From ddd7fb04673c7c04003de786ce83025a41c69fd1 Mon Sep 17 00:00:00 2001
From: Thomas Lindner <tom@dl6tom.de>
Date: Sat, 7 Jan 2023 17:10:03 +0100
Subject: [PATCH] add C style for loop

---
 bootstrap/emit.cc      | 44 +++++++++++++++++++++++++++++++-----------
 bootstrap/typecheck.cc | 35 +++++++++++++++++++++++----------
 bootstrap/xlang.g4     |  2 ++
 test/fib.x             |  8 ++------
 test/sieve.x           |  8 ++------
 5 files changed, 64 insertions(+), 33 deletions(-)

diff --git a/bootstrap/emit.cc b/bootstrap/emit.cc
index 5cfdbfb..fc358dd 100644
--- a/bootstrap/emit.cc
+++ b/bootstrap/emit.cc
@@ -56,43 +56,65 @@ std::any EmitVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     int block = blockcount++;
 
     loopstack.push_back(block);
-    output << "@while" << block << "_expr" << std::endl;
+    output << "@loop" << block << "_continue" << std::endl;
+    output << "@loop" << block << "_expr" << std::endl;
     tmpcount = 0;
     visitCondition(ctx->condition());
-    output << "  jnz " << last << ", @while" << block << "_body, @while"
-           << block << "_end" << std::endl;
-    output << "@while" << block << "_body" << std::endl;
+    output << "  jnz " << last << ", @loop" << block << "_body, @loop" << block
+           << "_end" << std::endl;
+    output << "@loop" << block << "_body" << std::endl;
     visitBlock(ctx->block(0));
-    output << "  jmp @while" << block << "_expr" << std::endl;
-    output << "@while" << block << "_end" << std::endl;
+    output << "  jmp @loop" << block << "_expr" << std::endl;
+    output << "@loop" << block << "_end" << std::endl;
+    loopstack.pop_back();
+    return {};
+  }
+  if (ctx->For()) {
+    int block = blockcount++;
+
+    loopstack.push_back(block);
+    tmpcount = 0;
+    visitValue(ctx->value(0));
+    output << "@loop" << block << "_expr" << std::endl;
+    tmpcount = 0;
+    visitCondition(ctx->condition());
+    output << "  jnz " << last << ", @loop" << block << "_body, @loop" << block
+           << "_end" << std::endl;
+    output << "@loop" << block << "_body" << std::endl;
+    visitBlock(ctx->block(0));
+    output << "@loop" << block << "_continue" << std::endl;
+    tmpcount = 0;
+    visitValue(ctx->value(1));
+    output << "  jmp @loop" << block << "_expr" << std::endl;
+    output << "@loop" << block << "_end" << std::endl;
     loopstack.pop_back();
     return {};
   }
   if (ctx->Break()) {
-    output << "  jmp @while" << loopstack.back() << "_end" << std::endl;
+    output << "  jmp @loop" << loopstack.back() << "_end" << std::endl;
     output << "@dead" << blockcount++ << std::endl;
     return {};
   }
   if (ctx->Continue()) {
-    output << "  jmp @while" << loopstack.back() << "_expr" << std::endl;
+    output << "  jmp @loop" << loopstack.back() << "_expr" << std::endl;
     output << "@dead" << blockcount++ << std::endl;
     return {};
   }
   if (ctx->Return()) {
     tmpcount = 0;
-    visitValue(ctx->value());
+    visitValue(ctx->value(0));
     output << "  ret " << last << std::endl;
     output << "@dead" << blockcount++ << std::endl;
     return {};
   }
   if (ctx->Print()) {
     tmpcount = 0;
-    visitValue(ctx->value());
+    visitValue(ctx->value(0));
     output << "  call $printf(l $printformat, ..., w " << last << ")"
            << std::endl;
     return {};
   }
-  visitValue(ctx->value());
+  visitValue(ctx->value(0));
   return {};
 }
 
diff --git a/bootstrap/typecheck.cc b/bootstrap/typecheck.cc
index 9e75038..69e2f29 100644
--- a/bootstrap/typecheck.cc
+++ b/bootstrap/typecheck.cc
@@ -75,22 +75,37 @@ std::any TypeCheckVisitor::visitBlock(xlangParser::BlockContext *ctx) {
 }
 
