Add meta-variables

This is an EPITA extension of the language, used mostly by internal
compiler machinery.

grammar.js

@@ -29,6 +29,7 @@ module.exports = grammar({
 
   conflicts: ($) => [
     [$._lvalue, $.array_expression],
+    [$._lvalue, $.record_expression],
     [$._lvalue, $._type_identifier],
   ],
 
@@ -73,6 +74,9 @@ module.exports = grammar({
       $.for_expression,
       $.break_expression,
       $.let_expression,
+
+      $.meta_cast,
+      $.meta_expression,
     ),
 
     nil_literal: (_) => "nil",
@@ -88,7 +92,10 @@ module.exports = grammar({
     // NOTE: includes reserved identifiers
     identifier: (_) => /[_a-zA-Z0-9]+/,
 
-    _type_identifier: ($) => alias($.identifier, $.type_identifier),
+    _type_identifier: ($) => choice(
+      alias($.identifier, $.type_identifier),
+      $.meta_type_identifier,
+    ),
 
     _field_identifier: ($) => alias($.identifier, $.field_identifier),
 
@@ -112,6 +119,7 @@ module.exports = grammar({
       $.identifier,
       $.record_value,
       $.array_value,
+      $.meta_lvalue,
     ),
 
     record_value: ($) => seq(
@@ -245,7 +253,12 @@ module.exports = grammar({
 
     // Declarations {{{
 
-    _declaration_chunks: ($) => repeat1($._declaration_chunk),
+    _declaration_chunks: ($) => repeat1(
+      choice(
+        $.meta_chunks,
+        $._declaration_chunk,
+      ),
+    ),
 
     _declaration_chunk: ($) => prec.left(
       choice(
@@ -335,6 +348,47 @@ module.exports = grammar({
     ),
 
     // }}}
+
+    // Meta-variables {{{
+
+    meta_chunks: ($) => seq(
+      "_chunks",
+      "(",
+      field("index", $.integer_literal),
+      ")",
+    ),
+
+    meta_cast: ($) => seq(
+      "_cast",
+      "(",
+      field("expression", $._expr),
+      ",",
+      field("type", $._type),
+      ")",
+    ),
+
+    meta_expression: ($) => seq(
+      "_exp",
+      "(",
+      field("index", $.integer_literal),
+      ")",
+    ),
+
+    meta_lvalue: ($) => seq(
+      "_lvalue",
+      "(",
+      field("index", $.integer_literal),
+      ")",
+    ),
+
+    meta_type_identifier: ($) => seq(
+      "_namety",
+      "(",
+      $.integer_literal,
+      ")",
+    ),
+
+    // }}}
   }
 });
 

src/grammar.json

@@ -89,6 +89,14 @@
         {
           "type": "SYMBOL",
           "name": "let_expression"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "meta_cast"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "meta_expression"
         }
       ]
     },
@@ -134,6 +142,9 @@
       "value": "[_a-zA-Z0-9]+"
     },
     "_type_identifier": {
+      "type": "CHOICE",
+      "members": [
+        {
           "type": "ALIAS",
           "content": {
             "type": "SYMBOL",
@@ -142,6 +153,12 @@
           "named": true,
           "value": "type_identifier"
         },
+        {
+          "type": "SYMBOL",
+          "name": "meta_type_identifier"
+        }
+      ]
+    },
     "_field_identifier": {
       "type": "ALIAS",
       "content": {
@@ -245,6 +262,10 @@
         {
           "type": "SYMBOL",
           "name": "array_value"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "meta_lvalue"
         }
       ]
     },
@@ -1063,9 +1084,18 @@
     "_declaration_chunks": {
       "type": "REPEAT1",
       "content": {
+        "type": "CHOICE",
+        "members": [
+          {
+            "type": "SYMBOL",
+            "name": "meta_chunks"
+          },
+          {
             "type": "SYMBOL",
             "name": "_declaration_chunk"
           }
+        ]
+      }
     },
     "_declaration_chunk": {
       "type": "PREC_LEFT",
@@ -1513,6 +1543,139 @@
           }
         }
       ]
+    },
+    "meta_chunks": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "_chunks"
+        },
+        {
+          "type": "STRING",
+          "value": "("
+        },
+        {
+          "type": "FIELD",
+          "name": "index",
+          "content": {
+            "type": "SYMBOL",
+            "name": "integer_literal"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": ")"
+        }
+      ]
+    },
+    "meta_cast": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "_cast"
+        },
+        {
+          "type": "STRING",
+          "value": "("
+        },
+        {
+          "type": "FIELD",
+          "name": "expression",
+          "content": {
+            "type": "SYMBOL",
+            "name": "_expr"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": ","
+        },
+        {
+          "type": "FIELD",
+          "name": "type",
+          "content": {
+            "type": "SYMBOL",
+            "name": "_type"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": ")"
+        }
+      ]
+    },
+    "meta_expression": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "_exp"
+        },
+        {
+          "type": "STRING",
+          "value": "("
+        },
+        {
+          "type": "FIELD",
+          "name": "index",
+          "content": {
+            "type": "SYMBOL",
+            "name": "integer_literal"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": ")"
+        }
+      ]
+    },
+    "meta_lvalue": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "_lvalue"
+        },
+        {
+          "type": "STRING",
+          "value": "("
+        },
+        {
+          "type": "FIELD",
+          "name": "index",
+          "content": {
+            "type": "SYMBOL",
+            "name": "integer_literal"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": ")"
+        }
+      ]
+    },
+    "meta_type_identifier": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "_namety"
+        },
+        {
+          "type": "STRING",
+          "value": "("
+        },
+        {
+          "type": "SYMBOL",
+          "name": "integer_literal"
+        },
+        {
+          "type": "STRING",
+          "value": ")"
+        }
+      ]
     }
   },
   "extras": [
@@ -1530,6 +1693,10 @@
       "_lvalue",
       "array_expression"
     ],
+    [
+      "_lvalue",
+      "record_expression"
+    ],
     [
       "_lvalue",
       "_type_identifier"

