feat(package): hemar: antlr grammar, but still does not work

package/hemar/grammar/antlr/_Hemar.g4

@@ -0,0 +1,149 @@
+grammar Hemar;
+
+// ----------------- parser rules -----------------
+
+hemar
+    : elements? EOF
+    ;
+
+elements
+    : element+
+    ;
+
+element
+    : tag
+    | TEXT
+    ;
+
+// tag
+tag
+    : OPEN path          CLOSE
+    | OPEN loopStatement CLOSE
+    | OPEN includeHeader CLOSE
+    | OPEN 'end'         CLOSE
+    | OPEN function      CLOSE
+    | OPEN OPEN          CLOSE      // literal "{[" output
+    ;
+
+// loop tag: "for" string "in" path
+loopStatement
+    : 'for' STRING 'in' path
+    ;
+
+// include tag: "include" path
+includeHeader
+    : 'include' path
+    ;
+
+// function tag
+function
+    : 'compute' language functionBody?   // "compute" language body
+    | 'compute' '-'      functionBody?   // "compute" - body
+    ;
+
+language
+    : 'dash'
+    | 'plpgsql'
+    ;
+
+// everything up to (but not including) "]}"
+// (raw body, including "{[" etc, at *token* level)
+functionBody
+    : ( ~CLOSE )*
+    ;
+
+// path
+path
+    : '.'
+    | segmentedPath
+    ;
+
+segmentedPath
+    : segment ('.' segment)*
+    ;
+
+segment
+    : STRING
+    | index
+    ;
+
+// index: \0 .. \9, \1.. \9\d*, and negative forms
+index
+    : '\\' DIGIT
+    | '\\' ONENINE DIGITS?
+    | '\\' '-' DIGIT
+    | '\\' '-' ONENINE DIGITS?
+    ;
+
+// ----------------- lexer rules -----------------
+
+OPEN  : '{[';
+CLOSE : ']}';
+
+// text outside tags: anything except the "{[" sequence
+TEXT
+    : TEXT_CHAR+
+    ;
+
+/*
+ * Strings used in paths/loop variables:
+ *   "..." with escapes similar to your spec.
+ */
+STRING
+    : '"' ( ESC | STRING_CHAR )* '"'
+    ;
+
+fragment STRING_CHAR
+    : ~["\\\r\n]
+    ;
+
+/*
+ * Escapes:
+ *   .   (literal dot)
+ *   ]}  (literal "]}")   -- note this is two chars after '\'
+ *   "   \" 
+ *   \   \\
+ *   /   \/
+ *   b f n r t
+ *   uXXXX (hex)
+ *   whitespace after backslash (your ws-in-escape)
+ */
+fragment ESC
+    : '\\'
+      (
+          '.'
+        | ']}'
+        | '"'
+        | '\\'
+        | '/'
+        | 'b'
+        | 'f'
+        | 'n'
+        | 'r'
+        | 't'
+        | 'u' HEX HEX HEX HEX
+        | WS_CHAR
+      )
+    ;
+
+// digits / hex
+DIGITS : DIGIT+ ;
+DIGIT  : [0-9] ;
+ONENINE: [1-9] ;
+HEX    : [0-9a-fA-F] ;
+
+// whitespace for normal lexing
+WS
+    : [ \t\r\n]+ -> skip
+    ;
+
+// whitespace used inside escapes
+fragment WS_CHAR
+    : [ \t\r\n]
+    ;
+
+
+fragment TEXT_CHAR
+    : ~'{'              // any except '{'
+    | '{' ~'['          // '{' only if not starting OPEN
+    ;