Add Cypher lexer (#1423)

This commit adds a lexer for Cypher.

Co-authored-by: Michael Camilleri <mike@inqk.net>

lib/rouge/demos/cypher

@@ -0,0 +1,5 @@
+// Cypher Mode for Rouge
+CREATE (john:Person {name: 'John'})
+MATCH (user)-[:friend]->(follower)
+WHERE user.name IN ['Joe', 'John', 'Sara', 'Maria', 'Steve'] AND follower.name =~ 'S.*'
+RETURN user.name, follower.name

lib/rouge/lexers/cypher.rb

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+# -*- coding: utf-8 -*- #
+# frozen_string_literal: true
+
+module Rouge
+  module Lexers
+    class Cypher < RegexLexer
+      tag 'cypher'
+      aliases 'cypher'
+      filenames '*.cypher'
+      mimetypes 'application/x-cypher-query'
+
+      title "Cypher"
+      desc 'The Cypher query language (neo4j.com/docs/cypher-manual)'
+
+      def self.functions
+        @functions ||= Set.new %w(
+          ABS ACOS ALLSHORTESTPATHS ASIN ATAN ATAN2 AVG CEIL COALESCE COLLECT
+          COS COT COUNT DATE DEGREES E ENDNODE EXP EXTRACT FILTER FLOOR
+          HAVERSIN HEAD ID KEYS LABELS LAST LEFT LENGTH LOG LOG10 LOWER LTRIM
+          MAX MIN NODE NODES PERCENTILECONT PERCENTILEDISC PI RADIANS RAND
+          RANGE REDUCE REL RELATIONSHIP RELATIONSHIPS REPLACE REVERSE RIGHT
+          ROUND RTRIM SHORTESTPATH SIGN SIN SIZE SPLIT SQRT STARTNODE STDEV
+          STDEVP STR SUBSTRING SUM TAIL TAN TIMESTAMP TOFLOAT TOINT TOINTEGER
+          TOSTRING TRIM TYPE UPPER
+        )
+      end
+
+      def self.predicates
+        @predicates ||= Set.new %w(
+          ALL AND ANY CONTAINS EXISTS HAS IN NONE NOT OR SINGLE XOR
+        )
+      end
+
+      def self.keywords
+        @keywords ||= Set.new %w(
+          AS ASC ASCENDING ASSERT BY CASE COMMIT CONSTRAINT CREATE CSV CYPHER
+          DELETE DESC DESCENDING DETACH DISTINCT DROP ELSE END ENDS EXPLAIN
+          FALSE FIELDTERMINATOR FOREACH FROM HEADERS IN INDEX IS JOIN LIMIT
+          LOAD MATCH MERGE NULL ON OPTIONAL ORDER PERIODIC PROFILE REMOVE
+          RETURN SCAN SET SKIP START STARTS THEN TRUE UNION UNIQUE UNWIND USING
+          WHEN WHERE WITH CALL YIELD
+        )
+      end
+
+      state :root do
+        rule %r/[\s]+/, Text
+        rule %r(//.*?$), Comment::Single
+
+        rule %r([*+\-<>=&|~%^]), Operator
+        rule %r/[{}),;\[\]]/, Str::Symbol
+
+        # literal number
+        rule %r/(\w+)(:)(\s*)(-?[._\d]+)/ do
+          groups Name::Label, Str::Delimiter, Text::Whitespace, Num
+        end
+
+        # function-like
+        # - "name("
+        # - "name  ("
+        # - "name ("
+        rule %r/(\w+)(\s*)(\()/ do |m|
+          name = m[1].upcase
+          if self.class.functions.include? name
+            groups Name::Function, Text::Whitespace, Str::Symbol
+          elsif self.class.keywords.include? name
+            groups Keyword, Text::Whitespace, Str::Symbol
+          else
+            groups Name, Text::Whitespace, Str::Symbol
+          end
+        end
+
+        rule %r/:\w+/, Name::Class
+
+        # number range
+        rule %r/(-?\d+)(\.\.)(-?\d+)/ do
+          groups Num, Operator, Num
+        end
+
+        # numbers
+        rule %r/(\d+\.\d*|\d*\.\d+)(e[+-]?\d+)?/i, Num::Float
+        rule %r/\d+e[+-]?\d+/i, Num::Float
+        rule %r/0[0-7]+/, Num::Oct
+        rule %r/0x[a-f0-9]+/i, Num::Hex
+        rule %r/\d+/, Num::Integer
+
+        rule %r([.\w]+:), Name::Property
+
+        # remaining "("
+        rule %r/\(/, Str::Symbol
+
+        rule %r/[.\w$]+/ do |m|
+          match = m[0].upcase
+          if self.class.predicates.include? match
+            token Operator::Word
+          elsif self.class.keywords.include? match
+            token Keyword
+          else
+            token Name
+          end
+        end
+
+        rule %r/"(\\\\|\\"|[^"])*"/, Str::Double
+        rule %r/'(\\\\|\\'|[^'])*'/, Str::Single
+        rule %r/`(\\\\|\\`|[^`])*`/, Str::Backtick
+      end
+    end
+  end
+end

spec/lexers/cypher_spec.rb

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+# -*- coding: utf-8 -*- #
+# frozen_string_literal: true
+
+describe Rouge::Lexers::Cypher do
+  let(:subject) { Rouge::Lexers::Cypher.new }
+
+  describe 'guessing' do
+    include Support::Guessing
+
+    it 'guesses by filename' do
+      assert_guess :filename => 'foo.cypher'
+    end
+
+    it 'guesses by mimetype' do
+      assert_guess :mimetype => 'application/x-cypher-query'
+    end
+  end
+end