src/node-types.json

@@ -51,6 +51,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -129,6 +141,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -163,6 +187,10 @@
         "multiple": false,
         "required": true,
         "types": [
+          {
+            "type": "meta_type_identifier",
+            "named": true
+          },
           {
             "type": "type_identifier",
             "named": true
@@ -179,6 +207,10 @@
         "multiple": false,
         "required": true,
         "types": [
+          {
+            "type": "meta_type_identifier",
+            "named": true
+          },
           {
             "type": "type_identifier",
             "named": true
@@ -203,6 +235,10 @@
             "type": "identifier",
             "named": true
           },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "record_value",
             "named": true
@@ -257,6 +293,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -305,6 +353,10 @@
             "type": "identifier",
             "named": true
           },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "record_value",
             "named": true
@@ -359,6 +411,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -453,6 +517,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -541,6 +617,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -625,6 +713,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -703,6 +803,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -791,6 +903,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -889,6 +1013,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -983,6 +1119,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -1037,6 +1185,10 @@
         "multiple": false,
         "required": false,
         "types": [
+          {
+            "type": "meta_type_identifier",
+            "named": true
+          },
           {
             "type": "type_identifier",
             "named": true
@@ -1097,6 +1249,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -1175,6 +1339,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -1253,6 +1429,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -1357,6 +1545,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -1399,6 +1599,10 @@
             "type": "import_declaration",
             "named": true
           },
+          {
+            "type": "meta_chunks",
+            "named": true
+          },
           {
             "type": "primitive_declaration",
             "named": true
@@ -1415,6 +1619,183 @@
       }
     }
   },
+  {
+    "type": "meta_cast",
+    "named": true,
+    "fields": {
+      "expression": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "array_expression",
+            "named": true
+          },
+          {
+            "type": "array_value",
+            "named": true
+          },
+          {
+            "type": "assignment_expression",
+            "named": true
+          },
+          {
+            "type": "binary_expression",
+            "named": true
+          },
+          {
+            "type": "break_expression",
+            "named": true
+          },
+          {
+            "type": "for_expression",
+            "named": true
+          },
+          {
+            "type": "function_call",
+            "named": true
+          },
+          {
+            "type": "identifier",
+            "named": true
+          },
+          {
+            "type": "if_expression",
+            "named": true
+          },
+          {
+            "type": "integer_literal",
+            "named": true
+          },
+          {
+            "type": "let_expression",
+            "named": true
+          },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
+          {
+            "type": "nil_literal",
+            "named": true
+          },
+          {
+            "type": "record_expression",
+            "named": true
+          },
+          {
+            "type": "record_value",
+            "named": true
+          },
+          {
+            "type": "sequence_expression",
+            "named": true
+          },
+          {
+            "type": "string_literal",
+            "named": true
+          },
+          {
+            "type": "unary_expression",
+            "named": true
+          },
+          {
+            "type": "while_expression",
+            "named": true
+          }
+        ]
+      },
+      "type": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "array_type",
+            "named": true
+          },
+          {
+            "type": "record_type",
+            "named": true
+          },
+          {
+            "type": "type_alias",
+            "named": true
+          }
+        ]
+      }
+    }
+  },
+  {
+    "type": "meta_chunks",
+    "named": true,
+    "fields": {
+      "index": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "integer_literal",
+            "named": true
+          }
+        ]
+      }
+    }
+  },
+  {
+    "type": "meta_expression",
+    "named": true,
+    "fields": {
+      "index": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "integer_literal",
+            "named": true
+          }
+        ]
+      }
+    }
+  },
+  {
+    "type": "meta_lvalue",
+    "named": true,
+    "fields": {
+      "index": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "integer_literal",
+            "named": true
+          }
+        ]
+      }
+    }
+  },
+  {
+    "type": "meta_type_identifier",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": false,
+      "required": true,
+      "types": [
+        {
+          "type": "integer_literal",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "parameters",
