1 files changed, 102 insertions, 0 deletions
diff --git a/lib/hcl2.rb b/lib/hcl2.rb
index fa7b2e7..e6f2fb8 100644
--- a/lib/hcl2.rb
+++ b/lib/hcl2.rb
@@ -1,7 +1,109 @@
 # frozen_string_literal: true
 
+require "parslet"
 require_relative "hcl2/version"
 
 module Hcl2
   class Error < StandardError; end
+
+  class Parser < ::Parslet::Parser
+    rule(:alpha) { match['a-zA-Z'] }
+    rule(:assign) { str('=') }
+    rule(:colon) { str(':') }
+    rule(:comma) { str(',') }
+    rule(:comment) { (str('#') | str('//')) >> ((str("\n") >> str("\r").maybe).absent? >> any).repeat >> eol }
+    rule(:crlf) { match('[\r\n]') }
+    rule(:digit) { match('\d') }
+    rule(:dot) { str('.') }
+    rule(:eol) { whitespace? >> crlf.repeat }
+    rule(:greater_than_or_equal_to) { str('>=') }
+    rule(:hyphen) { str('-') }
+    rule(:lbracket) { str('[') }
+    rule(:lcurly) { str('{') }
+    rule(:major) { number }
+    rule(:major_minor) { (number >> dot >> number) }
+    rule(:major_minor_patch) { number >> dot >> number >> dot >> number }
+    rule(:multiline_comment) { str('/*') >> (str('*/').absent? >> any).repeat >> str('*/') }
+    rule(:number) { digit.repeat }
+    rule(:plus) { str('+') }
+    rule(:pre_release) { hyphen >> (alpha | digit).repeat }
+    rule(:pre_release?) { pre_release.maybe }
+    rule(:quote) { str('"') }
+    rule(:rbracket) { str(']') }
+    rule(:rcurly) { str('}') }
+    rule(:slash) { str('/') }
+    rule(:space) { match('\s') }
+    rule(:tilda_wacka) { str('~>') }
+    rule(:version) { number >> dot >> number >> dot >> number >> pre_release? }
+    rule(:whitespace) { (multiline_comment | comment | space).repeat }
+    rule(:whitespace?) { whitespace.maybe }
+
+    rule(:pessimistic_version_constraint) do
+      tilda_wacka >> whitespace >> (
+        major_minor_patch |
+        major_minor |
+        major
+      )
+    end
+
+    rule(:greater_than_or_equal_to_version) do
+      greater_than_or_equal_to >> whitespace >> (
+        major_minor_patch |
+        major_minor |
+        major
+      )
+    end
+
+    rule(:version_constraint) do
+      pessimistic_version_constraint | greater_than_or_equal_to_version
+    end
+
+    rule :version_assignment do
+      str('version') >> whitespace >> assign >> whitespace >> quote >> version.as(:version) >> quote
+    end
+
+    rule :constraint_assignment do
+      str('constraints') >> whitespace >> assign >> whitespace >> quote >> version_constraint.as(:constraints) >> quote
+    end
+
+    rule :string do
+      quote >> (
+        digit | dot | alpha | str('~> ') | slash | colon | assign | plus
+      ).repeat(1).as(:value) >> quote
+    end
+
+    rule :array_item do
+      whitespace? >> string >> comma.maybe >> eol
+    end
+
+    rule :array do
+      lbracket >> eol >> array_item.repeat >> whitespace >> rbracket
+    end
+
+    rule :argument_value do
+      (array.as(:values) | string) >> eol
+    end
+
+    rule :argument do
+      whitespace >> alpha.repeat(1).as(:name) >> whitespace >> assign >> whitespace >> argument_value
+    end
+
+    rule :block_body do
+      lcurly >> crlf >> argument.repeat.as(:arguments) >> rcurly
+    end
+
+    rule :identifier do
+      whitespace >> quote >> (alpha | dot | slash).repeat(1).as(:name) >> quote >> whitespace
+    end
+
+    rule :block do
+      alpha.repeat(1).as(:type) >> identifier >> block_body
+    end
+
+    rule :blocks do
+      whitespace? >> (block >> eol.maybe).repeat(1).as(:blocks)
+    end
+
+    root(:blocks)
+  end
 end