meetup (C)

c/meetup/GNUmakefile

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+# The original 'makefile' has a flaw:
+# 1) it overrides CFLAGS
+# 2) it does not pass extra "FLAGS" to $(CC) that could come from environment
+#
+# It means :
+# - we need to edit 'makefile' for different builds (DEBUG, etc...), which is
+#   not practical at all.
+# - Also, it does not allow to run all tests without editing the test source
+#   code.
+#
+# To use this makefile (GNU make only):
+#   "make": build with all predefined tests (without editing test source code)
+#   "make debugall": build with all predefined tests and debug code
+#   "make mem": perform memcheck with all tests enabled
+#   "make unit": build standalone (unit) test
+#   "make debug": build standalone test with debugging code
+#
+# Original 'makefile' targets can be used (test, memcheck, clean, ...)
+
+.PHONY: default all mem unit debug std debugtest
+
+default: all
+
+# default is to build with all predefined tests
+BUILD := teststall
+
+include makefile
+
+all: CFLAGS+=-DTESTALL
+all: clean test
+
+debugall: CFLAGS+=-DDEBUG
+debugall: all
+
+debugtest: CFLAGS+=-DDEBUG
+debugtest: test
+
+mem: CFLAGS+=-DTESTALL
+mem: clean memcheck
+
+unit: CFLAGS+=-DUNIT_TEST
+unit: clean std
+
+debug: CFLAGS+=-DUNIT_TEST -DDEBUG
+debug: clean std
+
+debugtest: CFLAGS+=-DDEBUG
+debugtest: test
+
+std: src/*.c src/*.h
+	$(CC) $(CFLAGS) src/*.c -o test.out

c/meetup/README.md

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+# Meetup
+
+Calculate the date of meetups.
+
+Typically meetups happen on the same day of the week.  In this exercise, you
+will take a description of a meetup date, and return the actual meetup date.
+
+Examples of general descriptions are:
+
+- The first Monday of January 2017
+- The third Tuesday of January 2017
+- The wednesteenth of January 2017
+- The last Thursday of January 2017
+
+The descriptors you are expected to parse are:
+first, second, third, fourth, fifth, last, monteenth, tuesteenth, wednesteenth,
+thursteenth, friteenth, saturteenth, sunteenth
+
+Note that "monteenth", "tuesteenth", etc are all made up words. There was a
+meetup whose members realized that there are exactly 7 numbered days in a month
+that end in '-teenth'. Therefore, one is guaranteed that each day of the week
+(Monday, Tuesday, ...) will have exactly one date that is named with '-teenth'
+in every month.
+
+Given examples of a meetup dates, each containing a month, day, year, and
+descriptor calculate the date of the actual meetup.  For example, if given
+"The first Monday of January 2017", the correct meetup date is 2017/1/2.
+
+## Getting Started
+
+Make sure you have read the "Guides" section of the
+[C track][c-track] on the Exercism site. This covers
+the basic information on setting up the development environment expected
+by the exercises.
+
+## Passing the Tests
+
+Get the first test compiling, linking and passing by following the [three
+rules of test-driven development][3-tdd-rules].
+
+The included makefile can be used to create and run the tests using the `test`
+task.
+
+    make test
+
+Create just the functions you need to satisfy any compiler errors and get the
+test to fail. Then write just enough code to get the test to pass. Once you've
+done that, move onto the next test.
+
+As you progress through the tests, take the time to refactor your
+implementation for readability and expressiveness and then go on to the next
+test.
+
+Try to use standard C99 facilities in preference to writing your own
+low-level algorithms or facilities by hand.
+
+## Source
+
+Jeremy Hinegardner mentioned a Boulder meetup that happens on the Wednesteenth of every month [https://twitter.com/copiousfreetime](https://twitter.com/copiousfreetime)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[c-track]: https://exercism.io/my/tracks/c
+[3-tdd-rules]: http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd

c/meetup/makefile

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+### If you wish to use extra libraries (math.h for instance),
+### add their flags here (-lm in our case) in the "LIBS" variable.
+
+LIBS = -lm
+
+###
+CFLAGS  = -std=c99
+CFLAGS += -g
+CFLAGS += -Wall
+CFLAGS += -Wextra
+CFLAGS += -pedantic
+CFLAGS += -Werror
+CFLAGS += -Wmissing-declarations
+CFLAGS += -DUNITY_SUPPORT_64
+
+ASANFLAGS  = -fsanitize=address
+ASANFLAGS += -fno-common
+ASANFLAGS += -fno-omit-frame-pointer
+
+.PHONY: test
+test: tests.out
+	@./tests.out
+
+.PHONY: memcheck
+memcheck: test/*.c src/*.c src/*.h
+	@echo Compiling $@
+	@$(CC) $(ASANFLAGS) $(CFLAGS) src/*.c test/vendor/unity.c test/*.c -o memcheck.out $(LIBS)
+	@./memcheck.out
+	@echo "Memory check passed"
+
+.PHONY: clean
+clean:
+	rm -rf *.o *.out *.out.dSYM
+
+tests.out: test/*.c src/*.c src/*.h
+	@echo Compiling $@
+	@$(CC) $(CFLAGS) src/*.c test/vendor/unity.c test/*.c -o tests.out $(LIBS)

