Rework Paragraph parsing error handling. Add single paragraph functions

2 files changed, 39 insertions, 2 deletions

diff --git a/toolsrc/include/Paragraphs.h b/toolsrc/include/Paragraphs.h
index 79b66a67f..74f8218ca 100644
--- a/toolsrc/include/Paragraphs.h
+++ b/toolsrc/include/Paragraphs.h
@@ -8,8 +8,10 @@
 
 namespace vcpkg::Paragraphs
 {
-    std::vector<std::unordered_map<std::string, std::string>> get_paragraphs(const fs::path& control_path);
-    std::vector<std::unordered_map<std::string, std::string>> parse_paragraphs(const std::string& str);
+    expected<std::unordered_map<std::string, std::string>> get_single_paragraph(const fs::path& control_path);
+    expected<std::vector<std::unordered_map<std::string, std::string>>> get_paragraphs(const fs::path& control_path);
+    expected<std::unordered_map<std::string, std::string>> parse_single_paragraph(const std::string& str);
+    expected<std::vector<std::unordered_map<std::string, std::string>>> parse_paragraphs(const std::string& str);
 
     expected<SourceParagraph> try_load_port(const fs::path& control_path);
 
diff --git a/toolsrc/include/paragraph_parse_result.h b/toolsrc/include/paragraph_parse_result.h
new file mode 100644
index 000000000..47f20c08e
--- /dev/null
+++ b/toolsrc/include/paragraph_parse_result.h
@@ -0,0 +1,35 @@
+#pragma once
+#include <system_error>
+
+namespace vcpkg
+{
+    enum class paragraph_parse_result
+    {
+        SUCCESS = 0,
+        EXPECTED_ONE_PARAGRAPH
+    };
+
+    struct paragraph_parse_result_category_impl final : std::error_category
+    {
+        virtual const char* name() const noexcept override;
+
+        virtual std::string message(int ev) const noexcept override;
+    };
+
+    const std::error_category& paragraph_parse_result_category();
+
+    std::error_code make_error_code(paragraph_parse_result e);
+
+    paragraph_parse_result to_paragraph_parse_result(int i);
+
+    paragraph_parse_result to_paragraph_parse_result(std::error_code ec);
+}
+
+// Enable implicit conversion to std::error_code
+namespace std
+{
+    template <>
+    struct is_error_code_enum<vcpkg::paragraph_parse_result> : ::std::true_type
+    {
+    };
+}