Class ScriptParser

src/script_parser.cpp:25–419

{

class ScriptParser
{
public:
  explicit ScriptParser(std::vector<Token> tokens) : tokens_(std::move(tokens))
  {}

  std::vector<Ast::expr_ptr> parseAll()
  {
    std::vector<Ast::expr_ptr> stmts;
    while(!atEnd())
    {
      stmts.push_back(parseExpr(0));
      // consume optional semicolons between statements
      while(check(TokenType::Semicolon))
      {
        advance();
      }
    }
    return stmts;
  }

private:
  std::vector<Token> tokens_;
  size_t current_ = 0;

  // Binding power constants.  Higher value = tighter binding.
  static constexpr int kAssignmentBP = 2;
  static constexpr int kTernaryBP = 4;
  static constexpr int kComparisonBP = 10;
  static constexpr int kMulDivBP = 18;
  static constexpr int kPrefixBP = 20;  // tighter than any infix

  //--- Token access ---

  const Token& peek() const
  {
    return tokens_[current_];
  }

  const Token& advance()
  {
    const Token& tok = tokens_[current_];
    if(!atEnd())
      current_++;
    return tok;
  }

  bool atEnd() const
  {
    return peek().type == TokenType::EndOfInput;
  }

  bool check(TokenType type) const
  {
    return peek().type == type;
  }

  const Token& expect(TokenType type, const char* msg)