presets: Improve JSON parser and error messages

1 files changed, 73 insertions, 0 deletions

diff --git a/Source/cmJSONState.h b/Source/cmJSONState.h
new file mode 100644
index 0000000..4984c81
--- /dev/null
+++ b/Source/cmJSONState.h
@@ -0,0 +1,73 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#pragma once
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include <cstddef>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "cmJSONState.h"
+#include "cmStringAlgorithms.h"
+
+namespace Json {
+class Value;
+}
+
+class cmJSONState
+{
+  using Location = struct
+  {
+    int line;
+    int column;
+  };
+
+public:
+  using JsonPair = std::pair<const std::string, const Json::Value*>;
+  cmJSONState() = default;
+  cmJSONState(const std::string& filename, Json::Value* root);
+  void AddError(std::string const& errMsg);
+  void AddErrorAtValue(std::string const& errMsg, const Json::Value* value);
+  void AddErrorAtOffset(std::string const& errMsg, std::ptrdiff_t offset);
+  std::string GetErrorMessage(bool showContext = true);
+  std::string key();
+  std::string key_after(std::string const& key);
+  const Json::Value* value_after(std::string const& key);
+  void push_stack(std::string const& key, const Json::Value* value);
+  void pop_stack();
+
+  class Error
+  {
+  public:
+    Error(Location loc, std::string errMsg)
+      : location(loc)
+      , message(std::move(errMsg)){};
+    Error(std::string errMsg)
+      : location({ -1, -1 })
+      , message(std::move(errMsg)){};
+    std::string GetErrorMessage() const
+    {
+      std::string output = message;
+      if (location.line > 0) {
+        output = cmStrCat("Error: @", location.line, ",", location.column,
+                          ": ", output);
+      }
+      return output;
+    }
+    Location GetLocation() const { return location; }
+
+  private:
+    Location location;
+    std::string message;
+  };
+
+  std::vector<JsonPair> parseStack;
+  std::vector<Error> errors;
+  std::string doc;
+
+private:
+  std::string GetJsonContext(Location loc);
+  Location LocateInDocument(ptrdiff_t offset);
+};