implement user-programmable registers

 * %(register:r) expansion variable
 * set-register r value
 * !>(r)echo arbitrary shell command

Makefile

@@ -312,6 +312,7 @@ TIG_OBJS = \
 	src/grep.o \
 	src/ui.o \
 	src/apps.o \
+	src/registers.o \
 	$(GRAPH_OBJS) \
 	$(COMPAT_OBJS)
 

doc/manual.adoc

@@ -194,6 +194,8 @@ following variables.
 |%(repo:is-inside-work-tree)
 			|Whether Tig is running inside a work tree,
 			 either `true` or `false`.
+|%(register:x)		|A user-defined register value, where `x` is an ASCII
+			 character.
 |=============================================================================
 
 Example user-defined commands:
@@ -489,7 +491,8 @@ Prompt
 |:script <file>		|Execute commands from `<file>`.
 |:exec <flags><args...> |Execute command using `<args>` with external
 			 user-defined command option flags defined in `<flags>`.
-|:echo <args...>        |Display text in the status bar.
+|:echo <args...>	|Display text in the status bar.
+|:set-register <char> <args...>	|Load a value into the register named `<char>`.
 |=============================================================================
 
 [[external-commands]]

doc/tigrc.5.adoc

@@ -665,6 +665,8 @@ the command that should be executed.
 |<			|Exit Tig after executing the command.
 |>			|Re-open Tig instantly in the last displayed view after
 			 executing the command.
+|=(x)			|Run the command synchronously, and store the first
+			 line of output in the register named `x`.
 |=============================================================================
 
 Unless otherwise specified, commands are run in the foreground with their
@@ -717,6 +719,8 @@ following variable names, which are substituted before commands are run:
 |%(repo:is-inside-work-tree)
 			|Whether Tig is running inside a work tree,
 			 either `true` or `false`.
+|%(register:x)		|A user-defined register value, where `x` is an ASCII
+			 character.
 |=============================================================================
 
 Examples:

include/tig/argv.h

@@ -15,6 +15,7 @@
 #define TIG_ARGV_H
 
 #include "tig/tig.h"
+#include "tig/registers.h"
 
 /*
  * Argument array helpers.
@@ -62,6 +63,7 @@ typedef unsigned long argv_number;
 struct argv_env {
 	ARGV_ENV_INFO(ARGV_ENV_FIELDS)
 	unsigned long goto_lineno;
+	char *registers[SIZEOF_REGISTERS];
 	char search[SIZEOF_STR];
 	char none[1];
 };

include/tig/display.h

@@ -52,7 +52,7 @@ bool save_view(struct view *view, const char *path);
 bool vertical_split_is_enabled(enum vertical_split vsplit, int height, int width);
 int apply_vertical_split(int base_width);
 
-bool open_external_viewer(const char *argv[], const char *dir, bool silent, bool confirm, bool echo, bool quick, bool refresh, const char *notice);
+bool open_external_viewer(const char *argv[], const char *dir, bool silent, bool confirm, bool echo, bool quick, char register_key, bool refresh, const char *notice);
 void open_editor(const char *file, unsigned int lineno);
 void enable_mouse(bool enable);
 

include/tig/keys.h

@@ -84,6 +84,7 @@ struct run_request_flags {
 	bool internal;
 	bool echo;
 	bool quick;
+	char register_key;
 };
 
