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Refactor parse_command

Patch status: needinfo

Patch by Tony Crisci

Long description:

Change parse_command to make running commands easier and more efficient.

Caller is now responsible for allocating the yajl_gen and can pass NULL
if generating json is not required.

The CommandResult used as a return value has been typedeffed, contains
more information about the result of the command, and no longer contains
parsing state or a yajl gen.

The CommandResult used during command parsing itself has been renamed to
CommandResultIR to show that it is an intermediate representation of the
result used during parsing. The ConfigResult has been renamed similarly
for consistency.

To apply this patch, use:
curl http://cr.i3wm.org/patch/538/raw.patch | git am

b/generate-command-parser.pl

@@ -131,7 +131,7 @@ close($enumfh);
 
 # Third step: Generate the call function.
 open(my $callfh, '>', "GENERATED_${prefix}_call.h");
-my $resultname = uc(substr($prefix, 0, 1)) . substr($prefix, 1) . 'Result';
+my $resultname = uc(substr($prefix, 0, 1)) . substr($prefix, 1) . 'ResultIR';
 say $callfh "static void GENERATED_call(const int call_identifier, struct $resultname *result) {";
 say $callfh '    switch (call_identifier) {';
 my $call_id = 0;

b/include/commands.h

@@ -12,7 +12,7 @@
 #include "commands_parser.h"
 
 /** The beginning of the prototype for every cmd_ function. */
-#define I3_CMD Match *current_match, struct CommandResult *cmd_output
+#define I3_CMD Match *current_match, struct CommandResultIR *cmd_output
 
 /**
  * Initializes the specified 'Match' data structure and the initial state of

b/include/commands_parser.h

@@ -11,16 +11,11 @@
 
 #include <yajl/yajl_gen.h>
 
-/*
- * Holds the result of a call to any command. When calling
- * parse_command("floating enable, border none"), the parser will internally
- * use a struct CommandResult when calling cmd_floating and cmd_border.
- * parse_command will also return another struct CommandResult, whose
- * json_output is set to a map of individual json_outputs and whose
- * needs_tree_trender is true if any individual needs_tree_render was true.
- *
+/**
+ * An intermediate representation of the result of a command used during
+ * command parsing
  */
-struct CommandResult {
+struct CommandResultIR {
     /* The JSON generator to append a reply to. */
     yajl_gen json_gen;
 
@@ -33,4 +28,28 @@ struct CommandResult {
     bool needs_tree_render;
 };
 
-struct CommandResult *parse_command(const char *input);
+typedef struct CommandResult CommandResult;
+
+/**
+ * A struct that contains useful information about the result of a command
+ */
+struct CommandResult {
+    bool parse_error;
+    char *error_message; /* the error_message is currently only set for parse errors */
+    bool needs_tree_render;
+};
+
+/**
+ * Parses and executes the given command. If a yajl_gen is passed, a json reply
+ * will be generated in the format specified by the ipc protocol. Pass NULL if
+ * no json reply is required.
+ *
+ * Returns a CommandResult struct with useful information about the result of
+ * the command. Free with command_result_free()
+ */
+CommandResult *parse_command(const char *input, yajl_gen gen);
+
+/**
+ * Frees a CommandResult
+ */
+void command_result_free(CommandResult *result);

b/include/config_directives.h

@@ -18,7 +18,7 @@
 uint32_t modifiers_from_str(const char *str);
 
 /** The beginning of the prototype for every cfg_ function. */
-#define I3_CFG Match *current_match, struct ConfigResult *result
+#define I3_CFG Match *current_match, struct ConfigResultIR *result
 
 /* Defines a configuration function, that is, anything that can be called by
  * using 'call cfg_foo()' in parser-specs/.*.spec. Useful so that we don’t need

b/include/config_parser.h

@@ -18,7 +18,7 @@ extern pid_t config_error_nagbar_pid;
  * will be useful in the future when we implement a config parsing IPC command.
  *
  */
-struct ConfigResult {
+struct ConfigResultIR {
     /* The JSON generator to append a reply to. */
     yajl_gen json_gen;
 
@@ -28,7 +28,7 @@ struct ConfigResult {
     int next_state;
 };
 
