Class: Kramdown::Utils::StringScanner

Inherits:
StringScanner
  • Object
show all
Defined in:
lib/kramdown/utils/string_scanner.rb

Overview

This patched StringScanner adds line number information for current scan position and a start_line_number override for nested StringScanners.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(string, start_line_number = 1) ⇒ StringScanner

Takes the start line number as optional second argument.

Note: The original second argument is no longer used so this should be safe.



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# File 'lib/kramdown/utils/string_scanner.rb', line 26

def initialize(string, start_line_number = 1)
  super(string)
  @start_line_number = start_line_number || 1
  @previous_pos = 0
  @previous_line_number = @start_line_number
end

Instance Attribute Details

#start_line_number ⇒ Object (readonly)

The start line number. Used for nested StringScanners that scan a sub-string of the source document. The kramdown parser uses this, e.g., for span level parsers.



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# File 'lib/kramdown/utils/string_scanner.rb', line 21

def start_line_number
  @start_line_number
end

Instance Method Details

#current_line_number ⇒ Object

Returns the line number for current charpos.

NOTE: Requires that all line endings are normalized to ‘n’

NOTE: Normally we’d have to add one to the count of newlines to get the correct line number. However we add the one indirectly by using a one-based start_line_number.



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# File 'lib/kramdown/utils/string_scanner.rb', line 67

def current_line_number
  # Not using string[@previous_pos..best_pos].count('\n') because it is slower
  strscan = ::StringScanner.new(string)
  strscan.pos = @previous_pos
  old_pos = pos + 1
  @previous_line_number += 1 while strscan.skip_until(/\n/) && strscan.pos <= old_pos

  @previous_pos = (eos? ? pos : pos + 1)
  @previous_line_number
end

#pos=(pos) ⇒ Object

Sets the byte position of the scan pointer.

Note: This also resets some internal variables, so always use pos= when setting the position and don’t use any other method for that!



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# File 'lib/kramdown/utils/string_scanner.rb', line 37

def pos=(pos)
  if self.pos > pos
    @previous_line_number = @start_line_number
    @previous_pos = 0
  end
  super
end

#revert_pos(data) ⇒ Object

Revert the position to one saved by #save_pos.



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# File 'lib/kramdown/utils/string_scanner.rb', line 56

def revert_pos(data)
  self.pos = data[0]
  @previous_pos, @previous_line_number = data[1], data[2]
end

#save_pos ⇒ Object

Return information needed to revert the byte position of the string scanner in a performant way.

The returned data can be fed to #revert_pos to revert the position to the saved one.

Note: Just saving #pos won’t be enough.



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# File 'lib/kramdown/utils/string_scanner.rb', line 51

def save_pos
  [pos, @previous_pos, @previous_line_number]
end