msgid "" msgstr "" "Project-Id-Version: Chinese (Simplified Han script) (Boost Json Translation " "(zh_Hans))\n" "Report-Msgid-Bugs-To: \n" "POT-Creation-Date: 2026-06-06 22:46+0000\n" "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n" "Last-Translator: FULL NAME \n" "Language-Team: Chinese (Simplified Han script) \n" "Language: zh_Hans\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n" "Plural-Forms: nplurals=1; plural=0;\n" "X-Generator: Weblate 2026.5\n" #: :10 #, safe-html, strict-same msgid "" "= Contextual Conversions Previously in this section we've been assuming that " "there is a particular fitting JSON representation for a type. But this is " "not always the case. Often one needs to represent particular value with JSON " "of certain format in one situation and with another format in a different " "situation. This can be achieved with Boost.JSON by providing an extra " "argument---context." msgstr "" "= 上下文相关的转换 此前在本节中，我们一直假定某个类型存在一种特定且合适的 " "JSON 表示形式。但实际情况并非总是如此。很多时候，同一个值在不同场景下需要以不" "同的 JSON 格式来表示。在 Boost.JSON 中，可以通过提供一个额外的参数——上下文（" "context）——来实现这一点。" #: :17 #, safe-html, strict-same msgid "Let's implement conversion from `user_ns::ip_address` to a JSON string:" msgstr "我们来实现从`user_ns::ip_address`到JSON字符串的转换：" #: :25 #, safe-html, strict-same msgid "" "These `tag_invoke` overloads take an extra `as_string` parameter, which " "disambiguates this specific representation of `ip_address` from all other " "potential representations. In order to take advantage of them one needs to " "pass an `as_string` object to <> or <> as the " "last argument:" msgstr "" "这些`tag_invoke`重载接受一个额外的`as_string`参数，用于将`ip_address`的这种特" "定表示形式与其他所有可能的表示形式区分开来。要使用这些重载，需要" "将`as_string`对象作为最后一个参数传递给 <> 或 " "<>：" #: :36 #, safe-html, strict-same msgid "" "Note, that if there is no dedicated `tag_invoke` overload for a given type " "and a given context, the implementation falls back to overloads without " "context. Thus it is easy to combine contextual conversions with conversions " "provided by the library:" msgstr "" "请注意，如果对于给定类型和给定上下文没有专用的`tag_invoke`重载，实现将回退到" "不带上下文的重载。因此，可以轻松地将上下文相关的转换与库提供的转换结合起来：" #: :46 #, safe-html, strict-same msgid "Conversions for Third-Party Types" msgstr "第三方类型的转换" #: :47 #, safe-html, strict-same msgid "" "Normally, you wouldn't be able to provide conversions for types from third-" "party libraries and standard types, because it would require yout to put " "`tag_invoke` overloads into namespaces you do not control. But with contexts " "you can put the overloads into your namespaces. This is because the context " "will add its associated namespaces into the list of namespaces where " "`tag_invoke` overloads are searched." msgstr "" "通常，您无法为第三方库或标准库中的类型提供转换函数，因为这需要" "将`tag_invoke`重载放入您无法控制的命名空间中。但借助上下文，您可以将这些重载" "放在自己的命名空间里。这是因为上下文会将其关联的命名空间添加到搜" "索`tag_invoke`重载的命名空间列表中。" #: :54 #, safe-html, strict-same msgid "" "As an example, let's implement conversion for https://en.cppreference.com/w/" "cpp/chrono/system_clock[``std::chrono::system_clock::time_point``s] using " "https://en.wikipedia.org/wiki/ISO_8601[ISO 8601] format." msgstr "" "例如，我们来使用 https://en.wikipedia.org/wiki/ISO_8601[ISO 8601]格式，对 " "https://en.cppreference.com/w/cpp/chrono/" "system_clock[``std::chrono::system_clock::time_point``] 实现转换。" #: :63 #, safe-html, strict-same msgid "Reverse conversion is left out for brevity." msgstr "为简洁起见，反向转换在此省略。" #: :65 #, safe-html, strict-same msgid "" "The new context is used in a similar fashion to `as_string` previously in " "this