Class: Serbea::TemplateEngine

Inherits:
Erubi::Engine
  • Object
show all
Defined in:
lib/serbea/template_engine.rb

Constant Summary collapse

FRONT_MATTER_REGEXP = 
%r!\A(---\s*\n.*?\n?)^((---|\.\.\.)\s*$\n?)!m.freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(input, properties = {}) ⇒ TemplateEngine

Returns a new instance of TemplateEngine.



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# File 'lib/serbea/template_engine.rb', line 68

def initialize(input, properties={})
  properties[:regexp] = /{%(={1,2}|-|\#|%)?(.*?)([-=])?%}([ \t]*\r?\n)?/m
  properties[:strip_front_matter] = true unless properties.key?(:strip_front_matter)
  super process_serbea_input(input, properties), properties
end

Class Method Details

.directive(new_directive, directive_resolution) ⇒ Object 



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# File 'lib/serbea/template_engine.rb', line 17

def self.directive(new_directive, directive_resolution)
  directives[new_directive.to_s] = directive_resolution
end

.directives ⇒ Object 



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# File 'lib/serbea/template_engine.rb', line 21

def self.directives
  @directives ||= {
    "@" => ->(code, buffer) do
      pieces = code.split(" ")
      if pieces[0].start_with?(/[A-Z]/) # Ruby class name
        pieces[0].prepend " "
        pieces[0] << ".new("
      else # string or something else
        pieces[0].prepend "("
      end

      includes_block = false
      pieces.reverse.each do |piece|
        if piece == "do" && (pieces.last == "do" || pieces.last.end_with?("|"))
          piece.prepend(") ")
          includes_block = true
          break
        end
      end

      if includes_block
        buffer << "{%= render#{pieces.join(" ")} %}"
      else
        pieces.last << ")"
        buffer << "{%= render#{pieces.join(" ")} %}"
      end
    end,
    "`" => ->(code, buffer) do
      buffer << "{%= %`"
      buffer << code.gsub(%r("([^\\]?)\#{(.*?)}"), "\"\\1\#{h(\\2)}\"")
      buffer << ".strip %}"
    end
  }
end

.front_matter_preamble ⇒ Object 



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# File 'lib/serbea/template_engine.rb', line 60

def self.front_matter_preamble
  @front_matter_preamble ||= "frontmatter = YAML.load"
end

.front_matter_preamble=(varname) ⇒ Object 



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# File 'lib/serbea/template_engine.rb', line 56

def self.front_matter_preamble=(varname)
  @front_matter_preamble = varname
end

.has_yaml_header?(template) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/serbea/template_engine.rb', line 64

def self.has_yaml_header?(template)
  template.lines.first&.match? %r!\A---\s*\r?\n!
end

Instance Method Details

#process_serbea_input(template, properties) ⇒ Object 



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# File 'lib/serbea/template_engine.rb', line 74

def process_serbea_input(template, properties)
  buff = ""
  
  string = template.dup
  if properties[:strip_front_matter] && self.class.has_yaml_header?(string)
    if string = string.match(FRONT_MATTER_REGEXP)
      require "yaml" if self.class.front_matter_preamble.include?(" = YAML.load")

      string = "{% #{self.class.front_matter_preamble} <<~YAMLDATA\n" + 
        string[1].sub(/^---\n/,'') +
        "YAMLDATA\n%}" +
        string[2].sub(/^---\n/, '') +
        string.post_match
    end
  end
  
  # Ensure the raw "tag" will strip out all ERB-style processing
  until string.empty?
    text, code, string = string.partition(/{% raw %}(.*?){% endraw %}/m)
  
    buff << text
    if code.length > 0
      buff << $1.
        gsub("{{", "__RAW_START_PRINT__").
        gsub("}}", "__RAW_END_PRINT__").
        gsub("{%", "__RAW_START_EVAL__").
        gsub("%}", "__RAW_END_EVAL__")
    end
  end

  # Process any pipelines
  string = buff
  buff = ""
  until string.empty?
    text, code, string = string.partition(/{{(.*?)}}/m)
  
    buff << text
    if code.length > 0
      original_line_length = code.lines.size

      s = StringScanner.new($1)
      escaped_segment = ""
      segments = []
      until s.eos?
        portion = s.scan_until(/\|>?/)
        if portion
          if portion.end_with?('\|')
            # the pipe is escaped, so save that for later
            escaped_segment += portion.sub(/\\\|$/, "|")
          elsif escaped_segment.length > 0
            # we already have escaped content, so finish that up
            segments << escaped_segment + portion.sub(/\|>?$/, "")
            escaped_segment = ""
          else
            # let's find out if this is actionable now
            if s.check(/\|/)
              # nope, the next character is another pipe, so let's escape
              s.pos += 1
              escaped_segment += portion + "|"
            else
              # finally, we have liftoff!
              segments << portion.sub(/\|>?$/, "")
            end
          end
        else
          # we've reached the last bit of the code
          if escaped_segment.length > 0
            # escape and get the rest
            segments << escaped_segment + s.rest
          else
            # or just the rest will do
            segments << s.rest
          end
          s.terminate
        end
      end

      segments[0] = "pipeline(binding, (#{segments[0].strip}))"
      segments[1..-1].each_with_index do |segment, index|
        filter, args = segment.strip.match(/([^ :]*)(.*)/m).captures
        segments[index + 1] = ".filter(:" + filter
        if args == ""
          segments[index + 1] += ")"
        else
          segments[index + 1] += "," + args.sub(/^:/, "") + ")"
        end
      end

      subs = "{%= #{segments.join} %}"
      buff << subs

      (original_line_length - subs.lines.size).times do
        buff << "\n{% %}" # preserve original line length
      end
    end
  end

  # Process any render directives
  string = buff
  buff = ""
  until string.empty?
    text, code, string = string.partition(/{%@([a-z_`]+)?(.*?)%}/m)

    buff << text
    if code.length > 0
      directive = $1
      code = $2
      unless ["end", ""].include? code.strip
        directive = $1 ? self.class.directives[$1] : self.class.directives["@"]

        if directive
          additional_length = "#{buff}#{code}".lines.size
          directive.(code, buff)
          (additional_length - buff.lines.size).times do
            buff << "{% %}\n" # preserve original directive line length
          end
        else
          raise "Handler for Serbea template directive `#{$1}' not found"
        end
      else
        buff << "{% end %}"
      end
    end
  end

  buff
end