libnixf/Parse: parse expr ? attrpath (#353)

nix-community · Feb 12, 2024 · 8b596ef · 8b596ef
1 parent db3792e
commit 8b596ef
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diff --git a/libnixf/include/nixf/Basic/NodeKinds.inc b/libnixf/include/nixf/Basic/NodeKinds.inc
@@ -39,6 +39,7 @@ EXPR(ExprList)
 EXPR(ExprLambda)
 EXPR(ExprBinOp)
 EXPR(ExprUnaryOp)
+EXPR(ExprOpHasAttr)
 EXPR(ExprIf)
 EXPR(ExprAssert)
 EXPR(ExprLet)

diff --git a/libnixf/include/nixf/Basic/Nodes/Op.h b/libnixf/include/nixf/Basic/Nodes/Op.h
@@ -2,6 +2,7 @@
 
 #include "Basic.h"
 
+#include "nixf/Basic/Nodes/Attrs.h"
 #include "nixf/Basic/TokenKinds.h"
 
 #include <memory>
@@ -53,6 +54,24 @@ class ExprBinOp : public ExprOp {
   }
 };
 
+class ExprOpHasAttr : public ExprOp {
+  std::unique_ptr<Expr> E;
+  std::unique_ptr<AttrPath> Path;
+
+public:
+  ExprOpHasAttr(LexerCursorRange Range, std::unique_ptr<Op> O,
+                std::unique_ptr<Expr> E, std::unique_ptr<AttrPath> Path)
+      : ExprOp(NK_ExprOpHasAttr, Range, std::move(O)), E(std::move(E)),
+        Path(std::move(Path)) {}
+
+  [[nodiscard]] Expr *expr() const { return E.get(); }
+  [[nodiscard]] AttrPath *attrpath() const { return Path.get(); }
+
+  [[nodiscard]] ChildVector children() const override {
+    return {E.get(), Path.get()};
+  }
+};
+
 class ExprUnaryOp : public ExprOp {
   std::unique_ptr<Expr> E;
 

diff --git a/libnixf/src/Parse/ParseOp.cpp b/libnixf/src/Parse/ParseOp.cpp
@@ -132,6 +132,18 @@ std::unique_ptr<Expr> Parser::parseExprOpBP(unsigned LeftRBP) {
                                              std::move(Prefix), std::move(RHS));
         break;
       }
+    case tok_question: {
+      // expr_op '?' attrpath
+      consume();
+      assert(LastToken && "consume() should have set LastToken");
+      auto O = std::make_unique<Op>(Tok.range(), Tok.kind());
+
+      std::unique_ptr<AttrPath> Path = parseAttrPath();
+      LexerCursorRange Range{Prefix->lCur(), LastToken->rCur()};
+      Prefix = std::make_unique<ExprOpHasAttr>(
+          Range, std::move(O), std::move(Prefix), std::move(Path));
+      break;
+    }
     default:
       return Prefix;
     }

diff --git a/libnixf/test/Parse/ParseOp.cpp b/libnixf/test/Parse/ParseOp.cpp
@@ -42,4 +42,33 @@ TEST(Parser, UnaryOp) {
   ASSERT_EQ(UnaryOp.expr()->kind(), Node::NK_ExprSelect);
 }
 
+TEST(Parser, OpHasAttr) {
+  auto Src = R"(a ? b.c.d)"sv;
+
+  std::vector<Diagnostic> Diags;
+  Parser P(Src, Diags);
+  auto AST = P.parseExpr();
+
+  ASSERT_TRUE(AST);
+
+  ASSERT_EQ(AST->kind(), Node::NK_ExprOpHasAttr);
+
+  ASSERT_EQ(Diags.size(), 0);
+}
+
+TEST(Parser, OpHasAttr_empty) {
+  auto Src = R"(a ?)"sv;
+
+  std::vector<Diagnostic> Diags;
+  Parser P(Src, Diags);
+  auto AST = P.parseExpr();
+
+  ASSERT_TRUE(AST);
+
+  ASSERT_EQ(AST->kind(), Node::NK_ExprOpHasAttr);
+
+  // libnixf accepts emtpy attrpath while parsing.
+  ASSERT_EQ(Diags.size(), 0);
+}
+
 } // namespace