Add Janet lexer (rouge-ruby#1558)

This commit adds a lexer for Janet.

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

lib/rouge/demos/janet

@@ -0,0 +1,3 @@
+(defn a-fun
+  "A function"
+  (do-something))

lib/rouge/lexers/janet.rb

@@ -0,0 +1,217 @@
+# -*- coding: utf-8 -*- #
+# frozen_string_literal: true
+
+module Rouge
+  module Lexers
+    class Janet < RegexLexer
+      title "Janet"
+      desc "The Janet programming language (janet-lang.org)"
+
+      tag 'janet'
+      aliases 'jdn'
+
+      filenames '*.janet', '*.jdn'
+
+      mimetypes 'text/x-janet', 'application/x-janet'
+
+      def self.specials
+        @specials ||= Set.new %w(
+          break def do fn if quote quasiquote splice set unquote var while
+        )
+      end
+
+      def self.bundled
+        @bundled ||= Set.new %w(
+          % %= * *= + ++ += - -- -= -> ->> -?> -?>> / /= < <= = > >=
+          abstract? accumulate accumulate2 all all-bindings
+          all-dynamics and apply array array/concat array/ensure
+          array/fill array/insert array/new array/new-filled
+          array/peek array/pop array/push array/remove array/slice
+          array? as-> as?-> asm assert bad-compile bad-parse band
+          blshift bnot boolean? bor brshift brushift buffer buffer/bit
+          buffer/bit-clear buffer/bit-set buffer/bit-toggle
+          buffer/blit buffer/clear buffer/fill buffer/format
+          buffer/new buffer/new-filled buffer/popn buffer/push-byte
+          buffer/push-string buffer/push-word buffer/slice buffer?
+          bxor bytes? case cfunction? chr cli-main comment comp
+          compare compare= compare< compare<= compare> compare>=
+          compile complement comptime cond coro count debug
+          debug/arg-stack debug/break debug/fbreak debug/lineage
+          debug/stack debug/stacktrace debug/step debug/unbreak
+          debug/unfbreak debugger-env dec deep-not= deep= default
+          default-peg-grammar def- defer defmacro defmacro- defn defn-
+          defglobal describe dictionary? disasm distinct doc doc*
+          doc-format dofile drop drop-until drop-while dyn each eachk
+          eachp eachy edefer eflush empty? env-lookup eprin eprinf
+          eprint eprintf error errorf eval eval-string even? every?
+          extreme false? fiber/can-resume? fiber/current fiber/getenv
+          fiber/maxstack fiber/new fiber/root fiber/setenv
+          fiber/setmaxstack fiber/status fiber? file/close file/flush
+          file/open file/popen file/read file/seek file/temp
+          file/write filter find find-index first flatten flatten-into
+          flush for forv freeze frequencies function? gccollect
+          gcinterval gcsetinterval generate gensym get get-in getline
+          hash idempotent? identity import import* if-let if-not
+          if-with in inc indexed? int/s64 int/u64 int? interleave
+          interpose invert janet/build janet/config-bits janet/version
+          juxt juxt* keep keys keyword keyword? kvs label last length
+          let load-image load-image-dict loop macex macex1 make-env
+          make-image make-image-dict map mapcat marshal math/-inf
+          math/abs math/acos math/acosh math/asin math/asinh math/atan
+          math/atan2 math/atanh math/cbrt math/ceil math/cos math/cosh
+          math/e math/erf math/erfc math/exp math/exp2 math/expm1
+          math/floor math/gamma math/hypot math/inf math/log
+          math/log10 math/log1p math/log2 math/next math/pi math/pow
+          math/random math/rng math/rng-buffer math/rng-int
+          math/rng-uniform math/round math/seedrandom math/sin
+          math/sinh math/sqrt math/tan math/tanh math/trunc match max
+          mean merge merge-into min mod module/add-paths module/cache
+          module/expand-path module/find module/loaders module/loading
+          module/paths nan? nat? native neg? net/chunk net/close
+          net/connect net/read net/server net/write next nil? not not=
+          number? odd? one? or os/arch os/cd os/chmod os/clock
+          os/cryptorand os/cwd os/date os/dir os/environ os/execute
+          os/exit os/getenv os/link os/lstat os/mkdir os/mktime
+          os/perm-int os/perm-string os/readlink os/realpath os/rename
+          os/rm os/rmdir os/setenv os/shell os/sleep os/stat
+          os/symlink os/time os/touch os/umask os/which pairs parse
+          parser/byte parser/clone parser/consume parser/eof
+          parser/error parser/flush parser/has-more parser/insert
