better loop control

bootstrap/emit.cc

@@ -91,12 +91,24 @@ std::any EmitVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     return {};
   }
   if (ctx->Break()) {
-    output << "  jmp @loop" << loopstack.back() << "_end" << std::endl;
+    if (auto integer = ctx->Integer()) {
+      auto num = stoul(integer->getSymbol()->getText());
+      output << "  jmp @loop" << *(loopstack.end() - num) << "_end"
+             << std::endl;
+    } else {
+      output << "  jmp @loop" << loopstack.back() << "_end" << std::endl;
+    }
     output << "@dead" << blockcount++ << std::endl;
     return {};
   }
   if (ctx->Continue()) {
-    output << "  jmp @loop" << loopstack.back() << "_expr" << std::endl;
+    if (auto integer = ctx->Integer()) {
+      auto num = stoul(integer->getSymbol()->getText());
+      output << "  jmp @loop" << *(loopstack.end() - num) << "_continue"
+             << std::endl;
+    } else {
+      output << "  jmp @loop" << loopstack.back() << "_continue" << std::endl;
+    }
     output << "@dead" << blockcount++ << std::endl;
     return {};
   }

bootstrap/error.cc

@@ -18,11 +18,34 @@ bool ErrorListener::hasError() {
   return has_error;
 }
 
+void ErrorListener::breakTooMany(antlr4::Token *token, size_t num, size_t max) {
+  printError(token->getLine(), token->getCharPositionInLine(),
+             "tried to break " + std::to_string(num) + " loops, but only " +
+                 std::to_string(max) + " surrounding loops");
+}
+
+void ErrorListener::breakZero(antlr4::Token *token) {
+  printError(token->getLine(), token->getCharPositionInLine(),
+             "tried to break zero loops");
+}
+
 void ErrorListener::compilerError(const std::string &file, size_t line) {
   std::cerr << "compiler bug in " << file << ":" << line << std::endl;
   std::terminate();
 }
 
+void ErrorListener::continueTooMany(antlr4::Token *token, size_t num,
+                                    size_t max) {
+  printError(token->getLine(), token->getCharPositionInLine(),
+             "tried to continue " + std::to_string(num) + " loops, but only " +
+                 std::to_string(max) + " surrounding loops");
+}
+
+void ErrorListener::continueZero(antlr4::Token *token) {
+  printError(token->getLine(), token->getCharPositionInLine(),
+             "tried to continue zero loops");
+}
+
 void ErrorListener::duplicateFunction(antlr4::Token *token,
                                       const std::string &name) {
   printError(token->getLine(), token->getCharPositionInLine(),

bootstrap/error.hh

@@ -17,7 +17,11 @@ class ErrorListener : public antlr4::BaseErrorListener {
 
   bool hasError();
 
+  void breakTooMany(antlr4::Token *token, size_t num, size_t max);
+  void breakZero(antlr4::Token *token);
   [[noreturn]] void compilerError(const std::string &file, size_t line);
+  void continueTooMany(antlr4::Token *token, size_t num, size_t max);
+  void continueZero(antlr4::Token *token);
   void duplicateFunction(antlr4::Token *token, const std::string &name);
   void loopControlWithoutLoop(antlr4::Token *token);
   void shadowedVariable(antlr4::Token *token, const std::string &name);

bootstrap/typecheck.cc

@@ -109,14 +109,35 @@ std::any TypeCheckVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     return {};
   }
   if (ctx->Break()) {
-    if (!loopcount) {
-      errorlistener.loopControlWithoutLoop(ctx->Break()->getSymbol());
+    if (auto integer = ctx->Integer()) {
+      auto num = stoul(integer->getSymbol()->getText());
+      if (!num) {
+        errorlistener.breakZero(ctx->Break()->getSymbol());
+      }
+      if (num > loopcount) {
+        errorlistener.breakTooMany(ctx->Break()->getSymbol(), num, loopcount);
+      }
+    } else {
+      if (!loopcount) {
+        errorlistener.loopControlWithoutLoop(ctx->Break()->getSymbol());
+      }
     }
     return {};
   }
   if (ctx->Continue()) {
-    if (!loopcount) {
-      errorlistener.loopControlWithoutLoop(ctx->Continue()->getSymbol());
+    if (auto integer = ctx->Integer()) {
+      auto num = stoul(integer->getSymbol()->getText());
+      if (!num) {
+        errorlistener.continueZero(ctx->Break()->getSymbol());
+      }
+      if (num > loopcount) {
+        errorlistener.continueTooMany(ctx->Break()->getSymbol(), num,
+                                      loopcount);
+      }
+    } else {
+      if (!loopcount) {
+        errorlistener.loopControlWithoutLoop(ctx->Continue()->getSymbol());
+      }
     }
     return {};
   }

bootstrap/xlang.g4

@@ -10,8 +10,8 @@ block : LeftBrace statement* RightBrace;
 statement : If condition block (Else block)?
           | While condition block
           | For value Semicolon condition Semicolon value block
-          | Break Semicolon
-          | Continue Semicolon
+          | Break Integer? Semicolon
+          | Continue Integer? Semicolon
           | Return value Semicolon
           | Print value Semicolon
           | value Semicolon

test/sieve.x

@@ -1,15 +1,11 @@
 main() : int {
   print 2;
   for i := 3; i < 100; i =+ 2 {
-    composite := false;
     for j := 3; j < i; j =+ 2 {
       if i % j == 0 {
-        composite = true;
-        break;
+        continue 2;
       }
     }
-    if not composite {
-      print i;
-    }
+    print i;
   }
 }