Add Kotlin syntax highlighting support. (#406)

* WIP: added basic syntax highlighting for Kotlin.

* WIP: added a few more patterns.

* Fixed overcomplicated single-line comment pattern.

* Fixed source syntax docs address.

* Realigned single-line comment pattern.

* Added .. and ..< operators and new FIX.

* WIP: working on range operator patterns.

* Some more adjustments.

* Removed comment.

* Fixed double dots left-adiacent to number being colored as number and fixed lambda color.

* Update plugins/language_kotlin.lua

Co-authored-by: Guldoman <giulio.lettieri@gmail.com>

* Updated to use raw strings in the annotations and this patterns.

* Added block_comment.

* Fixed types indentation.

* Achieved perfection..

* Added patterns for $ after var and let function

* Added elvis operator.

* Added  pattern.

* Fixed elvis operator.

* Achieved true perfection.

* Added entry to meta-languages package.

* Bumped meta_languages version.

* Bumped meta_languages version and added second _.

* Update plugins/language_kotlin.lua

Co-authored-by: Guldoman <giulio.lettieri@gmail.com>

* Updated the range operator pattern.

* Update plugins/language_kotlin.lua

Co-authored-by: Guldoman <giulio.lettieri@gmail.com>

* Update plugins/language_kotlin.lua

Co-authored-by: Guldoman <giulio.lettieri@gmail.com>

* Update plugins/language_kotlin.lua

Co-authored-by: Guldoman <giulio.lettieri@gmail.com>

* Fixed last patterns and tidied up a bit.

