From 6ffaf4c2e26e90f7e75d2dd5461addcdb8741c85 Mon Sep 17 00:00:00 2001
From: Josh Wolfe <thejoshwolfe@gmail.com>
Date: Mon, 13 Nov 2017 22:56:20 -0700
Subject: [PATCH] parsec supports do loop

---
 src/parsec.cpp  | 58 ++++++++++++++++++++++++++++++++++++++++++++++---
 test/parsec.zig | 27 +++++++++++++++++++++++
 2 files changed, 82 insertions(+), 3 deletions(-)

diff --git a/src/parsec.cpp b/src/parsec.cpp
index 1cc4a8c184..273222b2d0 100644
--- a/src/parsec.cpp
+++ b/src/parsec.cpp
@@ -1987,6 +1987,59 @@ static AstNode *trans_unary_expr_or_type_trait_expr(Context *c, AstNode *block,
     return node;
 }
 
+static AstNode *trans_do_loop(Context *c, AstNode *block, DoStmt *stmt) {
+    stmt->getBody();
+    stmt->getCond();
+
+    AstNode *while_node = trans_create_node(c, NodeTypeWhileExpr);
+
+    AstNode *true_node = trans_create_node(c, NodeTypeBoolLiteral);
+    true_node->data.bool_literal.value = true;
+    while_node->data.while_expr.condition = true_node;
+
+    AstNode *body_node;
+    if (stmt->getBody()->getStmtClass() == Stmt::CompoundStmtClass) {
+        // there's already a block in C, so we'll append our condition to it.
+        // c: do {
+        // c:   a;
+        // c:   b;
+        // c: } while(c);
+        // zig: while (true) {
+        // zig:   a;
+        // zig:   b;
+        // zig:   if (!cond) break;
+        // zig: }
+        body_node = trans_stmt(c, false, block, stmt->getBody(), TransRValue);
+        if (body_node == nullptr) return nullptr;
+        assert(body_node->type == NodeTypeBlock);
+    } else {
+        // the C statement is without a block, so we need to create a block to contain it.
+        // c: do
+        // c:   a;
+        // c: while(c);
+        // zig: while (true) {
+        // zig:   a;
+        // zig:   if (!cond) break;
+        // zig: }
+        body_node = trans_create_node(c, NodeTypeBlock);
+        AstNode *child_statement = trans_stmt(c, false, body_node, stmt->getBody(), TransRValue);
+        if (child_statement == nullptr) return nullptr;
+        body_node->data.block.statements.append(child_statement);
+    }
+
+    // if (!cond) break;
+    AstNode *condition_node = trans_expr(c, true, body_node, stmt->getCond(), TransRValue);
+    if (condition_node == nullptr) return nullptr;
+    AstNode *terminator_node = trans_create_node(c, NodeTypeIfBoolExpr);
+    terminator_node->data.if_bool_expr.condition = trans_create_node_prefix_op(c, PrefixOpBoolNot, condition_node);
+    terminator_node->data.if_bool_expr.then_block = trans_create_node(c, NodeTypeBreak);
+    body_node->data.block.statements.append(terminator_node);
+
+    while_node->data.while_expr.body = body_node;
+
+    return while_node;
+}
+
 static AstNode *trans_stmt(Context *c, bool result_used, AstNode *block, Stmt *stmt, TransLRValue lrvalue) {
     Stmt::StmtClass sc = stmt->getStmtClass();
     switch (sc) {
@@ -2026,6 +2079,8 @@ static AstNode *trans_stmt(Context *c, bool result_used, AstNode *block, Stmt *s
             return trans_c_style_cast_expr(c, result_used, block, (CStyleCastExpr *)stmt, lrvalue);
         case Stmt::UnaryExprOrTypeTraitExprClass:
             return trans_unary_expr_or_type_trait_expr(c, block, (UnaryExprOrTypeTraitExpr *)stmt);
+        case Stmt::DoStmtClass:
+            return trans_do_loop(c, block, (DoStmt *)stmt);
         case Stmt::CaseStmtClass:
             emit_warning(c, stmt->getLocStart(), "TODO handle C CaseStmtClass");
             return nullptr;
@@ -2071,9 +2126,6 @@ static AstNode *trans_stmt(Context *c, bool result_used, AstNode *block, Stmt *s
         case Stmt::CoroutineBodyStmtClass:
             emit_warning(c, stmt->getLocStart(), "TODO handle C CoroutineBodyStmtClass");
             return nullptr;
-        case Stmt::DoStmtClass:
-            emit_warning(c, stmt->getLocStart(), "TODO handle C DoStmtClass");
-            return nullptr;
         case Stmt::BinaryConditionalOperatorClass:
             emit_warning(c, stmt->getLocStart(), "TODO handle C BinaryConditionalOperatorClass");
             return nullptr;
diff --git a/test/parsec.zig b/test/parsec.zig
index a6f23bd2a9..077dcf832c 100644
--- a/test/parsec.zig
+++ b/test/parsec.zig
@@ -804,6 +804,33 @@ pub fn addCases(cases: &tests.ParseCContext) {
         \\    };
         \\}
     );
+
+    cases.addC("do loop",
+        \\void foo(void) {
+        \\    int a = 2;
+        \\    do {
+        \\        a--;
+        \\    } while (a != 0);
+        \\
+        \\    int b = 2;
+        \\    do
+        \\        b--;
+        \\    while (b != 0);
+        \\}
+    ,
+        \\export fn foo() {
+        \\    var a: c_int = 2;
+        \\    while (true) {
+        \\        a -= 1;
+        \\        if (!(a != 0)) break;
+        \\    };
+        \\    var b: c_int = 2;
+        \\    while (true) {
+        \\        b -= 1;
+        \\        if (!(b != 0)) break;
+        \\    };
+        \\}
+    );
 }