mu-find: implement format=json2

Implement a new experimental json2 format for mu-find, which gets rid of
the ":" prefixes for fields, i.e., "subject" instead of ":subject".
Document it as well.

NEWS.org

@@ -35,6 +35,12 @@
     is a bit easier to manipulate than the emacs-style timestamps (same value,
     but expressed as a list).
 
+  - With 1.12.10, there is also an experimental ~--format=json2~, where key-names
+    are no longer prefixed with ~:~, so for example, "*subject"* instead of
+    "*:subject"*.
+
+  - With 1.12.9, the cleanup phase after indexing is significantly faster now
+
   - with 1.12.7, ~mu~ indexing is single-threaded again, to avoid cases of
     database-corruption. In *mu4e* that means you need to _wait_ until indexing is
     ready before you can continue (*mu4e* will warn you).
@@ -47,8 +53,6 @@
     in the mu4e version in its main-page; however, since this is optional no
     longer, the suffix has been removed.
 
-  - the cleanup phase after indexing is significantly faster now
-
 *** mu4e
 
   - message composition has been completely reworked to avoid a number of
@@ -69,9 +73,9 @@
     result you expected.
 
   - When you ask for bookmarks or maildirs through ~mu4e-search-bookmark~ or
-    ~mu4e-search-maildir~, unread counts are displayed in the (default) completions
+    ~mu4e-search-maildir~, unread counts are displayed in the (default)
-    UI next to the maildir or bookmark. If you don't want to see these counts,
+    completions UI next to the maildir or bookmark. If you don't want to see
-    set ~mu4e-hide-short-counts~ to non-~nil~.
+    these counts, set ~mu4e-hide-short-counts~ to non-~nil~.
 
   - A (experimental) "transient" menu has been added for mu4e. You can use it
     e.g., with something like:

lib/utils/mu-sexp.cc

@@ -228,6 +228,13 @@ Sexp::to_json_string(Format fopts) const
 {
 	std::stringstream sstrm;
 
+	const auto sym_name=[&](const std::string& sym) {
+		if (any_of(fopts & Format::NoColon) && sym[0] == ':')
+			return sym.substr(1); // remove colon
+		else
+			return sym;
+	};
+
 	switch (type()) {
 	case Type::List: {
 		// property-lists become JSON objects
@@ -237,16 +244,18 @@ Sexp::to_json_string(Format fopts) const
 			bool first{true};
 			while (it != list().end()) {
 				const auto key{it->symbol().name};
-				sstrm << (first ? "" : ",")  << quote(key) << ":";
+				sstrm << (first ? "" : ",")
+				      << quote(sym_name(key)) << ":";
 				++it;
 				const auto emacs_tstamp{*it};
-				sstrm << emacs_tstamp.to_json_string();
+				sstrm << emacs_tstamp.to_json_string(fopts);
 				++it;
 				first = false;
 				// special-case: tstamp-fields also get a "unix" value,
 				// which are easier to work with than the "emacs" timestamps
 				if (key == ":date" || key == ":changed")
-					sstrm << "," << quote(key + "-unix") << ":"
+					sstrm << "," << quote(sym_name(key) + "-unix")
+					      << ":"
 					      << unix_tstamp(emacs_tstamp);
 			}
 			sstrm << "}";
@@ -256,7 +265,7 @@ Sexp::to_json_string(Format fopts) const
 			sstrm << '[';
 			bool first{true};
 			for (auto&& child : list()) {
-				sstrm << (first ? "" : ", ") << child.to_json_string();
+				sstrm << (first ? "" : ", ") << child.to_json_string(fopts);
 				first = false;
 			}
 			sstrm << ']';
@@ -287,7 +296,6 @@ Sexp::to_json_string(Format fopts) const
 }
 
 
-
 Sexp&
 Sexp::del_prop(const std::string& pname)
 {

lib/utils/mu-sexp.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2020-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2020-2025 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
@@ -264,6 +264,8 @@ struct Sexp {
 		Default	  = 0,	/**< Nothing in particular */
 		SplitList = 1 << 0,	/**< Insert newline after list item */
 		TypeInfo  = 1 << 1, /**< Show type-info */
+		NoColon = 1 << 2, /**< In the Json output, remove the colon
+				       * prefixes for property keys */
 	};
 
 	/**
@@ -272,7 +274,7 @@ struct Sexp {
 	 * @return str
 	 */
 	std::string to_string(Format fopts=Format::Default) const;
-	std::string to_json_string(Format fopts=Format::Default) const;
+	std::string to_json_string(Format fopts) const;
 
 	Sexp& del_prop(const std::string& pname);
 
@@ -280,7 +282,7 @@ struct Sexp {
 	 * Some useful constants
 	 *
 	 */
-	static inline const auto nil_sym	= Sexp::Symbol{"nil"};
+	static inline const auto nil_sym = Sexp::Symbol{"nil"};
 	static inline const auto t_sym	= Sexp::Symbol{"t"};
 
 protected:

man/mu-find.1.org

@@ -34,8 +34,9 @@ would find all messages in 2009 with `snow' in the subject field, e.g:
 #+end_example
 
 Note, this the default, plain-text output, which is the default, so you don't
-have to use *--format=plain*. For other types of output (such as symlinks, XML or
+have to use *--format=plain*. For other types of output (such as symlinks, XML,
-s-expressions), see the discussion in the *OPTIONS*-section below about *--format*.
+s-expressions or JSON), see the discussion in the *OPTIONS*-section below about
+*--format*.
 