 struct run_request {

include/tig/registers.h

@@ -0,0 +1,159 @@
+/* Copyright (c) 2006-2017 Jonas Fonseca <[email protected]>
+ *
+ * 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 Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef TIG_REGISTERS_H
+#define TIG_REGISTERS_H
+
+#include "tig/types.h"
+
+/* Index 0 of the register array, corresponding to character key ASCII
+ * space, is kept empty and reserved for internal use as "no register".
+ */
+#define REGISTER_KEY_MIN '!'	/* corresponding to index 1 */
+#define REGISTER_KEY_MAX '~'	/* corresponding to index 94 */
+#define REGISTER_KEY_OFFSET 0x20
+#define SIZEOF_REGISTERS 1 + REGISTER_KEY_MAX - REGISTER_KEY_OFFSET
+
+#define REGISTER_FLAG_OPEN_STR  "=("
+#define REGISTER_FLAG_CLOSE_STR ")"
+#define REGISTER_ESC_CHAR       '\\'
+
+#define is_register_esc_char(ch) \
+	((ch) == REGISTER_ESC_CHAR)
+
+#define is_register_meta_char(ch) \
+	(is_register_esc_char(ch) \
+	 || ((ch) == REGISTER_FLAG_OPEN_STR[1]) \
+	 || ((ch) == REGISTER_FLAG_CLOSE_STR[0]) \
+	 || ((ch) == '"') \
+	 || ((ch) == '\''))
+
+#define at_register_flag_open(p) \
+	(((p)[0] == REGISTER_FLAG_OPEN_STR[0]) && ((p)[1] == REGISTER_FLAG_OPEN_STR[1]))
+
+#define at_register_flag_close(p) \
+	((p)[0] == REGISTER_FLAG_CLOSE_STR[0])
+
+#define at_register_escd_pair(p) \
+	(is_register_esc_char((p)[0]) && is_register_meta_char((p)[1]))
+
+#define register_key_to_index(key) \
+	((((key) >= REGISTER_KEY_MIN) && ((key) <= REGISTER_KEY_MAX)) ? (unsigned int) (key) - REGISTER_KEY_OFFSET : 0)
+
+bool register_set(const char key, const char *value);
+const char *register_get(const char key);
+
+/* metacharacters occur twice, once as an escaped sequence */
+#define REGISTER_INFO(_) \
+	_("\\\\",	'\\') \
+	_("\\(",	'(') \
+	_("\\)",	')') \
+	_("\\\"",	'"') \
+	_("\\'",	'\'') \
+	_("!",	'!') \
+	_("\"",	'"') \
+	_("#",	'#') \
+	_("$",	'$') \
+	_("%",	'%') \
+	_("&",	'&') \
+	_("'",	'\'') \
+	_("(",	'(') \
+	_(")",	')') \
+	_("*",	'*') \
+	_("+",	'+') \
+	_(",",	',') \
+	_("-",	'-') \
+	_(".",	'.') \
+	_("/",	'/') \
+	_("0",	'0') \
+	_("1",	'1') \
+	_("2",	'2') \
+	_("3",	'3') \
+	_("4",	'4') \
+	_("5",	'5') \
+	_("6",	'6') \
+	_("7",	'7') \
+	_("8",	'8') \
+	_("9",	'9') \
+	_(":",	':') \
+	_(";",	';') \
+	_("<",	'<') \
+	_("=",	'=') \
+	_(">",	'>') \
+	_("?",	'?') \
+	_("@",	'@') \
+	_("A",	'A') \
+	_("B",	'B') \
+	_("C",	'C') \
+	_("D",	'D') \
+	_("E",	'E') \
+	_("F",	'F') \
+	_("G",	'G') \
+	_("H",	'H') \
+	_("I",	'I') \
+	_("J",	'J') \
+	_("K",	'K') \
+	_("L",	'L') \
+	_("M",	'M') \
+	_("N",	'N') \
+	_("O",	'O') \
+	_("P",	'P') \
+	_("Q",	'Q') \
+	_("R",	'R') \
+	_("S",	'S') \
+	_("T",	'T') \
+	_("U",	'U') \
+	_("V",	'V') \
+	_("W",	'W') \
+	_("X",	'X') \
+	_("Y",	'Y') \
+	_("Z",	'Z') \
+	_("[",	'[') \
+	_("\\",	'\\') \
+	_("]",	']') \
+	_("^",	'^') \
+	_("_",	'_') \
+	_("`",	'`') \
+	_("a",	'a') \
+	_("b",	'b') \
+	_("c",	'c') \
+	_("d",	'd') \
+	_("e",	'e') \
+	_("f",	'f') \
+	_("g",	'g') \
+	_("h",	'h') \
+	_("i",	'i') \
+	_("j",	'j') \
+	_("k",	'k') \
+	_("l",	'l') \
+	_("m",	'm') \
+	_("n",	'n') \
+	_("o",	'o') \
+	_("p",	'p') \
+	_("q",	'q') \
+	_("r",	'r') \
+	_("s",	's') \
+	_("t",	't') \
+	_("u",	'u') \
+	_("v",	'v') \
+	_("w",	'w') \
+	_("x",	'x') \
+	_("y",	'y') \
+	_("z",	'z') \
+	_("{",	'{') \
+	_("|",	'|') \
+	_("}",	'}') \
+	_("~",	'~')
+
+#endif
+/* vim: set ts=8 sw=8 noexpandtab: */

src/argv.c

@@ -16,6 +16,7 @@
 #include "tig/repo.h"
 #include "tig/options.h"
 #include "tig/prompt.h"
+#include "tig/registers.h"
 
 static bool
 concat_argv(const char *argv[], char *buf, size_t buflen, const char *sep, bool quoted)
@@ -376,6 +377,12 @@ format_append_arg(struct format_context *format, const char ***dst_argv, const c
 	while (arg) {
 		const char *var = strstr(arg, "%(");
 		const char *closing = var ? strchr(var, ')') : NULL;
+
+		/* todo hardcoding is robust and compact but ugly */
+		if (var &&
+		    (!strcmp(var, "%(register:\\))") || !strcmp(var, "%(register:))")))
+			closing++;
+
 		const char *next = closing ? closing + 1 : NULL;
 		const int len = var ? var - arg : strlen(arg);
 
