This article will introduce you to the usage analysis of json_encode. Friends who are interested in understanding the php source code can try to refer to it.
I won’t talk about the advantages of json,
I have a habit, when I output json, I like to use sprintf to spell it into json format,
Two days ago, I was told by a friend that it was not standard and that json_encode must be used to generate the standard json format. Of course I was very depressed,
After using it for so many years, I just realized that this is not standard. Since I say it is not standard, then is the above the standard json format?
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I do this
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$ret_json='{"%s":"%s"}'; echo json_encode($ret_json,"a","abc"); |
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$ret_json='{"%s":"%s"}'; echo json_encode($ret_json,"a","abc"); |
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| static PHP_FUNCTION(json_encode) { zval *parameter; smart_str buf = {0}; long options = 0; if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z|l", ¶meter, &options) == FAILURE) { return; } JSON_G(error_code) = PHP_JSON_ERROR_NONE; php_json_encode(&buf, parameter, options TSRMLS_CC); ZVAL_STRINGL(return_value, buf.c, buf.len, 1); smart_str_free(&buf); } |
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| static PHP_FUNCTION(json_encode) { zval *parameter; smart_str buf = {0}; long options = 0; If (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z|l", ¶meter, &options) == FAILURE) { return; JSON_G(error_code) = PHP_JSON_ERROR_NONE; php_json_encode(&buf, parameter, options TSRMLS_CC); ZVAL_STRINGL(return_value, buf.c, buf.len, 1); smart_str_free(&buf); } | |
JSON_G(error_code) = PHP_JSON_ERROR_NONE;
It is a defined json error. This error can be obtained through the json_last_error function. Have you used it? I haven't used it anyway.
php_json_encode is the main operation
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PHP_JSON_API void php_json_encode(smart_str *buf, zval *val, int options TSRMLS_DC) /* {{{ */ |
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Obviously, there will be corresponding cases according to different types.
The most complex types are string, array, and object. Arrays and objects are the same operation.
Let’s take a look at the string first. It’s very long and the comments are written directly in the code.
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| /options should be supported only after version 5.3, and are binary masks composed of the following constants: JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_NUMERIC_CHECK, JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, JSON_FORCE_OBJECT, JSON_UNESCAPED_UNICODE. Although I haven't used it. . . static void json_escape_string(smart_str *buf, char *s, int len, int options TSRMLS_DC) /* {{{ */ { int pos = 0; unsigned short us; unsigned short *utf16; If (len == 0) {//If the length is 0, return double quotes directly "" smart_str_appendl(buf, """", 2); return; } If (options & PHP_JSON_NUMERIC_CHECK) {//Check whether it is a number from 0 to 9, if it is a number, the data will be returned directly as a long or double type. double d; int type; long p; If ((type = is_numeric_string(s, len, &p, &d, 0)) != 0) { If (type == IS_LONG) { smart_str_append_long(buf, p); } Else if (type == is_double) { If (!zend_isinf(d) && !zend_isnan(d)) { int l = spprintf(&tmp, 0, "%.*k", (int) EG(precision), d); smart_str_appendl (buf, tmp, l); efree(tmp); Php_error_docref (null TSRMLS_CC, E_WARNINING, "Double %.9g Does Not Conform to the Json Spec, Encoded as 0", d); through smart_str_appendc(buf, '0'); } return; } } utf16 = (unsigned short *) safe_emalloc(len, sizeof(unsigned short), 0); len = utf8_to_utf16(utf16, s, len); //The value you input will be processed once and converted into the corresponding Dec code, such as 1 is 49, a is 97, and saved in utf16. If (len <= 0) {//If len is less than 0, an error occurs. If you use json_encode to process GBK encoding, it will hang up here. If (utf16) { efree(utf16); } If (len < 0) { JSON_G(error_code) = PHP_JSON_ERROR_UTF8; If (!PG(display_errors)) { php_error_docref(NULL TSRMLS_CC, E_WARNING, "Invalid UTF-8 sequence in