 The search pattern is taken as a command-line parameter. If the search
 parameter consists of multiple parts (as in the example) they are
@@ -114,13 +115,15 @@ Note, if you specify a sortfield, by default, messages are sorted in reverse
 choice, but for dates it may be more useful to sort in the opposite direction.
 
 ** -n, --maxnum _number_
+
 If _number_ > 0, display maximally that number of entries. If not specified, all
 matching entries are displayed.
 
 ** --summary-len _number_
+
 If _number_ > 0, use that number of lines of the message to provide a summary.
 
-** --format plain|links|xml|sexp
+** --format plain|links|xml|sexp|json|json2
 
 Output results in the specified format.
 
@@ -131,8 +134,13 @@ Output results in the specified format.
 - *xml* formats the search results as XML.
 - *sexp* formats the search results as an s-expression as used in Lisp programming
   environments.
+- *json* formats the output as JSON; it is a direct translation of the *sexp* format
+- *json2* is a slightly more idiomatic JSON, for now the only difference with *json*
+  is that the latter avoids the ':' prefix in key-names (e.g., "subject" instead
+  of ":subject"). *json2* is still experimental.
 
 ** --linksdir _dir_ and -c, --clearlinks
+
 When using *--format=links*, output the results as a maildir with symbolic links
 to the found messages. This enables easy integration with mail-clients (see
 below for more information). *mu* will create the maildir if it does not exist
@@ -152,6 +160,7 @@ it automatically inserts a _.noindex_ file, to exclude the directory from *mu
 index*.
 
 ** --after _timestamp_
+
 Only show messages whose message files were last modified (*mtime*) after
 _timestamp_. _timestamp_ is a UNIX *time_t* value, the number of seconds since
 1970-01-01 (in UTC).
@@ -279,8 +288,6 @@ After restarting Wanderlust, the virtual folders should appear.
 
 *mu find* output is encoded according to the locale for *--format=plain* (the
 default format), and UTF-8 for all other formats (=sexp=, =xml=).
-
-
 * PERFORMANCE
 
 Some notes on performance, comparing the timings between some recent releases;
@@ -289,7 +296,6 @@ taking the total number for 10 test runs.
 1. time (repeat 10 mu find "" -n 50000 > /dev/null)
 2. time (repeat 10 mu find "" -n 50000 --include-related --threads > /dev/null)
 
-
 #+ATTR_MAN: :disable-caption t
 |       release | time 1 (sec) | time 2 (sec) |
 |---------------+--------------+--------------|
@@ -299,9 +305,6 @@ taking the total number for 10 test runs.
 |          1.10 | 9.8s         | 30.6s        |
 | 1.11 (master) | 10.1s        | 29.5s        |
 
-
-
-
 #+include: "exit-code.inc" :minlevel 1
 
 #+include: "bugs.inc" :minlevel 1

mu/mu-cmd-find.cc

@@ -1,5 +1,5 @@
  /*
-** Copyright (C) 2008-2024 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2008-2025 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
@@ -383,7 +383,10 @@ output_json(const Option<Message>& msg, const OutputInfo& info, const Options& o
 	if (!msg)
 		return Ok();
 
-	mu_println("{}{}", msg->sexp().to_json_string(), info.last ? "" : ",");
+	const Sexp::Format frm{opts.find.format == Format::Json2 ?  Sexp::Format::NoColon :
+		Sexp::Format::Default};
+
+	mu_println("{}{}", msg->sexp().to_json_string(frm), info.last ? "" : ",");
 
 	return Ok();
 }
@@ -443,6 +446,7 @@ get_output_func(const Options& opts)
 	case Format::Sexp:
 		return output_sexp;
 	case Format::Json:
+	case Format::Json2:
 		return output_json;
 	default:
 		throw Error(Error::Code::Internal,

mu/mu-options.cc

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2022-2024 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2022-2025 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
@@ -339,6 +339,9 @@ sub_find(CLI::App& sub, Options& opts)
 			{ Format::Json,
 			  {"json", "JSON"}
 			},
+			{ Format::Json2,
+			  {"json2", "more idiomatic JSON"}
+			},
 		}};
 
 	sub.add_flag("--threads,-t", opts.find.threads,

mu/mu-options.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2022-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2022-2025 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
@@ -149,7 +149,7 @@ struct Options {
 		std::string	bookmark;		/**<  use bookmark */
 		bool		analyze;		/**<  analyze query */
 
-		enum struct Format { Plain, Links, Xml, Json, Sexp, Exec };
+		enum struct Format { Plain, Links, Xml, Json, Json2, Sexp, Exec };
 		Format		format;			/**< Output format */
 		std::string	exec;			/**<  cmd to execute on matches */
 		bool		skip_dups;		/**< show only first with msg id */
@@ -256,7 +256,7 @@ struct Options {
 		bool	terminate;			/**< add \f between msgs in view */
 		OptSize summary_len;			/**< max # of lines for summary */
 
-		enum struct Format { Plain,  Sexp, Html };
+		enum struct Format { Plain, Sexp, Html };
 		Format format;				/**< output format*/
 
 		StringVec files;			/**< Message file(s) */