Add $DedupeReminders global variable.

man/remind.1.in

@@ -2520,6 +2520,26 @@ This variable can be set only to "/" or "-".  It holds the character
 used to separate portions of a date when \fBRemind\fR prints a DATE or
 DATETIME value.
 .TP
+.B $DedupeReminders
+If this variable is set to 1, then Remind will suppress duplicate
+reminders.  A given reminder is considered to be a duplicate of a
+previous one if it has the \fIexact\fR same trigger date, trigger
+time, and body.  By default, this variable is set to 0 and Remind does
+not suppress duplicate reminders.
+.RS
+.PP
+As an example, consider the following reminder file:
+.nf
+        SET $DedupeReminders 1
+        REM Wednesday MSG Phooey
+        REM 20 MSG Phooey
+.fi
+.PP
+On Wednesday, 20 November 2024, only \fIone\fR "Phooey" will be issued.
+In December of 2024, "Phooey" will be issued every Wednesday as well
+as on Friday, 20 December 2024
+.RE
+.TP
 .B $DefaultColor
 This variable can be set to a string that has the form of three
 space-separated numbers.  Each number must be an integer from 0 to

src/Makefile.in

@@ -26,9 +26,10 @@ MANS=		$(srcdir)/../man/rem2ps.1 $(srcdir)/../man/remind.1 \
 .SUFFIXES:
 .SUFFIXES: .c .o
 
-REMINDSRCS=	calendar.c dynbuf.c dorem.c dosubst.c expr.c files.c funcs.c \
+REMINDSRCS= calendar.c dedupe.c dynbuf.c dorem.c dosubst.c expr.c	\
-		globals.c hbcal.c init.c main.c md5.c moon.c omit.c queue.c \
+		files.c funcs.c globals.c hbcal.c init.c main.c md5.c	\
-		sort.c token.c trigger.c userfns.c utils.c var.c
+		moon.c omit.c queue.c sort.c token.c trigger.c		\
+		userfns.c utils.c var.c
 
 REMINDHDRS=config.h custom.h dynbuf.h err.h globals.h lang.h \
 	   md5.h protos.h rem2ps.h types.h version.h

src/calendar.c

@@ -2054,8 +2054,6 @@ static int DoCalRem(ParsePtr p, int col)
     if ((dse == DSEToday) ||
         (DoSimpleCalDelta &&
          ShouldTriggerReminder(&trig, &tim, dse, &err))) {
-        NumTriggered++;
-
         /* The parse_ptr should not be nested, but just in case... */
         if (!p->isnested) {
             if (DBufPuts(&raw_buf, p->pos) != OK) {
@@ -2152,9 +2150,20 @@ static int DoCalRem(ParsePtr p, int col)
             }
         }
         s = DBufValue(&obuf);
+        if (DedupeReminders) {
+            if (ShouldDedupe(dse, tim.ttime, DBufValue(&obuf))) {
+                DBufFree(&obuf);
+                DBufFree(&raw_buf);
+                DBufFree(&pre_buf);
+                FreeTrig(&trig);
+                return OK;
+            }
+        }
+
         if (!DoSimpleCalendar) while (isempty(*s)) s++;
         DBufPuts(&pre_buf, s);
         s = DBufValue(&pre_buf);
+        NumTriggered++;
         e = NEW(CalEntry);
         if (!e) {
             DBufFree(&obuf);