+          parser/new parser/produce parser/state parser/status
+          parser/where partial partition peg/compile peg/match pos?
+          postwalk pp prewalk prin prinf print printf product prompt
+          propagate protect put put-in quit range reduce reduce2
+          repeat repl require resume return reverse reversed root-env
+          run-context scan-number seq setdyn shortfn signal slice
+          slurp some sort sort-by sorted sorted-by spit stderr stdin
+          stdout string string/ascii-lower string/ascii-upper
+          string/bytes string/check-set string/find string/find-all
+          string/format string/from-bytes string/has-prefix?
+          string/has-suffix? string/join string/repeat string/replace
+          string/replace-all string/reverse string/slice string/split
+          string/trim string/triml string/trimr string? struct struct?
+          sum symbol symbol? table table/clone table/getproto
+          table/new table/rawget table/setproto table/to-struct table?
+          take take-until take-while tarray/buffer tarray/copy-bytes
+          tarray/length tarray/new tarray/properties tarray/slice
+          tarray/swap-bytes thread/close thread/current thread/new
+          thread/receive thread/send trace tracev true? truthy? try
+          tuple tuple/brackets tuple/setmap tuple/slice
+          tuple/sourcemap tuple/type tuple? type unless unmarshal
+          untrace update update-in use values var- varfn varglobal
+          walk walk-ind walk-dict when when-let when-with with
+          with-dyns with-syms with-vars yield zero? zipcoll
+        )
+      end
+
+      def name_token(name)
+        if self.class.specials.include? name
+          Keyword
+        elsif self.class.bundled.include? name
+          Keyword::Reserved
+        else
+          Name::Function
+        end
+      end
+
+      punctuation = %r/[_!@$%^&*+=~<>.?\/-]/o
+      symbol = %r/([[:alpha:]]|#{punctuation})([[:word:]]|#{punctuation}|:)*/o
+
+      state :root do
+        rule %r/#.*?$/, Comment::Single
+        rule %r/\s+/m, Text::Whitespace
+
+        rule %r/(true|false|nil)\b/, Name::Constant
+        rule %r/(['~])(#{symbol})/ do
+          groups Operator, Str::Symbol
+        end
+        rule %r/:([[:word:]]|#{punctuation}|:)*/, Keyword::Constant
+
+        # radix-specified numbers
+        rule %r/[+-]?\d{1,2}r[\w.]+(&[+-]?\w+)?/, Num::Float
+
+        # hex numbers
+        rule %r/[+-]?0x\h[\h_]*(\.\h[\h_]*)?/, Num::Hex
+        rule %r/[+-]?0x\.\h[\h_]*/, Num::Hex
+
+        # decimal numbers (Janet treats all decimals as floats)
+        rule %r/[+-]?\d[\d_]*(\.\d[\d_]*)?([e][+-]?\d+)?/i, Num::Float
+        rule %r/[+-]?\.\d[\d_]*([e][+-]?\d+)?/i, Num::Float
+
+        rule %r/@?"/, Str::Double, :string
+        rule %r/@?(`+).*?\1/m, Str::Heredoc
+
+        rule %r/\(/, Punctuation, :function
+
+        rule %r/(')([\(\[])/ do
+          groups Operator, Punctuation
+          push :quote
+        end
+
+        rule %r/(~)([\(\[])/ do
+          groups Operator, Punctuation
+          push :quasiquote
+        end
+
+        rule %r/[\#~,';\|]/, Operator
+
+        rule %r/@?[({\[]/, Punctuation, :push
+        rule %r/[)}\]]/, Punctuation, :pop!
+
+        rule symbol, Name
+      end
+
+      state :string do
+        rule %r/"/, Str::Double, :pop!
+        rule %r/\\(u\h{4}|U\h{6})/, Str::Escape
+        rule %r/\\./, Str::Escape
+        rule %r/[^"\\]+/, Str::Double
+      end
+
+      state :function do
+        rule symbol do |m|
+          case m[0]
+          when "quote"
+            token Keyword
+            goto :quote
+          when "quasiquote"
+            token Keyword
+            goto :quasiquote
+          else
+            token name_token(m[0])
+            goto :root
+          end
+        end
+
+        mixin :root
+      end
+
+      state :quote do
+        rule %r/[\(\[]/, Punctuation, :push
+        rule symbol, Str::Symbol
+        mixin :root
+      end
+
+      state :quasiquote do
+        rule %r/(,)(\()/ do
+          groups Operator, Punctuation
+          push :function
+        end
+        rule %r/(\()(\s*)(unquote)(\s+)(\()/ do
+          groups Punctuation, Text, Keyword, Text, Punctuation
+          push :root
+          push :function
+        end
+
+        rule %r/(,)(#{symbol})/ do
+          groups Operator, Name
+        end
+        rule %r/(\()(\s*)(unquote)(\s+)(#{symbol})/ do
+          groups Punctuation, Text, Keyword, Text, Name
+        end
+
+        mixin :quote
+      end
+    end
+  end
+end

