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Class: SyntaxSuggest::ExplainSyntax

Relationships & Source Files
Inherits: Object
Defined in: lib/syntax_suggest/explain_syntax.rb

Overview

Explains syntax errors based on their source

example:

source = "def foo; puts 'lol'" # Note missing end
explain ExplainSyntax.new(
  code_lines: CodeLine.from_source(source)
).call
explain.errors.first
# => "Unmatched keyword, missing `end' ?"

When the error cannot be determined by lexical counting then ripper is run against the input and the raw ripper errors returned.

Example:

source = "1 * " # Note missing a second number
explain ExplainSyntax.new(
  code_lines: CodeLine.from_source(source)
).call
explain.errors.first
# => "syntax error, unexpected end-of-input"

Constant Summary

Class Method Summary

Instance Method Summary

  • #call
  • #errors

    Returns an array of syntax error messages.

  • #missing

    Returns an array of missing elements.

  • #why(miss)

    Converts a missing string to an human understandable explanation.

Constructor Details

.new(code_lines:) ⇒ ExplainSyntax

[ GitHub ] 

  


# File 'lib/syntax_suggest/explain_syntax.rb', line 40



def initialize(code_lines:)
  @code_lines = code_lines
  @left_right = LeftRightLexCount.new
  @missing = nil
end


  







Instance Method Details



  

    #call  
  

  [ GitHub ]


  

  


# File 'lib/syntax_suggest/explain_syntax.rb', line 46



def call
  @code_lines.each do |line|
    line.lex.each do |lex|
      @left_right.count_lex(lex)
    end
  end

  self
end


  








  

    #errors  
  



  

    

Returns an array of syntax error messages



If no missing pairs are found it falls back on the original ripper error messages


  



  [ GitHub ]


  

  


# File 'lib/syntax_suggest/explain_syntax.rb', line 95



def errors
  if missing.empty?
    return RipperErrors.new(@code_lines.map(&:original).join).call.errors
  end

  missing.map { |miss| why(miss) }
end


  








  

    #missing  
  



  

    

Returns an array of missing elements



For example this:



ExplainSyntax.new(code_lines: lines).missing
# => ["}"]



Would indicate that the source is missing a ‘}` character in the source code


  



  [ GitHub ]


  

  


# File 'lib/syntax_suggest/explain_syntax.rb', line 65



def missing
  @missing ||= @left_right.missing
end


  








  

    #why(miss)  
  



  

    

Converts a missing string to an human understandable explanation.



Example:



explain.why("}")
# => "Unmatched `{', missing `}' ?"


  



  [ GitHub ]


  

  


# File 'lib/syntax_suggest/explain_syntax.rb', line 77



def why(miss)
  case miss
  when "keyword"
    "Unmatched `end', missing keyword (`do', `def`, `if`, etc.) ?"
  when "end"
    "Unmatched keyword, missing `end' ?"
  else
    inverse = INVERSE.fetch(miss) {
      raise "Unknown explain syntax char or key: #{miss.inspect}"
    }
    "Unmatched `#{inverse}', missing `#{miss}' ?"
  end
end