src/dedupe.c

@@ -0,0 +1,175 @@
+/***************************************************************/
+/*                                                             */
+/*  DEDUPE.C                                                   */
+/*                                                             */
+/*  Code to suppress duplicate reminders                       */
+/*                                                             */
+/*  This file is part of REMIND.                               */
+/*  Copyright (C) 1992-2024 by Dianne Skoll                    */
+/*  SPDX-License-Identifier: GPL-2.0-only                      */
+/*                                                             */
+/***************************************************************/
+
+#include "config.h"
+#include "types.h"
+#include "globals.h"
+#include "protos.h"
+#include <stdlib.h>
+#include <string.h>
+
+#define DEDUPE_HASH_SLOTS 64
+typedef struct dedupe_entry {
+    struct dedupe_entry *next;
+    int trigger_date;
+    int trigger_time;
+    char const *body;
+} DedupeEntry;
+
+static DedupeEntry *DedupeTable[DEDUPE_HASH_SLOTS];
+
+/***************************************************************/
+/*                                                             */
+/*  FreeDedupeEntry                                            */
+/*                                                             */
+/*  Free a DedupeEntry object                                  */
+/*                                                             */
+/***************************************************************/
+static void
+FreeDedupeEntry(DedupeEntry *e)
+{
+    if (e->body) {
+        free((char *) e->body);
+    }
+    free(e);
+}
+
+/***************************************************************/
+/*                                                             */
+/*  GetDedupeBucket                                            */
+/*                                                             */
+/*  Get the bucket for a given date and body                   */
+/*                                                             */
+/***************************************************************/
+static unsigned int
+GetDedupeBucket(int trigger_date, int trigger_time, char const *body)
+{
+    unsigned int bucket = trigger_date;
+    if (trigger_time != NO_TIME) {
+        bucket += trigger_time;
+    }
+    bucket += HashVal(body);
+    return bucket % DEDUPE_HASH_SLOTS;
+}
+
+/***************************************************************/
+/*                                                             */
+/*  FindDedupeEntry                                            */
+/*                                                             */
+/*  Check if we have a dedupe entry for a given date and body  */
+/*                                                             */
+/***************************************************************/
+static DedupeEntry *
+FindDedupeEntry(int trigger_date, int trigger_time, char const *body)
+{
+    DedupeEntry *e;
+
+    unsigned int bucket = GetDedupeBucket(trigger_date, trigger_time, body);
+
+    e = DedupeTable[bucket];
+    while(e) {
+        if (e->trigger_date == trigger_date &&
+            e->trigger_time == trigger_time &&
+            !strcmp(body, e->body)) {
+            return e;
+        }
+        e = e->next;
+    }
+    return NULL;
+}
+
+/***************************************************************/
+/*                                                             */
+/*  InsertDedupeEntry                                          */
+/*                                                             */
+/*  Insert a dedupe entry for given date and body.             */
+/*                                                             */
+/***************************************************************/
+static void
+InsertDedupeEntry(int trigger_date, int trigger_time, char const *body)
+{
+    DedupeEntry *e;
+
+    unsigned int bucket = GetDedupeBucket(trigger_date, trigger_time, body);
+
+    e = malloc(sizeof(DedupeEntry));
+    if (!e) {
+        return; /* No error checking... what can we do? */
+    }
+    e->trigger_date = trigger_date;
+    e->trigger_time = trigger_time;
+    e->body = strdup(body);
+    if (!e->body) {
+        free(e);
+        return;
+    }
+
+    e->next = DedupeTable[bucket];
+    DedupeTable[bucket] = e;
+}
+
+/***************************************************************/
+/*                                                             */
+/*  ShouldDedupe                                               */
+/*                                                             */
+/*  Returns 1 if we've already issued this exact reminder; 0   */
+/*  otherwise.  If it returns 0, remembers that we have seen   */
+/*  the reminder                                               */
+/*                                                             */
+/***************************************************************/
+int
+ShouldDedupe(int trigger_date, int trigger_time, char const *body)
+{
+    DedupeEntry *e = FindDedupeEntry(trigger_date, trigger_time, body);
+
+    if (e) {
+        return 1;
+    }
+    InsertDedupeEntry(trigger_date, trigger_time, body);
+    return 0;
+}
+
+/***************************************************************/
+/*                                                             */
+/*  ClearDedupeTable                                           */
+/*                                                             */
+/*  Free all the storage used by the dedupe table              */
+/*                                                             */
+/***************************************************************/
+void
+ClearDedupeTable(void)
+{
+    DedupeEntry *e, *next;
+    for (int i=0; i<DEDUPE_HASH_SLOTS; i++) {
+        e = DedupeTable[i];
+        while (e) {
+            next = e->next;
+            FreeDedupeEntry(e);
+            e = next;
+        }
+        DedupeTable[i] = NULL;
+    }
+}
+/***************************************************************/
+/*                                                             */
+/*  InitDedupeTable                                            */
+/*                                                             */
+/*  Initialize the dedupe table at program startup             */
+/*                                                             */
+/***************************************************************/
+void
+InitDedupeTable(void)
+{
+    for (int i=0; i<DEDUPE_HASH_SLOTS; i++) {
+        DedupeTable[i] = NULL;
+    }
+}

src/dorem.c

@@ -1315,6 +1315,14 @@ int TriggerReminder(ParsePtr p, Trigger *t, TimeTrig *tim, int dse, int is_queue
         }
     }
 
