href_extractor: example code extracting href elements

It does so in a streaming manner using the "Streaming HTML parser".

docs/examples/Makefile.inc

@@ -12,4 +12,4 @@ check_PROGRAMS = 10-at-a-time anyauthput cookie_interface debug fileupload \
 COMPLICATED_EXAMPLES = curlgtk.c curlx.c htmltitle.cc cacertinmem.c	   \
   ftpuploadresume.c ghiper.c hiperfifo.c htmltidy.c multithread.c	   \
   opensslthreadlock.c sampleconv.c synctime.c threaded-ssl.c evhiperfifo.c \
-  smooth-gtk-thread.c version-check.pl
+  smooth-gtk-thread.c version-check.pl href_extractor.c

docs/examples/href_extractor.c

@@ -0,0 +1,86 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+/*
+ * This example uses the "Streaming HTML parser" to extract the href pieces in
+ * a streaming manner from a downloaded HTML. Kindly donated by Michał
+ * Kowalczyk.
+ *
+ * The parser is found at
+ * http://code.google.com/p/streamhtmlparser/
+ */
+
+#include <stdio.h>
+#include <curl/curl.h>
+#include <htmlstreamparser.h>
+
+
+static size_t write_callback(void *buffer, size_t size, size_t nmemb,
+                             void *hsp)
+{
+  size_t realsize = size * nmemb, p;
+  for (p = 0; p < realsize; p++) {
+    html_parser_char_parse(hsp, ((char *)buffer)[p]);
+    if (html_parser_cmp_tag(hsp, "a", 1))
+      if (html_parser_cmp_attr(hsp, "href", 4))
+        if (html_parser_is_in(hsp, HTML_VALUE_ENDED)) {
+          html_parser_val(hsp)[html_parser_val_length(hsp)] = '\0';
+          printf("%s\n", html_parser_val(hsp));
+        }
+  }
+  return realsize;
+}
+
+int main(int argc, char *argv[])
+{
+  char tag[1], attr[4], val[128];
+  CURL *curl;
+  HTMLSTREAMPARSER *hsp;
+
+  if (argc != 2) {
+    printf("Usage: %s URL\n", argv[0]);
+    return EXIT_FAILURE;
+  }
+
+  curl = curl_easy_init();
+
+  hsp = html_parser_init();
+
+  html_parser_set_tag_to_lower(hsp, 1);
+  html_parser_set_attr_to_lower(hsp, 1);
+  html_parser_set_tag_buffer(hsp, tag, sizeof(tag));
+  html_parser_set_attr_buffer(hsp, attr, sizeof(attr));
+  html_parser_set_val_buffer(hsp, val, sizeof(val)-1);
+
+  curl_easy_setopt(curl, CURLOPT_URL, argv[1]);
+  curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
+  curl_easy_setopt(curl, CURLOPT_WRITEDATA, hsp);
+  curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1);
+
+  curl_easy_perform(curl);
+
+  curl_easy_cleanup(curl);
+
+  html_parser_cleanup(hsp);
+
+  return EXIT_SUCCESS;
+}