Class: LogStashCompilerLSCLGrammar::LogStash::Compiler::LSCL::AST::Branch

Inherits:

Node

• Object
• Treetop::Runtime::SyntaxNode
• Node
• LogStashCompilerLSCLGrammar::LogStash::Compiler::LSCL::AST::Branch

Defined in:

lib/logstash/compiler/lscl.rb

Constant Summary

Constants included from Helpers

Helpers::AND_METHOD, Helpers::BOOLEAN_DSL_METHOD_SIGNATURE, Helpers::NAND_METHOD, Helpers::OR_METHOD, Helpers::XOR_METHOD

Instance Method Summary

• #expr ⇒ Object
• #expr_body(node) ⇒ Object
• #expr_cond(node) ⇒ Object
• #javaify_sexpr(sexpr) ⇒ Object

Methods inherited from Node

#section_type

Methods included from Helpers

#base_id, #base_protocol, #base_source_with_metadata, #base_source_with_metadata=, #compose, #compose_for, #jdsl, jdsl, #line_and_column, #source_meta

Instance Method Details

#expr ⇒ Object

# File 'lib/logstash/compiler/lscl.rb', line 215

def expr
  # Build this stuff as s-expressions for convenience at first
  # This will turn if/elsif/else blocks into nested if/else trees

  exprs = []
  else_stack = [] # For turning if / elsif / else into nested ifs

  self.recursive_select(Plugin, If, Elsif, Else).each do |node|
    if node.is_a?(If)
      exprs << :if
      exprs << expr_cond(node)
      exprs << expr_body(node)
    elsif node.is_a?(Elsif)
      condition = expr_cond(node)
      body = expr_body(node)
      else_stack << [:if, condition, body]
    elsif node.is_a?(Else)
      body = expr_body(node)
      if else_stack.size >= 1
        else_stack.last << body
      else
        exprs << body
      end
    end
  end

  else_stack.reverse.each_cons(2) do |cons|
    later,earlier = cons
    earlier << later
  end
  exprs << else_stack.first

  # Then convert to the imperative java IR
  javaify_sexpr(exprs)
end

#expr_body(node) ⇒ Object

# File 'lib/logstash/compiler/lscl.rb', line 282

def expr_body(node)
  [:compose, *node.recursive_select(Plugin, Branch).map(&:expr)]
end

#expr_cond(node) ⇒ Object

# File 'lib/logstash/compiler/lscl.rb', line 278

def expr_cond(node)
  node.elements.find {|e| e.is_a?(Condition)}.expr
end

#javaify_sexpr(sexpr) ⇒ Object

# File 'lib/logstash/compiler/lscl.rb', line 251

def javaify_sexpr(sexpr)
  return nil if sexpr.nil?

  head, tail = sexpr.first
  tail = sexpr[1..-1]

  if head == :if
    condition, t_branch, f_branch = tail

    java_t_branch = t_branch && javaify_sexpr(t_branch)
    java_f_branch = f_branch && javaify_sexpr(f_branch)

    if java_t_branch || java_f_branch
      # We use the condition as the source with metadata because it hashes correctly
      # It's hard to use the 'real' source due to the re-branching from if / elsif into if/else only
      # branches. We should come back and improve this at some point if that makes a difference
      jdsl.iIf(condition.source_with_metadata, condition, java_t_branch || jdsl.noop, java_f_branch || jdsl.noop)
    else
      jdsl.noop()
    end
  elsif head == :compose
    tail && tail.size > 0 ? compose(*tail) : jdsl.noop
  else
    raise "Unknown expression #{sexpr}!"
  end
end