+    /* If this is a dupe and we are de-duping, do nothing */
+    if (DedupeReminders) {
+        if (ShouldDedupe(dse, tim->ttime, DBufValue(&buf))) {
+            DBufFree(&buf);
+            return OK;
+        }
+    }
+
 /* If we are sorting, just queue it up in the sort buffer */
     if (SortByDate) {
         if (InsertIntoSortBuffer(dse, tim->ttime, DBufValue(&buf),

src/globals.h

@@ -139,6 +139,7 @@ EXTERN  INIT(   int     UseVTColors, 0);
 EXTERN  INIT(   int     Use256Colors, 0);
 EXTERN  INIT(   int     UseTrueColors, 0);
 EXTERN  INIT(   int     TerminalBackground, TERMINAL_BACKGROUND_UNKNOWN);
+EXTERN  INIT(   int     DedupeReminders, 0);
 
 /* Latitude and longitude */
 EXTERN  INIT(   int       LatDeg, 0);

src/init.c

@@ -192,6 +192,8 @@ void InitRemind(int argc, char const *argv[])
 
     PurgeFP = NULL;
 
+    InitDedupeTable();
+
     /* Make sure remind is not installed set-uid or set-gid */
     if (getgid() != getegid() ||
         getuid() != geteuid()) {

src/main.c

@@ -226,6 +226,7 @@ PerIterationInit(void)
     DefaultColorB = -1;
     NumTriggered = 0;
     ClearLastTriggers();
+    ClearDedupeTable();
 }
 
 /***************************************************************/

src/protos.h

@@ -249,3 +249,8 @@ void print_builtinfunc_tokens(void);
 void print_remind_tokens(void);
 void get_var_hash_stats(int *total, int *maxlen, double *avglen);
 void get_userfunc_hash_stats(int *total, int *maxlen, double *avglen);
+
+/* Dedupe code */
+int ShouldDedupe(int trigger_date, int trigger_time, char const *body);
+void ClearDedupeTable(void);
+void InitDedupeTable(void);

src/var.c

@@ -864,6 +864,7 @@ static SysVar SysVarArr[] = {
     {"DateSep",        1,  SPECIAL_TYPE, date_sep_func,        0,      0 },
     {"DateTimeSep",    1,  SPECIAL_TYPE, datetime_sep_func,    0,      0 },
     {"December",       1,  STR_TYPE,     &DynamicMonthName[11],0,      0 },
+    {"DedupeReminders",1,  INT_TYPE,     &DedupeReminders,     0,      1 },
     {"DefaultColor",   1,  SPECIAL_TYPE, default_color_func,   0,      0 },
     {"DefaultPrio",    1,  INT_TYPE,     &DefaultPrio,         0,      9999 },
     {"DefaultTDelta",  1,  INT_TYPE,     &DefaultTDelta,       0,      1440 },

tests/dedupe.rem

@@ -0,0 +1,25 @@
+SET $DedupeReminders 1
+SET $SuppressLRM 1
+REM Wednesday MSG foo
+FLUSH
+REM 8 MSG foo
+FLUSH
+REM Wednesday MSG Bar
+FLUSH
+REM Wednesday MSG Bar
+FLUSH
+REM Wednesday AT 23:59 +1440 MSG with_time
+FLUSH
+REM AT 23:59 +1440 MSG with_time
+FLUSH
+REM AT 23:58 +1440 MSG with_time
+FLUSH
+
+REM 8 RUN echo %"foo%"
+FLUSH
+REM 8 RUN echo %"foo%"
+FLUSH
+REM Wed RUN echo %"foo%"
+FLUSH
+REM Wed RUN echo %"bar%"
+FLUSH

tests/test-rem

@@ -586,6 +586,10 @@ rm -f ../tests/once.timestamp
 # Newlines in calendar output
 (echo 'REM 16 MSG foo%_bar%_baz wookie quux apple   %_    %_    %_  blech'; echo "REM 16 MSG ANOTHER") | ../src/remind -c -w80 - 1 sep 1990 >> ../tests/test.out 2>&1
 
