Class: ZplRender::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/zpl_render/parser.rb

Overview

Tokenizes a ZPL II stream into [command, params] pairs.

Commands are introduced by the format prefix (^, changeable via ^CC/~CC) or the control prefix (~, changeable via ^CT/~CT). The command code is two characters, except ^A where the second character is the font designator (^A@ remains its own command). Parameters run until the next prefix character.

Defined Under Namespace

Classes: Command

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(zpl) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/zpl_render/parser.rb', line 23

def initialize(zpl)
  @zpl = zpl.to_s
end

Class Method Details

.parse(zpl) ⇒ Object 



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# File 'lib/zpl_render/parser.rb', line 19

def self.parse(zpl)
  new(zpl).parse
end

Instance Method Details

#parse ⇒ Object 



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# File 'lib/zpl_render/parser.rb', line 27

def parse
  commands = []
  caret = "^"
  tilde = "~"
  i = 0
  len = @zpl.length

  while i < len
    ch = @zpl[i]
    unless ch == caret || ch == tilde
      i += 1
      next
    end

    prefix = ch == caret ? :caret : :tilde
    code = @zpl[i + 1, 2].to_s
    if code.empty?
      i += 1
      next
    end

    name = nil
    font = nil
    if code[0]&.upcase == "A" && code != "A@" && prefix == :caret
      name = "A"
      font = code[1]
    else
      name = code.upcase
    end
    i += 3 # prefix + two command characters (^A consumes its font char)

    # ^CC/~CC and ^CT/~CT take effect immediately: their parameter is a
    # single character that becomes the new prefix.
    if name == "CC" || name == "CT"
      new_prefix = @zpl[i]
      if new_prefix
        caret = new_prefix if name == "CC"
        tilde = new_prefix if name == "CT"
        i += 1
      end
      next
    end

    # parameters: everything until the next prefix character
    j = i
    j += 1 while j < len && @zpl[j] != caret && @zpl[j] != tilde
    params = @zpl[i...j].to_s

    if name == "A"
      params = "#{font}#{params}"
    end

    # CR/LF are ignorable in ZPL streams
    params = params.delete("\r\n") unless %w[GF DG DB].include?(name)
    params = params.strip if %w[GF DG DB].include?(name)

    commands << Command.new(name: name, params: params, prefix: prefix)
    i = j
  end

  commands
end