Class: Archsight::Query::Parser

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

Overview

Recursive descent parser for the architecture query language.

Instance Method Summary collapse

Constructor Details

#initialize(tokens) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/archsight/query/parser.rb', line 8

def initialize(tokens)
  @tokens = tokens
  @position = 0
end

Instance Method Details

#parse ⇒ Object 



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# File 'lib/archsight/query/parser.rb', line 13

def parse
  # Check for kind filter prefix: "Kind: expression"
  kind_filter = nil
  # Check it's a valid Kind (starts with capital letter)
  if current_token.type == :IDENTIFIER && peek_token&.type == :COLON && (current_token.value =~ /^[A-Z]/)
    kind_filter = current_token.value
    advance # consume identifier
    advance # consume colon
  end

  # Expression is optional when kind filter is present
  # "TechnologyArtifact:" is valid and returns all resources of that kind
  expression = if current_token.type == :EOF
                 nil
               else
                 parse_or_expression
               end

  # Empty query (no kind filter and no expression) is an error
  if kind_filter.nil? && expression.nil?
    raise Archsight::Query::ParseError.new(
      "Empty query: expected kind filter or expression",
      position: 0,
      source: nil
    )
  end

  expect(:EOF)

  Archsight::Query::AST::QueryNode.new(kind_filter, expression)
end