+# Dedupe feature
+../src/remind -c ../tests/dedupe.rem 1 November 2023 >> ../tests/test.out 2>&1
+../src/remind -q ../tests/dedupe.rem 8 November 2023 >> ../tests/test.out 2>&1
+
 # Remove references to SysInclude, which is build-specific
 grep -F -v '$SysInclude' < ../tests/test.out > ../tests/test.out.1 && mv -f ../tests/test.out.1 ../tests/test.out
 

tests/test.cmp

@@ -2729,6 +2729,7 @@ Variable  Value
                  $DateSep  "-"
              $DateTimeSep  "@"
                 $December  "December"
+         $DedupeReminders  0           [0, 1]
             $DefaultColor  "-1 -1 -1"
              $DefaultPrio  5000        [0, 9999]
            $DefaultTDelta  0           [0, 1440]
@@ -13377,7 +13378,93 @@ No reminders.
 |          |          |          |          |          |          |          |
 |          |          |          |          |          |          |          |
 +----------+----------+----------+----------+----------+----------+----------+
-
++----------------------------------------------------------------------------+
+|                               November 2023                                |
++----------+----------+----------+----------+----------+----------+----------+
+|  Sunday  |  Monday  | Tuesday  |Wednesday | Thursday |  Friday  | Saturday |
++----------+----------+----------+----------+----------+----------+----------+
+|          |          |          |1         |2         |3         |4         |
+|          |          |          |          |          |          |          |
+|          |          |          |11:58pm   |11:58pm   |11:58pm   |11:58pm   |
+|          |          |          |with_time |with_time |with_time |with_time |
+|          |          |          |          |          |          |          |
+|          |          |          |11:59pm   |11:59pm   |11:59pm   |11:59pm   |
+|          |          |          |with_time |with_time |with_time |with_time |
+|          |          |          |          |          |          |          |
+|          |          |          |foo       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |Bar       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |bar       |          |          |          |
++----------+----------+----------+----------+----------+----------+----------+
+|5         |6         |7         |8         |9         |10        |11        |
+|          |          |          |          |          |          |          |
+|11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |
+|with_time |with_time |with_time |with_time |with_time |with_time |with_time |
+|          |          |          |          |          |          |          |
+|11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |
+|with_time |with_time |with_time |with_time |with_time |with_time |with_time |
+|          |          |          |          |          |          |          |
+|          |          |          |foo       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |Bar       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |bar       |          |          |          |
++----------+----------+----------+----------+----------+----------+----------+
+|12        |13        |14        |15        |16        |17        |18        |
+|          |          |          |          |          |          |          |
+|11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |
+|with_time |with_time |with_time |with_time |with_time |with_time |with_time |
+|          |          |          |          |          |          |          |
+|11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |
+|with_time |with_time |with_time |with_time |with_time |with_time |with_time |
+|          |          |          |          |          |          |          |
+|          |          |          |foo       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |Bar       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |bar       |          |          |          |
++----------+----------+----------+----------+----------+----------+----------+
+|19        |20        |21        |22        |23        |24        |25        |
+|          |          |          |          |          |          |          |
+|11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |
+|with_time |with_time |with_time |with_time |with_time |with_time |with_time |
+|          |          |          |          |          |          |          |
+|11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |
+|with_time |with_time |with_time |with_time |with_time |with_time |with_time |
+|          |          |          |          |          |          |          |
+|          |          |          |foo       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |Bar       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |bar       |          |          |          |
++----------+----------+----------+----------+----------+----------+----------+
+|26        |27        |28        |29        |30        |          |          |
+|          |          |          |          |          |          |          |
+|11:58pm   |11:58pm   |11:58pm   |11:58pm   |11:58pm   |          |          |
+|with_time |with_time |with_time |with_time |with_time |          |          |
+|          |          |          |          |          |          |          |
+|11:59pm   |11:59pm   |11:59pm   |11:59pm   |11:59pm   |          |          |
+|with_time |with_time |with_time |with_time |with_time |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |foo       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |Bar       |          |          |          |
+|          |          |          |          |          |          |          |
+|          |          |          |bar       |          |          |          |
++----------+----------+----------+----------+----------+----------+----------+
+Reminders for Wednesday, 8th November, 2023:
+
+foo
+
+Bar
+
+with_time
+
+with_time
+
+foo
+bar
 # Remind Tokens
 
 addomit
@@ -13623,6 +13710,7 @@ $Daemon
 $DateSep
 $DateTimeSep
 $December
+$DedupeReminders
 $DefaultColor
 $DefaultPrio
 $DefaultTDelta