 std::any TypeCheckVisitor::visitStatement(xlangParser::StatementContext *ctx) {
-  if (auto condition = ctx->condition()) {
+  if (ctx->If()) {
+    scope.enter();
+    auto condition = ctx->condition();
     auto type = std::any_cast<Type>(visitCondition(condition));
-
     if (type != Type::Boolean) {
       errorlistener.typeMismatch(condition->getStart(), Type::Boolean, type);
     }
-    if (ctx->While()) {
-      loopcount++;
-    }
     visitBlock(ctx->block(0));
-    if (ctx->While()) {
-      loopcount--;
-    }
     if (ctx->Else()) {
       visitBlock(ctx->block(1));
     }
+    scope.leave();
+    return {};
+  }
+  if (ctx->While() || ctx->For()) {
+    scope.enter();
+    if (ctx->For()) {
+      visitValue(ctx->value(0));
+    }
+    auto condition = ctx->condition();
+    auto type = std::any_cast<Type>(visitCondition(condition));
+    if (type != Type::Boolean) {
+      errorlistener.typeMismatch(condition->getStart(), Type::Boolean, type);
+    }
+    if (ctx->For()) {
+      visitValue(ctx->value(1));
+    }
+    loopcount++;
+    visitBlock(ctx->block(0));
+    loopcount--;
+    scope.leave();
     return {};
   }
   if (ctx->Break()) {
@@ -106,10 +121,10 @@ std::any TypeCheckVisitor::visitStatement(xlangParser::StatementContext *ctx) {
     return {};
   }
   if (ctx->Return()) {
-    auto type = std::any_cast<Type>(visitValue(ctx->value()));
+    auto type = std::any_cast<Type>(visitValue(ctx->value(0)));
 
     if (type != returntype) {
-      errorlistener.typeMismatch(ctx->value()->getStart(), returntype, type);
+      errorlistener.typeMismatch(ctx->value(0)->getStart(), returntype, type);
     }
   }
   visitChildren(ctx);
diff --git a/bootstrap/xlang.g4 b/bootstrap/xlang.g4
index 3b32a1b..2eb22e8 100644
--- a/bootstrap/xlang.g4
+++ b/bootstrap/xlang.g4
@@ -9,6 +9,7 @@ type  : TypeInteger
 block : LeftBrace statement* RightBrace;
 statement : If condition block (Else block)?
           | While condition block
+          | For value Semicolon condition Semicolon value block
           | Break Semicolon
           | Continue Semicolon
           | Return value Semicolon
@@ -54,6 +55,7 @@ TypeBoolean : 'bool';
 If  : 'if';
 Else  : 'else';
 While : 'while';
+For : 'for';
 Break : 'break';
 Continue  : 'continue';
 Return  : 'return';
diff --git a/test/fib.x b/test/fib.x
index c785953..9222d17 100644
--- a/test/fib.x
+++ b/test/fib.x
@@ -1,9 +1,7 @@
 main() : int {
-  i := 0;
-  while i < 10 {
+  for i := 0; i < 10; i =+ 1 {
     print fib_rec(i);
     print fib_iter(i);
-    i =+ 1;
   }
 }
 
@@ -17,12 +15,10 @@ fib_rec(n : int) : int {
 fib_iter(n : int) : int {
   x0 := 1;
   x1 := 1;
-  i := 0;
-  while i < n {
+  for i := 0; i < n; i =+ 1 {
     t := x0 + x1;
     x0 = x1;
     x1 = t;
-    i =+ 1;
   }
   return x0;
 }
diff --git a/test/sieve.x b/test/sieve.x
index f97ec62..eba644c 100644
--- a/test/sieve.x
+++ b/test/sieve.x
@@ -1,19 +1,15 @@
 main() : int {
   print 2;
-  i := 3;
-  while i < 100 {
+  for i := 3; i < 100; i =+ 2 {
     composite := false;
-    j := 3;
-    while j < i {
+    for j := 3; j < i; j =+ 2 {
       if i % j == 0 {
         composite = true;
         break;
       }
-      j =+ 2;
     }
     if not composite {
       print i;
     }
-    i =+ 2;
   }
 }