[PATCH Hpricot] latest changes from mainline fast_xs

Hi all,

Hopefully the new maintainer of Hpricot will see this because I have no
idea who to send it to now...

I originally had a version of this patch posted in _why's Trac sometime
in 2008 until he took Trac down.  I've tried emailing him directly on
several occasions since and never got a response, last was February
2009.  Come to think of it, the only time I ever got any response from
him was my initial email to him about fast_xs back in October 2007.


So here it is, I've rebased my patch against
2c961095954d5aaa5c046f4c773c62c3d5902ef4 on
git://github.com/whymirror/hpricot.git

Also I have an entire repo up on git://git.bogomips.org/hpricot and
viewable from http://git.bogomips.org/cgit/hpricot.git


From 636e3f453b2bbc0c7486b91eda452fe4767e4bbc Mon Sep 17 00:00:00 2001
From: Eric Wong <[e-mail]>
Date: Sat, 7 Feb 2009 21:31:15 -0800
Subject: [PATCH] * ext/fast_xs: latest changes from mainline fast_xs

- alloca() dependency removed.  An extra memory allocation and
  memory copy is saved by writing directly to the string object
  returned by rb_str_new(0, len) (both the Ruby 1.8.6 and 1.9
  code has this usage in it, so it should be safe :)
  This also allows fast_xs to work on strings larger than
  the stack size.
- general readability and cleanups
- fast_xs works with Ruby 1.9
- Don't rely on ruby_digitmap being a valid symbol
---

 ext/fast_xs/fast_xs.c |  101 ++++++++++++++++++++++++-------------------------
 1 files changed, 50 insertions(+), 51 deletions(-)

diff --git a/ext/fast_xs/fast_xs.c b/ext/fast_xs/fast_xs.c
index 4a30a6c..04b175f 100644
--- a/ext/fast_xs/fast_xs.c
+++ b/ext/fast_xs/fast_xs.c
@@ -1,8 +1,5 @@
-#define VERSION	"0.1"
-
 #include <ruby.h>
 #include <assert.h>
-/* #include <stdio.h> */
 
 #ifndef RARRAY_LEN
 #define RARRAY_LEN(arr)  RARRAY(arr)->len
@@ -72,11 +69,6 @@ static const int cp_1252[] = {
 		n = cp_1252[n - 128]; \
 	} while(0)
 
-#define return_const_len(x) do { \
-	memcpy(buf, x, sizeof(x) - 1); \
-	return (sizeof(x) - 1); \
-} while (0)
-
 static inline size_t bytes_for(int n)
 {
 	if (n < 1000)
@@ -91,18 +83,24 @@ static inline size_t bytes_for(int n)
 	return sizeof("&#9999999;") - 1;
 }
 
-static long escape(char *buf, int n)
+static size_t escape(char *buf, int n)
 {
+
+#define return_const_len(x) do { \
+	memcpy(buf, x, sizeof(x) - 1); \
+	return (sizeof(x) - 1); \
+} while (0)
+
 	/* handle ASCII first */
 	if (likely(n < 128)) {
-		if (likely(n >= 0x20 || n == 0x9 || n == 0xA || n == 0xD)) {
-			if (unlikely(n == 34))
+		if (likely(n >= 0x20 || n == '\t' || n == '\n' || n == '\r')) {
+			if (unlikely(n == '"'))
 				return_const_len("&quot;");
-			if (unlikely(n == 38))
+			if (unlikely(n == '&'))
 				return_const_len("&amp;");
-			if (unlikely(n == 60))
+			if (unlikely(n == '<'))
 				return_const_len("&lt;");
-			if (unlikely(n == 62))
+			if (unlikely(n == '>'))
 				return_const_len("&gt;");
 			buf[0] = (char)n;
 			return 1;
@@ -112,16 +110,18 @@ static long escape(char *buf, int n)
 		return 1;
 	}
 
+#undef return_const_len
+
 	CP_1252_ESCAPE(n);
 
 	if (VALID_VALUE(n)) {
 		/* return snprintf(buf, sizeof("&#1114111;"), "&#%i;", n); */
-		RUBY_EXTERN const char ruby_digitmap[];
-		int rv = 3; /* &#; */
+		static const char digitmap[] = "0123456789";
+		size_t rv = sizeof("&#;") - 1;
 		buf += bytes_for(n);
 		*--buf = ';';
 		do {
-			*--buf = ruby_digitmap[(int)(n % 10)];
+			*--buf = digitmap[(int)(n % 10)];
 			++rv;
 		} while (n /= 10);
 		*--buf = '#';
@@ -132,27 +132,6 @@ static long escape(char *buf, int n)
 	return 1;
 }
 
-#undef return_const_len
-
-static long escaped_len(int n)
-{
-	if (likely(n < 128)) {
-		if (unlikely(n == 34))
-			return (sizeof("&quot;") - 1);
-		if (unlikely(n == 38))
-			return (sizeof("&amp;") - 1);
-		if (unlikely(n == 60 || n == 62))
-			return (sizeof("&gt;") - 1);
-		return 1;
-	}
-
-	CP_1252_ESCAPE(n);
-
-	if (VALID_VALUE(n))
-		return bytes_for(n);
-	return 1;
-}
-
 static VALUE unpack_utf8(VALUE self)
 {
 	return rb_funcall(self, unpack_id, 1, U_fmt);
@@ -163,28 +142,48 @@ static VALUE unpack_uchar(VALUE self)
 	return rb_funcall(self, unpack_id, 1, C_fmt);
 }
 
-VALUE fast_xs(VALUE self)
+/*
+ * escapes strings for XML
+ * The double-quote (") character is translated to "&quot;"
+ */
+static VALUE fast_xs(VALUE self)
 {
 	long i;
-	struct RArray *array;
-	char *s, *c;
-	long s_len = 0;
+	VALUE array;
+	char *c;
+	size_t s_len;
 	VALUE *tmp;
+	VALUE rv;
+
+	array = rb_rescue(unpack_utf8, self, unpack_uchar, self);
+
+	for (tmp = RARRAY_PTR(array), s_len = i = RARRAY_LEN(array);
+	     --i >= 0;
+	     tmp++) {
+		int n = NUM2INT(*tmp);
+		if (likely(n < 128)) {
+			if (unlikely(n == '"'))
+				s_len += (sizeof("&quot;") - 2);
+			if (unlikely(n == '&'))
+				s_len += (sizeof("&amp;") - 2);
+			if (unlikely(n == '>' || n == '<'))
+				s_len += (sizeof("&gt;") - 2);
+			continue;
+		}
 
-	array = RARRAY(rb_rescue(unpack_utf8, self, unpack_uchar, self));
+		CP_1252_ESCAPE(n);
 
-	tmp = RARRAY_PTR(array);
-	for (i = RARRAY_LEN(array); --i >= 0; tmp++)
-		s_len += escaped_len(NUM2INT(*tmp));
+		if (VALID_VALUE(n))
+			s_len += bytes_for(n) - 1;
+	}
 
-	c = s = alloca(s_len + 1);
+	rv = rb_str_new(NULL, s_len);
+	c = RSTRING_PTR(rv);
 
-	tmp = RARRAY_PTR(array);
-	for (i = RARRAY_LEN(array); --i >= 0; tmp++)
+	for (tmp = RARRAY_PTR(array), i = RARRAY_LEN(array); --i >= 0; tmp++)
 		c += escape(c, NUM2INT(*tmp));
 
-	*c = '\0';
-	return rb_str_new(s, s_len);
+	return rv;
 }
 
 void Init_fast_xs(void)
-- 
Eric Wong