spec/lexers/janet_spec.rb

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

spec/visual/samples/janet

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+# Constants
+nil
+true
+false
+
+# Symbols
+symbol
+kebab-case-symbol
+snake_case_symbol
+my-module/my-fuction
+*****
+!%$^*__--__._+++===~-crazy-symbol
+*global-var*
+你好
+symbols:with:colons
+_
+
+# Keywords
+:keyword
+:range
+:0x0x0x0
+:a-keyword
+::
+:
+
+# Numbers
+0
++0.0
+-10_000
+16r1234abcd
+0x23.23
+1e10
+1.6e-4
+7r343_111_266.6&+10
+
+# Strings
+"This is a string."
+"This\nis\na\nstring."
+"\u004a"
+"\U01F5DD"
+"This
+is
+a
+string."
+``
+This
+is
+a
+string
+``
+`
+This is
+a string.
+`
+
+# Buffers
+@""
+@"Buffer."
+@``Another buffer``
+@`
+Yet another buffer
+`
+
+# Tuples
+(do 1 2 3)
+[do 1 2 3]
+
+# Arrays
+@(:one :two :three)
+@[:one :two :three]
+
+# Structs
+{}
+{:key1 "value1" :key2 :value2 :key3 3}
+{(1 2 3) (4 5 6)}
+{@[] @[]}
+{1 2 3 4 5 6}
+
+# Tables
+@{}
+@{:key1 "value1" :key2 :value2 :key3 3}
+@{(1 2 3) (4 5 6)}
+@{@[] @[]}
+@{1 2 3 4 5 6}
+
+# Special forms
+(def anumber (+ 1 2 3 4 5))
+(var a 1)
+(fn identity [x] x)
+
+# Function definitions
+(defn triangle-area
+  "Calculates the area of a triangle."
+  [base height]
+  (print "calculating area of a triangle...")
+  (* base height 0.5))
+
+(defn ignore-extra
+  [x &]
+  (+ x 1))
+
+# Function calls
+(print (triangle-area 5 10))
+(nil? nil)
+(not= 1 1)
+(put @{:a 1} :b 2)
+(type @{:a 1})
+(type {:a 1})
+(in [:a :b :c] 1)
+(type [:a :b])
+(type '(:a :b))
+(tuple/type '[])
+(tuple/type '())
+(first [1 2 3])
+(drop [1 2 3])
+(+ 1 2 3)
+(apply + [1 2 3])
+(+ ;[2 3 5 7 11])
+(|(+ 1 1 2 3 5 $) 8)
+
+# Quotes
+(quote 1)
+(quote hi)
+(quote quote)
+'(1 2 3)
+'(print 1 2 3)
+'x
+'(print "hello world")
+(quote (print "hello world"))
+(def name 'myfunction)
+(def args '[x y z])
+(defn body '[(print x) (print y) (print z)])
+
+# Quasiquotes
+~x
+~(def ,name (fn ,name ,args ,body))
+~(+ 1 ,(inc 1))
+(quasiquote (+ 1 (unquote (inc 1))))
+(quasiquote (+ 1 (unquote (inc (inc 1)))))