diff --git a/src/array_allocator.c b/src/array_allocator.c
index 9af926f..b408ef7 100644
--- a/src/array_allocator.c
+++ b/src/array_allocator.c
@@ -114,3 +114,9 @@ int array_compare_element_int32(const int32_t *n1, const int32_t *n2)
 {
     return *n1 - *n2;
 }
+
+int array_compare_element_id_name(const id_name_pair_t *pair1,
+        const id_name_pair_t *pair2)
+{
+    return fc_compare_int64(pair1->id, pair2->id);
+}
diff --git a/src/array_allocator.h b/src/array_allocator.h
index cc5a17d..36f8764 100644
--- a/src/array_allocator.h
+++ b/src/array_allocator.h
@@ -39,6 +39,13 @@ typedef struct
     int32_t elts[0];
 } I32Array;
 
+typedef struct
+{
+    int alloc;
+    int count;
+    id_name_pair_t elts[0];
+} IdNameArray;
+
 typedef struct array_allocator_context
 {
     struct fast_allocator_context allocator;
@@ -67,10 +74,15 @@ extern "C" {
         fast_allocator_free(&ctx->allocator, array);
     }
 
+    /* comparator for 64 bits integer */
     int array_compare_element_int64(const int64_t *n1, const int64_t *n2);
 
+    /* comparator for 32 bits integer */
     int array_compare_element_int32(const int32_t *n1, const int32_t *n2);
 
+    /* comparator for id name pair (sorted by id) */
+    int array_compare_element_id_name(const id_name_pair_t *pair1,
+            const id_name_pair_t *pair2);
 
 #define i64_array_allocator_init(ctx, min_bits, max_bits) \
     array_allocator_init(ctx, "i64", sizeof(int64_t), min_bits, max_bits)
@@ -79,7 +91,8 @@ extern "C" {
     (I64Array *)array_allocator_alloc(ctx, target_count)
 
 #define i64_array_allocator_realloc(ctx, old_array, target_count) \
-    (I64Array *)array_allocator_realloc(ctx, (VoidArray *)old_array, target_count)
+    (I64Array *)array_allocator_realloc(ctx, \
+            (VoidArray *)old_array, target_count)
 
 #define i64_array_allocator_free(ctx, array) \
     array_allocator_free(ctx, (VoidArray *)array)
@@ -92,12 +105,28 @@ extern "C" {
     (I32Array *)array_allocator_alloc(ctx, target_count)
 
 #define i32_array_allocator_realloc(ctx, old_array, target_count) \
-    (I32Array *)array_allocator_realloc(ctx, (VoidArray *)old_array, target_count)
+    (I32Array *)array_allocator_realloc(ctx, \
+            (VoidArray *)old_array, target_count)
 
 #define i32_array_allocator_free(ctx, array) \
     array_allocator_free(ctx, (VoidArray *)array)
 
 
+#define id_name_array_allocator_init(ctx, min_bits, max_bits) \
+    array_allocator_init(ctx, "id_name", sizeof(id_name_pair_t), \
+            min_bits, max_bits)
+
+#define id_name_array_allocator_alloc(ctx, target_count) \
+    (IdNameArray *)array_allocator_alloc(ctx, target_count)
+
+#define id_name_array_allocator_realloc(ctx, old_array, target_count) \
+    (IdNameArray *)array_allocator_realloc(ctx, \
+            (VoidArray *)old_array, target_count)
+
+#define id_name_array_allocator_free(ctx, array) \
+    array_allocator_free(ctx, (VoidArray *)array)
+
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/sorted_array.c b/src/sorted_array.c
index a23b36d..7d32d45 100644
--- a/src/sorted_array.c
+++ b/src/sorted_array.c
@@ -154,27 +154,3 @@ int sorted_array_delete(SortedArrayContext *ctx,
     }
     return 0;
 }
-
-int sorted_array_compare_int64(const int64_t *n1, const int64_t *n2)
-{
-    int64_t sub;
-    sub = *n1 - *n2;
-    if (sub < 0) {
-        return -1;
-    } else if (sub > 0) {
-        return 1;
-    } else {
-        return 0;
-    }
-}
-
-int sorted_array_compare_int32(const int32_t *n1, const int32_t *n2)
-{
-    return *n1 - *n2;
-}
-
-int sorted_array_compare_id_name_pair(const id_name_pair_t *pair1,
-        const id_name_pair_t *pair2)
-{
-    return fc_compare_int64(pair1->id, pair2->id);
-}
diff --git a/src/sorted_array.h b/src/sorted_array.h
index cad1b42..beb6e4f 100644
--- a/src/sorted_array.h
+++ b/src/sorted_array.h
@@ -16,7 +16,7 @@
 #ifndef SORTED_ARRAY_H
 #define SORTED_ARRAY_H
 
-#include "common_define.h"
+#include "array_allocator.h"
 
 typedef struct sorted_array_context
 {
@@ -81,29 +81,18 @@ extern "C" {
                 element_size, ctx->compare_func);
     }
 
-    /* comparator for 64 bits integer */
-    int sorted_array_compare_int64(const int64_t *n1, const int64_t *n2);
-
-    /* comparator for 32 bits integer */
-    int sorted_array_compare_int32(const int32_t *n1, const int32_t *n2);
-
-    /* comparator for id name pair (sorted by id) */
-    int sorted_array_compare_id_name_pair(const id_name_pair_t *pair1,
-            const id_name_pair_t *pair2);
-
-
 #define sorted_i64_array_init(ctx, allow_duplication) \
     sorted_array_init(ctx, sizeof(int64_t), allow_duplication, \
-            (int (*)(const void *, const void *))sorted_array_compare_int64)
+            (int (*)(const void *, const void *))array_compare_element_int64)
 
 #define sorted_i32_array_init(ctx, allow_duplication) \
     sorted_array_init(ctx, sizeof(int32_t), allow_duplication, \
-            (int (*)(const void *, const void *))sorted_array_compare_int32)
+            (int (*)(const void *, const void *))array_compare_element_int32)
 
 #define sorted_id_name_array_init(ctx, allow_duplication) \
     sorted_array_init(ctx, sizeof(id_name_pair_t), allow_duplication, \
             (int (*)(const void *, const void *)) \
-            sorted_array_compare_id_name_pair)
+            array_compare_element_id_name)
 
 
 #ifdef __cplusplus