Add EBNF grammar derived from parser.cpp

[Copilot]

The repository lacked a formal grammar specification for the Zenith language. This PR adds grammar.ebnf at the repo root, generated directly from src/parser/parser.cpp with rule names corresponding to parser method names.

Changes

• grammar.ebnf — New file containing the complete EBNF grammar for Zenith, covering all 36 parser methods as named rules:
  • Top-level: parse, parseImport, parseTemplate
  • Declarations: parseVarDecl, parseFunction, parseObject, parseUnion, parseActorDecl, parseConstructor, parseField
  • Expressions: parseExpression, parsePrimary, parseNewExpression, parseFunctionCall, parseMemberAccess, parseArrayAccess, parseArrowFunction, parseArrowFunctionParams
  • Statements: parseStatement, parseBlock, parseIfStmt, parseForStmt, parseWhileStmt, parseDoWhileStmt, parseReturnStmt, parseScopeBlock, parseUnsafeBlock
  • Types & annotations: parseType, parseAnnotation, parseAnnotations, parseTemplateParameters
  • Structural helpers: builtInType, binaryOp, accessModifier, param, structField, terminal definitions

Example rules

parseVarDecl = [ "hoist" ]
               ( ( builtInType | IDENTIFIER ) IDENTIFIER [ "[" parseExpression "]" ]
               | ( "let" | "var" | "dynamic" ) IDENTIFIER [ "[" parseExpression "]" ] [ ":" parseType ] )
               [ "=" parseExpression ] ;

parseFunction = ( "fun" [ parseType ] | parseType ) IDENTIFIER parseParameters
               [ "->" parseType ] parseBlock ;

parseActorDecl = "actor" IDENTIFIER [ ":" IDENTIFIER ]
                "{" { parseMessageHandler | ( parseAnnotations parseObjectPrimary ) } "}" ;

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[Copilot]

Copilot wasn't able to review any files in this pull request.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.