Module: Puppet::Pops::Parser::InterpolationSupport

Included in:
Lexer2
Defined in:
lib/puppet/pops/parser/interpolation_support.rb

Overview

This module is an integral part of the Lexer. It defines interpolation support PERFORMANCE NOTE: There are 4 very similar methods in this module that are designed to be as performant as possible. While it is possible to parameterize them into one common method, the overhead of passing parameters and evaluating conditional logic has a negative impact on performance.

Constant Summary collapse

PATTERN_VARIABLE =
%r{(::)?(\w+::)*\w+}

Instance Method Summary collapse

Instance Method Details

#enqueue_until(brace_count) ⇒ Object

Enqueues lexed tokens until either end of input, or the given brace_count is reached


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# File 'lib/puppet/pops/parser/interpolation_support.rb', line 188

def enqueue_until brace_count
  scn = @scanner
  ctx = @lexing_context
  queue = @token_queue
  queue_base = @token_queue[0]

  scn.skip(self.class::PATTERN_WS)
  queue_size = queue.size
  until scn.eos? do
    token = lex_token
    if token
      if token.equal?(queue_base)
        # A nested #interpolate_dq call shifted the queue_base token from the @token_queue. It must
        # be put back since it is intended for the top level #interpolate_dq call only.
        queue.insert(0, token)
        next # all relevant tokens are already on the queue
      end
      token_name = token[0]
      ctx[:after] = token_name
      if token_name == :RBRACE && ctx[:brace_count] == brace_count
        qlength = queue.size - queue_size
        if qlength == 1
          # Single token is subject to replacement
          queue[-1] = transform_to_variable(queue[-1])
        elsif qlength > 1 && [:DOT, :LBRACK].include?(queue[queue_size + 1][0])
          # A first word, number of name token followed by '[' or '.' is subject to replacement
          # But not for other operators such as ?, +, - etc. where user must use a $ before the name
          # to get a variable
          queue[queue_size] = transform_to_variable(queue[queue_size])
        end
        return
      end
      queue << token
    else
      scn.skip(self.class::PATTERN_WS)
    end
  end
end

#interpolate_dqObject

This is the starting point for a double quoted string with possible interpolation The structure mimics that of the grammar. The logic is explicit (where the former implementation used parameters/structures) given to a generic handler. (This is both easier to understand and faster).


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# File 'lib/puppet/pops/parser/interpolation_support.rb', line 17

def interpolate_dq
  scn = @scanner
  ctx = @lexing_context
  before = scn.pos
  # skip the leading " by doing a scan since the slurp_dqstring uses last matched when there is an error
  scn.scan(/"/)
  value,terminator = slurp_dqstring()
  text = value
  after = scn.pos
  loop do
    case terminator
    when '"'
      # simple case, there was no interpolation, return directly
      return emit_completed([:STRING, text, scn.pos-before], before)
    when '${'
      count = ctx[:brace_count]
      ctx[:brace_count] += 1
      # The ${ terminator is counted towards the string part
      enqueue_completed([:DQPRE, text, scn.pos-before], before)
      # Lex expression tokens until a closing (balanced) brace count is reached
      enqueue_until count
      break
    when '$'
      varname = scn.scan(PATTERN_VARIABLE)
      if varname
        # The $ is counted towards the variable
        enqueue_completed([:DQPRE, text, after-before-1], before)
        enqueue_completed([:VARIABLE, varname, scn.pos - after + 1], after - 1)
        break
      else
        # false $ variable start
        text += terminator
        value,terminator = slurp_dqstring()
        text += value
        after = scn.pos
      end
    end
  end
  interpolate_tail_dq
  # return the first enqueued token and shift the queue
  @token_queue.shift
end

