parse-time-string: add a date/time parser to notmuch

[notmuch] / parse-time-string / parse-time-string.h

diff --git a/parse-time-string/parse-time-string.h b/parse-time-string/parse-time-string.h
new file mode 100644 (file)
index 0000000..bfa4ee3
--- /dev/null
+++ b/parse-time-string/parse-time-string.h
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+/*
+ * parse time string - user friendly date and time parser
+ * Copyright © 2012 Jani Nikula
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Jani Nikula <jani@nikula.org>
+ */
+
+#ifndef PARSE_TIME_STRING_H
+#define PARSE_TIME_STRING_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <time.h>
+
+/* return values for parse_time_string() */
+enum {
+    PARSE_TIME_OK = 0,
+    PARSE_TIME_ERR,            /* unspecified error */
+    PARSE_TIME_ERR_LIB,                /* library call failed */
+    PARSE_TIME_ERR_ALREADYSET, /* attempt to set unit twice */
+    PARSE_TIME_ERR_FORMAT,     /* generic date/time format error */
+    PARSE_TIME_ERR_DATEFORMAT, /* date format error */
+    PARSE_TIME_ERR_TIMEFORMAT, /* time format error */
+    PARSE_TIME_ERR_INVALIDDATE,        /* date value error */
+    PARSE_TIME_ERR_INVALIDTIME,        /* time value error */
+    PARSE_TIME_ERR_KEYWORD,    /* unknown keyword */
+};
+
+/* round values for parse_time_string() */
+enum {
+    PARSE_TIME_ROUND_DOWN = -1,
+    PARSE_TIME_NO_ROUND = 0,
+    PARSE_TIME_ROUND_UP = 1,
+    PARSE_TIME_ROUND_UP_INCLUSIVE = 2,
+};
+
+/**
+ * parse_time_string() - user friendly date and time parser
+ * @s:         string to parse
+ * @t:         pointer to time_t to store parsed time in
+ * @ref:       pointer to time_t containing reference date/time, or NULL
+ * @round:     PARSE_TIME_NO_ROUND, PARSE_TIME_ROUND_DOWN, or
+ *             PARSE_TIME_ROUND_UP
+ *
+ * Parse a date/time string 's' and store the parsed date/time result
+ * in 't'.
+ *
+ * A reference date/time is used for determining the "date/time units"
+ * (roughly equivalent to struct tm members) not specified by 's'. If
+ * 'ref' is non-NULL, it must contain a pointer to a time_t to be used
+ * as reference date/time. Otherwise, the current time is used.
+ *
+ * If 's' does not specify a full date/time, the 'round' parameter
+ * specifies if and how the result should be rounded as follows:
+ *
+ *   PARSE_TIME_NO_ROUND: All date/time units that are not specified
+ *   by 's' are set to the corresponding unit derived from the
+ *   reference date/time.
+ *
+ *   PARSE_TIME_ROUND_DOWN: All date/time units that are more accurate
+ *   than the most accurate unit specified by 's' are set to the
+ *   smallest valid value for that unit. Rest of the unspecified units
+ *   are set as in PARSE_TIME_NO_ROUND.
+ *
+ *   PARSE_TIME_ROUND_UP: All date/time units that are more accurate
+ *   than the most accurate unit specified by 's' are set to the
+ *   smallest valid value for that unit. The most accurate unit
+ *   specified by 's' is incremented by one (and this is rolled over
+ *   to the less accurate units as necessary), unless the most
+ *   accurate unit is seconds. Rest of the unspecified units are set
+ *   as in PARSE_TIME_NO_ROUND.
+ *
+ *   PARSE_TIME_ROUND_UP_INCLUSIVE: Same as PARSE_TIME_ROUND_UP, minus
+ *   one second, unless the most accurate unit specified by 's' is
+ *   seconds. This is useful for callers that require a value for
+ *   inclusive comparison of the result.
+ *
+ * Return 0 (PARSE_TIME_OK) for succesfully parsed date/time, or one
+ * of PARSE_TIME_ERR_* on error. 't' is not modified on error.
+ */
+int parse_time_string (const char *s, time_t *t, const time_t *ref, int round);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* PARSE_TIME_STRING_H */