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Users who wish to implement custom parsing strategies may create their own handler to use with an instance of <<ref_basic_parser>>. The handler implements the function signatures required by SAX event interface. In <<examples_validate>> example we define the "null" parser, which throws out the parsed results, to use in the implementation of a function that determines if a JSON text is valid.
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CPU consumption per I/O cycle is bounded
每个 I/O 周期的 CPU 消耗是有上限的
Memory consumption per I/O cycle is bounded
每个 I/O 周期的内存消耗是有上限的
Jitter, unfairness, and latency is reduced
减少抖动、不公平性和延迟
Less total memory is required to process the full input
处理完整输入所需的总内存更少
To use the <<ref_stream_parser>>, declare an instance. Then call <<ref_stream_parser_write>> zero or more times with successive buffers representing the input JSON. When there are no more buffers, call <<ref_stream_parser_finish>>. The function <<ref_stream_parser_done>> returns `true` after a successful call to `write` or `finish` if parsing is complete.
要使用 &lt;<ref_stream_parser>&gt;，请先声明一个实例。然后对表示输入 JSON 的连续缓冲区零次或多次调用 &lt;<ref_stream_parser_write>&gt;。当没有更多缓冲区时，调用 &lt;<ref_stream_parser_finish>&gt;。在成功调用`write`或`finish`后，若解析已完成，函数 &lt;<ref_stream_parser_done>&gt; 将返回`true`。</ref_stream_parser_done></ref_stream_parser_finish></ref_stream_parser_write></ref_stream_parser>
In the following example a JSON text is parsed from standard input a line at a time. Error codes are used instead. The function <<ref_stream_parser_finish>> is used to indicate the end of the input:
在以下示例中，JSON文本从标准输入逐行解析。此处使用错误码替代异常。函数&lt;<ref_stream_parser_finish>&gt;用于指示输入结束：</ref_stream_parser_finish>
This example will break, if comments are enabled, because of
如果启用了注释，此示例将失效，原因
`std::getline` use (see the warning in <<non_standard_json>> section).
在于使用了 `std::getline`（参见 &lt;<non_standard_json>&gt; 章节中的警告）。</non_standard_json>
We can complicate the example further by extracting _several_ JSON values from the sequence of lines.
我们可以通过从行序列中提取_多个_JSON值来进一步复杂化此示例。
Controlling Memory
控制内存
After default construction, or after <<ref_stream_parser_reset>> is called with no arguments, the <<ref_value>> produced after a successful parse operation uses the default memory resource. To use a different memory resource, call `reset` with the resource to use. Here we use a <<ref_monotonic_resource>>, which is optimized for parsing but not subsequent modification:
在默认构造之后，或在无参调用 &lt;<ref_stream_parser_reset>&gt; 之后，成功解析操作所生成的 &lt;<ref_value>&gt; 将使用默认内存资源。若要使用不同的内存资源，可调用 `reset`并传入目标资源。以下示例使用了 &lt;<ref_monotonic_resource>&gt;，该资源针对解析进行了优化，但不适合后续修改</ref_monotonic_resource></ref_value></ref_stream_parser_reset>
To achieve performance and memory efficiency, the parser uses a temporary storage area to hold intermediate results. This storage is reused when parsing more than one JSON text, reducing the total number of calls to allocate memory and thus improving performance. Upon construction, the memory resource used to perform allocations for this temporary storage area may be specified. Otherwise, the default memory resource is used. In addition to a memory resource, the parser can make use of a caller-owned buffer for temporary storage. This can help avoid dynamic allocations for small inputs. The following example uses a four kilobyte temporary buffer for the parser, and falls back to the default memory resource if needed:
为实现性能与内存效率，解析器使用一块临时存储区来保存中间结果。在解析多个 JSON 文本时，该存储区会被复用，从而减少内存分配的总次数，提升性能。构造解析器时，可指定用于此临时存储区分配的内存资源；若未指定，则使用默认内存资源。此外，解析器还可利用调用方提供的缓冲区作为临时存储，有助于避免对小型输入进行动态分配。以下示例为解析器提供了一个 4 KB 的临时缓冲区，并在需要时回退到默认内存资源：
Avoiding Dynamic Allocations
避免动态分配
Through careful specification of buffers and memory resources, it is possible to eliminate all dynamic allocation completely when parsing JSON, for the case where the entire JSON text is available in a single character buffer, as shown here:
通过精心指定缓冲区和内存资源，可以在解析 JSON 时完全消除所有动态内存分配，前提是整个JSON文本在单个字符缓冲区中可用，如下所示：
Custom Parsers
自定义解析器
Users who wish to implement custom parsing strategies may create their own handler to use with an instance of <<ref_basic_parser>>. The handler implements the function signatures required by SAX event interface. In <<examples_validate>> example we define the "null" parser, which throws out the parsed results, to use in the implementation of a function that determines if a JSON text is valid.
希望实现自定义解析策略的用户可以创建自己的处理器（handler），并与 &lt;<ref_basic_parser>&gt; 实例配合使用。该处理器需实现 SAX 事件接口所要求的函数签名。在 &lt;<examples_validate>&gt; 示例中，我们定义了一个“空”解析器（null parser），它会丢弃所有解析结果，用于实现一个判断 JSON 文本是否有效的函数。</examples_validate></ref_basic_parser>
English Chinese (Simplified Han script) Actions
The <<ref_value>> returned in the preceding examples use the <<default_memory_resource,default memory resource>>. The following code uses a <<ref_monotonic_resource>>, which results in faster parsing. `jv` is marked `const` to prevent subsequent modification, because containers using a monotonic resource waste memory when mutated.
