PHP的json_encode分析

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{a : 'abc'} {'a' : 'abc'} {a : "abc"} {"a" : "abc"}

1 2	$ret_json='{"%s":"%s"}'; echo json_encode($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", &parameter, &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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PHP_JSON_API void php_json_encode(smart_str *buf, zval *val, int options TSRMLS_DC) /* {{{ */ {         switch (Z_TYPE_P(val))         {                 case IS_NULL:                         smart_str_appendl(buf, "null", 4); //输出NULL                         break;                   case IS_BOOL:                         if (Z_BVAL_P(val)) {                                 smart_str_appendl(buf, "true", 4);//输出true                         } else {                                 smart_str_appendl(buf, "false", 5);//输出false                         }                         break;                   case IS_LONG:                         smart_str_append_long(buf, Z_LVAL_P(val));//输出长整形的值                         break;                   case IS_DOUBLE:                         {                                 char *d = NULL;                                 int len;                                 double dbl = Z_DVAL_P(val);                                   if (!zend_isinf(dbl) && !zend_isnan(dbl)) {//非无穷尽                                         len = spprintf(&d, 0, "%.*k", (int) EG(precision), dbl);                                         smart_str_appendl(buf, d, len);                                         efree(d);                                 } else {                                         php_error_docref(NULL TSRMLS_CC, E_WARNING, "double %.9g does not conform to the JSON spec, encoded as 0", dbl);                                         smart_str_appendc(buf, '0');                                 }                        }                         break;                   case IS_STRING://字符串                         json_escape_string(buf, Z_STRVAL_P(val), Z_STRLEN_P(val), options TSRMLS_CC);                         break;                   case IS_ARRAY://数组和对象                 case IS_OBJECT:                         json_encode_array(buf, &val, options TSRMLS_CC);                         break;                   default:                         php_error_docref(NULL TSRMLS_CC, E_WARNING, "type is unsupported, encoded as null");                         smart_str_appendl(buf, "null", 4);                         break;         }           return; }

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//options应该是5.3版本之后才支持的，由以下常量组成的二进制掩码： 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.虽然我没用过。。。 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) {//如果长度为0，则直接返回 双引号 ""                 smart_str_appendl(buf, """", 2);                 return;         }           if (options & PHP_JSON_NUMERIC_CHECK) {//检测是否为0-9的数字，如果是数字，那么就会直接把数据作为long或double类型返回。                 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)) {                                         char *tmp;                                         int l = spprintf(&tmp, 0, "%.*k", (int) EG(precision), d);                                         smart_str_appendl(buf, tmp, l);                                         efree(tmp);                                 } else {                                         php_error_docref(NULL TSRMLS_CC, E_WARNING, "double %.9g does not conform to the JSON spec, encoded as 0", d);                                         smart_str_appendc(buf, '0');                                 }                         }                         return;                 }           }           utf16 = (unsigned short *) safe_emalloc(len, sizeof(unsigned short), 0);         len = utf8_to_utf16(utf16, s, len); //这里会对你输入的值一次处理转成对应的Dec码，比如1是49，a是97这样的，保存到utf16中。         if (len //如果len小于0 说明出错。如果用json_encode处理GBK的编码，就会在这里挂掉。                 if (utf16) {                         efree(utf16);                 }                 if (len                         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, '"'); //输入 "   //下面这一段代码就是将一些特殊字符转义如 双引号，反斜线等等         while (pos         {                 us = utf16[pos++];                   switch (us)                 {                         case '"':                                 if (options & PHP_JSON_HEX_QUOT) {                                         smart_str_appendl(buf, "\u0022", 6);                                 } else {                                         smart_str_appendl(buf, "\"", 2);                                 }                                 break;                           case '\':                                 smart_str_appendl(buf, "\\", 2);                                 break; case '/':                                 smart_str_appendl(buf, "\/", 2);                                 break;                           case '':                                 smart_str_appendl(buf, "\b", 2);                                 break;                           case '':                                 smart_str_appendl(buf, "\f", 2);                                 break;                           case ' ':                                 smart_str_appendl(buf, "\n", 2);                                 break;                           case ' ':                                 smart_str_appendl(buf, "\r", 2);                                 break;                           case ' ':                                 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) {                                         smart_str_appendl(buf, "\u0027", 6);                                 } else {                                         smart_str_appendc(buf, ''');                                 }                                 break;                           default: //一直到这里，没有特殊字符就会把值append到buf中                                 if (us >= ' ' && (us & 127) == us) {                                         smart_str_appendc(buf, (unsigned char) us);                                 } else {                                         smart_str_appendl(buf, "\u", 2);                                         us = REVERSE16(us);                                           smart_str_appendc(buf, digits[us & ((1                                         us >>= 4;                                         smart_str_appendc(buf, digits[us & ((1                                         us >>= 4;                                         smart_str_appendc(buf, digits[us & ((1                                         us >>= 4;                                         smart_str_appendc(buf, digits[us & ((1                                 }                                 break;                 }         }         smart_str_appendc(buf, '"'); //结束 双引号。         efree(utf16); }

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