Class: Emerald::PreProcessor

Inherits:
Object
  • Object
show all
Defined in:
lib/emerald/preprocessor.rb

Overview

Preprocess the emerald code and add notion of indentation so it may be parsed by a context free grammar. Removes all whitespace and adds braces to denote indentation.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ PreProcessor 



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# File 'lib/emerald/preprocessor.rb', line 14

def initialize
  reset
end

Instance Method Details

#check_and_enter_literal(line) ⇒ Object 



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# File 'lib/emerald/preprocessor.rb', line 126

def check_and_enter_literal(line)
  if line.rstrip.end_with?('->')
    @in_literal = true
    @current_indent += 2
    @templateless_literal = false
    @preserve_html_literal = false
  elsif line.rstrip.end_with?('=>')
    @in_literal = true
    @current_indent += 2
    @templateless_literal = true
    @preserve_html_literal = false
  elsif line.rstrip.end_with?('~>')
    @in_literal = true
    @current_indent += 2
    @templateless_literal = true
    @preserve_html_literal = true
  end
end

#check_new_indent(new_indent) ⇒ Object

Compares the value of the new_indent with the old indentation. Invoked by: process_emerald



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# File 'lib/emerald/preprocessor.rb', line 60

def check_new_indent(new_indent)
  if new_indent > @current_indent
    open_tags(new_indent)
  elsif new_indent < @current_indent
    close_tags(new_indent)
  end
end

#close_entered_tags(new_indent) ⇒ Object

Append closing braces if not in literal and new indent is less than old one



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# File 'lib/emerald/preprocessor.rb', line 96

def close_entered_tags(new_indent)
  (1..((@current_indent - new_indent) / 2)).each do
    @output += "}\n"
    @b_count -= 1
  end
end

#close_literal(new_indent) ⇒ Object

Append closing braces if in literal and new indent is less than old one



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# File 'lib/emerald/preprocessor.rb', line 85

def close_literal(new_indent)
  @output += "$\n"
  @in_literal = false

  (2..((@current_indent - new_indent) / 2)).each do
    @output += "}\n"
    @b_count -= 1
  end
end

#close_tags(new_indent) ⇒ Object 



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# File 'lib/emerald/preprocessor.rb', line 75

def close_tags(new_indent)
  if @in_literal
    close_literal(new_indent)
  else
    close_entered_tags(new_indent)
  end
  @current_indent = new_indent
end

#open_tags(new_indent) ⇒ Object 



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# File 'lib/emerald/preprocessor.rb', line 68

def open_tags(new_indent)
  return if @in_literal
  @output += "{\n"
  @b_count += 1
  @current_indent = new_indent
end

#process_emerald(input) ⇒ Object

Process the emerald to remove indentation and replace with brace convention for an easier time parsing with context free grammar



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# File 'lib/emerald/preprocessor.rb', line 31

def process_emerald(input)
  input.each_line.with_index do |line, line_number|
    if @in_literal
      if line[0...-1].empty?
        new_indent = @current_indent
        line = " "*@current_indent + "\n"
      else
        new_indent = line.length - line.lstrip.length
      end
    else 
      next if line.lstrip.empty?
      new_indent = line.length - line.lstrip.length
    end

    check_new_indent(new_indent)
    @output += remove_indent_whitespace(line)
    @source_map[@output.lines.length] = {
      source_line: line_number + 1
    }
    check_and_enter_literal(line)
  end

  close_tags(0)

  [@output, @source_map]
end

#remove_indent_whitespace(line) ⇒ Object

Crop off only Emerald indent whitespace to preserve whitespace in the literal. Since $ is the end character, we need to escape it in the literal.



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# File 'lib/emerald/preprocessor.rb', line 105

def remove_indent_whitespace(line)
  if @in_literal
    # Ignore indent whitespace, only count post-indent as the literal,
    # but keep any extra whitespace that might exist for literals
    cropped = line[@current_indent..-1] || ''
    if @templateless_literal
      # this is a fun one https://www.ruby-forum.com/topic/143645
      cropped = cropped.gsub("\\"){ "\\\\" }
    end

    unless @preserve_html_literal
      cropped = @encoder.encode cropped
    end

    # Escape $ since we use it as a terminator for literals, and encode HTML
    cropped.gsub('$', "\\$")
  else
    line.lstrip
  end
end

#reset ⇒ Object

Reset class variables, used for testing



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# File 'lib/emerald/preprocessor.rb', line 19

def reset
  @in_literal = false
  @templateless_literal = false
  @current_indent = 0
  @b_count = 0
  @output = ''
  @encoder = HTMLEntities.new
  @source_map = {}
end