c/meetup/src/meetup.c

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+#include "meetup.h"
+#include <time.h>
+#include <stdlib.h>
+
+/* The explanation tells about 'fifth', not included in tests.
+ * I will manage this, returning "-1" if it does not exist.
+ */
+
+/* convert the 2/3 first chars of string to big endian integer */
+#define S2BE(a, b) ((a<<8)+b)
+#define S3BE(a, b, c) ((a<<16)+(b<<8)+c)
+
+#define TEENTH 42
+#define LAST   21
+
+static int str2day(const char *d)
+{
+    switch (S2BE(*d, *(d+1))) {
+        case S2BE('M', 'o'): return 1;
+        case S2BE('T', 'u'): return 2;
+        case S2BE('W', 'e'): return 3;
+        case S2BE('T', 'h'): return 4;
+        case S2BE('F', 'r'): return 5;
+        case S2BE('S', 'a'): return 6;
+        case S2BE('S', 'u'): return 0;
+    }
+    return -1;
+}
+
+static int str2nth(const char *d)
+{
+    switch (S3BE(*d, *(d+1), *(d+2))) {
+        case S3BE('f', 'i', 'r'): return 0;
+        case S3BE('s', 'e', 'c'): return 1;
+        case S3BE('t', 'h', 'i'): return 2;
+        case S3BE('f', 'o', 'u'): return 3;
+        case S3BE('f', 'i', 'f'): return 4;
+        case S3BE('l', 'a', 's'): return LAST;
+        case S3BE('t', 'e', 'e'): return TEENTH;
+    }
+    return -1;
+}
+
+static int m_1st(unsigned y, unsigned m)
+{
+    struct tm time = {
+        .tm_year=y-1900,
+        .tm_mon=m-1,
+        .tm_mday=1
+    };
+    mktime (&time);
+    return time.tm_wday;
+}
+
+static int m_ndays(unsigned y, unsigned m)
+{
+    static int days[]={31, 42, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+    return m!=2 ? days[m-1]:
+        (!(y % 4) && (y % 100 || !(y % 400)))? 29: 28;
+
+}
+
+int meetup_day_of_month(unsigned int yy, unsigned int mm, const char *sweek,
+                        const char *sday)
+{
+
+    int nth, ndays, wanted, res=-1;
+
+    ndays=m_ndays(yy, mm);
+    if ((nth=str2nth(sweek))<0 || (wanted=str2day(sday))<0)
+        return -1;
+    if ((res=wanted-m_1st(yy, mm)+1) <= 0)
+        res+=7;
+
+    if (nth<5) {
+        if ((res+=7*nth)>ndays)
+            res=-1;
+    } else if (nth==TEENTH) {
+        if ((res+=7)<13)
+            res+=7;
+    } else {                                      /* last */
+        if ((res+=7*4)>ndays)
+            res-=7;
+    }
+
+    return res;
+}
+
+/* See GNUmakefile below for explanation
+ * https://github.com/braoult/exercism/blob/master/c/templates/GNUmakefile
+ */
+#ifdef UNIT_TEST
+int main(int ac, char **av)
+{
+    int arg=1;
+    unsigned y, m;
+
+    for (; arg<ac-3; arg+=4) {
+        y=atoi(av[arg]);
+        m=atoi(av[arg+1]);
+        printf("meetup(%d, %d, %s, %s)=%d\n",
+               y, m, av[arg+2], av[arg+3],
+               meetup_day_of_month(y, m, av[arg+2], av[arg+3]));
+    }
+}
+#endif

c/meetup/src/meetup.h

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+#ifndef MEETUP_H
+#define MEETUP_H
+
+int meetup_day_of_month(unsigned int year, unsigned int month, const char *week,
+                        const char *day_of_week);
+
+/* See GNUmakefile below for explanation
+ * https://github.com/braoult/exercism/blob/master/c/templates/GNUmakefile
+ */
+#if defined UNIT_TEST || defined DEBUG
+#include <stdio.h>
+#include <stdlib.h>
+#endif
+#ifdef  TESTALL
+#undef  TEST_IGNORE
+#define TEST_IGNORE() {}
+#endif
+
+#endif