Miscallleneous stuff (#27)

* Null literal

* Unit expression, required for `for {...} ()` case

* Add `return` expression

* Add `throw` expression

* Apply changes per review

Remove redundant token fun call.

corpus/expressions.txt

@@ -150,6 +150,7 @@ def main() {
     doThing()
   } catch {
     case e: SomeException => prinlnt(e.message)
+    case NonFatal(ex) => throw new SomeException(ex)
   } finally {
     tryAnotherThing()
   }
@@ -172,16 +173,28 @@ def main() {
         (finally_clause (infix_expression (identifier) (operator_identifier) (integer_literal))))
       (try_expression
         (block (call_expression (identifier) (arguments)))
-        (catch_clause (case_block (case_clause
-          (typed_pattern
-            (identifier)
-            (type_identifier))
-          (call_expression
-            (identifier)
-            (arguments (field_expression
-              (identifier)
-              (identifier)))))))
-        (finally_clause (block (call_expression (identifier) (arguments)))))
+        (catch_clause
+          (case_block
+            (case_clause
+              (typed_pattern
+                (identifier)
+                (type_identifier))
+              (call_expression
+                (identifier)
+                (arguments (field_expression
+                  (identifier)
+                  (identifier)))))
+            (case_clause
+              (case_class_pattern
+                (type_identifier)
+                (identifier))
+              (throw_expression (instance_expression (call_expression (identifier) (arguments (identifier))))
+              )
+            )
+          )
+        )
+        (finally_clause (block (call_expression (identifier) (arguments))))
+        )
       (try_expression (call_expression (identifier) (arguments))
         (catch_clause (case_block (case_clause
           (identifier) 
@@ -331,3 +344,43 @@ class C {
             (prefix_expression (identifier))
             (operator_identifier)
             (identifier)))))))
+
+===============================
+Unit expressions
+===============================
+
+val x = ()
+def f(): Unit = { (   
+); }
+
+---
+(compilation_unit
+  (val_definition (identifier) (unit))
+  (function_definition (identifier) (parameters) (type_identifier) (block (unit)))
+  )
+
+===============================
+Return expressions
+===============================
+
+def f: Unit = return
+def g(a: A): B = { f(); return null.asInstanceOf[B] }
+
+---
+
+(compilation_unit
+  (function_definition (identifier) (type_identifier) (return_expression))
+  (function_definition
+    (identifier)
+    (parameters (parameter (identifier) (type_identifier)))
+    (type_identifier)
+    (block
+      (call_expression
+        (identifier)
+        (arguments))
+      (return_expression
+        (generic_function (field_expression (null_literal) (identifier))
+        (type_arguments (type_identifier))))
+      )
+    )
+  )

corpus/literals.txt

@@ -164,3 +164,12 @@ val myOtherSymbol = 'thing
 (compilation_unit
   (val_definition (identifier) (symbol_literal))
   (val_definition (identifier) (symbol_literal)))
+
+==========================
+Null
+==========================
+
+lazy val nullObject: String = null
+
+---
+(compilation_unit (val_definition (modifiers) (identifier) (type_identifier) (null_literal)))

grammar.js

@@ -518,7 +518,10 @@ module.exports = grammar({
       $.case_block,
       $.block,
       $.identifier,
-      $.literal
+      $.literal,
+      $.unit,
+      $.return_expression,
+      $.throw_expression
     ),
 
     if_expression: $ => prec.right(seq(
@@ -643,7 +646,8 @@ module.exports = grammar({
       $.boolean_literal,
       $.character_literal,
       $.symbol_literal,
-      $.string
+      $.string,
+      $.null_literal
     ),
 
     integer_literal: $ => token(
@@ -751,6 +755,14 @@ module.exports = grammar({
       $._automatic_semicolon
     ),
 
