unicode::bidi_reorder - add optional substring indices.

3 files changed, 43 insertions, 9 deletions

diff --git a/unicode/book.xml b/unicode/book.xml
index c0e0485..4838364 100644
--- a/unicode/book.xml
+++ b/unicode/book.xml
@@ -2835,13 +2835,17 @@ See COPYING for distribution information.
               <funcdef>int <function>unicode::bidi_reorder</function></funcdef>
 	      <paramdef>std::u32string &amp;<parameter>string</parameter></paramdef>
 	      <paramdef>std::vector&lt;unicode_bidi_level_t&gt; &amp;<parameter>embedding_level</parameter></paramdef>
-	      <paramdef>const std::function&lt;void (size_t, size_t) noexcept&gt; &amp;<parameter>reorder_callback</parameter></paramdef>
+	      <paramdef>const std::function&lt;void (size_t, size_t) noexcept&gt; &amp;<parameter>reorder_callback</parameter>=[](size_t, size_t){}</paramdef>
+	      <paramdef>size_t <parameter>starting_pos</parameter>=0</paramdef>
+	      <paramdef>size_t <parameter>n</parameter>=(size_t)-1</paramdef>
 	    </funcprototype>
 
 	    <funcprototype>
               <funcdef>void <function>unicode::bidi_reorder</function></funcdef>
 	      <paramdef>std::vector&lt;unicode_bidi_level_t&gt; &amp;<parameter>embedding_level</parameter></paramdef>
-	      <paramdef>const std::function&lt;void (size_t, size_t) noexcept&gt; &amp;<parameter>reorder_callback</parameter></paramdef>
+	      <paramdef>const std::function&lt;void (size_t, size_t) noexcept&gt; &amp;<parameter>reorder_callback</parameter>=[](size_t, size_t){}</paramdef>
+	      <paramdef>size_t <parameter>starting_pos</parameter>=0</paramdef>
+	      <paramdef>size_t <parameter>n</parameter>=(size_t)-1</paramdef>
 	    </funcprototype>
 
 	    <funcprototype>
@@ -3012,6 +3016,20 @@ auto [levels, level]=unicode::bidi_calc(types);
 		an empty string in case of a mismatch.
               </para>
             </listitem>
+
+	    <listitem>
+	      <para>
+		<function>unicode::bidi_reorder</function>
+		reorders the entire <parameter>string</parameter> and its
+		<parameter>embedding_level</parameter>s by default.
+		The optional
+		<parameter>starting_pos</parameter> and
+		<parameter>n</parameter> parameters limit the reordering
+		to the indicated subset of the original string (specified
+		as the starting position offset index, and the number of
+		characters).
+	      </para>
+	    </listitem>
           </itemizedlist>
 
 	  <refsect2 id="unicode_cpp_bidi_literals">
diff --git a/unicode/courier-unicode.h.in b/unicode/courier-unicode.h.in
index a3a59f4..469b456 100644
--- a/unicode/courier-unicode.h.in
+++ b/unicode/courier-unicode.h.in
@@ -2234,12 +2234,16 @@ std::tuple<std::vector<unicode_bidi_level_t>,
 int bidi_reorder(std::u32string &string,
 		 std::vector<unicode_bidi_level_t> &levels,
 		 const std::function<void (size_t, size_t)>
-		 &reorder_callback=[](size_t, size_t){});
+		 &reorder_callback=[](size_t, size_t){},
+		 size_t starting_pos=0,
+		 size_t n=(size_t)-1);
 
 //! Dry-run reorder bidirectional text
 void bidi_reorder(std::vector<unicode_bidi_level_t> &levels,
 		  const std::function<void (size_t, size_t)>
-		  &reorder_callback=[](size_t, size_t){});
+		  &reorder_callback=[](size_t, size_t){},
+		  size_t starting_pos=0,
+		  size_t n=(size_t)-1);
 
 //! Remove directional markers
 
diff --git a/unicode/unicodecpp.C b/unicode/unicodecpp.C
index 48cc3c6..8c43b31 100644
--- a/unicode/unicodecpp.C
+++ b/unicode/unicodecpp.C
@@ -669,19 +669,23 @@ extern "C" {
 
 int unicode::bidi_reorder(std::u32string &string,
 			  std::vector<unicode_bidi_level_t> &levels,
-			  const std::function<void (size_t, size_t)> &lambda)
+			  const std::function<void (size_t, size_t)> &lambda,
+			  size_t pos,
+			  size_t n)
 {
 	size_t s=string.size();
 
 	if (s != levels.size())
 		return -1;
 
-	if (!s)
+	if (pos >= s)
 		return 0;
 
+	if (n > s-pos)
+		n=s-pos;
 	cb_wrapper<void (size_t, size_t)> cb{lambda};
 
-	unicode_bidi_reorder(&string[0], &levels[0], s,
+	unicode_bidi_reorder(&string[pos], &levels[pos], n,
 			     reorder_callback,
 			     reinterpret_cast<void *>(&cb));
 
@@ -690,16 +694,24 @@ int unicode::bidi_reorder(std::u32string &string,
 }
 
 void unicode::bidi_reorder(std::vector<unicode_bidi_level_t> &levels,
-			   const std::function<void (size_t, size_t)> &lambda)
+			   const std::function<void (size_t, size_t)> &lambda,
+			   size_t pos,
+			   size_t n)
 {
 	size_t s=levels.size();
 
 	if (!s)
 		return;
 
+	if (pos >= s)
+		return;
+
+	if (n > s-pos)
+		n=s-pos;
+
 	cb_wrapper<void (size_t, size_t)> cb{lambda};
 
-	unicode_bidi_reorder(0, &levels[0], s, reorder_callback,
+	unicode_bidi_reorder(0, &levels[pos], n, reorder_callback,
 			     reinterpret_cast<void *>(&cb));
 	cb.rethrow();