前述示例中返回的 &lt;<ref_value>&gt; 使用了 &lt;<default_memory_resource,default memory="" resource="">&gt;（默认内存资源）。以下代码使用了 &lt;<ref_monotonic_resource>&gt;，从而实现更快的解析。`jv` 被标记为 `const` 以防止后续修改，因为使用单调内存资源的容器在被修改时会浪费内存。</ref_monotonic_resource></default_memory_resource,default></ref_value>
Non-Standard JSON
非标准JSON
Custom Parsers
自定义解析器
Even when using error codes, exceptions thrown from the underlying {ref_memory_resource} are still possible:
即使使用错误码，底层 {ref_memory_resource} 仍可能抛出异常：
a series of member function calls to a user provided handler. This allows custom behaviors to be implemented for representing the document in memory.
为对用户提供的处理器的一系列成员函数调用，从而允许自定义内存中文档的表示行为
<<ref_parse_options>>
&lt;<ref_parse_options>&gt;</ref_parse_options>
of JSON texts each contained in a single contiguous character buffer, returning each result as a <<ref_value>>.
一系列 JSON 文本（每个文本均位于单独的连续字符缓冲区中），并将每个结果作为&lt;<ref_value>&gt;返回。</ref_value>
<<ref_stream_parser>>
&lt;<ref_stream_parser>&gt;</ref_stream_parser>
of JSON texts incrementally, returning each result as a <<ref_value>>.
一系列JSON文本，并将每个结果作为&lt;<ref_value>&gt;返回</ref_value>
<<ref_value_stack>>
&lt;<ref_value_stack>&gt;</ref_value_stack>
A low level building block used for efficiently building a <<ref_value>>. The
一种用于高效构建 &lt;<ref_value>&gt; 的低层构建块。</ref_value>
parsers use this internally, and users may use it to adapt foreign parsers to produce this library's containers. |===
解析器在内部使用它，用户也可以使用它来适配外部解析器以生成此库的容器。|===
Name
一个 SAX 推送式解析器实现，它将序列化的 JSON 文本转换为对用户提供的处理器的一系列成员函数调用，从而允许自定义内存中文档的表示行为。
Through careful specification of buffers and memory resources, it is possible to eliminate all dynamic allocation completely when parsing JSON, for the case where the entire JSON text is available in a single character buffer, as shown here:
通过精心指定缓冲区和内存资源，可以在解析 JSON 时完全消除所有动态内存分配，前提是整个JSON文本在单个字符缓冲区中可用，如下所示：
Users who wish to implement custom parsing strategies may create their own handler to use with an instance of <<ref_basic_parser>>. The handler implements the function signatures required by SAX event interface. In <<examples_validate>> example we define the "null" parser, which throws out the parsed results, to use in the implementation of a function that determines if a JSON text is valid.
希望实现自定义解析策略的用户可以创建自己的处理器（handler），并与 &lt;<ref_basic_parser>&gt; 实例配合使用。该处理器需实现 SAX 事件接口所要求的函数签名。在 &lt;<examples_validate>&gt; 示例中，我们定义了一个“空”解析器（null parser），它会丢弃所有解析结果，用于实现一个判断 JSON 文本是否有效的函数。</examples_validate></ref_basic_parser>

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Users who wish to implement custom parsing strategies may create their own handler to use with an instance of <<ref_basic_parser>>. The handler implements the function signatures required by SAX event interface. In <<examples_validate>> example we define the "null" parser, which throws out the parsed results, to use in the implementation of a function that determines if a JSON text is valid.
Users who wish to implement custom parsing strategies may create their own handler to use with an instance of <<ref_basic_parser>>. The handler implements the function signatures required by SAX event interface. In <<examples_validate>> example we define the "希望实现自定义解析策略的用户可以创建自己的处理器（handler），并与 &lt;<ref_basic_parser>&gt; 实例配合使用。该处理器需实现 SAX 事件接口所要求的函数签名。在 &lt;<examples_validate>&gt; 示例中，我们定义了一个“空”解析器（null" parser, which throws out the parsed results, to use in the implementation of a function that determines if a JSON text is valid.），它会丢弃所有解析结果，用于实现一个判断 JSON 文本是否有效的函数。</examples_validate></ref_basic_parser>
06/05/2026
User avatar admin

String added in the repository
Users who wish to implement custom parsing strategies may create their own handler to use with an instance of <<ref_basic_parser>>. The handler implements the function signatures required by SAX event interface. In <<examples_validate>> example we define the "null" parser, which throws out the parsed results, to use in the implementation of a function that determines if a JSON text is valid.
Users who wish to implement custom parsing strategies may create their own handler to use with an instance of <<ref_basic_parser>>. The handler implements the function signatures required by SAX event interface. In <<examples_validate>> example we define the "null" parser, which throws out the parsed results, to use in the implementation of a function that determines if a JSON text is valid.
06/05/2026
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Flags
safe-html, strict-same
Unit identifier
42872
Source string location
:260
String age
06/05/2026
Last updated
06/06/2026
Source string age
06/05/2026
Translation file AsciiDoc file
doc/pages/io/parsing_zh_Hans.adoc, string 61