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Optimize array_slice for packed arrays with large offsets
If the offset is 100000, and there are no gaps in the packed/unpacked array, then advance the pointer once by 100000, instead of looping and skipping 100000 times. Add a new test of array_slice handling unset offsets. Closes GH-4860.
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Tyson Andre
Nikita Popov
parent
9f98fddb7b
commit
e7ff590d0d
@ -369,3 +369,6 @@ PHP 8.0 UPGRADE NOTES
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14. Performance Improvements
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========================================
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- array_slice() on a packed array will no longer scan the whole array to find
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the start offset. This may significantly reduce the runtime of the function
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with large offsets and small lengths.
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@ -3455,6 +3455,32 @@ PHP_FUNCTION(array_splice)
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}
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/* }}} */
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/* {{{ find_bucket_at_offset(HashTable* ht, zend_long offset)
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Finds the bucket at the given valid offset */
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static inline Bucket* find_bucket_at_offset(HashTable* ht, zend_long offset)
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{
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zend_long pos;
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Bucket *bucket;
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ZEND_ASSERT(offset >= 0 && offset <= ht->nNumOfElements);
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if (HT_IS_WITHOUT_HOLES(ht)) {
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/* There's no need to iterate over the array to filter out holes if there are no holes */
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/* This properly handles both packed and unpacked arrays. */
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return ht->arData + offset;
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}
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/* Otherwise, this code has to iterate over the HashTable and skip holes in the array. */
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pos = 0;
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ZEND_HASH_FOREACH_BUCKET(ht, bucket) {
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if (pos >= offset) {
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/* This is the bucket of the array element at the requested offset */
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return bucket;
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}
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++pos;
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} ZEND_HASH_FOREACH_END();
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/* Return a pointer to the end of the bucket array. */
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return ht->arData + ht->nNumUsed;
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}
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/* {{{ proto array array_slice(array input, int offset [, int length [, bool preserve_keys]])
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Returns elements specified by offset and length */
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PHP_FUNCTION(array_slice)
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@ -3466,7 +3492,6 @@ PHP_FUNCTION(array_slice)
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zend_bool length_is_null = 1; /* Whether an explicit length has been omitted */
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zend_bool preserve_keys = 0; /* Whether to preserve keys while copying to the new array */
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uint32_t num_in; /* Number of elements in the input array */
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uint32_t pos; /* Current position in the array */
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zend_string *string_key;
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zend_ulong num_key;
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@ -3507,50 +3532,61 @@ PHP_FUNCTION(array_slice)
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/* Initialize returned array */
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array_init_size(return_value, (uint32_t)length);
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/* Start at the beginning and go until we hit offset */
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pos = 0;
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if (HT_IS_PACKED(Z_ARRVAL_P(input)) &&
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(!preserve_keys ||
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(offset == 0 && HT_IS_WITHOUT_HOLES(Z_ARRVAL_P(input))))) {
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zend_hash_real_init_packed(Z_ARRVAL_P(return_value));
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ZEND_HASH_FILL_PACKED(Z_ARRVAL_P(return_value)) {
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ZEND_HASH_FOREACH_VAL(Z_ARRVAL_P(input), entry) {
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pos++;
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if (pos <= offset) {
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// Contains modified variants of ZEND_HASH_FOREACH_VAL
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{
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HashTable *ht = Z_ARRVAL_P(input);
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Bucket *p = find_bucket_at_offset(ht, offset);
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Bucket *end = ht->arData + ht->nNumUsed;
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/* Start at the beginning and go until we hit offset */
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if (HT_IS_PACKED(Z_ARRVAL_P(input)) &&
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(!preserve_keys ||
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(offset == 0 && HT_IS_WITHOUT_HOLES(Z_ARRVAL_P(input))))) {
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zend_hash_real_init_packed(Z_ARRVAL_P(return_value));
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ZEND_HASH_FILL_PACKED(Z_ARRVAL_P(return_value)) {
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for (; p != end; p++) {
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if (__fill_idx >= length) {
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break;
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}
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entry = &p->val;
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if (UNEXPECTED(Z_TYPE_P(entry) == IS_UNDEF)) {
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continue;
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}
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if (UNEXPECTED(Z_ISREF_P(entry)) &&
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UNEXPECTED(Z_REFCOUNT_P(entry) == 1)) {
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entry = Z_REFVAL_P(entry);
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}
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Z_TRY_ADDREF_P(entry);
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ZEND_HASH_FILL_ADD(entry);
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}
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} ZEND_HASH_FILL_END();
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} else {
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zend_long n = 0; /* Current number of elements */
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for (; p != end; p++) {
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entry = &p->val;
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if (UNEXPECTED(Z_TYPE_P(entry) == IS_UNDEF)) {
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continue;
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}
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if (pos > offset + length) {
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if (n >= length) {
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break;
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}
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if (UNEXPECTED(Z_ISREF_P(entry)) &&
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UNEXPECTED(Z_REFCOUNT_P(entry) == 1)) {
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entry = Z_REFVAL_P(entry);
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}
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Z_TRY_ADDREF_P(entry);
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ZEND_HASH_FILL_ADD(entry);
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} ZEND_HASH_FOREACH_END();
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} ZEND_HASH_FILL_END();
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} else {
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ZEND_HASH_FOREACH_KEY_VAL(Z_ARRVAL_P(input), num_key, string_key, entry) {
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pos++;
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if (pos <= offset) {
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continue;