argument"); } smart_str_appendl(buf, "null", 4); } else { smart_str_appendl(buf, """", 2); } return; } smart_str_appendc(buf, '"'); //Input " //The following code is to escape some special characters such as double quotes, backslashes, etc. while (pos < len) { us = utf16[pos++]; switch (us) { case '"': If (options & PHP_JSON_HEX_QUOT) { to smart_str_appendl(buf, """, 2); } break; case '': smart_str_appendl(buf, "\", 2); break; case '/': smart_str_appendl(buf, "/", 2); break; case 'b': smart_str_appendl(buf, "b", 2); break; case 'f': smart_str_appendl(buf, "f", 2); break; case 'n': smart_str_appendl(buf, "n", 2); break; case 'r': smart_str_appendl(buf, "r", 2); break; case 't': smart_str_appendl(buf, "t", 2); break; case '<': if (options & PHP_JSON_HEX_TAG) { smart_str_appendl(buf, "u003C", 6); } else { smart_str_appendc(buf, '<'); } break; case '>': if (options & PHP_JSON_HEX_TAG) { smart_str_appendl(buf, "u003E", 6); } else { smart_str_appendc(buf, '>'); } break; case '&': if (options & PHP_JSON_HEX_AMP) { smart_str_appendl(buf, "u0026", 6); } else { smart_str_appendc(buf, '&'); } break; case ''': if (options & PHP_JSON_HEX_APOS) { to smart_str_appendc(buf, '''); } break; default: //Up to here, if there are no special characters, the value will be appended to buf If (us >= ' ' && (us & 127) == us) { smart_str_appendc(buf, (unsigned char) us); because Smart_Str_appendc (buf, digits [us & ((1 & lt; & lt; 4) - 1)]; through Smart_Str_appendc (buf, digits [us & ((1 & lt; & lt; 4) - 1)]; through Smart_Str_appendc (buf, digits [us & ((1 & lt; & lt; 4) - 1)]; through Smart_Str_appendc (buf, digits [us & ((1 & lt; & lt; 4) - 1)]; break; } } smart_str_appendc(buf, '"'); //End double quotes. efree(utf16); } |
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Let’s look at arrays and objects, they are also very simple,
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| static void json_encode_array(smart_str *buf, zval **val, int options TSRMLS_DC) /* {{{ */ { int i, r; HashTable *myht; if (Z_TYPE_PP(val) == IS_ARRAY) { myht = HASH_OF(*val); r = (options & PHP_JSON_FORCE_OBJECT) ? PHP_JSON_OUTPUT_OBJECT : json_determine_array_type(val TSRMLS_CC); } else { myht = Z_OBJPROP_PP(val); r = PHP_JSON_OUTPUT_OBJECT; } if (myht && myht->nApplyCount > 1) { php_error_docref(NULL TSRMLS_CC, E_WARNING, "recursion detected"); smart_str_appendl(buf, "null", 4); return; } //开始标签 if (r == PHP_JSON_OUTPUT_ARRAY) { smart_str_appendc(buf, '['); } else { smart_str_appendc(buf, '{'); } i = myht ? zend_hash_num_elements(myht) : 0; if (i > 0) { char *key; zval **data; ulong index; uint key_len; HashPosition pos; HashTable *tmp_ht; int need_comma = 0; zend_hash_internal_pointer_reset_ex(myht, &pos); //便利哈希表 for (;; zend_hash_move_forward_ex(myht, &pos)) { i = zend_hash_get_current_key_ex(myht, &key, &key_len, &index, 0, &pos); if (i == HASH_KEY_NON_EXISTANT) break; if (zend_hash_get_current_data_ex(myht, (void **) &data, &pos) == SUCCESS) { tmp_ht = HASH_OF(*data); if (tmp_ht) { tmp_ht->nApplyCount++; } if (r == PHP_JSON_OUTPUT_ARRAY) { if (need_comma) { smart_str_appendc(buf, ','); } else { need_comma = 1; } //将值append到 buf中 php_json_encode(buf, *data, options TSRMLS_CC); } else if (r == PHP_JSON_OUTPUT_OBJECT) { if (i == HASH_KEY_IS_STRING) { if (key[0] == '' && Z_TYPE_PP(val) == IS_OBJECT) { /* Skip protected and private members. */ if (tmp_ht) { tmp_ht->nApplyCount--; } continue; } if (need_comma) { smart_str_appendc(buf, ','); } else { need_comma = 1; } json_escape_string(buf, key, key_len - 1, options & ~PHP_JSON_NUMERIC_CHECK TSRMLS_CC); smart_str_appendc(buf, ':'); php_json_encode(buf, *data, options TSRMLS_CC); } else { if (need_comma) { smart_str_appendc(buf, ','); } else { need_comma = 1; } smart_str_appendc(buf, '"'); smart_str_append_long(buf, (long) index); smart_str_appendc(buf, '"'); smart_str_appendc(buf, ':'); php_json_encode(buf, *data, options TSRMLS_CC); } } if (tmp_ht) { tmp_ht->nApplyCount--; } } } } //结束标签 if (r == PHP_JSON_OUTPUT_ARRAY) { smart_str_appendc(buf, ']'); } else { smart_str_appendc(buf, '}'); } } |
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通过简单分析，证明了一个问题，跟我上面用sprintf的方法其实是一样的，都是拼接字符串，
而且 为了性能，更应该鼓励用sprintf来拼接json格式，
因为 json_encode会进行很多 循环操作，而且所消耗的性能是线性的 O(n^2)。
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