     "named": true,
@@ -1433,6 +1814,10 @@
         "multiple": true,
         "required": false,
         "types": [
+          {
+            "type": "meta_type_identifier",
+            "named": true
+          },
           {
             "type": "type_identifier",
             "named": true
@@ -1469,6 +1854,10 @@
         "multiple": false,
         "required": false,
         "types": [
+          {
+            "type": "meta_type_identifier",
+            "named": true
+          },
           {
             "type": "type_identifier",
             "named": true
@@ -1539,6 +1928,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -1573,6 +1974,10 @@
         "multiple": false,
         "required": true,
         "types": [
+          {
+            "type": "meta_type_identifier",
+            "named": true
+          },
           {
             "type": "type_identifier",
             "named": true
@@ -1599,6 +2004,10 @@
         "multiple": true,
         "required": false,
         "types": [
+          {
+            "type": "meta_type_identifier",
+            "named": true
+          },
           {
             "type": "type_identifier",
             "named": true
@@ -1633,6 +2042,10 @@
             "type": "identifier",
             "named": true
           },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "record_value",
             "named": true
@@ -1693,6 +2106,18 @@
           "type": "let_expression",
           "named": true
         },
+        {
+          "type": "meta_cast",
+          "named": true
+        },
+        {
+          "type": "meta_expression",
+          "named": true
+        },
+        {
+          "type": "meta_lvalue",
+          "named": true
+        },
         {
           "type": "nil_literal",
           "named": true
@@ -1784,6 +2209,22 @@
           "type": "let_expression",
           "named": true
         },
+        {
+          "type": "meta_cast",
+          "named": true
+        },
+        {
+          "type": "meta_chunks",
+          "named": true
+        },
+        {
+          "type": "meta_expression",
+          "named": true
+        },
+        {
+          "type": "meta_lvalue",
+          "named": true
+        },
         {
           "type": "nil_literal",
           "named": true
@@ -1850,6 +2291,10 @@
       "multiple": false,
       "required": true,
       "types": [
+        {
+          "type": "meta_type_identifier",
+          "named": true
+        },
         {
           "type": "type_identifier",
           "named": true
@@ -1943,6 +2388,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -2003,6 +2460,10 @@
         "multiple": false,
         "required": false,
         "types": [
+          {
+            "type": "meta_type_identifier",
+            "named": true
+          },
           {
             "type": "type_identifier",
             "named": true
@@ -2057,6 +2518,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -2151,6 +2624,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -2229,6 +2714,18 @@
             "type": "let_expression",
             "named": true
           },
+          {
+            "type": "meta_cast",
+            "named": true
+          },
+          {
+            "type": "meta_expression",
+            "named": true
+          },
+          {
+            "type": "meta_lvalue",
+            "named": true
+          },
           {
             "type": "nil_literal",
             "named": true
@@ -2301,6 +2798,26 @@
     "type": "]",
     "named": false
   },
+  {
+    "type": "_cast",
+    "named": false
+  },
+  {
+    "type": "_chunks",
+    "named": false
+  },
+  {
+    "type": "_exp",
+    "named": false
+  },
+  {
+    "type": "_lvalue",
+    "named": false
+  },
+  {
+    "type": "_namety",
+    "named": false
+  },
   {
     "type": "array",
     "named": false

test/corpus/meta-variables.txt

@@ -0,0 +1,65 @@
+================================================================================
+Meta chunks
+================================================================================
+
+_chunks(42)
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (meta_chunks
+    index: (integer_literal)))
+
+================================================================================
+Cast
+================================================================================
+
+_cast(42, string)
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (meta_cast
+    expression: (integer_literal)
+    type: (type_alias
+      (type_identifier))))
+
+================================================================================
+Meta expression
+================================================================================
+
+_exp(42)
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (meta_expression
+    index: (integer_literal)))
+
+================================================================================
+Meta lvalue
+================================================================================
+
+_lvalue(42)
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (meta_lvalue
+    index: (integer_literal)))
+
+================================================================================
+Meta type identifier
+================================================================================
+
+var a : _namety(42) := "I'm So Meta Even This Acronym"
+
+--------------------------------------------------------------------------------
+
+(source_file
+  (variable_declaration
+    name: (identifier)
+    type: (meta_type_identifier
+      (integer_literal))
+    (operator)
+    value: (string_literal)))