Method: AutoStacker24::Preprocessor.interpolate

Defined in:

lib/autostacker24/template_preprocessor.rb

.interpolate(s) ⇒ Object

interpolates a string with ‘@’ expressions and returns a string or a hash it implements the following non context free grammar in pseudo antlr3

string : RAW? (expr RAW?)*; expr : ‘@’ ‘name (attr+ | map)? ‘’?; name : ID (‘::’ ID)?; attr : (‘.’ ID)+; map : ‘[’ key (‘,’ key)? ‘]’; key : ID | expr; ID : [a-zA-Z0-9]+; RAW : (~[‘@’]* | FILE)=; FILE : ‘@file://’ [^@\s]+ (‘@’ | ‘ ’); FILE_C : ‘@[^] ‘}’;

# File 'lib/autostacker24/template_preprocessor.rb', line 93

def self.interpolate(s)
  parts = []
  while s.length > 0
    raw, s = parse_raw(s)
    parts << raw unless raw.empty?
    expr, s = parse_expr(s)
    parts << expr if expr
  end
  case parts.length
    when 0 then ''
    when 1 then parts[0]
    else {'Fn::Join' => ['', parts]}
  end
end