2 #define I3__FILE__ "commands_parser.c"
4 * vim:ts=4:sw=4:expandtab
6 * i3 - an improved dynamic tiling window manager
7 * © 2009 Michael Stapelberg and contributors (see also: LICENSE)
9 * commands_parser.c: hand-written parser to parse commands (commands are what
10 * you bind on keys and what you can send to i3 using the IPC interface, like
11 * 'move left' or 'workspace 4').
13 * We use a hand-written parser instead of lex/yacc because our commands are
14 * easy for humans, not for computers. Thus, it’s quite hard to specify a
15 * context-free grammar for the commands. A PEG grammar would be easier, but
16 * there’s downsides to every PEG parser generator I have come across so far.
18 * This parser is basically a state machine which looks for literals or strings
19 * and can push either on a stack. After identifying a literal or string, it
20 * will either transition to the current state, to a different state, or call a
21 * function (like cmd_move()).
23 * Special care has been taken that error messages are useful and the code is
24 * well testable (when compiled with -DTEST_PARSER it will output to stdout
25 * instead of actually calling any function).
37 // Macros to make the YAJL API a bit easier to use.
38 #define y(x, ...) (command_output.json_gen != NULL ? yajl_gen_##x(command_output.json_gen, ##__VA_ARGS__) : 0)
39 #define ystr(str) (command_output.json_gen != NULL ? yajl_gen_string(command_output.json_gen, (unsigned char *)str, strlen(str)) : 0)
41 /*******************************************************************************
42 * The data structures used for parsing. Essentially the current state and a
43 * list of tokens for that state.
45 * The GENERATED_* files are generated by generate-commands-parser.pl with the
46 * input parser-specs/commands.spec.
47 ******************************************************************************/
49 #include "GENERATED_command_enums.h"
51 typedef struct token {
54 /* This might be __CALL */
55 cmdp_state next_state;
57 uint16_t call_identifier;
61 typedef struct tokenptr {
66 #include "GENERATED_command_tokens.h"
68 /*******************************************************************************
69 * The (small) stack where identified literals are stored during the parsing
70 * of a single command (like $workspace).
71 ******************************************************************************/
74 /* Just a pointer, not dynamically allocated. */
75 const char *identifier;
86 /* 10 entries should be enough for everybody. */
87 static struct stack_entry stack[10];
90 * Pushes a string (identified by 'identifier') on the stack. We simply use a
91 * single array, since the number of entries we have to store is very small.
94 static void push_string(const char *identifier, char *str) {
95 for (int c = 0; c < 10; c++) {
96 if (stack[c].identifier != NULL)
98 /* Found a free slot, let’s store it here. */
99 stack[c].identifier = identifier;
100 stack[c].val.str = str;
101 stack[c].type = STACK_STR;
105 /* When we arrive here, the stack is full. This should not happen and
106 * means there’s either a bug in this parser or the specification
107 * contains a command with more than 10 identified tokens. */
108 fprintf(stderr, "BUG: commands_parser stack full. This means either a bug "
109 "in the code, or a new command which contains more than "
110 "10 identified tokens.\n");
114 // TODO move to a common util
115 static void push_long(const char *identifier, long num) {
116 for (int c = 0; c < 10; c++) {
117 if (stack[c].identifier != NULL) {
121 stack[c].identifier = identifier;
122 stack[c].val.num = num;
123 stack[c].type = STACK_LONG;
127 /* When we arrive here, the stack is full. This should not happen and