---------

Co-authored-by: Guldoman <giulio.lettieri@gmail.com>

2 files changed, 135 insertions, 1 deletions

diff --git a/manifest.json b/manifest.json
index b4bb072..fc2a09c 100644
--- a/manifest.json
+++ b/manifest.json
@@ -113,6 +113,7 @@
         "language_json": {},
         "language_jsx": {},
         "language_julia": {},
+        "language_kotlin": {},
         "language_lilypond": {},
         "language_liquid": {},
         "language_lobster": {},
@@ -164,7 +165,7 @@
       "id": "meta_languages",
       "mod_version": "3",
       "type": "meta",
-      "version": "0.1.14"
+      "version": "0.1.15"
     },
     {
       "description": "Align multiple carets and selections *([clip](https://user-images.githubusercontent.com/2798487/165631951-532f8d24-d596-4dd0-9d21-ff53c71ed32f.mp4))*",
@@ -1161,6 +1162,16 @@
       "version": "0.1"
     },
     {
+      "description": "Syntax for the [Kotlin](https://kotlinlang.org/docs/home.html) programming language",
+      "id": "language_kotlin",
+      "mod_version": "3",
+      "path": "plugins/language_kotlin.lua",
+      "tags": [
+        "language"
+      ],
+      "version": "0.1"
+    },
+    {
       "checksum": "08a9f8635b09a98cec9dfca8bb65f24fd7b6585c7e8308773e7ddff9a3e5a60f",
       "description": "Syntax for [Kaitai](http://kaitai.io/) struct files",
       "id": "language_ksy",
diff --git a/plugins/language_kotlin.lua b/plugins/language_kotlin.lua
new file mode 100644
index 0000000..288ba34
--- /dev/null
+++ b/plugins/language_kotlin.lua
@@ -0,0 +1,123 @@
+-- mod-version:3
+local syntax = require "core.syntax"
+
+syntax.add {
+  name = "Kotlin",
+  files = { "%.kt$" },
+  comment = "//",
+  block_comment = { "/*", "*/" },
+  patterns = {
+    { pattern = "//.*",                              type = "comment"  }, -- Comment, single-line
+    { pattern = { "/%*", "%*/" },                    type = "comment"  }, -- Comment, multi-line
+    { pattern = { '"', '"', '\\' },                  type = "string"   }, -- String, quotation marks
+    { pattern = { "'", "'", '\\' },                  type = "string"   }, -- String, apices
+    { pattern = "'\\x%x?%x?%x?%x'",                  type = "string"   }, -- Character hexadecimal escape sequence
+    { pattern = "'\\u%x%x%x%x'",                     type = "string"   }, -- Character unicode escape sequence
+    { pattern = "'\\?.'",                            type = "string"   }, -- Character literal
+    { pattern = "-?0x%x+",                           type = "number"   }, -- ?
+    { pattern = "-?%d+[%deE]*f?",                    type = "number"   }, -- ?
+    { pattern = "-?%.?%d+f?",                        type = "number"   }, -- ?
+    { regex   = [[\-\>(?=\s)]],                      type = "operator" }, -- Lambda
+    { regex   = [[\.{2}\<?\s?(?=[\\-]?[a-z0-9])]],   type = "operator" }, -- Range operators
+    { pattern = "[%+%-=/%*%^%%<>!~|&]",              type = "operator" }, -- Operators
+    { regex   = [[\?(?=\.)]],                        type = "operator" }, -- ?. operator
+    { pattern = "[%a_][%w_]*%f[(]",                  type = "function" }, -- Function/Method/Class
+    { regex   = [[let(?=\s\{)]],                     type = "function" }, -- ? operator
+    { regex   = [[\?\:(?=\s?)]],                     type = "operator" }, -- elvis operator
+    { regex   = [[this(?=\.?\@?)]],                  type = "keyword"  }, -- this keyword
+    { regex   = "\\@\\w+",                           type = "keyword2" }, -- Annotations
+    { regex   = [[[a-zA-Z]+\@(?=\s?[a-zA-Z])]],      type = "keyword2" }, -- Annotations (this pattern is lower priority than the `this keyword` pattern)
+    { regex   = "[A-Z][A-Z_]+",                      type = "keyword2" }, -- Constants, FULL UPPERCASE
+    { pattern = "import()%s+()[%w_.]+",              type = { "keyword", "normal", "normal" } },
+    { pattern = "[%a_][%w_]*",                       type = "symbol"   }, -- ?
+  },
+  symbols = {
+    -- Hard keywords
+    ["as"]           = "keyword",
+    ["break"]        = "keyword",
+    ["class"]        = "keyword",
+    ["continue"]     = "keyword",
+    ["do"]           = "keyword",
+    ["else"]         = "keyword",
+    ["for"]          = "keyword",
+    ["fun"]          = "keyword",
+    ["if"]           = "keyword",
+    ["in"]           = "keyword",
+    ["!in"]          = "keyword",
+    ["interface"]    = "keyword",
+    ["is"]           = "keyword",
+    ["!is"]          = "keyword",
+    ["object"]       = "keyword",
+    ["package"]      = "keyword",
+    ["return"]       = "keyword",
+    ["super"]        = "keyword",
+    ["this"]         = "keyword",
+    ["throw"]        = "keyword",
+    ["try"]          = "keyword",
+    ["typealias"]    = "keyword",
+    ["typeof"]       = "keyword",
+    ["val"]          = "keyword",
+    ["var"]          = "keyword",
+    ["when"]         = "keyword",
+    ["while"]        = "keyword",
+
+    -- Soft keywords
+    ["by"]           = "keyword",
+    ["catch"]        = "keyword",
+    ["constructor"]  = "keyword",
+    ["delegate"]     = "keyword",
+    ["dynamic"]      = "keyword",
+    ["field"]        = "keyword",
+    ["file"]         = "keyword",
+    ["finally"]      = "keyword",
+    ["get"]          = "keyword",
+    ["import"]       = "keyword",
+    ["init"]         = "keyword",
+    ["param"]        = "keyword",
+    ["property"]     = "keyword",
+    ["receiver"]     = "keyword",
+    ["set"]          = "keyword",
+    ["setparam"]     = "keyword",
+    ["value"]        = "keyword",
+    ["where"]        = "keyword",
+
+    -- Modifier keywords
+    ["abstract"]     = "keyword",
+    ["actual"]       = "keyword",
+    ["annotation"]   = "keyword",
+    ["companion"]    = "keyword",
+    ["const"]        = "keyword",
+    ["crossinline"]  = "keyword",
+    ["data"]         = "keyword",
+    ["enum"]         = "keyword",
+    ["expect"]       = "keyword",
+    ["external"]     = "keyword",
+    ["final"]        = "keyword",
+    ["inline"]       = "keyword",
+    ["inner"]        = "keyword",
+    ["infix"]        = "keyword",
+    ["internal"]     = "keyword",
+    ["lateinit"]     = "keyword",
+    ["noinline"]     = "keyword",
+    ["open"]         = "keyword",
+    ["operator"]     = "keyword",
+    ["out"]          = "keyword",
+    ["override"]     = "keyword",
+    ["private"]      = "keyword",
+    ["protected"]    = "keyword",
+    ["public"]       = "keyword",
+    ["reified"]      = "keyword",
+    ["sealed"]       = "keyword",
+    ["suspend"]      = "keyword",
+    ["tailrec"]      = "keyword",
+    ["vararg"]       = "keyword",
+
+    -- Special identifiers
+    ["it"]           = "keyword",
+
+    -- Boolean
+    ["true"]         = "literal",
+    ["false"]        = "literal",
+    ["null"]         = "literal",
+  },
+}