@@ -468,6 +475,10 @@ argv_format(struct argv_env *argv_env, const char ***dst_argv, const char *src_a
 #define FORMAT_REPO_VAR(type, name) \
 	{ "%(repo:" #name ")", STRING_SIZE("%(repo:" #name ")"), type ## _formatter, &repo.name, "" },
 		REPO_INFO(FORMAT_REPO_VAR)
+#define FORMAT_REGISTER_VAR(namestr, keychar) \
+	{ "%(register:" namestr ")", STRING_SIZE("%(register:" namestr ")"), argv_string_formatter, \
+	  argv_env->registers[ MIN(keychar,REGISTER_KEY_MAX) - REGISTER_KEY_OFFSET ], "" },
+		REGISTER_INFO(FORMAT_REGISTER_VAR)
 	};
 	struct format_context format = { vars, ARRAY_SIZE(vars), "", 0, file_filter };
 	int argc;

src/display.c

@@ -20,6 +20,7 @@
 #include "tig/draw.h"
 #include "tig/display.h"
 #include "tig/watch.h"
+#include "tig/registers.h"
 
 static void set_terminal_modes(void);
 
@@ -61,19 +62,29 @@ open_script(const char *path)
 }
 
 bool
-open_external_viewer(const char *argv[], const char *dir, bool silent, bool confirm, bool echo, bool quick, bool do_refresh, const char *notice)
+open_external_viewer(const char *argv[], const char *dir, bool silent, bool confirm, bool echo, bool quick, char register_key, bool do_refresh, const char *notice)
 {
 	bool ok;
 
-	if (echo) {
+	if (echo || register_key) {
 		char buf[SIZEOF_STR] = "";
 
 		io_run_buf(argv, buf, sizeof(buf), dir, false);
 		if (*buf) {
-			report("%s", buf);
+			if (register_key)
+				register_set(register_key, buf);
+			if (echo)
+				report("%s", buf);
+			else
+				report_clear();
 			return true;
 		} else {
-			report("No output");
+			if (register_key)
+				register_set(register_key, "");
+			if (echo)
+				report("No output");
+			else
+				report_clear();
 			return false;
 		}
 	} else if (silent || is_script_executing()) {
@@ -148,7 +159,7 @@ open_editor(const char *file, unsigned int lineno)
 	if (lineno && opt_editor_line_number && string_format(lineno_cmd, "+%u", lineno))
 		editor_argv[argc++] = lineno_cmd;
 	editor_argv[argc] = file;
-	if (!open_external_viewer(editor_argv, repo.cdup, false, false, false, false, true, EDITOR_LINENO_MSG))
+	if (!open_external_viewer(editor_argv, repo.cdup, false, false, false, false, 0, true, EDITOR_LINENO_MSG))
 		opt_editor_line_number = false;
 }
 

src/keys.c

@@ -449,7 +449,7 @@ static size_t run_requests;
 
 DEFINE_ALLOCATOR(realloc_run_requests, struct run_request, 8)
 
-#define COMMAND_FLAGS ":!?@<+>"
+#define COMMAND_FLAGS ":!?@<+>="
 
 enum status_code
 parse_run_request_flags(struct run_request_flags *flags, const char **argv)
@@ -475,6 +475,21 @@ parse_run_request_flags(struct run_request_flags *flags, const char **argv)
 			flags->echo = 1;
 		} else if (*argv[0] == '>') {
 			flags->quick = 1;
+		} else if (at_register_flag_open(argv[0])
+			   && at_register_escd_pair(argv[0] + 2)
+			   && at_register_flag_close(argv[0] + 4)) {
+			flags->register_key = argv[0][3];
+			argv[0] += 5;
+			continue;
+		} else if (at_register_flag_open(argv[0])
+			   && argv[0][2] >= REGISTER_KEY_MIN
+			   && argv[0][2] <= REGISTER_KEY_MAX
+			   && at_register_flag_close(argv[0] + 3)) {
+			flags->register_key = argv[0][2];
+			argv[0] += 4;
+			continue;
+		} else if (at_register_flag_open(argv[0])) {
+			return error("Invalid register flag");
 		} else if (*argv[0] != '!') {
 			break;
 		}
@@ -519,7 +534,7 @@ get_run_request(enum request request)
 const char *
 format_run_request_flags(const struct run_request *req)
 {
-	static char flags[8];
+	static char flags[16];
 	int flagspos = 0;
 
 	memset(flags, 0, sizeof(flags));
@@ -530,15 +545,23 @@ format_run_request_flags(const struct run_request *req)
 		flags[flagspos] = '!'; /* Optional, if other flags are defined */
 
 	if (req->flags.silent)
-	    flags[flagspos++] = '@';
+		flags[flagspos++] = '@';
 	if (req->flags.confirm)
-	    flags[flagspos++] = '?';
+		flags[flagspos++] = '?';
 	if (req->flags.exit)
 		flags[flagspos++] = '<';
 	if (req->flags.echo)
 		flags[flagspos++] = '+';
 	if (req->flags.quick)
 		flags[flagspos++] = '>';
+	if (req->flags.register_key) {
+		flags[flagspos++] = REGISTER_FLAG_OPEN_STR[0];
+		flags[flagspos++] = REGISTER_FLAG_OPEN_STR[1];
+		if (is_register_meta_char(req->flags.register_key))
+			flags[flagspos++] = REGISTER_ESC_CHAR;
+		flags[flagspos++] = req->flags.register_key;
+		flags[flagspos++] = REGISTER_FLAG_CLOSE_STR[0];
+	}
 	if (flagspos > 1)
 		flags[flagspos++] = 0;