Finish parsing expressions

cclox_src/error_handler.cc

@@ -1,10 +1,19 @@
 #include "error_handler.hh"
+#include "tokenizer.hh"
 #include <iostream>
 
 void ErrorHandler::error(int line, const std::string &message) {
   report(line, "", message);
 }
 
+void ErrorHandler::error(Token token, const std::string &message) {
+  if (token.type == TokenType::EOFILE) {
+    report(token.line, " at end", message);
+  } else {
+    report(token.line, " at '" + token.lexeme + "'", message);
+  }
+}
+
 void ErrorHandler::report(int line, const std::string &where, const std::string &message) {
   std::cout << "[line " << line << "] Error" << where << ": " << message << '\n';
   had_error = true;

cclox_src/error_handler.hh

@@ -1,11 +1,13 @@
 #ifndef ERROR_HANDLER_HH
 #define ERROR_HANDLER_HH
 
+#include "tokenizer.hh"
 #include <string>
 
 struct ErrorHandler {
   ErrorHandler() : had_error{false} {};
   void error(int line, const std::string &message);
+  void error(Token token, const std::string &message);
   void report(int line, const std::string &where, const std::string &message);
 
   bool had_error;

cclox_src/interpreter.cc

@@ -1,9 +1,11 @@
 #include "interpreter.hh"
 #include "error_handler.hh"
 #include "tokenizer.hh"
+#include "parser.hh"
 #include <cstdint>
 #include <fstream>
 #include <iostream>
+#include <optional>
 #include <sysexits.h>
 
 #define PROMPT "> "
@@ -50,7 +52,11 @@ void run(const std::string &code) {
   Scanner scanner{code};
   std::vector<Token> tokens = scanner.scan_tokens();
 
-  for (const auto &token : tokens) {
-    std::cout << token << '\n';
+  Parser parser{tokens};
+  std::optional<Expr> expression = parser.parse();
+
+  if (expression) {
+    AstPrinter printer{};
+		std::cout << printer.print(*expression) << '\n';
   }
 }

cclox_src/main.cc

@@ -8,26 +8,12 @@
 ErrorHandler error_handler{};
 
 int main(int argc, char *argv[]) {
-  (void)argc;
-  (void)argv;
-  // if (argc > 2) {
-  //   std::cout << "Usage: cclox [script]\n";
-  //   exit(EX_USAGE);
-  // }
-  //
-  // run_interpreter(argc, argv);
+  if (argc > 2) {
+    std::cout << "Usage: cclox [script]\n";
+    exit(EX_USAGE);
+  }
 
-  Token unary_op{TokenType::MINUS, "-", Object{}, 1};
-  Expr left{Unary(unary_op, Literal(123))};
-
-  Token op{TokenType::STAR, "*", Object{}, 1};
-
-  Expr right{Grouping(Literal(45.67))};
-
-  Expr expr{Binary(left, op, right)};
-
-  AstPrinter printer{};
-  std::cout << printer.print(expr) << '\n';
+  run_interpreter(argc, argv);
 
   return 0;
 }

cclox_src/parser.cc

@@ -3,5 +3,6 @@
 
 #include "parser/expr.cc"
 #include "parser/printer.cc"
+#include "parser/parser.cc"
 
 #endif

cclox_src/parser.hh

@@ -1,7 +1,8 @@
-#ifndef PARSER_HH
-#define PARSER_HH
+#ifndef MAIN_PARSER_HH
+#define MAIN_PARSER_HH
 
 #include "parser/expr.hh"
 #include "parser/printer.hh"
+#include "parser/parser.hh"
 
