Feat: Initial Hi language grammar for declarations

grammar.ne

@@ -0,0 +1,79 @@
+@{%
+const moo = require('moo');
+
+const lexer = moo.compile({
+  ws:      /[ \t]+/,
+  nl:      { match: /\n/, lineBreaks: true },
+  comment: /\/\/.*?$/,
+  number:  /0|[1-9][0-9]*/,
+  string:  /"(?:\\["\\]|[^\n"\\])*"/,
+  lbrace:  '{',
+  rbrace:  '}',
+  identifier: /[a-zA-Z_][a-zA-Z0-9_]*/,
+  colon:   ':',
+  eq:      '=',
+  lparen:  '(',
+  rparen:  ')',
+});
+%}
+
+@lexer lexer
+
+# Main entry point: a program is a series of statements
+Program -> _ Statements _ {% ([,,stmts]) => ({ type: 'Program', body: stmts }) %}
+
+# Statements are separated by newlines
+Statements -> Statement (_NL Statement):* _ {% 
+  (d) => {
+    const stmts = [d[0]];
+    for (const rest of d[1]) {
+      stmts.push(rest[1]);
+    }
+    return stmts.filter(s => s !== null); // Filter out empty lines
+  }
+%}
+
+# A statement can be a declaration, assignment, or expression
+Statement -> Declaration {% id %}
+           | Assignment {% id %}
+           | OutputCall {% id %}
+           | Comment {% id %}
+
+Comment -> %comment {% d => ({ type: 'Comment', value: d[0].value }) %}
+
+Declaration -> %identifier _ %colon _ Expression {% 
+  (d) => ({ 
+    type: 'VariableDeclaration',
+    identifier: d[0].value,
+    value: d[4]
+  }) 
+%}
+
+Assignment -> %identifier _ %eq _ Expression {% 
+  (d) => ({ 
+    type: 'Assignment',
+    identifier: d[0].value,
+    value: d[4]
+  }) 
+%}
+
+OutputCall -> %identifier %lparen _ Expression _ %rparen {%
+  (d) => {
+    // For now, only allow '_' as the function name
+    if (d[0].value !== '_') {
+        throw new Error("Only the '_' function is supported for output.");
+    }
+    return { type: 'OutputCall', arguments: [d[3]] }
+  }
+%}
+
+# Expressions (very simple for now)
+Expression -> Literal {% id %}
+
+Literal -> %number {% d => ({ type: 'NumericLiteral', value: Number(d[0].value) }) %}
+         | %string {% d => ({ type: 'StringLiteral', value: d[0].value }) %}
+
+# Whitespace and Newlines
+_ -> (%ws | %comment):* {% () => null %}
+_NL -> (_ %nl):+ {% () => null %}
+