Class: Vines::Services::VQL::Compiler

Inherits:
Object
  • Object
show all
Defined in:
lib/vines/services/vql/compiler.rb

Overview

Compiles Vines Query Language queries into JavaScript for CouchDB views and SQL for sqlite queries. The output of the compiler is a fully formed query that can be sent directly to the database.

Instance Method Summary collapse

Instance Method Details

#to_full_js(services) ⇒ Object

Return the compiled CouchDB map function for all services. Raise an exception on compilation failure. The exception’s error message can be shown to the user to debug the syntax.



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# File 'lib/vines/services/vql/compiler.rb', line 38

def to_full_js(services)
  maps = services.map do |service|
    expr = VinesQL.parse(service.code.strip)
    %Q{
      try {
        var match = #{expr.js};
        if (match) {
          emit([0, '#{service.id}'], {name: name, os: os});
          emit([1, name], '#{service.id}');
        }
      } catch(e) {
        log(e.message);
      }
    }
  end

  %Q{
    function(doc) {
      if (doc.type != 'System') return;
      var name = doc['_id'].replace('system:', '');
      var os = doc.ohai.kernel.os.toLowerCase().replace('gnu/', '');
      #{maps.join}
    }
  }
end

#to_js(code) ⇒ Object

Return the compiled CouchDB map function. Raise an exception on compilation failure. The exception’s error message can be shown to the user to debug the syntax.

Raises:

  • (ArgumentError) 


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# File 'lib/vines/services/vql/compiler.rb', line 15

def to_js(code)
  raise ArgumentError, 'code required' if code.nil? || code.strip.empty?
  expr = VinesQL.parse(code.strip)
  %Q{
    function(doc) {
      if (doc.type != 'System') return;
      try {
        var match = #{expr.js};
        if (match) {
          var name = doc['_id'].replace('system:', '');
          var os = doc.ohai.kernel.os.toLowerCase().replace('gnu/', '');
          emit(name, os);
        }
      } catch(e) {
        log(e.message);
      }
    }
  }
end

#to_sql(code) ⇒ Object

Return the compiled sqlite SQL query along with an array of parameter replacement values. Raise an exception on compilation failure. The exception’s error message can be shown to the user to debug the syntax.

Raises:

  • (ArgumentError) 


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# File 'lib/vines/services/vql/compiler.rb', line 67

def to_sql(code)
  raise ArgumentError, 'code required' if code.nil? || code.strip.empty?
  expr = VinesQL.parse(code.strip)

  keys, values = expr.params.partition.each_with_index {|p, ix| ix % 2 == 0 }
  joins = keys.each_with_index.map do |k, ix|
    "inner join attributes a%s on id=a%s.system_id and a%s.key=?" % [ix, ix, ix]
  end

  where = expr.sql.tap do |sql|
    values.size.times do |ix|
      sql.sub!(/(^|[^\.])value/, "\\1a#{ix}.value")
    end
  end

  sql = %Q{
    select name, os from systems
    #{joins.join("\n")}
    where #{where}
    order by name
  }

  [sql, [keys, values].flatten]
end