deploy: 94fe31eb9b

examples/parse_error_position.cpp

@@ -0,0 +1,42 @@
+#include <iostream>
+#include <utility>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+// line and column (both starting at 1) of a byte index in a text
+std::pair<std::size_t, std::size_t> line_column(const std::string& input, std::size_t byte)
+{
+    std::size_t line = 1;
+    std::size_t column = 1;
+    for (std::size_t i = 0; i + 1 < byte && i < input.size(); ++i)
+    {
+        if (input[i] == '\n')
+        {
+            ++line;
+            column = 1;
+        }
+        else
+        {
+            ++column;
+        }
+    }
+    return {line, column};
+}
+
+int main()
+{
+    const std::string input = "{\n  \"a\": 1,\n  \"b\": ]\n}";
+
+    try
+    {
+        const json j = json::parse(input);
+        std::cout << j << '\n';
+    }
+    catch (const json::parse_error& e)
+    {
+        const auto position = line_column(input, e.byte);
+        std::cout << e.what() << '\n';
+        std::cout << "byte " << e.byte << " = line " << position.first << ", column " << position.second << '\n';
+    }
+}