Implement &. in desugar

sorbet · Nov 14, 2017 · 93ae72f · 93ae72f
1 parent 690590a
commit 93ae72f
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Showing 3 changed files with 33 additions and 0 deletions.
diff --git a/ast/desugar/Desugar.cc b/ast/desugar/Desugar.cc
@@ -291,6 +291,29 @@ unique_ptr<Expression> node2TreeImpl(core::Context ctx, unique_ptr<parser::Node>
             auto send = mkSend(what->loc, rec, a->method, args, flags);
             result.swap(send);
         },
+        [&](parser::CSend *a) {
+            core::NameRef tempRecv =
+                ctx.state.freshNameUnique(core::UniqueNameKind::Desugar, core::Names::assignTemp());
+            core::Loc recvLoc = a->receiver->loc;
+
+            // NOTE(nelhage): We actually desugar into a call to `nil?`. If an
+            // object has overridden `nil?`, this technically will not match
+            // Ruby's behavior.
+
+            auto assgn = mkAssign(recvLoc, tempRecv, node2TreeImpl(ctx, a->receiver));
+            auto cond = mkSend0(a->loc, mkLocal(recvLoc, tempRecv), core::Names::nil_p());
+
+            unique_ptr<parser::Node> sendNode = make_unique<parser::Send>(
+                a->loc, make_unique<parser::LVar>(recvLoc, tempRecv), a->method, move(a->args));
+            auto send = node2TreeImpl(ctx, sendNode);
+
+            unique_ptr<Expression> nil = make_unique<Nil>(a->loc);
+            auto iff = mkIf(a->loc, cond, nil, send);
+            InsSeq::STATS_store stats;
+            stats.emplace_back(move(assgn));
+            auto res = mkInsSeq(a->loc, stats, move(iff));
+            result.swap(res);
+        },
         [&](parser::Self *a) {
             unique_ptr<Expression> self = make_unique<Self>(what->loc, ctx.state.defn_todo());
             result.swap(self);

diff --git a/core/Context.cc b/core/Context.cc
@@ -131,6 +131,9 @@ static UTF8Desc ampersand_DESC{(char *)ampersand_str, (int)strlen(ampersand_str)
 static const char *lambda_str = "lambda";
 static UTF8Desc lambda_DESC{(char *)lambda_str, (int)strlen(lambda_str)};
 
+static const char *nil_p_str = "nil?";
+static UTF8Desc nil_p_DESC{(char *)nil_p_str, (int)strlen(nil_p_str)};
+
 static const char *todo_str = "<todo sym>";
 static UTF8Desc todo_DESC{(char *)todo_str, (int)strlen(todo_str)};
 
@@ -274,6 +277,7 @@ GlobalState::GlobalState(spdlog::logger &logger) : logger(logger), errors(*this)
     NameRef ampersand_id = enterNameUTF8(ampersand_DESC);
     NameRef block_call_id = enterNameUTF8(block_call_DESC);
     NameRef lambda_id = enterNameUTF8(lambda_DESC);
+    NameRef nil_p_id = enterNameUTF8(nil_p_DESC);
 
     DEBUG_ONLY(Error::check(init_id == Names::initialize()));
     DEBUG_ONLY(Error::check(andAnd_id == Names::andAnd()));
@@ -313,6 +317,7 @@ GlobalState::GlobalState(spdlog::logger &logger) : logger(logger), errors(*this)
     DEBUG_ONLY(Error::check(ampersand_id == Names::ampersand()));
     DEBUG_ONLY(Error::check(block_call_id == Names::blockCall()));
     DEBUG_ONLY(Error::check(lambda_id == Names::lambda()));
+    DEBUG_ONLY(Error::check(nil_p_id == Names::nil_p()));
 
     SymbolRef no_symbol_id = synthesizeClass(no_symbol_DESC);
     SymbolRef top_id = synthesizeClass(top_DESC); // BasicObject

diff --git a/core/Names.h b/core/Names.h
@@ -317,6 +317,11 @@ CheckSize(UniqueName, 8, 4)
     static inline NameRef lambda() {
         return NameRef(38);
     }
+
+    // nil?
+    static inline NameRef nil_p() {
+        return NameRef(39);
+    }
 };
 
 class Name {