From: Heng Li <lh3@me.com>
Date: Thu, 17 Sep 2015 23:43:17 +0000 (-0400)
Subject: simplified kbtree iter example
X-Git-Url: http://www.kaiwu.me/postgresql/commit/static/gitweb.js?a=commitdiff_plain;h=777ef8f8d58d432b4f2f5b42ac9962c8f35c83c5;p=klib.git

simplified kbtree iter example
---

diff --git a/index.html b/index.html
index 6834bbc..521ac6a 100644
--- a/index.html
+++ b/index.html
@@ -193,6 +193,8 @@ Error message and password prompt
 
 <li>CSS</li>
 
+<li>Draft of 'KBtree: generic ordered map'</li>
+
 <li>Generic Programming in C</li>
 
 <li>KBtree: generic ordered map</li>
@@ -5767,7 +5769,7 @@ pre .xml .cdata {
 <div created="20141130022153074" creator="l" modified="20141130022153293" modifier="lh" title="$:/status/UserName">
 <pre>lh3</pre>
 </div>
-<div list="[[KBtree: generic ordered map]] About" title="$:/StoryList">
+<div list="[[Draft of 'KBtree: generic ordered map']] About" title="$:/StoryList">
 <pre></pre>
 </div>
 <div modified="20141130024552231" modifier="lh3" title="$:/temp/advancedsearch">
@@ -5914,6 +5916,53 @@ code {
   color: #333333;
 }</pre>
 </div>
+<div created="20141130174442465" creator="lh3" draft.of="KBtree: generic ordered map" draft.title="KBtree: generic ordered map" modified="20150917234218743" modifier="lh3" tags="[[Library Documentations]]" title="Draft of 'KBtree: generic ordered map'">
+<pre>!!Synopsis
+* Functionality: generic balanced search tree based on B-tree.
+* Library source code: [[kbtree.h|https://github.com/attractivechaos/klib/blob/master/kbtree.h]]
+* Dependencies: none
+* Related articles: [[B-tree vs binary search tree|https://attractivechaos.wordpress.com/2008/09/24/b-tree-vs-binary-search-tree/]] and [[Another look at my old benchmark|https://attractivechaos.wordpress.com/2008/10/07/another-look-at-my-old-benchmark/]]
+!!Example
+!!!Example 1: count distinct words on the command line
+```c
+// gcc -O2 this_prog.c; ./a.out two one three two three three
+#include &lt;stdio.h&gt;
+#include &quot;kbtree.h&quot;
+
+typedef struct {
+    char *key;
+    int count;
+} elem_t;
+
+#define elem_cmp(a, b) (strcmp((a).key, (b).key))
+KBTREE_INIT(str, elem_t, elem_cmp)
+
+int main(int argc, char *argv[])
+{
+    kbtree_t(str) *b;
+    elem_t *p, t;
+    kbitr_t itr;
+    int i;
+    b = kb_init(str, KB_DEFAULT_SIZE);
+    for (i = 1; i &lt; argc; ++i) {
+        // no need to allocate; just use pointer
+        t.key = argv[i], t.count = 1;
+        p = kb_getp(str, b, &amp;t); // kb_get() also works
+        // IMPORTANT: put() only works if key is absent
+        if (!p) kb_putp(str, b, &amp;t);
+        else ++p-&gt;count;
+    }
+    // ordered tree traversal
+    kb_itr_first(str, b, &amp;itr); // get an iterator pointing to the first
+    for (; kb_itr_valid(&amp;itr); kb_itr_next(str, b, &amp;itr)) { // move on
+        p = &amp;kb_itr_key(elem_t, &amp;itr);
+        printf(&quot;%d\t%s\n&quot;, p-&gt;count, p-&gt;key);
+    }
+    kb_destroy(str, b);
+    return 0;
+}
+```</pre>
+</div>
 <div created="20141130035053305" creator="lh3" modified="20141201010131035" modifier="lh3" tags="TableOfContents" title="Generic Programming in C">
 <pre>For the implementation of generic [[containers|http://en.wikipedia.org/wiki/Container_(abstract_data_type)]], klib extensively uses C
 macros. To use these data structures, we usually need to instantiate methods by
@@ -6052,7 +6101,7 @@ as type-specific code. A generic library written with `void*` will not get such
 performance boost.
 </pre>
 </div>
-<div created="20141130174442465" creator="lh3" modified="20150917232716687" modifier="lh3" tags="[[Library Documentations]]" title="KBtree: generic ordered map">
+<div created="20141130174442465" creator="lh3" modified="20150917234135558" modifier="lh3" tags="[[Library Documentations]]" title="KBtree: generic ordered map">
 <pre>!!Synopsis
 * Functionality: generic balanced search tree based on B-tree.
 * Library source code: [[kbtree.h|https://github.com/attractivechaos/klib/blob/master/kbtree.h]]
@@ -6077,6 +6126,7 @@ int main(int argc, char *argv[])
 {
     kbtree_t(str) *b;
     elem_t *p, t;
+    kbitr_t itr;
     int i;
     b = kb_init(str, KB_DEFAULT_SIZE);
     for (i = 1; i &lt; argc; ++i) {
@@ -6088,13 +6138,9 @@ int main(int argc, char *argv[])
         else ++p-&gt;count;
     }
     // ordered tree traversal
-    if (kb_size(b) &gt; 0) { // not working on empty trees
-        kbitr_t itr;
-        kb_itr_first(str, b, &amp;itr); // get the first iterator
-        do {
-            p = &amp;kb_itr_key(elem_t, &amp;itr); // get pointer to the key
-            printf(&quot;%d\t%s\n&quot;, p-&gt;count, p-&gt;key);
-        } while (kb_itr_next(str, b, &amp;itr)); // move on
+    for (kb_itr_first(str, b, &amp;itr); kb_itr_valid(&amp;itr); kb_itr_next(str, b, &amp;itr)) {
+        p = &amp;kb_itr_key(elem_t, &amp;itr);
+        printf(&quot;%d\t%s\n&quot;, p-&gt;count, p-&gt;key);
     }
     kb_destroy(str, b);
     return 0;