update btree -- add procedure

Author: fuli

include/btree.h

@@ -411,16 +411,9 @@ namespace alg {
 
 // remove key[i] from x and also the child
 // shrink the size & set the child-0 to left
-int j;
-for (j=i;j<x->n-1;j++) {
-x->key[j] = x->key[j+1];
-}
-
-for (j=i+1;j<x->n;j++) {
-x->c[j] = x->c[j+1];
-}
-x->n = x->n - 1;
+delete_i(x, i);
 
+int j;
 // append x.c[i] into left sibling
 for (j=0;j<ci->n;j++) {
 left->key[left->n + j] = ci->key[j];
@@ -450,16 +443,9 @@ namespace alg {
 ci->n = ci->n + 1;
 // remove key[i] from x and also the child
 // shrink the size & set the child-0 to ci
-int j;
-for (j=i;j<x->n-1;j++) {
-x->key[j] = x->key[j+1];
-}
-
-for (j=i+1;j<x->n;j++) {
-x->c[j] = x->c[j+1];
-}
-x->n = x->n - 1;
+delete_i(x, i);
 
+int j;
 // append right sibling into x.c[i]
 for (j=0;j<right->n;j++) {
 ci->key[ci->n + j] = right->key[j];
@@ -490,6 +476,21 @@ namespace alg {
 }
 }
 
+/**
+ * delete ith node
+ */
+void delete_i(node x, int32_t i) {
+int j;
+for (j=i;j<x->n-1;j++) {
+x->key[j] = x->key[j+1];
+}
+
+for (j=i+1;j<x->n;j++) {
+x->c[j] = x->c[j+1];
+}
+x->n = x->n - 1;
+}
+
 /**
  * Load the root block
  */