spec/visual/samples/cypher

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+// Cypher for Rouge
+CREATE (john:Person {name: 'John'})
+CREATE (joe:Person {name: 'Joe'})
+CREATE (steve:Person {name: 'Steve'})
+CREATE (sara:Person {name: 'Sara'})
+CREATE (maria:Person {name: 'Maria'})
+CREATE (john)-[:KNOWS]->(joe)-[:KNOWS]->(steve)
+CREATE (john)-[:KNOWS]->(sara)-[:KNOWS]->(maria)
+
+MATCH (joe { name: 'Joe' })-[:knows*2..2]-(friend_of_friend)
+WHERE NOT (joe)-[:knows]-(friend_of_friend)
+RETURN friend_of_friend.name, COUNT(*)
+ORDER BY COUNT(*) DESC , friend_of_friend.name
+
+LOAD CSV WITH HEADERS FROM "https://dl.dropboxusercontent.com/u/14493611/movies_setup.csv" AS row
+MERGE (m:Movie {title:row.title}) ON CREATE SET m.tagline = row.tagline,m.released=row.released
+MERGE (p:Person {name:row.name}) ON CREATE SET p.born = row.born
+FOREACH (_ in CASE row.type WHEN "ACTED_IN" then [1] else [] end |
+   MERGE (p)-[r:ACTED_IN]->(m) ON CREATE SET r.roles = split(row.roles,";")[0..-1]
+)
+FOREACH (_ in CASE row.type WHEN "DIRECTED" then [1] else [] end | MERGE (p)-[:DIRECTED]->(m))
+FOREACH (_ in CASE row.type WHEN "PRODUCED" then [1] else [] end | MERGE (p)-[:PRODUCED]->(m))
+FOREACH (_ in CASE row.type WHEN "WROTE"    then [1] else [] end | MERGE (p)-[:WROTE   ]->(m))
+FOREACH (_ in CASE row.type WHEN "REVIEWED" then [1] else [] end | MERGE (p)-[:REVIEWED]->(m))
+
+MATCH (n:Person { name: $name })
+RETURN n
+
+UNWIND $props AS properties
+CREATE (n:Person)
+SET n = properties
+RETURN n
+
+MATCH (n)
+WHERE id(n)= $id
+RETURN n.name
+
+START n=node:people(name = $value)
+RETURN n
+
+MATCH (n) RETURN n // This is an end of line comment
+
+MATCH (n) WHERE n.property = '//This is NOT a comment' RETURN n
+
+MATCH (a:Person { name: 'Keanu Reeves' })
+RETURN [(a)-->(b) WHERE b:Movie | b.released] AS years
+
+// alias with backticks
+MATCH (p:Person {born:  1965})
+RETURN p.name AS name, p.born AS `birth year`
+
+// complex queries
+LOAD CSV WITH HEADERS FROM 'https://data.neo4j.com/advanced-cypher/movies2.csv' AS row
+MERGE (m:Movie {id:toInteger(row.movieId)})
+   ON CREATE SET m.title=row.title, m.avgVote=toFloat(row.avgVote),
+      m.releaseYear=toInteger(row.releaseYear), m.genres=split(row.genres,":")
+MERGE (p:Person {id: toInteger(row.personId)})
+   ON CREATE SET p.name = row.name, p.born = toInteger(row.birthYear),
+      p.died = toInteger(row.deathYear)
+WITH row, m, p
+CALL apoc.do.when(row.personType = 'ACTOR',
+     "MERGE (p)-[:ACTED_IN {roles: split(coalesce(row.characters,''), ':')}]->(m)
+          ON CREATE SET p:Actor",
+     "MERGE (p)-[:DIRECTED]->(m)
+          ON CREATE SET p:Director",
+      {row:row, m:m, p:p}) YIELD value AS value
+SET p:Person  // cannot end query with APOC call
+
+PROFILE LOAD CSV WITH HEADERS FROM
+     'https://data.neo4j.com/advanced-cypher/movies2.csv' AS row
+WITH row.movieId as movieId, row.title as title, row.genres as genres,
+toInteger(row.releaseYear) as releaseYear, toFloat(row.avgVote) as avgVote,
+collect({id: row.personId, name:row.name, born: toInteger(row.birthYear), died:toInteger(row.deathYear),personType: row.personType, roles: split(coalesce(row.characters,""),':')}) as people
+MERGE (m:Movie {id:movieId})
+   ON CREATE SET m.title=title, m.avgVote=avgVote,
+      m.releaseYear=releaseYear, m.genres=split(genres,":")
+WITH *
+UNWIND people as person
+MERGE (p:Person {id: person.id})
+   ON CREATE SET p.name = person.name, p.born = person.born, p.died = person.died
+WITH  m, person, p
+CALL apoc.do.when(person.personType = 'ACTOR',
+     "MERGE (p)-[:ACTED_IN {roles: person.roles}]->(m)
+                ON CREATE SET p:Actor",
+     "MERGE (p)-[:DIRECTED]->(m)
+         ON CREATE SET p:Director",
+     {m:m, p:p, person:person}) YIELD value AS value
+RETURN count()  // cannot end query with APOC call
+
+MATCH (m:Movie)
+WITH collect(m.title) AS Movies, collect (m.released) AS Released
+WITH Movies, Released,
+[x IN Released | date().year - x + 1] AS YearsAgo
+RETURN Movies, YearsAgo
+
+MATCH (p:Person)-[rel:ACTED_IN]->(m:Movie {title: 'The Matrix'})
+RETURN p, rel, m
+
+MATCH (p:Person)-[rel]->(:Movie {title:'The Matrix'})
+RETURN p.name, type(rel)
+
+RETURN sign(-17), sign(0.1), sign(0xABCDEF), sign(000)