fields: make combi-fields introspectable

And add the display of combination-fields to 'mu info fields'.

lib/message/mu-fields.cc

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2022-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2022-2024 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -19,11 +19,59 @@
 
 #include "mu-fields.hh"
 #include "mu-flags.hh"
+#include "utils/mu-utils.hh"
 
 #include "utils/mu-test-utils.hh"
 
 using namespace Mu;
 
+const Mu::CombiFields&
+Mu::combi_fields()
+{
+	static CombiFields cfields = {
+		CombiField{ "recip",
+		  { field_from_id(Field::Id::To),
+		    field_from_id(Field::Id::Cc),
+		    field_from_id(Field::Id::Bcc)}},
+		CombiField { "contact",
+		  { field_from_id(Field::Id::To),
+		    field_from_id(Field::Id::Cc),
+		    field_from_id(Field::Id::Bcc),
+		    field_from_id(Field::Id::From)}},
+		CombiField { "",
+		  { field_from_id(Field::Id::To),
+		    field_from_id(Field::Id::Cc),
+		    field_from_id(Field::Id::Bcc),
+		    field_from_id(Field::Id::From),
+		    field_from_id(Field::Id::Subject),
+		    field_from_id(Field::Id::BodyText),
+		    field_from_id(Field::Id::EmbeddedText),
+		  }}
+	};
+
+	return cfields;
+}
+
+const Mu::FieldsVec&
+Mu::fields_from_name(const std::string& name) {
+
+	static const FieldsVec empty;
+	const auto& cfields{combi_fields()};
+	const auto it = seq_find_if(cfields, [&](auto cfield) {
+		return cfield.name == name;
+	});
+
+	return it == cfields.end() ? empty : it->fields;
+}
+
+bool
+Mu::field_is_combi(const std::string& name)
+{
+	return name != "" && seq_some(combi_fields(),[&](auto cfield) {
+		return cfield.name == name;
+	});
+}
+
 std::string
 Field::xapian_term(const std::string& s) const
 {

lib/message/mu-fields.hh

@@ -402,7 +402,7 @@ static constexpr std::array<Field, Field::id_size()>
 		{},
 		'r',
 		Field::Flag::Value |
-				Field::Flag::BooleanTerm |
+		Field::Flag::BooleanTerm |
 		Field::Flag::IncludeInSexp
 	    },
 	    {
@@ -534,6 +534,25 @@ Option<Field> field_from_name(const std::string& name) {
 	}
 }
 
+using FieldsVec = std::vector<Field>; /**< Vec of fields */
+
+/**
+ * Describe a combination-field, i.e., a pseudo-field that
+ * expands to some real fields, as a query shortcut.
+ */
+struct CombiField {
+	std::string_view name;	/**< name of the combi-field */
+	FieldsVec fields;	/**< fields this resolves to */
+};
+using CombiFields = std::vector<CombiField>; /**< vec of combi-fields */
+
+/**
+ * Get information about the combination fields
+ *
+ * @return vector with information.
+ */
+const CombiFields&  combi_fields();
+
 /**
  * Return combination-fields such
  * as "contact", "recip" and "" (empty)
@@ -542,48 +561,16 @@ Option<Field> field_from_name(const std::string& name) {
  *
  * @return list of matching fields
  */
-using FieldsVec = std::vector<Field>;
-static inline
-const FieldsVec& fields_from_name(const std::string& name) {
-
-	static const FieldsVec none{};
-	static const FieldsVec recip_fields ={
-		field_from_id(Field::Id::To),
-		field_from_id(Field::Id::Cc),
-		field_from_id(Field::Id::Bcc)};
-
-	static const FieldsVec contact_fields = {
-		field_from_id(Field::Id::To),
-		field_from_id(Field::Id::Cc),
-		field_from_id(Field::Id::Bcc),
-		field_from_id(Field::Id::From),
-	};
-	static const FieldsVec empty_fields= {
-		field_from_id(Field::Id::To),
-		field_from_id(Field::Id::Cc),
-		field_from_id(Field::Id::Bcc),
-		field_from_id(Field::Id::From),
-		field_from_id(Field::Id::Subject),
-		field_from_id(Field::Id::BodyText),
-		field_from_id(Field::Id::EmbeddedText),
-	};
-
-	if (name == "recip")
-		return recip_fields;
-	else if (name == "contact")
-		return contact_fields;
-	else if (name.empty())
-		return empty_fields;
-	else
-		return none;
-}
-
-static inline bool
-field_is_combi (const std::string& name)
-{
-	return name == "recip" || name == "contact";
-}
+const FieldsVec& fields_from_name(const std::string& name);
 
+/**
+ * Is the field a combination field?
+ *
+ * @param name name of the field
+ *
+ * @return true or false
+ */
+bool field_is_combi (const std::string& name);
 
 /**
  * Get the Field::Id for some number, or nullopt if it does not match

mu/mu-cmd-info.cc

@@ -136,6 +136,37 @@ topic_fields(const Options& opts)
 	return Ok();
 }
 
+static Result<void>
+topic_combi_fields(const Options& opts)
+{
+	using namespace std::string_literals;
+
+	Table fields;
+	fields.add_row({"combi-field", "fields"});
+
+	seq_for_each(combi_fields(), [&](const auto& cfield) {
+
+		std::string fnames;
+		seq_for_each(cfield.fields, [&](auto&& field) {
+			if (!fnames.empty())
+				fnames += ", ";
+			fnames +=  mu_format("{}", field.name);
+		});
+
+		const std::string empty{"<empty>"};
+
+		fields.add_row({cfield.name.empty() ? empty : mu_format("{}", cfield.name),
+				fnames});
+	});
+
+	colorify(fields, opts);
+	std::cout << "# Combination fields\n" << fields << '\n';
+
+	return Ok();
+}
+
+
+
 static Result<void>
 topic_flags(const Options& opts)
 {
@@ -290,7 +321,9 @@ Mu::mu_cmd_info(const Mu::Store& store, const Options& opts)
 	else if (topic == "fields") {
 		topic_fields(opts);
 		std::cout << std::endl;
-		return topic_flags(opts);
+		topic_combi_fields(opts);
+		std::cout << std::endl;
+		topic_flags(opts);
 	} else if (topic == "mu") {
 		return topic_mu(opts);
 	} else {