initial setup and simple term parser

Author: look

.ruby-gemset

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+query-parser

.ruby-version

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+2.4.0

Gemfile

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+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gem 'parslet'
+gem 'minitest'
+gem 'awesome_print'
+gem 'pry'

Gemfile.lock

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+GEM
+  remote: https://rubygems.org/
+  specs:
+    awesome_print (1.7.0)
+    blankslate (3.1.3)
+    coderay (1.1.1)
+    method_source (0.8.2)
+    minitest (5.10.1)
+    parslet (1.7.1)
+      blankslate (>= 2.0, <= 4.0)
+    pry (0.10.4)
+      coderay (~> 1.1.0)
+      method_source (~> 0.8.1)
+      slop (~> 3.4)
+    slop (3.6.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  awesome_print
+  minitest
+  parslet
+  pry
+
+BUNDLED WITH
+   1.14.6

term_parser.rb

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+require 'parslet'
+
+class TermParser < Parslet::Parser
+  rule(:term) { match('[a-zA-Z0-9]').repeat(1) }
+  rule(:space)  { match('\s').repeat(1) }
+  rule(:query) { (term.as(:term) >> (space >> term.as(:term)).repeat).as(:query) }
+  root(:query)
+end
+
+class TermTransformer < Parslet::Transform
+  rule(:term => simple(:term)) { term.to_s }
+  rule(:query => sequence(:terms)) { TermQuery.new(terms) }
+end
+
+# A query represented by a list of parsed user terms
+class TermQuery
+  attr_accessor :terms
+
+  def initialize(terms)
+    self.terms = terms
+  end
+
+  def to_elasticsearch
+    {
+      :query => {
+        :match => {
+          :title => {
+            :query => terms.join(" "),
+            :operator => "or"
+          }
+        }
+      }
+    }
+  end
+end

tests.rb

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+require_relative 'term_parser'
+require 'minitest/autorun'
+require 'awesome_print'
+
+class ParserTests < Minitest::Test
+  def test_term_parser
+    tree = TermParser.new.parse("foo bar baz")
+    ap tree
+
+    term_query = TermTransformer.new.apply(tree)
+    ap term_query.to_elasticsearch
+  end
+end