Merge pull request #1888 from chef/dr/nginx_parser

add the Nginx parser

lib/utils/nginx_parser.rb

@@ -0,0 +1,74 @@
+# encoding: utf-8
+# author: Dominik Richter
+# author: Christoph Hartmann
+
+require 'parslet'
+
+class NginxParser < Parslet::Parser
+  root :outermost
+  # only designed for rabbitmq config files for now:
+  rule(:outermost) { filler? >> exp.repeat }
+
+  rule(:filler?) { one_filler.repeat }
+  rule(:one_filler) { match('\s+') | match["\n"] | comment }
+  rule(:space)   { match('\s+') }
+  rule(:comment) { str('#') >> (match["\n\r"].absent? >> any).repeat }
+
+  rule(:exp) {
+    section | assignment
+  }
+  rule(:assignment) {
+    (identifier >> values.maybe.as(:args)).as(:assignment) >> str(';') >> filler?
+  }
+
+  rule(:identifier) {
+    (match('[a-zA-Z]') >> match('[a-zA-Z0-9_]').repeat).as(:identifier) >> space >> space.repeat
+  }
+
+  rule(:value) {
+    ((match('[#;{]').absent? >> any) >> (
+      str('\\') >> any | match('[#;{]|\s').absent? >> any
+    ).repeat).as(:value) >> space.repeat
+  }
+  rule(:values) {
+    value.repeat >> space.maybe
+  }
+
+  rule(:section) {
+    identifier.as(:section) >> values.maybe.as(:args) >> str('{') >> filler? >> exp.repeat.as(:expressions) >> str('}') >> filler?
+  }
+end
+
+class NginxTransform < Parslet::Transform
+  Group = Struct.new(:id, :args, :body)
+  Exp = Struct.new(:key, :vals)
+
+  def self.assemble_binary(seq)
+    b = ErlangBitstream.new
+    seq.each { |i| b.add(i) }
+    b.value
+  end
+
+  rule(section: { identifier: simple(:x) }, args: subtree(:y), expressions: subtree(:z)) { Group.new(x.to_s, y, z) }
+  rule(assignment: { identifier: simple(:x), args: subtree(:y) }) { Exp.new(x.to_s, y) }
+  rule(value: simple(:x)) { x.to_s }
+end
+
+class NginxConfig
+  def self.parse(content)
+    lex = NginxParser.new.parse(content)
+    tree = NginxTransform.new.apply(lex)
+    gtree = NginxTransform::Group.new(nil, '', tree)
+    read_nginx_group(gtree)
+  end
+
+  def self.read_nginx_group(t)
+    agg_conf = Hash.new([])
+    agg_conf['_'] = t.args unless t.args == ''
+
+    groups, conf = t.body.partition { |i| i.is_a? NginxTransform::Group }
+    conf.each { |x| agg_conf[x.key] += [x.vals.join(' ')] }
+    groups.each { |x| agg_conf[x.id] += [read_nginx_group(x)] }
+    agg_conf
+  end
+end

test/unit/utils/nginx_parser_test.rb

@@ -0,0 +1,84 @@
+# encoding: utf-8
+# author: Dominik Richter
+# author: Christoph Hartmann
+
+require 'helper'
+require 'utils/nginx_parser'
+
+describe NginxParser do
+  def parse(c)
+    NginxParser.new.parse(c)
+  end
+
+  def parsestr(c)
+    parse(c).to_s
+  end
+
+  def parse_file(f)
+    parse(File.read(f))
+  end
+
+  it 'parses an empty nginx file' do
+    _(parsestr('')).must_equal ''
+  end
+
+  it 'parses a file with a comment' do
+    _(parsestr("# some nice comment")).must_equal "# some nice comment"
+  end
+
+  it 'parses a simple assignment' do
+    _(parsestr("assignment a;")).must_equal "[{:assignment=>{:identifier=>\"assignment\"@0, :args=>[{:value=>\"a\"@11}]}}]"
+  end
+
+  it 'parses an empty group' do
+    _(parsestr("group {}")).must_equal "[{:section=>{:identifier=>\"group\"@0}, :args=>\"\", :expressions=>[]}]"
+  end
+
+  it 'parses a group with parameters' do
+    _(parsestr("group a b {}")).must_equal "[{:section=>{:identifier=>\"group\"@0}, :args=>[{:value=>\"a\"@6}, {:value=>\"b\"@8}], :expressions=>[]}]"
+  end
+
+  it 'parses a group with a body' do
+    _(parsestr("group {\na b;\n}")).must_equal "[{:section=>{:identifier=>\"group\"@0}, :args=>\"\", :expressions=>[{:assignment=>{:identifier=>\"a\"@8, :args=>[{:value=>\"b\"@10}]}}]}]"
+  end
+
+  it 'parses a group with arguments and a body' do
+    _(parsestr("group c {\na b;\n}")).must_equal "[{:section=>{:identifier=>\"group\"@0}, :args=>[{:value=>\"c\"@6}], :expressions=>[{:assignment=>{:identifier=>\"a\"@10, :args=>[{:value=>\"b\"@12}]}}]}]"
+  end
+
+  it 'parses nested groups' do
+    _(parsestr("f {g {h {\n# comment\n}}}")).must_equal "[{:section=>{:identifier=>\"f\"@0}, :args=>\"\", :expressions=>[{:section=>{:identifier=>\"g\"@3}, :args=>\"\", :expressions=>[{:section=>{:identifier=>\"h\"@6}, :args=>\"\", :expressions=>[]}]}]}]"
+  end
+end
+
+describe NginxTransform do
+  def parse(c)
+    NginxTransform.new.apply(NginxParser.new.parse(c))
+  end
+
+  it 'transforms and empty file' do
+    _(parse('')).must_equal ''
+  end
+
+  it 'transforms an assignment' do
+    _(parse('a b;')).must_equal [NginxTransform::Exp.new('a', ['b'])]
+  end
+
+  it 'transforms an empty group' do
+    _(parse('group {}')).must_equal [NginxTransform::Group.new('group','',[])]
+  end
+
+  it 'transforms a simple group' do
+    _(parse("group a {\na b;\n}")).must_equal [NginxTransform::Group.new('group',['a'],[NginxTransform::Exp.new('a', ['b'])])]
+  end
+
+  it 'transforms a deeply nested group' do
+    _(parse("f { g { h {\na b;\n}}}")).must_equal [
+      NginxTransform::Group.new('f', '', [
+        NginxTransform::Group.new('g', '', [
+          NginxTransform::Group.new('h', '', [NginxTransform::Exp.new('a', ['b'])])
+        ])
+      ])
+    ]
+  end
+end