+    null_literal: $ => 'null',
+
+    unit: $ => seq('(', ')'),
+
+    return_expression: $ => prec.left(seq('return', optional($._expression))),
+
+    throw_expression: $ => prec.left(seq('throw', $._expression)),
+
     comment: $ => token(choice(
       seq('//', /.*/),
       seq(

src/grammar.json

@@ -2681,6 +2681,18 @@
         {
           "type": "SYMBOL",
           "name": "literal"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "unit"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "return_expression"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "throw_expression"
         }
       ]
     },
@@ -3352,6 +3364,10 @@
         {
           "type": "SYMBOL",
           "name": "string"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "null_literal"
         }
       ]
     },
@@ -3768,6 +3784,65 @@
         }
       ]
     },
+    "null_literal": {
+      "type": "STRING",
+      "value": "null"
+    },
+    "unit": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "("
+        },
+        {
+          "type": "STRING",
+          "value": ")"
+        }
+      ]
+    },
+    "return_expression": {
+      "type": "PREC_LEFT",
+      "value": 0,
+      "content": {
+        "type": "SEQ",
+        "members": [
+          {
+            "type": "STRING",
+            "value": "return"
+          },
+          {
+            "type": "CHOICE",
+            "members": [
+              {
+                "type": "SYMBOL",
+                "name": "_expression"
+              },
+              {
+                "type": "BLANK"
+              }
+            ]
+          }
+        ]
+      }
+    },
+    "throw_expression": {
+      "type": "PREC_LEFT",
+      "value": 0,
+      "content": {
+        "type": "SEQ",
+        "members": [
+          {
+            "type": "STRING",
+            "value": "throw"
+          },
+          {
+            "type": "SYMBOL",
+            "name": "_expression"
+          }
+        ]
+      }
+    },
     "comment": {
       "type": "TOKEN",
       "content": {

src/node-types.json

@@ -125,6 +125,10 @@
         "type": "match_expression",
         "named": true
       },
+      {
+        "type": "null_literal",
+        "named": true
+      },
       {
         "type": "parenthesized_expression",
         "named": true
@@ -133,6 +137,10 @@
         "type": "prefix_expression",
         "named": true
       },
+      {
+        "type": "return_expression",
+        "named": true
+      },
       {
         "type": "string",
         "named": true
@@ -141,6 +149,10 @@
         "type": "symbol_literal",
         "named": true
       },
+      {
+        "type": "throw_expression",
+        "named": true
+      },
       {
         "type": "try_expression",
         "named": true
@@ -148,6 +160,10 @@
       {
         "type": "tuple_expression",
         "named": true
+      },
+      {
+        "type": "unit",
+        "named": true
       }
     ]
   },
@@ -191,6 +207,10 @@
         "type": "integer_literal",
         "named": true
       },
+      {
+        "type": "null_literal",
+        "named": true
+      },
       {
         "type": "string",
         "named": true
@@ -2219,6 +2239,21 @@
       }
     }
   },
+  {
+    "type": "return_expression",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": false,
+      "required": false,
+      "types": [
+        {
+          "type": "_expression",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "stable_identifier",
     "named": true,
@@ -2285,6 +2320,21 @@
       ]
     }
   },
+  {
+    "type": "throw_expression",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": false,
+      "required": true,
+      "types": [
+        {
+          "type": "_expression",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "trait_definition",
     "named": true,
@@ -2695,6 +2745,11 @@
       }
     }
   },
+  {
+    "type": "unit",
+    "named": true,
+    "fields": {}
+  },
   {
     "type": "upper_bound",
     "named": true,
@@ -3263,6 +3318,10 @@
     "type": "new",
     "named": false
   },
+  {
+    "type": "null_literal",
+    "named": true
+  },
   {
     "type": "object",
     "named": false
@@ -3287,6 +3346,10 @@
     "type": "protected",
     "named": false
   },
+  {
+    "type": "return",
+    "named": false
+  },
   {
     "type": "sealed",
     "named": false
@@ -3295,6 +3358,10 @@
     "type": "symbol_literal",
     "named": true
   },
+  {
+    "type": "throw",
+    "named": false
+  },
   {
     "type": "trait",
     "named": false