grammar.treetop

require "treetop"
require "logstash/config/config_ast"

grammar LogStashConfig
  rule config
    _ plugin_section _ (_ plugin_section)* _ <LogStash::Config::AST::Config>
  end

  rule comment
    (whitespace? "#" [^\r\n]* "\r"? "\n")+ <LogStash::Config::AST::Comment>
  end

  rule _
    (comment / whitespace)* <LogStash::Config::AST::Whitespace>
  end

  rule whitespace
    [ \t\r\n]+ <LogStash::Config::AST::Whitespace>
  end

  rule plugin_section
    plugin_type _ "{"
      _ (branch_or_plugin _)*
    "}"
    <LogStash::Config::AST::PluginSection>
  end

  rule branch_or_plugin
    branch / plugin
  end

  rule plugin_type
    ("input" / "filter" / "output")
  end

  rule plugins
    (plugin (_ plugin)*)?
    <LogStash::Config::AST::Plugins>
  end

  rule plugin
    name _ "{"
      _
      attributes:( attribute (whitespace _ attribute)*)?
      _
    "}"
    <LogStash::Config::AST::Plugin>
  end

  rule name
    (
      ([A-Za-z0-9_-]+ <LogStash::Config::AST::Name>)
      / string
    )
  end

  rule attribute
    name _ "=>" _ value
    <LogStash::Config::AST::Attribute>
  end

  rule value
    plugin / bareword / string / number / array / hash
  end

  rule array_value
    bareword / string / number / array / hash
  end

  rule bareword
    [A-Za-z_] [A-Za-z0-9_]+
    <LogStash::Config::AST::Bareword>
  end

  rule double_quoted_string
    ( '"' ( '\"' / !'"' . )* '"' <LogStash::Config::AST::String>)
  end

  rule single_quoted_string
    ( "'" ( "\\'" / !"'" . )* "'" <LogStash::Config::AST::String>)
  end

  rule string
    double_quoted_string / single_quoted_string
  end

  rule regexp
    ( '/' ( '\/' / !'/' . )* '/'  <LogStash::Config::AST::RegExp>)
  end

  rule number
    "-"? [0-9]+ ("." [0-9]*)?
    <LogStash::Config::AST::Number>
  end

  rule array
    "["
    _
    (
      value (_ "," _ value)*
    )?
    _
    "]"
    <LogStash::Config::AST::Array>
  end

  rule hash
    "{"
      _
      hashentries?
      _
    "}"
    <LogStash::Config::AST::Hash>
  end

  rule hashentries
    hashentry (whitespace hashentry)*
    <LogStash::Config::AST::HashEntries>
  end

  rule hashentry
    name:(number / bareword / string) _ "=>" _ value
    <LogStash::Config::AST::HashEntry>
  end

  # Conditions
  rule branch
    if (_ else_if)* (_ else)?
    <LogStash::Config::AST::Branch>
  end

  rule if
    "if" _ condition _ "{" _ (branch_or_plugin _)* "}"
    <LogStash::Config::AST::If>
  end

  rule else_if
    "else" _ "if" _ condition _ "{" _ ( branch_or_plugin _)* "}"
    <LogStash::Config::AST::Elsif>
  end

  rule else
    "else" _ "{" _ (branch_or_plugin _)* "}"
    <LogStash::Config::AST::Else>
  end

  rule condition
    expression (_ boolean_operator _ expression)*
    <LogStash::Config::AST::Condition>
  end

  rule expression
    (
        ("(" _ condition _ ")")
      / negative_expression
      / in_expression
      / not_in_expression
      / compare_expression
      / regexp_expression
      / rvalue
    ) <LogStash::Config::AST::Expression>
  end

  rule negative_expression
    (
        ("!" _ "(" _ condition _ ")")
      / ("!" _ selector)
    ) <LogStash::Config::AST::NegativeExpression>
  end

  rule in_expression
    rvalue _ in_operator _ rvalue
    <LogStash::Config::AST::InExpression>
  end

  rule not_in_expression
    rvalue _ not_in_operator _ rvalue
    <LogStash::Config::AST::NotInExpression>
  end

  rule in_operator
    "in"
  end

  rule not_in_operator
    "not " _ "in"
  end

  rule rvalue
    string / number / selector / array / method_call / regexp
  end

  rule method_call
      method _ "(" _
        (
          rvalue ( _ "," _ rvalue )*
        )?
      _ ")"
    <LogStash::Config::AST::MethodCall>
  end

  rule method
    bareword
  end

  rule compare_expression
    rvalue _ compare_operator _ rvalue
    <LogStash::Config::AST::ComparisonExpression>
  end
  
  rule compare_operator 
    ("==" / "!=" / "<=" / ">=" / "<" / ">") 
    <LogStash::Config::AST::ComparisonOperator>
  end

  rule regexp_expression
    rvalue _  regexp_operator _ (string / regexp)
    <LogStash::Config::AST::RegexpExpression>
  end

  rule regexp_operator
    ("=~" / "!~") <LogStash::Config::AST::RegExpOperator>
  end


  rule boolean_operator
    ("and" / "or" / "xor" / "nand")
    <LogStash::Config::AST::BooleanOperator>
  end

  rule selector
    selector_element+
    <LogStash::Config::AST::Selector>
  end

  rule selector_element
    "[" [^\],]+ "]"
    <LogStash::Config::AST::SelectorElement>
  end

end