-struct ConfigResult *parse_config(const char *input, struct context *context);
+struct ConfigResultIR *parse_config(const char *input, struct context *context);
 
 /**
  * Parses the given file by first replacing the variables, then calling

b/src/assignments.c

@@ -45,13 +45,13 @@ void run_assignments(i3Window *window) {
             DLOG("execute command %s\n", current->dest.command);
             char *full_command;
             sasprintf(&full_command, "[id=\"%d\"] %s", window->id, current->dest.command);
-            struct CommandResult *command_output = parse_command(full_command);
+            CommandResult *command_output = parse_command(full_command, NULL);
             free(full_command);
 
             if (command_output->needs_tree_render)
                 needs_tree_render = true;
 
-            yajl_gen_free(command_output->json_gen);
+            command_result_free(command_output);
         }
 
         /* Store that we ran this assignment to not execute it again */

b/src/commands.c

@@ -16,22 +16,29 @@
 #include "shmlog.h"
 
 // Macros to make the YAJL API a bit easier to use.
-#define y(x, ...) yajl_gen_ ## x (cmd_output->json_gen, ##__VA_ARGS__)
-#define ystr(str) yajl_gen_string(cmd_output->json_gen, (unsigned char*)str, strlen(str))
-#define ysuccess(success) do { \
-    y(map_open); \
-    ystr("success"); \
-    y(bool, success); \
-    y(map_close); \
-} while (0)
-#define yerror(message) do { \
-    y(map_open); \
-    ystr("success"); \
-    y(bool, false); \
-    ystr("error"); \
-    ystr(message); \
-    y(map_close); \
-} while (0)
+#define y(x, ...) if (cmd_output->json_gen != NULL) yajl_gen_ ## x (cmd_output->json_gen, ##__VA_ARGS__);
+
+#define ystr(str) if (cmd_output->json_gen != NULL) yajl_gen_string(cmd_output->json_gen, (unsigned char*)str, strlen(str));
+
+#define ysuccess(success) if (cmd_output->json_gen != NULL) { \
+    do { \
+        y(map_open); \
+        ystr("success"); \
+        y(bool, success); \
+        y(map_close); \
+    } while (0); \
+}
+
+#define yerror(message) if (cmd_output->json_gen != NULL) { \
+    do { \
+        y(map_open); \
+        ystr("success"); \
+        y(bool, false); \
+        ystr("error"); \
+        ystr(message); \
+        y(map_close); \
+    } while (0); \
+}
 
 /** When the command did not include match criteria (!), we use the currently
  * focused container. Do not confuse this case with a command which included
@@ -95,7 +102,7 @@ static Output *get_output_of_con(Con *con) {
  * and return true, signaling that no further workspace switching should occur in the calling function.
  *
  */
-static bool maybe_back_and_forth(struct CommandResult *cmd_output, char *name) {
+static bool maybe_back_and_forth(struct CommandResultIR *cmd_output, char *name) {
     Con *ws = con_get_workspace(focused);
 
     /* If we switched to a different workspace, do nothing */

b/src/commands_parser.c

@@ -35,8 +35,8 @@
 #include "all.h"
 
 // Macros to make the YAJL API a bit easier to use.
-#define y(x, ...) yajl_gen_ ## x (command_output.json_gen, ##__VA_ARGS__)
-#define ystr(str) yajl_gen_string(command_output.json_gen, (unsigned char*)str, strlen(str))
+#define y(x, ...) if (command_output.json_gen != NULL) yajl_gen_ ## x (command_output.json_gen, ##__VA_ARGS__)
+#define ystr(str) if (command_output.json_gen != NULL) yajl_gen_string(command_output.json_gen, (unsigned char*)str, strlen(str))
 
 /*******************************************************************************
  * The data structures used for parsing. Essentially the current state and a
@@ -179,8 +179,8 @@ static cmdp_state state;
 #ifndef TEST_PARSER
 static Match current_match;
 #endif
-static struct CommandResult subcommand_output;
-static struct CommandResult command_output;
+static struct CommandResultIR subcommand_output;
+static struct CommandResultIR command_output;
 
