Merge ccdd97e60a into 147e183c68

src/libexpr/include/nix/expr/json-to-value.hh

@@ -12,6 +12,13 @@ struct Value;
 
 MakeError(JSONParseError, Error);
 
-void parseJSON(EvalState & state, const std::string_view & s, Value & v);
+/**
+ * Parse the string into the Value
+ * @param state
+ * @param s
+ * @param v
+ * @param allowComments Whether to allow comments in the JSON
+ */
+void parseJSON(EvalState & state, const std::string_view & s, Value & v, bool allowComments = false);
 
 } // namespace nix

src/libexpr/json-to-value.cc

@@ -201,10 +201,11 @@ public:
     }
 };
 
-void parseJSON(EvalState & state, const std::string_view & s_, Value & v)
+void parseJSON(EvalState & state, const std::string_view & s_, Value & v, bool allowComments)
 {
     JSONSax parser(state, v);
-    bool res = json::sax_parse(s_, &parser);
+    bool res = json::sax_parse(
+        s_, &parser, nlohmann::detail::input_format_t::json, /* strict= */ true, /* ignore_comments= */ allowComments);
     if (!res)
         throw JSONParseError("Invalid JSON Value");
 }

src/libexpr/primops.cc

@@ -2539,11 +2539,11 @@ static RegisterPrimOp primop_toJSON({
 });
 
 /* Parse a JSON string to a value. */
-static void prim_fromJSON(EvalState & state, const PosIdx pos, Value ** args, Value & v)
+static void prim_fromJSON(EvalState & state, const PosIdx pos, Value ** args, Value & v, bool allow_comments)
 {
     auto s = state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.fromJSON");
     try {
-        parseJSON(state, s, v);
+        parseJSON(state, s, v, allow_comments);
     } catch (JSONParseError & e) {
         e.addTrace(state.positions[pos], "while decoding a JSON string");
         throw;
@@ -2562,7 +2562,38 @@ static RegisterPrimOp primop_fromJSON({
 
       returns the value `{ x = [ 1 2 3 ]; y = null; }`.
     )",
-    .fun = prim_fromJSON,
+    .fun =
+        [](EvalState & state, const PosIdx pos, Value ** args, Value & v) {
+            return prim_fromJSON(state, pos, args, v, false);
+        },
+});
+
+static RegisterPrimOp primop_fromJSONC({
+    .name = "__fromJSONC",
+    .args = {"e"},
+    .doc = R"(
+      Convert a JSON string, potentially with comments, to a Nix value.
+      For example,
+
+      ```nix
+      builtins.fromJSONC ''
+      {
+       // This is a comment
+       "x": [1, 2, 3],
+       /* This is another comment */
+       "y": null
+      }
+      ''
+      ```
+
+      returns the value `{ x = [ 1 2 3 ]; y = null; }`.
+
+      This function supports JSON with comments.
+    )",
+    .fun =
+        [](EvalState & state, const PosIdx pos, Value ** args, Value & v) {
+            return prim_fromJSON(state, pos, args, v, true);
+        },
 });
 
 /* Store a string in the Nix store as a source file that can be used

tests/functional/lang/eval-okay-fromjson-comments.exp

@@ -0,0 +1 @@
+true

tests/functional/lang/eval-okay-fromjson-comments.nix

@@ -0,0 +1,61 @@
+builtins.fromJSONC ''
+  {
+    // This is a comment
+    "Video": {
+        /* Multi line comment single line */
+        "Title":  "The Penguin Chronicles",
+        "Width":  1920,
+        "Height": 1080,
+        /**
+         * Multi line comment
+         * with multiple lines
+         */
+        "EmbeddedData": [3.14159, 23493,null, true  ,false, -10],
+        "Thumb": {
+            "Url":    "http://www.example.com/video/5678931",
+            "Width":  200,
+            "Height": 250
+        },
+        "Animated" : false,
+        "IDs": [116, 943, 234, 38793, true  ,false,null, -100],
+        "Escapes": "\"\\\/\t\n\r\t",
+        "Subtitle" : false,
+        "Latitude":  37.7668,
+        "Longitude": -122.3959
+      }
+  }
+'' == {
+  Video = {
+    Title = "The Penguin Chronicles";
+    Width = 1920;
+    Height = 1080;
+    EmbeddedData = [
+      3.14159
+      23493
+      null
+      true
+      false
+      (0 - 10)
+    ];
+    Thumb = {
+      Url = "http://www.example.com/video/5678931";
+      Width = 200;
+      Height = 250;
+    };
+    Animated = false;
+    IDs = [
+      116
+      943
+      234
+      38793
+      true
+      false
+      null
+      (0 - 100)
+    ];
+    Escapes = "\"\\\/\t\n\r\t"; # supported in JSON but not Nix: \b\f
+    Subtitle = false;
+    Latitude = 37.7668;
+    Longitude = -122.3959;
+  };
+}