Class: Zon::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/zon/parser.rb

Constant Summary collapse

STRUCT = 
0
ARRAY = 
1

Instance Method Summary collapse

Constructor Details

#initialize(tokens) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/zon/parser.rb', line 11

def initialize(tokens)
  @tokens = tokens
  @curr = nil
end

Instance Method Details

#next ⇒ Object 



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# File 'lib/zon/parser.rb', line 16

def next
  begin
    @curr = @tokens.next
  rescue
    @curr = nil
  end
end

#next_equals ⇒ Object 



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# File 'lib/zon/parser.rb', line 135

def next_equals
  self.next

  if not @curr or not @curr.type == Lexer::TokenType::EQUALS
    raise "Expected '=' token but got '#{@curr.value}'"
  end
end

#next_key ⇒ Object 



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# File 'lib/zon/parser.rb', line 91

def next_key
  self.next

  if @curr and @curr.type == Lexer::TokenType::LITERAL
    @curr.value[1..].to_sym # create sym from string without the '.'
  elsif
    raise "Expected literal token but got '#{@curr.value}'"
  end
end

#next_token?(type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/zon/parser.rb', line 79

def next_token?(type)
  self.peek_token.type == type 
end

#next_value ⇒ Object 



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# File 'lib/zon/parser.rb', line 101

def next_value
  self.next

  raise "No token for value" if not @curr

  value = nil

  if @curr.type == Lexer::TokenType::LITERAL
    value = @curr.value[1..].to_sym
  elsif @curr.type == Lexer::TokenType::STRING
    value = @curr.value[1..-2]
  elsif @curr.type == Lexer::TokenType::NUMBER
    begin
      if @curr.value.include? "."
        value = Float(@curr.value)
      else
        value = Integer(@curr.value)
      end
    rescue
      raise "Unable to parse number from value '#{@curr.value}'"
    end
  elsif @curr.type == Lexer::TokenType::BOOLEAN
    if @curr.value == "true"
      value = true
    else
      value = false
    end
  end

  raise "Unable to parse value from '#{@curr.value}'" if not value

  value
end

#parse ⇒ Object 



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# File 'lib/zon/parser.rb', line 24

def parse
  if self.next_token? Lexer::TokenType::LBRACE
    self.next

    if self.next_token? Lexer::TokenType::RBRACE # '.{ }'
      self.next
      return {} # this could either be a array or a struct... we don't know
    end

    v = self.parse

    if v.is_a? Symbol and self.next_token? Lexer::TokenType::EQUALS
      # This is a Zon struct, i.e. translate it to a Ruby hash
      k = v
      self.next_equals # skip equals
      v = self.parse

      h = {k => v}

      loop do # fetch remaining key value pairs
        self.next if self.next_token? Lexer::TokenType::COMMA
        if self.next_token? Lexer::TokenType::RBRACE
          self.next
          break
        end

        k = self.next_key
        self.next_equals
        v = self.parse
        h[k] = v
      end

      return h
    else
      # Must be an array
      
      a = [v]

      loop do # fetch remaining values
        self.next if self.next_token? Lexer::TokenType::COMMA
        if self.next_token? Lexer::TokenType::RBRACE
          self.next
          break
        end
        
        a.append self.parse
      end

      return a
    end
  else
    return self.next_value
  end
end

#peek_token ⇒ Object 



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# File 'lib/zon/parser.rb', line 83

def peek_token
  begin
    @tokens.peek
  rescue
    nil
  end
end