 #endif

cclox_src/parser/parser.cc

@@ -0,0 +1,186 @@
+#include "parser.hh"
+#include "expr.hh"
+#include "../error_handler.hh"
+#include "../tokenizer.hh"
+#include <optional>
+
+extern ErrorHandler error_handler;
+
+std::optional<Expr> Parser::parse() {
+  try {
+    return expression();
+  } catch (ParseException e) {
+    return std::nullopt;
+  }
+}
+
+Expr Parser::expression() {
+  return equality();
+}
+
+Expr Parser::equality() {
+  Expr expr = comparison();
+
+  while (match({TokenType::BANG_EQUAL, TokenType::EQUAL_EQUAL})) {
+    Token op   = previous();
+    Expr right = comparison();
+    expr       = Binary(expr, op, right);
+  }
+
+  return expr;
+}
+
+Expr Parser::comparison() {
+  Expr expr = term();
+
+  while (match({TokenType::GREATER, TokenType::GREATER_EQUAL, TokenType::LESS, TokenType::LESS_EQUAL})) {
+    Token op   = previous();
+    Expr right = term();
+    expr       = Binary(expr, op, right);
+  }
+
+  return expr;
+}
+
+Expr Parser::term() {
+  Expr expr = factor();
+
+  while (match({TokenType::MINUS, TokenType::PLUS})) {
+    Token op = previous();
+    Expr right = factor();
+    expr = Binary(expr, op, right);
+  }
+
+  return expr;
+}
+
+Expr Parser::factor() {
+  Expr expr = unary();
+
+  while (match({TokenType::SLASH, TokenType::STAR})) {
+    Token op   = previous();
+    Expr right = unary();
+    expr       = Binary(expr, op, right);
+  }
+
+  return expr;
+}
+
+Expr Parser::unary() {
+  if (match({TokenType::BANG, TokenType::MINUS})) {
+    Token op   = previous();
+    Expr right = unary();
+
+    return Unary(op, right);
+  }
+
+  return primary();
+}
+
+Expr Parser::primary() {
+  if (match({TokenType::FALSE})) {
+    return Literal(false);
+  }
+
+  if (match({TokenType::TRUE})) {
+    return Literal(true);
+  }
+
+  if (match({TokenType::NIL})) {
+    return Literal(Object{});
+  }
+
+  if (match({TokenType::NUMBER, TokenType::STRING})) {
+    return Literal(previous().literal);
+  }
+
+  if (match({TokenType::LEFT_PAREN})) {
+    Expr expr = expression();
+    consume(TokenType::RIGHT_PAREN, "Expect ')' after expression.");
+    return Grouping(expr);
+  }
+
+  throw error(peek(), "Expect expression.");
+}
+
+Token Parser::advance() {
+  if (!is_at_end()) {
+    ++current;
+  }
+
+  return previous();
+}
+
+Token Parser::peek() {
+  return tokens.at(current);
+}
+
+Token Parser::previous() {
+  return tokens.at(current - 1);
+}
+
+Token Parser::consume(TokenType type, std::string &&message) {
+  if (check(type)) {
+    return advance();
+  }
+
+  throw error(peek(), message);
+}
+
+bool Parser::match(std::vector<TokenType> types) {
+  for (const auto &type : types) {
+    if (check(type)) {
+      advance();
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool Parser::check(TokenType type) {
+  if (is_at_end()) {
+    return false;
+  }
+
+  return peek().type == type;
+}
+
+bool Parser::is_at_end() {
+  return peek().type == TokenType::EOFILE;
+}
+
+ParseException Parser::error(Token token, std::string &message) {
+  error_handler.error(token, message);
+  return ParseException{};
+}
+
+ParseException Parser::error(Token token, std::string &&message) {
+  return error(token, message);
+}
+
+void Parser::synchronize() {
+  advance();
+
+  while (!is_at_end()) {
+    if (previous().type == TokenType::SEMICOLON) {
+      return;
+    }
+
+    switch (peek().type) {
+      case TokenType::CLASS:
+      case TokenType::FUN:
+      case TokenType::VAR:
+      case TokenType::FOR:
+      case TokenType::IF:
+      case TokenType::WHILE:
+      case TokenType::PRINT:
+      case TokenType::RETURN:
+        return;
+      default:
+        break;
+    }
+
+    advance();
+  }
+}

cclox_src/parser/parser.hh

@@ -0,0 +1,47 @@
+#ifndef PARSER_HH
+#define PARSER_HH
+
+#include "expr.hh"
+#include "../tokenizer.hh"
+#include <cstddef>
+#include <exception>
+#include <optional>
+#include <vector>
+
+struct ParseException : public std::exception {
+  ParseException() : message{""} {}
+  ParseException(const std::string& message) : message{message} {}
+  const char* what() const noexcept override {
+      return message.c_str();
+  }
+
+private:
+  std::string message;
+};
+
+struct Parser {
+  Parser(std::vector<Token> tokens) : tokens{tokens} {}
+  std::optional<Expr> parse();
+  Expr expression();
+  Expr equality();
+  Expr comparison();
+  Expr term();
+  Expr factor();
+  Expr unary();
+  Expr primary();
+  Token advance();
+  Token peek();
+  Token previous();
+  Token consume(TokenType type, std::string &&message);
+  bool match(std::vector<TokenType> types);
+  bool check(TokenType type);
+  bool is_at_end();
+  ParseException error(Token token, std::string &message);
+  ParseException error(Token token, std::string &&message);
+  void synchronize();
+
+  std::vector<Token> tokens;
+  size_t current = 0;
+};
+
+#endif

cclox_src/parser/printer.cc

@@ -22,6 +22,10 @@ std::string AstPrinter::print(const Expr &expr) {
       switch (literal->value.type) {
         case ObjectType::NIL:
           return "nil";
+        case ObjectType::BOOL: {
+          bool value = std::get<bool>(literal->value.value);
+          return (value ? "true" : "false");
+        }
         case ObjectType::IDENTIFIER:
         case ObjectType::STRING_LIT: {
           std::string value = std::get<std::string>(literal->value.value);

cclox_src/scanner/object.cc

@@ -6,6 +6,8 @@ std::ostream &operator<<(std::ostream &os, const ObjectType &type) {
     case ObjectType::NIL:
       os << "ObjectType::NIL";
       break;
+    case ObjectType::BOOL:
+      os << "ObjectType::BOOL";
     case ObjectType::IDENTIFIER:
       os << "ObjectType::IDENTIFIER";
       break;
@@ -26,6 +28,9 @@ std::ostream &operator<<(std::ostream &os, const Object &obj) {
   switch (obj.type) {
     case ObjectType::NIL:
       break;
+    case ObjectType::BOOL:
+      os << ", " << std::to_string(std::get<bool>(obj.value));
+      break;
     case ObjectType::IDENTIFIER:
     case ObjectType::STRING_LIT:
       os << ", " << std::get<std::string>(obj.value);