128 * means there’s either a bug in this parser or the specification
129 * contains a command with more than 10 identified tokens. */
130 fprintf(stderr, "BUG: commands_parser stack full. This means either a bug "
131 "in the code, or a new command which contains more than "
132 "10 identified tokens.\n");
136 // TODO move to a common util
137 static const char *get_string(const char *identifier) {
138 for (int c = 0; c < 10; c++) {
139 if (stack[c].identifier == NULL)
141 if (strcmp(identifier, stack[c].identifier) == 0)
142 return stack[c].val.str;
147 // TODO move to a common util
148 static long get_long(const char *identifier) {
149 for (int c = 0; c < 10; c++) {
150 if (stack[c].identifier == NULL)
152 if (strcmp(identifier, stack[c].identifier) == 0)
153 return stack[c].val.num;
159 // TODO move to a common util
160 static void clear_stack(void) {
161 for (int c = 0; c < 10; c++) {
162 if (stack[c].type == STACK_STR && stack[c].val.str != NULL)
163 free(stack[c].val.str);
164 stack[c].identifier = NULL;
165 stack[c].val.str = NULL;
166 stack[c].val.num = 0;
170 /*******************************************************************************
172 ******************************************************************************/
174 static cmdp_state state;
176 static Match current_match;
178 static struct CommandResultIR subcommand_output;
179 static struct CommandResultIR command_output;
181 #include "GENERATED_command_call.h"
183 static void next_state(const cmdp_token *token) {
184 if (token->next_state == __CALL) {
185 subcommand_output.json_gen = command_output.json_gen;
186 subcommand_output.needs_tree_render = false;
187 GENERATED_call(token->extra.call_identifier, &subcommand_output);
188 state = subcommand_output.next_state;
189 /* If any subcommand requires a tree_render(), we need to make the
190 * whole parser result request a tree_render(). */
191 if (subcommand_output.needs_tree_render)
192 command_output.needs_tree_render = true;
197 state = token->next_state;
198 if (state == INITIAL) {
204 * Parses a string (or word, if as_word is true). Extracted out of
205 * parse_command so that it can be used in src/workspace.c for interpreting
206 * workspace commands.
209 char *parse_string(const char **walk, bool as_word) {
210 const char *beginning = *walk;
211 /* Handle quoted strings (or words). */
215 for (; **walk != '\0' && **walk != '"'; (*walk)++)
216 if (**walk == '\\' && *(*walk + 1) != '\0')
220 /* For a string (starting with 's'), the delimiters are
221 * comma (,) and semicolon (;) which introduce a new
222 * operation or command, respectively. Also, newlines
224 while (**walk != ';' && **walk != ',' &&
225 **walk != '\0' && **walk != '\r' &&
229 /* For a word, the delimiters are white space (' ' or
230 * '\t'), closing square bracket (]), comma (,) and
232 while (**walk != ' ' && **walk != '\t' &&
233 **walk != ']' && **walk != ',' &&
234 **walk != ';' && **walk != '\r' &&
235 **walk != '\n' && **walk != '\0')
239 if (*walk == beginning)
242 char *str = scalloc(*walk - beginning + 1, 1);
243 /* We copy manually to handle escaping of characters. */
245 for (inpos = 0, outpos = 0;
246 inpos < (*walk - beginning);
248 /* We only handle escaped double quotes and backslashes to not break
249 * backwards compatibility with people using \w in regular expressions
251 if (beginning[inpos] == '\\' && (beginning[inpos + 1] == '"' || beginning[inpos + 1] == '\\'))
253 str[outpos] = beginning[inpos];
260 * Parses and executes the given command. If a caller-allocated yajl_gen is
261 * passed, a json reply will be generated in the format specified by the ipc
262 * protocol. Pass NULL if no json reply is required.
264 * Free the returned CommandResult with command_result_free().
