docs: added parser documentation

src/parser.cpp

@@ -1,4 +1,3 @@
-// src/parser.cpp
 #include "parser.hpp"
 #include "ast.hpp"
 
@@ -42,40 +41,28 @@ bool Parser::accept(TokenType t) {
 void Parser::expect(TokenType t) {
     if (!accept(t)) {
         std::cout << display_tokentype(t) << std::endl;
-    throw std::runtime_error("parser: unexpected token at position "
-                             + std::to_string(peek().start));
+        throw std::runtime_error("parser: unexpected token at position " + std::to_string(peek().start));
     }
 }
 
-// Try to parse a definition of the form:
-//   <variable> '=' <term> ';'
-// Returns true if a definition was parsed and stored in defs.
+// parse expressions like "main = \ x . x;"
 bool Parser::tryParseDefinition() {
-  if (peek().type == TokenType::VARIABLE
-   && position+1 < tokens.size()
-   && tokens[position+1].type == TokenType::EQUALS)
-  {
-    std::string name = get().lexeme;  // consume VARIABLE
-    expect(TokenType::EQUALS);            // consume '='
+    if (peek().type == TokenType::VARIABLE && position+1 < tokens.size() && tokens[position+1].type == TokenType::EQUALS) {
+        std::string name = get().lexeme;
+        expect(TokenType::EQUALS);
 
-    // parse the right-hand term
-    std::unique_ptr<Expr> value = parseTerm();
+        std::unique_ptr<Expr> value = parseApplication();
 
-    // require a semicolon (EOL token)
         expect(TokenType::EOL);
 
-    // store in definitions map
         defs.emplace(std::move(name), std::move(value));
         return true;
     }
     return false;
 }
 
-// <simple> ::= '\' <variable>+ '.' <term>
-//            | <variable>
-//            | '(' <term> ')'
+// parse simple expressions like "\ x . x" or "x" or stuff in parenthesis
 std::unique_ptr<Expr> Parser::parseSimple() {
-  // abstraction with one-or-more parameters
     if (accept(TokenType::LAMBDA)) {
         std::vector<std::string> params;
         while (peek().type == TokenType::VARIABLE) {
@@ -83,76 +70,52 @@ std::unique_ptr<Expr> Parser::parseSimple() {
         }
         expect(TokenType::DOT);
 
-    std::unique_ptr<Expr> body = parseTerm();
-    // right-nest them: \p1.\p2.…body
+        std::unique_ptr<Expr> body = parseApplication();
         for (auto it = params.rbegin(); it != params.rend(); ++it) {
             body = std::make_unique<Abstraction>(*it, std::move(body));
         }
         return body;
     }
 
-  // variable
     if (peek().type == TokenType::VARIABLE) {
         const auto &tok = get();
         return std::make_unique<Variable>(tok.lexeme);
     }
 
-  // parenthesized term
     if (accept(TokenType::LPAREN)) {
-    std::unique_ptr<Expr> e = parseTerm();
+        std::unique_ptr<Expr> e = parseApplication();
         expect(TokenType::RPAREN);
         return e;
     }
 
-  throw std::runtime_error("parser: expected \\, variable, or '(' at position "
-                         + std::to_string(peek().start));
+    throw std::runtime_error("parser: expected \\, variable, or '(' at position " + std::to_string(peek().start));
 }
 
-// <application> ::= <simple> { <simple> }
+// parse function applications
 std::unique_ptr<Expr> Parser::parseApplication() {
     std::unique_ptr<Expr> expr = parseSimple();
     while (true) {
         TokenType t = peek().type;
-    if (t == TokenType::VARIABLE ||
-        t == TokenType::LAMBDA   ||
-        t == TokenType::LPAREN)
-    {
+        if (t == TokenType::VARIABLE || t == TokenType::LAMBDA || t == TokenType::LPAREN) {
             std::unique_ptr<Expr> rhs = parseSimple();
             expr = std::make_unique<Application>(std::move(expr), std::move(rhs));
-    } else {
-      break;
         }
+        else break;
     }
     return expr;
 }
 
-// <term> ::= <application>
-std::unique_ptr<Expr> Parser::parseTerm() {
-  return parseApplication();
-}
-
-// parse exactly one term and expect EOC
-std::unique_ptr<Expr> Parser::parse() {
-  std::unique_ptr<Expr> root = parseTerm();
-  expect(TokenType::EOC);
-  return root;
-}
-
-// <program> ::= { <definition> | <term> EOL } EOC
+// uuum... i think the name says it?
 std::vector<std::unique_ptr<Expr>> Parser::parseProgram() {
     std::vector<std::unique_ptr<Expr>> results;
 
     while (peek().type != TokenType::EOC) {
-    // first try a definition
-    if (tryParseDefinition())
-      continue;
+        if (tryParseDefinition()) continue;
 
-    // otherwise a bare term ending in EOL
-    results.push_back(parseTerm());
+        results.push_back(parseApplication());
         expect(TokenType::EOL);
     }
 
     expect(TokenType::EOC);
     return results;
 }
-

src/print.cpp

@@ -3,6 +3,8 @@
 #include <sstream>
 #include <vector>
 
+// thank you chatgpt lol
+
 // Forward‐declare
 static void _print(const Expr* e, std::ostream& out);
 
@@ -51,6 +53,6 @@ static void _print(const Expr* e, std::ostream& out) {
     }
 
     // fallback
-    out << "<??>";
+    out << "print: unknown expression";
 }