 #include "GENERATED_command_call.h"
 
@@ -205,18 +205,24 @@ static void next_state(const cmdp_token *token) {
     }
 }
 
-struct CommandResult *parse_command(const char *input) {
+/*
+ * Parses and executes the given command. If a yajl_gen is passed, a json reply
+ * will be generated in the format specified by the ipc protocol. Pass NULL if
+ * no json reply is required.
+ *
+ * Returns a CommandResult struct with useful information about the result of
+ * the command. Free with command_result_free()
+ */
+CommandResult *parse_command(const char *input, yajl_gen gen) {
     DLOG("COMMAND: *%s*\n", input);
     state = INITIAL;
+    CommandResult *result = scalloc(sizeof(CommandResult));
 
-/* A YAJL JSON generator used for formatting replies. */
-#if YAJL_MAJOR >= 2
-    command_output.json_gen = yajl_gen_alloc(NULL);
-#else
-    command_output.json_gen = yajl_gen_alloc(NULL, NULL);
-#endif
+    /* A YAJL JSON generator used for formatting replies. */
+    command_output.json_gen = (gen != NULL ? gen : NULL);
 
     y(array_open);
+
     command_output.needs_tree_render = false;
 
     const char *walk = input;
@@ -382,6 +388,9 @@ struct CommandResult *parse_command(const char *input) {
             ELOG("Your command: %s\n", input);
             ELOG("              %s\n", position);
 
+            result->parse_error = true;
+            result->error_message = errormessage;
+
             /* Format this error message as a JSON reply. */
             y(map_open);
             ystr("success");
@@ -400,7 +409,6 @@ struct CommandResult *parse_command(const char *input) {
             y(map_close);
 
             free(position);
-            free(errormessage);
             clear_stack();
             break;
         }
@@ -408,7 +416,16 @@ struct CommandResult *parse_command(const char *input) {
 
     y(array_close);
 
-    return &command_output;
+    result->needs_tree_render = command_output.needs_tree_render;
+    return result;
+}
+
+void command_result_free(CommandResult *result) {
+    if (result == NULL)
+        return;
+
+    FREE(result->error_message);
+    FREE(result);
 }
 
 /*******************************************************************************
@@ -446,6 +463,10 @@ int main(int argc, char *argv[]) {
         fprintf(stderr, "Syntax: %s <command>\n", argv[0]);
         return 1;
     }
-    parse_command(argv[1]);
+    yajl_gen gen = yajl_gen_alloc(NULL);
+
+    parse_command(argv[1], gen);
+
+    yajl_gen_free(gen);
 }
 #endif

b/src/config_parser.c

@@ -232,8 +232,8 @@ static void clear_criteria(void *unused_criteria) {
 
 static cmdp_state state;
 static Match current_match;
-static struct ConfigResult subcommand_output;
-static struct ConfigResult command_output;
+static struct ConfigResultIR subcommand_output;
+static struct ConfigResultIR command_output;
 
 /* A list which contains the states that lead to the current state, e.g.
  * INITIAL, WORKSPACE_LAYOUT.
@@ -304,7 +304,7 @@ static char *single_line(const char *start) {
     return result;
 }
 
-struct ConfigResult *parse_config(const char *input, struct context *context) {
+struct ConfigResultIR *parse_config(const char *input, struct context *context) {
     /* Dump the entire config file into the debug log. We cannot just use
      * DLOG("%s", input); because one log message must not exceed 4 KiB. */
     const char *dumpwalk = input;
@@ -1004,7 +1004,7 @@ void parse_file(const char *f) {
     context = scalloc(sizeof(struct context));
     context->filename = f;
 
-    struct ConfigResult *config_output = parse_config(new, context);
+    struct ConfigResultIR *config_output = parse_config(new, context);
     yajl_gen_free(config_output->json_gen);
 
     check_for_duplicate_bindings(context);

b/src/ipc.c

@@ -117,20 +117,24 @@ IPC_HANDLER(command) {
     char *command = scalloc(message_size + 1);
     strncpy(command, (const char*)message, message_size);
     LOG("IPC: received: *%s*\n", command);
-    struct CommandResult *command_output = parse_command((const char*)command);
+    yajl_gen gen = yajl_gen_alloc(NULL);
+
+    CommandResult *command_output = parse_command((const char*)command, gen);
     free(command);
 
     if (command_output->needs_tree_render)
         tree_render();
 
