From afc1667e644c1e95dc5643383c5227abb33d48e1 Mon Sep 17 00:00:00 2001
From: Dianne Skoll <dianne@skoll.ca>
Date: Thu, 2 Mar 2023 09:39:14 -0500
Subject: [PATCH] Implement htmlescape() built-in function.

---
 man/remind.1.in |  4 ++++
 src/funcs.c     | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 tests/test.cmp  | 22 ++++++++++++++++++++++
 tests/test.rem  |  7 +++++++
 4 files changed, 82 insertions(+)

diff --git a/man/remind.1.in b/man/remind.1.in
index 72f1b463..e88ab7a0 100644
--- a/man/remind.1.in
+++ b/man/remind.1.in
@@ -3074,6 +3074,10 @@ Support for Hebrew dates - see the section "THE HEBREW CALENDAR"
 .B hour(tq_time)
 Returns the hour component of \fItime\fR.
 .TP
+.B htmlescape(s_str)
+Returns a modified copy of \fIstr\fR where "<" is replaced with
+"&lt;"; ">" is replaced with "&gt;" and "&" is replaced with "&amp;"
+.TP
 .B iif(si_test1, x_arg1, [si_test2, x_arg2,...], x_default)
 If \fItest1\fR is not zero or the null string, returns \fIarg1\fR.
 Otherwise, if \fItest2\fR is not zero or the null string, returns
diff --git a/src/funcs.c b/src/funcs.c
index 7246a9ea..272e4d57 100644
--- a/src/funcs.c
+++ b/src/funcs.c
@@ -101,6 +101,7 @@ static int FHebday         (func_info *);
 static int FHebmon         (func_info *);
 static int FHebyear        (func_info *);
 static int FHour           (func_info *);
+static int FHtmlEscape     (func_info *);
 static int FIif            (func_info *);
 static int FIndex          (func_info *);
 static int FIsdst          (func_info *);
@@ -265,6 +266,7 @@ BuiltinFunc Func[] = {
     {   "hebmon",       1,      1,      0,          FHebmon },
     {   "hebyear",      1,      1,      0,          FHebyear },
     {   "hour",         1,      1,      1,          FHour   },
+    {   "htmlescape",   1,      1,      1,          FHtmlEscape },
     {   "iif",          1,      NO_MAX, 1,          FIif    },
     {   "index",        2,      3,      1,          FIndex  },
     {   "isany",        1,      NO_MAX, 1,          FIsAny  },
@@ -2248,6 +2250,53 @@ static int FHebyear(func_info *info)
     RETVAL = y;
     return OK;
 }
+
+/****************************************************************/
+/*                                                              */
+/* htmlescape - replace <. > and & by &lt; &gt; and &amp;       */
+/*                                                              */
+/****************************************************************/
+
+static int FHtmlEscape(func_info *info)
+{
+    DynamicBuffer dbuf;
+    char const *s;
+    int r;
+
+    ASSERT_TYPE(0, STR_TYPE);
+
+    DBufInit(&dbuf);
+
+    s = ARGSTR(0);
+    while(*s) {
+        switch(*s) {
+        case '<':
+            r = DBufPuts(&dbuf, "&lt;");
+            break;
+
+        case '>':
+            r = DBufPuts(&dbuf, "&gt;");
+            break;
+
+        case '&':
+            r = DBufPuts(&dbuf, "&amp;");
+            break;
+
+        default:
+            r = DBufPutc(&dbuf, *s);
+            break;
+        }
+        if (r != OK) {
+            DBufFree(&dbuf);
+            return r;
+        }
+        s++;
+    }
+    r = RetStrVal(DBufValue(&dbuf), info);
+    DBufFree(&dbuf);
+    return r;
+}
+
 /****************************************************************/
 /*                                                              */
 /*  FEasterdate - calc. easter Sunday from a year.              */
diff --git a/tests/test.cmp b/tests/test.cmp
index bf820e93..0f250295 100644
--- a/tests/test.cmp
+++ b/tests/test.cmp
@@ -4786,6 +4786,28 @@ FUNSET circle square rectangle
 SET a square(5)
 ../tests/test.rem(867): Undefined function: `square'
 
+# htmlescape
+set a htmlescape("foo")
+htmlescape("foo") => "foo"
+REM MSG [a]
+../tests/test.rem(871): Trig = Saturday, 16 February, 1991
+a => "foo"
+foo
+
+set a htmlescape("<&>")
+htmlescape("<&>") => "&lt;&amp;&gt;"
+REM MSG [a]
+../tests/test.rem(873): Trig = Saturday, 16 February, 1991
+a => "&lt;&amp;&gt;"
+&lt;&amp;&gt;
+
+set a htmlescape("@&^#*@&^##$*&@><><@#@#><@#>%%_#$foobarquux")
+htmlescape("@&^#*@&^##$*&@><><@#@#><@#>%%_#$foobarqu"...) => "@&amp;^#*@&amp;^##$*&amp;@&gt;&lt;&gt;&l"...
+REM MSG [a]
+../tests/test.rem(875): Trig = Saturday, 16 February, 1991
+a => "@&amp;^#*@&amp;^##$*&amp;@&gt;&lt;&gt;&l"...
+@&amp;^#*@&amp;^##$*&amp;@&gt;&lt;&gt;&lt;@#@#&gt;&lt;@#&gt;%_#$foobarquux
+
 # Don't want Remind to queue reminders
 EXIT
 
diff --git a/tests/test.rem b/tests/test.rem
index ec06a43c..bb032559 100644
--- a/tests/test.rem
+++ b/tests/test.rem
@@ -866,6 +866,13 @@ FUNSET circle square rectangle
 # Should fail
 SET a square(5)
 
+# htmlescape
+set a htmlescape("foo")
+REM MSG [a]
+set a htmlescape("<&>")
+REM MSG [a]
+set a htmlescape("@&^#*@&^##$*&@><><@#@#><@#>%%_#$foobarquux")
+REM MSG [a]
 # Don't want Remind to queue reminders
 EXIT