Spreadsheet/XSV: Add at() accessors

These are just aliases for operator[].
Also make the headers() getter return a vector of empty strings when the
csv file has no explicit headers.

Userland/Applications/Spreadsheet/Readers/XSV.cpp

@@ -48,8 +48,17 @@ void XSV::set_error(ReadError error)
 Vector<String> XSV::headers() const
 {
     Vector<String> headers;
-    for (auto& field : m_names)
+    if (has_explicit_headers()) {
-        headers.append(field.is_string_view ? field.as_string_view : field.as_string.view());
+        for (auto& field : m_names)
+            headers.append(field.is_string_view ? field.as_string_view : field.as_string.view());
+    } else {
+        // No headers read, grab one of the rows and generate empty names
+        if (m_rows.is_empty())
+            return headers;
+
+        for ([[maybe_unused]] auto& field : m_rows.first())
+            headers.append(String::empty());
+    }
 
     return headers;
 }
@@ -263,6 +272,11 @@ const XSV::Row XSV::operator[](size_t index) const
     return const_cast<XSV&>(*this)[index];
 }
 
+XSV::Row XSV::at(size_t index) const
+{
+    return this->operator[](index);
+}
+
 XSV::Row XSV::operator[](size_t index)
 {
     VERIFY(m_rows.size() > index);

Userland/Applications/Spreadsheet/Readers/XSV.h

@@ -49,7 +49,7 @@ ParserBehaviour operator|(ParserBehaviour left, ParserBehaviour right);
 struct ParserTraits {
     String separator;
     String quote { "\"" };
-    enum {
+    enum QuoteEscape {
         Repeat,
         Backslash,
     } quote_escape { Repeat };
@@ -103,6 +103,7 @@ public:
 
     size_t size() const { return m_rows.size(); }
     Vector<String> headers() const;
+    [[nodiscard]] bool has_explicit_headers() const { return (static_cast<u32>(m_behaviours) & static_cast<u32>(ParserBehaviour::ReadHeaders)) != 0; }
 
     class Row {
     public:
@@ -115,7 +116,11 @@ public:
         StringView operator[](StringView name) const;
         StringView operator[](size_t column) const;
 
+        template<typename T>
+        StringView at(T column) const { return this->operator[](column); }
+
         size_t index() const { return m_index; }
+        size_t size() const { return m_xsv.headers().size(); }
 
         // FIXME: Implement begin() and end(), keeping `Field' out of the API.
 
@@ -166,6 +171,8 @@ public:
     const Row operator[](size_t index) const;
     Row operator[](size_t index);
 
+    Row at(size_t index) const;
+
     auto begin() { return RowIterator<false>(*this); }
     auto end() { return RowIterator<false>(*this, m_rows.size()); }