+    command_result_free(command_output);
+
     const unsigned char *reply;
     ylength length;
-    yajl_gen_get_buf(command_output->json_gen, &reply, &length);
+    yajl_gen_get_buf(gen, &reply, &length);
 
     ipc_send_message(fd, length, I3_IPC_REPLY_TYPE_COMMAND,
                      (const uint8_t*)reply);
 
-    yajl_gen_free(command_output->json_gen);
+    yajl_gen_free(gen);
 }
 
 static void dump_rect(yajl_gen gen, const char *name, Rect r) {

b/src/key_press.c

@@ -76,9 +76,12 @@ void handle_key_press(xcb_key_press_event_t *event) {
     if (bind == NULL)
         return;
 
+    yajl_gen gen = yajl_gen_alloc(NULL);
+
     char *command_copy = sstrdup(bind->command);
-    struct CommandResult *command_output = parse_command(command_copy);
+    CommandResult *command_output = parse_command(command_copy, gen);
     free(command_copy);
+    command_result_free(command_output);
 
     if (command_output->needs_tree_render)
         tree_render();
@@ -95,7 +98,7 @@ void handle_key_press(xcb_key_press_event_t *event) {
 
     yajl_handle handle = yajl_alloc(&command_error_callbacks, &parse_conf, NULL, NULL);
 #endif
-    yajl_gen_get_buf(command_output->json_gen, &reply, &length);
+    yajl_gen_get_buf(gen, &reply, &length);
 
     current_nesting_level = 0;
     parse_error_key = false;
@@ -127,5 +130,5 @@ void handle_key_press(xcb_key_press_event_t *event) {
 
     yajl_free(handle);
 
-    yajl_gen_free(command_output->json_gen);
+    yajl_gen_free(gen);
 }

152	@@ -45,13 +45,13 @@ void run_assignments(i3Window *window) {
153	DLOG("execute command %s\n", current->dest.command);
154	char *full_command;
155	sasprintf(&full_command, "[id=\"%d\"] %s", window->id, current->dest.command);
156	- struct CommandResult *command_output = parse_command(full_command);
157	+ CommandResult *command_output = parse_command(full_command, NULL);
158	free(full_command);
159
160	if (command_output->needs_tree_render)
161	needs_tree_render = true;
162
163	- yajl_gen_free(command_output->json_gen);
164	+ command_result_free(command_output);
165	}
166
167	/* Store that we ran this assignment to not execute it again */

172	@@ -16,22 +16,29 @@
173	#include "shmlog.h"
174
175	// Macros to make the YAJL API a bit easier to use.
176	-#define y(x, ...) yajl_gen_ ## x (cmd_output->json_gen, ##__VA_ARGS__)
177	-#define ystr(str) yajl_gen_string(cmd_output->json_gen, (unsigned char*)str, strlen(str))
178	-#define ysuccess(success) do { \
179	- y(map_open); \
180	- ystr("success"); \
181	- y(bool, success); \
182	- y(map_close); \
183	-} while (0)
184	-#define yerror(message) do { \
185	- y(map_open); \
186	- ystr("success"); \
187	- y(bool, false); \
188	- ystr("error"); \
189	- ystr(message); \
190	- y(map_close); \
191	-} while (0)
192	+#define y(x, ...) if (cmd_output->json_gen != NULL) yajl_gen_ ## x (cmd_output->json_gen, ##__VA_ARGS__);
193	+
194	+#define ystr(str) if (cmd_output->json_gen != NULL) yajl_gen_string(cmd_output->json_gen, (unsigned char*)str, strlen(str));
195	+
196	+#define ysuccess(success) if (cmd_output->json_gen != NULL) { \
197	+ do { \
198	+ y(map_open); \
199	+ ystr("success"); \
200	+ y(bool, success); \
201	+ y(map_close); \
202	+ } while (0); \
203	+}
204	+
205	+#define yerror(message) if (cmd_output->json_gen != NULL) { \
206	+ do { \
207	+ y(map_open); \
208	+ ystr("success"); \
209	+ y(bool, false); \
210	+ ystr("error"); \
211	+ ystr(message); \
212	+ y(map_close); \
213	+ } while (0); \
214	+}
215
216	/** When the command did not include match criteria (!), we use the currently
217	* focused container. Do not confuse this case with a command which included
218	@@ -95,7 +102,7 @@ static Output get_output_of_con(Con con) {
219	* and return true, signaling that no further workspace switching should occur in the calling function.
220	*
221	*/
222	-static bool maybe_back_and_forth(struct CommandResult cmd_output, char name) {
223	+static bool maybe_back_and_forth(struct CommandResultIR cmd_output, char name) {
224	Con *ws = con_get_workspace(focused);
225
226	/* If we switched to a different workspace, do nothing */

