.1.

[kschiess]

Can you post an example where this happens?

[ravinggenius]

Sure. https://github.com/rip-lang/rip/blob/master/lib/rip/utilities/location.rb#L17

If you are inclined, you can checkout master and run the tests. You should have plenty of errors when upgrading to 1.6.1 :). By the way I think the change that causes the issue is https://github.com/kschiess/parslet/compare/1.6.0...1.6.1#diff-a78d1f31f8b81cd6a311f6a9be948008R40.

[kschiess]

If you care for a fix, you should give me a more specific test case to work from. My time is limited.

[ravinggenius]

I'm sorry. I didn't mean to be unhelpful in the previous post.

I followed one of the errors in my test. parse_tree is Parslet's parse tree before any transforms are applied. Notice that :integer and :sign are both instances of Parslet::Slice. Also notice that the :sign slice is not displaying correctly.

[15] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first
=> {:start=>{:sign=>#<Parslet::Slice:0x3ff5bddc3d70>, :integer=>"1"@0}, :location=>".."@1, :exclusivity=>nil, :end=>{:sign=>#<Parslet::Slice:0x3ff5bddbf70c>, :integer=>"3"@3}}
[16] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start]
=> {:sign=>#<Parslet::Slice:0x3ff5bdcb7634>, :integer=>"1"@0}
[17] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start][:sign]
=> #<Parslet::Slice:0x3ff5bdc04c3c>
[18] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start][:sign].offset
NoMethodError: undefined method `charpos' for "+":String
from /usr/local/opt/rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/parslet-1.6.1/lib/parslet/slice.rb:40:in `offset'
[19] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start][:integer]
=> "1"@0
[20] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start][:integer].offset
=> 0
[21] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start][:integer].class
=> Parslet::Slice
[22] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start][:sign].class
=> Parslet::Slice
[23] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start][:sign].inspect
NoMethodError: undefined method `charpos' for "+":String
from /usr/local/opt/rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/parslet-1.6.1/lib/parslet/slice.rb:40:in `offset'
[24] pry(#<Rip::Compiler::Parser>):1> parse_tree[:module].first[:start][:sign].to_s
=> 0

[ravinggenius]

After parsing answer = 42, I get an assignment node where the right hand side looks like {:integer=>"42"@9}. Before passing the tree to the transform class, I run it through a normalization class which, among other things, adds a sign to numbers. After normalization the integer node above looks like {:sign=>"+"@9, :integer=>"42"@9}. To do this, I have to manually create a Parslet::Slice.

In parslet 1.6.0, I could call Parslet::Slice.new("+", 9, <line-cache-from-the-integer-node>). In parslet 1.6.1 this no longer works, as Parslet::Slice#initialize has a different signature. Is Parslet::Slice part of parslet's public API, or is it an implementation detail that I shouldn't use directly?

[kschiess]

)`. In parslet 1.6.1 this no longer works, as`Parslet::Slice#initialize`has a different signature. Is `Parslet::Slice` part of parslet's public API, or is it an implementation detail that I shouldn't use directly?

Yeah, Parslet::Slice#initialize is as private as it gets. Not that I will change things around a lot, just that I will want to be able to.

k

[ravinggenius]

Got it. Instead of using a private class, would it be better for me to just have multiple transform rules (one for {:integer=>"42"@9} and another for {:sign=>"+"@9, :integer=>"42"@9}). Can transform rules call each other?

[kschiess]

No. I recommend code duplication.

[ravinggenius]

Okay. Thanks for the help.