#interpolate_tail_dqObject


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# File 'lib/puppet/pops/parser/interpolation_support.rb', line 60

def interpolate_tail_dq
  scn = @scanner
  ctx = @lexing_context
  before = scn.pos
  value,terminator = slurp_dqstring
  text = value
  after = scn.pos
  loop do
    case terminator
    when '"'
      # simple case, there was no further interpolation, return directly
      enqueue_completed([:DQPOST, text, scn.pos-before], before)
      return
    when '${'
      count = ctx[:brace_count]
      ctx[:brace_count] += 1
      # The ${ terminator is counted towards the string part
      enqueue_completed([:DQMID, text, scn.pos-before], before)
      # Lex expression tokens until a closing (balanced) brace count is reached
      enqueue_until count
      break
    when '$'
      varname = scn.scan(PATTERN_VARIABLE)
      if varname
        # The $ is counted towards the variable
        enqueue_completed([:DQMID, text, after-before-1], before)
        enqueue_completed([:VARIABLE, varname, scn.pos - after + 1], after - 1)
        break
      else
        # false $ variable start
        text += terminator
        value,terminator = slurp_dqstring
        text += value
        after = scn.pos
      end
    end
  end
  interpolate_tail_dq
end

#interpolate_tail_uqObject


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# File 'lib/puppet/pops/parser/interpolation_support.rb', line 146

def interpolate_tail_uq
  scn = @scanner
  ctx = @lexing_context
  before = scn.pos
  value,terminator = slurp_uqstring
  text = value
  after = scn.pos
  loop do
    case terminator
    when ''
      # simple case, there was no further interpolation, return directly
      enqueue_completed([:DQPOST, text, scn.pos-before], before)
      return
    when '${'
      count = ctx[:brace_count]
      ctx[:brace_count] += 1
      # The ${ terminator is counted towards the string part
      enqueue_completed([:DQMID, text, scn.pos-before], before)
      # Lex expression tokens until a closing (balanced) brace count is reached
      enqueue_until count
      break
    when '$'
      varname = scn.scan(PATTERN_VARIABLE)
      if varname
        # The $ is counted towards the variable
        enqueue_completed([:DQMID, text, after-before-1], before)
        enqueue_completed([:VARIABLE, varname, scn.pos - after + 1], after - 1)
        break
      else
        # false $ variable start
        text += terminator
        value,terminator = slurp_uqstring
        text += value
        after = scn.pos
      end
    end
  end
  interpolate_tail_uq
end

#interpolate_uqObject

This is the starting point for a un-quoted string with possible interpolation The logic is explicit (where the former implementation used parameters/strucures) given to a generic handler. (This is both easier to understand and faster).


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# File 'lib/puppet/pops/parser/interpolation_support.rb', line 105

def interpolate_uq
  scn = @scanner
  ctx = @lexing_context
  before = scn.pos
  value,terminator = slurp_uqstring()
  text = value
  after = scn.pos
  loop do
    case terminator
    when ''
      # simple case, there was no interpolation, return directly
      enqueue_completed([:STRING, text, scn.pos-before], before)
      return
    when '${'
      count = ctx[:brace_count]
      ctx[:brace_count] += 1
      # The ${ terminator is counted towards the string part
      enqueue_completed([:DQPRE, text, scn.pos-before], before)
      # Lex expression tokens until a closing (balanced) brace count is reached
      enqueue_until count
      break
    when '$'
      varname = scn.scan(PATTERN_VARIABLE)
      if varname
        # The $ is counted towards the variable
        enqueue_completed([:DQPRE, text, after-before-1], before)
        enqueue_completed([:VARIABLE, varname, scn.pos - after + 1], after - 1)
        break
      else
        # false $ variable start
        text += terminator
        value,terminator = slurp_uqstring()
        text += value
        after = scn.pos
      end
    end
  end
  interpolate_tail_uq
  nil
end

#interpolate_uq_to(lexer) ⇒ Object

Interpolates unquoted string and transfers the result to the given lexer (This is used when a second lexer instance is used to lex a substring)


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# File 'lib/puppet/pops/parser/interpolation_support.rb', line 241

def interpolate_uq_to(lexer)
  interpolate_uq
  queue = @token_queue
  until queue.empty? do
    lexer.enqueue(queue.shift)
  end
end

#transform_to_variable(token) ⇒ Object


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# File 'lib/puppet/pops/parser/interpolation_support.rb', line 227

def transform_to_variable(token)
  token_name = token[0]
  if [:NUMBER, :NAME, :WORD].include?(token_name) || self.class::KEYWORD_NAMES[token_name] || @taskm_keywords[token_name]
    t = token[1]
    ta = t.token_array
    [:VARIABLE, self.class::TokenValue.new([:VARIABLE, ta[1], ta[2]], t.offset, t.locator)]
  else
    token
  end
end