231	@@ -35,8 +35,8 @@
232	#include "all.h"
233
234	// Macros to make the YAJL API a bit easier to use.
235	-#define y(x, ...) yajl_gen_ ## x (command_output.json_gen, ##__VA_ARGS__)
236	-#define ystr(str) yajl_gen_string(command_output.json_gen, (unsigned char*)str, strlen(str))
237	+#define y(x, ...) if (command_output.json_gen != NULL) yajl_gen_ ## x (command_output.json_gen, ##__VA_ARGS__)
238	+#define ystr(str) if (command_output.json_gen != NULL) yajl_gen_string(command_output.json_gen, (unsigned char*)str, strlen(str))
239
240	/*******************************************************************************
241	* The data structures used for parsing. Essentially the current state and a
242	@@ -179,8 +179,8 @@ static cmdp_state state;
243	#ifndef TEST_PARSER
244	static Match current_match;
245	#endif
246	-static struct CommandResult subcommand_output;
247	-static struct CommandResult command_output;
248	+static struct CommandResultIR subcommand_output;
249	+static struct CommandResultIR command_output;
250
251	#include "GENERATED_command_call.h"
252
253	@@ -205,18 +205,24 @@ static void next_state(const cmdp_token *token) {
254	}
255	}
256
257	-struct CommandResult parse_command(const char input) {
258	+/*
259	+ * Parses and executes the given command. If a yajl_gen is passed, a json reply
260	+ * will be generated in the format specified by the ipc protocol. Pass NULL if
261	+ * no json reply is required.
262	+ *
263	+ * Returns a CommandResult struct with useful information about the result of
264	+ * the command. Free with command_result_free()
265	+ */
266	+CommandResult parse_command(const char input, yajl_gen gen) {
267	DLOG("COMMAND: %s\n", input);
268	state = INITIAL;
269	+ CommandResult *result = scalloc(sizeof(CommandResult));
270
271	-/* A YAJL JSON generator used for formatting replies. */
272	-#if YAJL_MAJOR >= 2
273	- command_output.json_gen = yajl_gen_alloc(NULL);
274	-#else
275	- command_output.json_gen = yajl_gen_alloc(NULL, NULL);
276	-#endif
277	+ /* A YAJL JSON generator used for formatting replies. */
278	+ command_output.json_gen = (gen != NULL ? gen : NULL);
279
280	y(array_open);
281	+
282	command_output.needs_tree_render = false;
283
284	const char *walk = input;
285	@@ -382,6 +388,9 @@ struct CommandResult parse_command(const char input) {
286	ELOG("Your command: %s\n", input);
287	ELOG(" %s\n", position);
288
289	+ result->parse_error = true;
290	+ result->error_message = errormessage;
291	+
292	/* Format this error message as a JSON reply. */
293	y(map_open);
294	ystr("success");
295	@@ -400,7 +409,6 @@ struct CommandResult parse_command(const char input) {
296	y(map_close);
297
298	free(position);
299	- free(errormessage);
300	clear_stack();
301	break;
302	}
303	@@ -408,7 +416,16 @@ struct CommandResult parse_command(const char input) {
304
305	y(array_close);
306
307	- return &command_output;
308	+ result->needs_tree_render = command_output.needs_tree_render;
309	+ return result;
310	+}
311	+
312	+void command_result_free(CommandResult *result) {
313	+ if (result == NULL)
314	+ return;
315	+
316	+ FREE(result->error_message);
317	+ FREE(result);
318	}
319
320	/*******************************************************************************
321	@@ -446,6 +463,10 @@ int main(int argc, char *argv[]) {
322	fprintf(stderr, "Syntax: %s <command>\n", argv[0]);
323	return 1;
324	}
325	- parse_command(argv[1]);
326	+ yajl_gen gen = yajl_gen_alloc(NULL);
327	+
328	+ parse_command(argv[1], gen);
329	+
330	+ yajl_gen_free(gen);
331	}
332	#endif

