Module: Piggly::Parser

Defined in:
lib/piggly/parser.rb,
lib/piggly/parser/nodes.rb,
lib/piggly/parser/traversal.rb

Overview

Pl/pgSQL Parser, returns a tree of NodeClass values (see nodes.rb)

Defined Under Namespace

Modules: Nodes, Traversal Classes: Failure

Class Method Summary collapse

Class Method Details

.grammar_path ⇒ Object 



34
 
# File 'lib/piggly/parser.rb', line 34

def grammar_path; "#{File.dirname(__FILE__)}/parser/grammar.tt" end

.nodes_path ⇒ Object 



35
 
# File 'lib/piggly/parser.rb', line 35

def nodes_path;   "#{File.dirname(__FILE__)}/parser/nodes.rb"   end

.parse(string) ⇒ Object

Returns lazy parse tree (only parsed when the value is needed)



15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
 
# File 'lib/piggly/parser.rb', line 15

def parse(string)
  Util::Thunk.new do
    p = parser

    begin
      # Ensure input is UTF-8 encoded
      input = string.dup.force_encoding('UTF-8')
      # Downcase input for case-insensitive parsing
      input = input.downcase
      tree = p.parse(input)
      tree or raise Failure, "#{p.failure_reason}"
    ensure
      # Restore the original string after parsing
      input.replace(string)
    end
  end
end

.parser ⇒ Object

Returns treetop parser (recompiled as needed)



38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
 
# File 'lib/piggly/parser.rb', line 38

def parser
  return @parser if @parser
  
  load_support

  # @todo: Compare with the version of treetop
  if Util::File.stale?(parser_path, grammar_path)
    # Regenerate the parser when the grammar is updated
    Treetop::Compiler::GrammarCompiler.new.compile(grammar_path, parser_path)
    # Remove existing constant before loading to avoid warnings
    Object.send(:remove_const, :PigglyParser) if Object.const_defined?(:PigglyParser)
    Object.send(:remove_const, :PigglyParserParser) if Object.const_defined?(:PigglyParserParser)
    load parser_path
    @parser = nil  # Clear cache when regenerating
  else
    require parser_path unless defined?(::PigglyParser::Parser)
  end

  @parser ||= ::PigglyParser::Parser.new
end

.parser_path ⇒ Object 



33
 
# File 'lib/piggly/parser.rb', line 33

def parser_path;  "#{File.dirname(__FILE__)}/parser/parser.rb"  end