Class: Resyma::Evaluator

Inherits:
Object
  • Object
show all
Defined in:
lib/resyma/parsetree.rb

Overview

Evaluator for Resyma::Core::ParseTree

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Evaluator

Returns a new instance of Evaluator.



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# File 'lib/resyma/parsetree.rb', line 61

def initialize
  @rules = {}
end

Instance Method Details

#def_rule(type) {|AST, The, filename, lino| ... } ⇒ nil

Define a evaluation rule

Parameters:

  • type (Symbol, Array<Symbol>) —

    Type(s) assocating to the rule

Yield Parameters:

  • AST (Parser::AST::Node) —

    of the node

  • The (Binding) —

    environment surrounding the DSL

  • filename (String) —

    Source location

  • lino (Integer) —

    Source location

Returns:

  • (nil) —

    Nothing



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# File 'lib/resyma/parsetree.rb', line 76

def def_rule(type, &block)
  types = type.is_a?(Array) ? type : [type]
  types.each { |sym| @rules[sym] = block }
  nil
end

#evaluate(parsetree, bd, filename, lino) ⇒ Object

Evaluate AST of the parse tree

Parameters:

  • parsetree (Resyma::Core::ParseTree) —

    A parse tree whose ‘ast` is not `nil`

  • bd (Binding) —

    Environment

  • filename (String) —

    Source location

  • lino (Integer) —

    Source location

Returns:

  • (Object) —

    Reterning value of corresponding evaluating rule



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# File 'lib/resyma/parsetree.rb', line 93

def evaluate(parsetree, bd, filename, lino)
  if parsetree.ast.nil?
    raise NoASTError,
          "AST of parse trees is necessary for evaluation"
  end

  evaluate_ast(parsetree.ast, bd, filename, lino)
end

#evaluate_ast(ast, bd, filename, lino) ⇒ Object

Evaluate the AST by defined rules

Parameters:

  • ast (Parser::AST::Node) —

    An abstract syntax tree

  • bd (Binding) —

    Environment

  • filename (String) —

    Source location

  • lino (Integer) —

    Source location

Returns:

  • (Object) —

    Returning value of corresponding evaluating rule



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# File 'lib/resyma/parsetree.rb', line 112

def evaluate_ast(ast, bd, filename, lino)
  evaluator = @rules[ast.type]
  if evaluator.nil?
    fallback ast, bd, filename, lino
  else
    evaluator.call(ast, bd, filename, lino)
  end
end

#fallback(ast, bd, filename, lino) ⇒ Object

Fallback evaluating method. AST whose type is not defined by current

evaluator will be passed to this method. The default action is unparse
the AST by `unparser` and evaluate the string by `eval`

Parameters:

  • ast (Parser::AST::Node) —

    An abstract syntax tree

  • bd (Binding) —

    The environment

  • filename (String) —

    Source location

  • lino (Integer) —

    Source location

Returns:

  • (Object) —

    Evaluating result



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# File 'lib/resyma/parsetree.rb', line 133

def fallback(ast, bd, filename, lino)
  string = Unparser.unparse(ast)
  eval(string, bd, filename, lino)
end