337	@@ -232,8 +232,8 @@ static void clear_criteria(void *unused_criteria) {
338
339	static cmdp_state state;
340	static Match current_match;
341	-static struct ConfigResult subcommand_output;
342	-static struct ConfigResult command_output;
343	+static struct ConfigResultIR subcommand_output;
344	+static struct ConfigResultIR command_output;
345
346	/* A list which contains the states that lead to the current state, e.g.
347	* INITIAL, WORKSPACE_LAYOUT.
348	@@ -304,7 +304,7 @@ static char single_line(const char start) {
349	return result;
350	}
351
352	-struct ConfigResult parse_config(const char input, struct context *context) {
353	+struct ConfigResultIR parse_config(const char input, struct context *context) {
354	/* Dump the entire config file into the debug log. We cannot just use
355	* DLOG("%s", input); because one log message must not exceed 4 KiB. */
356	const char *dumpwalk = input;
357	@@ -1004,7 +1004,7 @@ void parse_file(const char *f) {
358	context = scalloc(sizeof(struct context));
359	context->filename = f;
360
361	- struct ConfigResult *config_output = parse_config(new, context);
362	+ struct ConfigResultIR *config_output = parse_config(new, context);
363	yajl_gen_free(config_output->json_gen);
364
365	check_for_duplicate_bindings(context);

370	@@ -117,20 +117,24 @@ IPC_HANDLER(command) {
371	char *command = scalloc(message_size + 1);
372	strncpy(command, (const char*)message, message_size);
373	LOG("IPC: received: %s\n", command);
374	- struct CommandResult command_output = parse_command((const char)command);
375	+ yajl_gen gen = yajl_gen_alloc(NULL);
376	+
377	+ CommandResult command_output = parse_command((const char)command, gen);
378	free(command);
379
380	if (command_output->needs_tree_render)
381	tree_render();
382
383	+ command_result_free(command_output);
384	+
385	const unsigned char *reply;
386	ylength length;
387	- yajl_gen_get_buf(command_output->json_gen, &reply, &length);
388	+ yajl_gen_get_buf(gen, &reply, &length);
389
390	ipc_send_message(fd, length, I3_IPC_REPLY_TYPE_COMMAND,
391	(const uint8_t*)reply);
392
393	- yajl_gen_free(command_output->json_gen);
394	+ yajl_gen_free(gen);
395	}
396
397	static void dump_rect(yajl_gen gen, const char *name, Rect r) {

36	@@ -131,7 +131,7 @@ close($enumfh);
37
38	# Third step: Generate the call function.
39	open(my $callfh, '>', "GENERATED_${prefix}_call.h");
40	-my $resultname = uc(substr($prefix, 0, 1)) . substr($prefix, 1) . 'Result';
41	+my $resultname = uc(substr($prefix, 0, 1)) . substr($prefix, 1) . 'ResultIR';
42	say $callfh "static void GENERATED_call(const int call_identifier, struct $resultname *result) {";
43	say $callfh ' switch (call_identifier) {';
44	my $call_id = 0;

49	@@ -12,7 +12,7 @@
50	#include "commands_parser.h"
51
52	/** The beginning of the prototype for every cmd_ function. */
53	-#define I3_CMD Match current_match, struct CommandResult cmd_output
54	+#define I3_CMD Match current_match, struct CommandResultIR cmd_output
55
56	/**
57	* Initializes the specified 'Match' data structure and the initial state of