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}
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if (pos > offset + length) {
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break;
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}
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n++;
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num_key = p->h;
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string_key = p->key;
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if (string_key) {
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entry = zend_hash_add_new(Z_ARRVAL_P(return_value), string_key, entry);
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} else {
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if (preserve_keys) {
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entry = zend_hash_index_add_new(Z_ARRVAL_P(return_value), num_key, entry);
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if (string_key) {
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entry = zend_hash_add_new(Z_ARRVAL_P(return_value), string_key, entry);
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} else {
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entry = zend_hash_next_index_insert_new(Z_ARRVAL_P(return_value), entry);
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if (preserve_keys) {
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entry = zend_hash_index_add_new(Z_ARRVAL_P(return_value), num_key, entry);
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} else {
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entry = zend_hash_next_index_insert_new(Z_ARRVAL_P(return_value), entry);
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}
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}
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zval_add_ref(entry);
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}
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zval_add_ref(entry);
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} ZEND_HASH_FOREACH_END();
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}
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}
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}
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/* }}} */
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105
ext/standard/tests/array/array_slice_variation11.phpt
Normal file
105
ext/standard/tests/array/array_slice_variation11.phpt
Normal file
@ -0,0 +1,105 @@
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--TEST--
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Test array_slice() function : usage variations - array has holes in buckets
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--FILE--
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<?php
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/* Prototype : array array_slice(array $input, int $offset [, int $length [, bool $preserve_keys]])
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* Description: Returns elements specified by offset and length
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* Source code: ext/standard/array.c
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*/
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/*
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* Check that results of array_slice are correct when there are holes in buckets caused by unset()
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*/
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echo "*** Testing array_slice() : usage variations ***\n";
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function dump_slice(array $input, $offsetToUnset, int $offset, int $length) {
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unset($input[$offsetToUnset]);
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var_dump(array_slice($input, $offset, $length));
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}
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echo "\n-- Call array_slice() on array with string keys--\n";
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$input = ['one' => 'un', 'two' => 'deux', 23 => 'twenty-three', 'zero'];
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dump_slice($input, 'two', 0, 1);
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dump_slice($input, 'two', 0, 2);
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dump_slice($input, 'two', 0, 3);
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dump_slice($input, 23, 1, 2);
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echo "\n-- Call array_slice() on array with packed keys--\n";
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$input = [10, 11, 12, 'thirteen'];
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dump_slice($input, 0, 0, 1);
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dump_slice($input, 1, 0, 1);
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dump_slice($input, 1, 0, 3);
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dump_slice($input, 1, -1, 1);
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dump_slice($input, 1, 0, 3);
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dump_slice($input, 1, -3, 3);
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echo "Done";
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?>
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--EXPECT--
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*** Testing array_slice() : usage variations ***
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-- Call array_slice() on array with string keys--
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array(1) {
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["one"]=>
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string(2) "un"
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}
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array(2) {
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["one"]=>
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string(2) "un"
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[0]=>
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string(12) "twenty-three"
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}
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array(3) {
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["one"]=>
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string(2) "un"
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[0]=>
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string(12) "twenty-three"
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[1]=>
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string(4) "zero"
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}
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array(2) {
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["two"]=>
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string(4) "deux"
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[0]=>
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string(4) "zero"
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}
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-- Call array_slice() on array with packed keys--
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array(1) {
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[0]=>
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int(11)
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}
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array(1) {
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[0]=>
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int(10)
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}
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array(3) {
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[0]=>
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int(10)
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[1]=>
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int(12)
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[2]=>
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string(8) "thirteen"
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}
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array(1) {
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[0]=>
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string(8) "thirteen"
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}
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array(3) {
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[0]=>
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int(10)
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[1]=>
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int(12)
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[2]=>
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string(8) "thirteen"
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}
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array(3) {
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[0]=>
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int(10)
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[1]=>
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int(12)
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[2]=>
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string(8) "thirteen"
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}
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Done
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