266 CommandResult *parse_command(const char *input, yajl_gen gen) {
267 DLOG("COMMAND: *%s*\n", input);
269 CommandResult *result = scalloc(1, sizeof(CommandResult));
271 /* A YAJL JSON generator used for formatting replies. */
272 command_output.json_gen = gen;
275 command_output.needs_tree_render = false;
277 const char *walk = input;
278 const size_t len = strlen(input);
280 const cmdp_token *token;
283 // TODO: make this testable
285 cmd_criteria_init(¤t_match, &subcommand_output);
288 /* The "<=" operator is intentional: We also handle the terminating 0-byte
289 * explicitly by looking for an 'end' token. */
290 while ((size_t)(walk - input) <= len) {
291 /* skip whitespace and newlines before every token */
292 while ((*walk == ' ' || *walk == '\t' ||
293 *walk == '\r' || *walk == '\n') &&
297 cmdp_token_ptr *ptr = &(tokens[state]);
298 token_handled = false;
299 for (c = 0; c < ptr->n; c++) {
300 token = &(ptr->array[c]);
303 if (token->name[0] == '\'') {
304 if (strncasecmp(walk, token->name + 1, strlen(token->name) - 1) == 0) {
305 if (token->identifier != NULL)
306 push_string(token->identifier, sstrdup(token->name + 1));
307 walk += strlen(token->name) - 1;
309 token_handled = true;
315 if (strcmp(token->name, "number") == 0) {
316 /* Handle numbers. We only accept decimal numbers for now. */
319 long int num = strtol(walk, &end, 10);
320 if ((errno == ERANGE && (num == LONG_MIN || num == LONG_MAX)) ||
321 (errno != 0 && num == 0))
324 /* No valid numbers found */
328 if (token->identifier != NULL)
329 push_long(token->identifier, num);
331 /* Set walk to the first non-number character */
334 token_handled = true;
338 if (strcmp(token->name, "string") == 0 ||
339 strcmp(token->name, "word") == 0) {
340 char *str = parse_string(&walk, (token->name[0] != 's'));
342 if (token->identifier)
343 push_string(token->identifier, str);
344 /* If we are at the end of a quoted string, skip the ending
349 token_handled = true;
354 if (strcmp(token->name, "end") == 0) {
355 if (*walk == '\0' || *walk == ',' || *walk == ';') {
357 token_handled = true;
358 /* To make sure we start with an appropriate matching
359 * datastructure for commands which do *not* specify any
360 * criteria, we re-initialize the criteria system after
362 // TODO: make this testable
364 if (*walk == '\0' || *walk == ';')
365 cmd_criteria_init(¤t_match, &subcommand_output);
373 if (!token_handled) {
374 /* Figure out how much memory we will need to fill in the names of
375 * all tokens afterwards. */
377 for (c = 0; c < ptr->n; c++)
378 tokenlen += strlen(ptr->array[c].name) + strlen("'', ");
380 /* Build up a decent error message. We include the problem, the
381 * full input, and underline the position where the parser
384 char *possible_tokens = smalloc(tokenlen + 1);
385 char *tokenwalk = possible_tokens;
386 for (c = 0; c < ptr->n; c++) {
387 token = &(ptr->array[c]);
388 if (token->name[0] == '\'') {
389 /* A literal is copied to the error message enclosed with
392 strcpy(tokenwalk, token->name + 1);
393 tokenwalk += strlen(token->name + 1);
396 /* Any other token is copied to the error message enclosed
397 * with angle brackets. */
399 strcpy(tokenwalk, token->name);
400 tokenwalk += strlen(token->name);
403 if (c < (ptr->n - 1)) {
409 sasprintf(&errormessage, "Expected one of these tokens: %s",
411 free(possible_tokens);
413 /* Contains the same amount of characters as 'input' has, but with
414 * the unparseable part highlighted using ^ characters. */
415 char *position = smalloc(len + 1);
416 for (const char *copywalk = input; *copywalk != '\0'; copywalk++)
417 position[(copywalk - input)] = (copywalk >= walk ? '^' : ' ');
418 position[len] = '\0';
420 ELOG("%s\n", errormessage);
421 ELOG("Your command: %s\n", input);
422 ELOG(" %s\n", position);
424 result->parse_error = true;
425 result->error_message = errormessage;
427 /* Format this error message as a JSON reply. */
431 /* We set parse_error to true to distinguish this from other
432 * errors. i3-nagbar is spawned upon keypresses only for parser
440 ystr("errorposition");
452 result->needs_tree_render = command_output.needs_tree_render;
457 * Frees a CommandResult
459 void command_result_free(CommandResult *result) {
463 FREE(result->error_message);
467 /*******************************************************************************
468 * Code for building the stand-alone binary test.commands_parser which is used
469 * by t/187-commands-parser.t.
470 ******************************************************************************/
475 * Logs the given message to stdout while prefixing the current time to it,
476 * but only if debug logging was activated.
477 * This is to be called by DLOG() which includes filename/linenumber
480 void debuglog(char *fmt, ...) {
484 fprintf(stdout, "# ");
485 vfprintf(stdout, fmt, args);
489 void errorlog(char *fmt, ...) {
493 vfprintf(stderr, fmt, args);
497 int main(int argc, char *argv[]) {
499 fprintf(stderr, "Syntax: %s <command>\n", argv[0]);
502 yajl_gen gen = yajl_gen_alloc(NULL);
504 CommandResult *result = parse_command(argv[1], gen);
506 command_result_free(result);