New :to_html_relaxed filter and html-encode*.

* filter.c (to_html_relaxed_k): New keyword symbol variable.
(to_html_relaxed_table): New static array.
(html_encode_star): New static function.
(filter_init): Initialize new symbol variable.
Register new filter. Register html-encode* function.

* txr.1: Documented :to_html_relaxed filter and
html-encode* function.

2 files changed, 36 insertions, 1 deletions

diff --git a/filter.c b/filter.c
index d7812454..70e6cf87 100644
--- a/filter.c
+++ b/filter.c
@@ -45,6 +45,7 @@
 
 val filters;
 val filter_k, lfilt_k, rfilt_k, to_html_k, from_html_k;
+val to_html_relaxed_k;
 val upcase_k, downcase_k;
 val topercent_k, frompercent_k, tourl_k, fromurl_k;
 val tonumber_k, toint_k, tofloat_k, hextoint_k;
@@ -284,6 +285,13 @@ static struct filter_pair to_html_table[] = {
   { 0, 0 }
 };
 
+static struct filter_pair to_html_relaxed_table[] = {
+  { wli("<"), wli("&lt;") },
+  { wli(">"), wli("&gt;") },
+  { wli("&"), wli("&amp;") },
+  { 0, 0 }
+};
+
 static struct filter_pair from_html_table[] = {
   { wli("&quot;"),      wli("\"") },
   { wli("&amp;"),       wli("&") },
@@ -675,6 +683,11 @@ static val html_encode(val str)
   return trie_filter_string(get_filter(to_html_k), str);
 }
 
+static val html_encode_star(val str)
+{
+  return trie_filter_string(get_filter(to_html_relaxed_k), str);
+}
+
 static val html_decode(val str)
 {
   return trie_filter_string(get_filter(from_html_k), str);
@@ -689,6 +702,7 @@ void filter_init(void)
   lfilt_k = intern(lit("lfilt"), keyword_package);
   rfilt_k = intern(lit("rfilt"), keyword_package);
   to_html_k = intern(lit("to_html"), keyword_package);
+  to_html_relaxed_k = intern(lit("to_html_relaxed"), keyword_package);
   from_html_k = intern(lit("from_html"), keyword_package);
   upcase_k = intern(lit("upcase"), keyword_package);
   downcase_k = intern(lit("downcase"), keyword_package);
@@ -702,6 +716,7 @@ void filter_init(void)
   hextoint_k = intern(lit("hextoint"), keyword_package);
 
   sethash(filters, to_html_k, build_filter(to_html_table, t));
+  sethash(filters, to_html_relaxed_k, build_filter(to_html_relaxed_table, t));
   {
     val trie = build_filter(from_html_table, nil);
     trie_add(trie, lit("&#"), func_n1(html_numeric_handler));
@@ -731,5 +746,7 @@ void filter_init(void)
   reg_fun(intern(lit("url-encode"), user_package), func_n2o(url_encode, 1));
   reg_fun(intern(lit("url-decode"), user_package), func_n2o(url_decode, 1));
   reg_fun(intern(lit("html-encode"), user_package), func_n1(html_encode));
+  reg_fun(intern(lit("html-encode*"), user_package),
+          func_n1(html_encode_star));
   reg_fun(intern(lit("html-decode"), user_package), func_n1(html_decode));
 }
diff --git a/txr.1 b/txr.1
index 45d49946..62e48c8f 100644
--- a/txr.1
+++ b/txr.1
@@ -7629,6 +7629,14 @@ ampersand sequences. For instance
 is replaced by
 .codn &gt; .
 
+.coIP :to_html_relaxed
+Filter text to HTML, representing special characters using HTML
+ampersand sequences. Unlike
+.codn :to_html ,
+this filter doesn't treat the single and double quote characters.
+It is not suitable for preparing HTML fragments which end up
+inserted into HTML tag attributes.
+
 .coIP :from_html
 Filter text with HTML codes into text in which the codes are replaced by the
 corresponding characters. For instance
@@ -35622,7 +35630,7 @@ encoded data are retained as
 characters in the decoded strings. Otherwise,
 plus characters are converted to spaces.
 
-.coNP Functions @ html-encode and @ html-decode
+.coNP Functions @, html-encode @, html-encode* and @ html-decode
 .synb
 .mets (html-encode << text-string )
 .mets (html-decode << html-string )
@@ -35673,6 +35681,16 @@ From this,
 produces
 .strn "&lt;p&gt;Hello, world!&lt;/p&gt;" .
 
+The
+.code html-encode*
+function is similar to
+.code html-encode
+except that it does not encode the single and double quote characters
+(ASCII 39 and 34, respectively). Text prepared by this function may not
+be suitable for insertion into a HTML template, depending on the
+context of its insertion. It is suitable as text placed between
+tags but not necessary as tag attribute material.
+
 .SS* Filter Module
 The filter module provides a trie (pronounced "try") data structure,
 which is suitable for representing dictionaries for efficient filtering.