62	@@ -11,16 +11,11 @@
63
64	#include <yajl/yajl_gen.h>
65
66	-/*
67	- * Holds the result of a call to any command. When calling
68	- * parse_command("floating enable, border none"), the parser will internally
69	- * use a struct CommandResult when calling cmd_floating and cmd_border.
70	- * parse_command will also return another struct CommandResult, whose
71	- * json_output is set to a map of individual json_outputs and whose
72	- * needs_tree_trender is true if any individual needs_tree_render was true.
73	- *
74	+/**
75	+ * An intermediate representation of the result of a command used during
76	+ * command parsing
77	*/
78	-struct CommandResult {
79	+struct CommandResultIR {
80	/* The JSON generator to append a reply to. */
81	yajl_gen json_gen;
82
83	@@ -33,4 +28,28 @@ struct CommandResult {
84	bool needs_tree_render;
85	};
86
87	-struct CommandResult parse_command(const char input);
88	+typedef struct CommandResult CommandResult;
89	+
90	+/**
91	+ * A struct that contains useful information about the result of a command
92	+ */
93	+struct CommandResult {
94	+ bool parse_error;
95	+ char error_message; / the error_message is currently only set for parse errors */
96	+ bool needs_tree_render;
97	+};
98	+
99	+/**
100	+ * Parses and executes the given command. If a yajl_gen is passed, a json reply
101	+ * will be generated in the format specified by the ipc protocol. Pass NULL if
102	+ * no json reply is required.
103	+ *
104	+ * Returns a CommandResult struct with useful information about the result of
105	+ * the command. Free with command_result_free()
106	+ */
107	+CommandResult parse_command(const char input, yajl_gen gen);
108	+
109	+/**
110	+ * Frees a CommandResult
111	+ */
112	+void command_result_free(CommandResult *result);

117	@@ -18,7 +18,7 @@
118	uint32_t modifiers_from_str(const char *str);
119
120	/** The beginning of the prototype for every cfg_ function. */
121	-#define I3_CFG Match current_match, struct ConfigResult result
122	+#define I3_CFG Match current_match, struct ConfigResultIR result
123
124	/* Defines a configuration function, that is, anything that can be called by
125	* using 'call cfg_foo()' in parser-specs/.*.spec. Useful so that we don’t need

130	@@ -18,7 +18,7 @@ extern pid_t config_error_nagbar_pid;
131	* will be useful in the future when we implement a config parsing IPC command.
132	*
133	*/
134	-struct ConfigResult {
135	+struct ConfigResultIR {
136	/* The JSON generator to append a reply to. */
137	yajl_gen json_gen;
138
139	@@ -28,7 +28,7 @@ struct ConfigResult {
140	int next_state;
141	};
142
143	-struct ConfigResult parse_config(const char input, struct context *context);
144	+struct ConfigResultIR parse_config(const char input, struct context *context);
145
146	/**
147	* Parses the given file by first replacing the variables, then calling

402	@@ -76,9 +76,12 @@ void handle_key_press(xcb_key_press_event_t *event) {
403	if (bind == NULL)
404	return;
405
406	+ yajl_gen gen = yajl_gen_alloc(NULL);
407	+
408	char *command_copy = sstrdup(bind->command);
409	- struct CommandResult *command_output = parse_command(command_copy);
410	+ CommandResult *command_output = parse_command(command_copy, gen);
411	free(command_copy);
412	+ command_result_free(command_output);
413
414	if (command_output->needs_tree_render)
415	tree_render();
416	@@ -95,7 +98,7 @@ void handle_key_press(xcb_key_press_event_t *event) {
417
418	yajl_handle handle = yajl_alloc(&command_error_callbacks, &parse_conf, NULL, NULL);
419	#endif
420	- yajl_gen_get_buf(command_output->json_gen, &reply, &length);
421	+ yajl_gen_get_buf(gen, &reply, &length);
422
423	current_nesting_level = 0;
424	parse_error_key = false;
425	@@ -127,5 +130,5 @@ void handle_key_press(xcb_key_press_event_t *event) {
426
427	yajl_free(handle);
428
429	- yajl_gen_free(command_output->json_gen);
430	+ yajl_gen_free(gen);
431	}