section." msgstr "这个新上下文的使用方式与本节前面介绍的`as_string`类似。" #: :73 #, safe-html, strict-same msgid "" "One particular use case that is enabled by contexts is adaptor libraries " "that define JSON conversion logic for types from a different library." msgstr "" "上下文支持的一个特定用例是适配器库，这些库为来自不同库的类型定义JSON转换逻辑" "。" #: :76 #, safe-html, strict-same msgid "Passing Data to Conversion Functions" msgstr "向转换函数传递数据" #: :77 #, safe-html, strict-same msgid "" "Contexts we used so far were empty classes. But contexts may have data " "members and member functions just as any class. Implementers of conversion " "functions can take advantage of that to have conversions configurable at " "runtime or pass special objects to conversions (e.g. allocators)." msgstr "" "到目前为止，我们使用的上下文都是空类。但上下文可以像普通类一样拥有数据成员和" "成员函数。转换函数的实现者可以利用这一点，在运行时对转换行为进行配置，或向转" "换函数传递特殊对象（例如分配器）。" #: :82 #, safe-html, strict-same msgid "" "Let's rewrite conversion for ``system_clock::time_point``s to allow any " "format supported by `std::strftime`." msgstr "" "我们来重写``system_clock::time_point``的转换，以支持`std::strftime`所支持的任" "意格式。" #: :90 #, safe-html, strict-same msgid "" "This `tag_invoke` overload lets us change date conversion format at runtime. " "Also note, that there is no ambiguity between `as_iso_8601` overload and " "`date_format` overload. You can use both in your program:" msgstr "" "这个`tag_invoke`重载允许我们在运行时更改日期转换的格式。另外请注意" "，`as_iso_8601`重载和`date_format`重载之间不存在歧义。您可以在程序中使用两者" "：" #: :99 #, safe-html, strict-same msgid "Combining Contexts" msgstr "组合上下文" #: :100 #, safe-html, strict-same msgid "" "Often it is needed to use several conversion contexts together. For example, " "consider a log of remote users identified by IP addresses accessing a " "system. We can represent it as " "`std::vector>`. " "We want to serialize both ``ip_address``es and ``time_point``s as strings, " "but for this we need both `as_string` and `as_iso_8601` contexts. To combine " "several contexts just use {std_tuple}. Conversion functions will select the " "first element of the tuple for which a `tag_invoke` overload exists and will " "call that overload. As usual, `tag_invoke` overloads that don't use contexts " "and library-provided generic conversions are also supported. Thus, here's " "our example:" msgstr "" "通常需要同时使用多个转换上下文。例如，考虑一个记录远程用户（通过 IP 地址标识" "）访问系统的日志，我们可以将其表示为 " "`std::vector>`。我们希望将``ip_address``和``time_point``都序列化为字符" "串，但这需要同时使用`as_string`和`as_iso_8601`两个上下文。要组合多个上下文，" "只需使用{std_tuple}。转换函数会从元组中选择第一个存在对应 `tag_invoke` 重载的" "元素，并调用该重载。与往常一样，不使用上下文的`tag_invoke`重载和库提供的通用" "转换也受支持。因此，我们的示例如下：" #: :117 #, safe-html, strict-same msgid "" "In this snippet `time_point` is converted using `tag_invoke` overload that " "takes `as_iso_8601`, `ip_address` is converted using `tag_invoke` overload " "that takes `as_string`, and {std_vector} is converted using a generic " "conversion provided by the library." msgstr "" "在此代码片段中，`time_point`通过接受`as_iso_8601`的`tag_invoke`重载进行转换" "，`ip_address`通过接受`as_string`的`tag_invoke`重载进行转换，而{std_vector}则" "使用库提供的通用转换进行转换。" #: :122 #, safe-html, strict-same msgid "Contexts and Composite Types" msgstr "上下文与复合类型" #: :123 #, safe-html, strict-same msgid "" "As was shown previously, generic conversions provided by the library forward " "contexts to conversions of nested objects. And in the case when you want to " "provide your own conversion function for a composite type enabled by a " "particular context, you usually also need to do that." msgstr "" "如前所示，库提供的通用转换会将上下文传递给嵌套对象的转换函数。因此，当您希望" "为特定上下文启用的某个复合类型提供自己的转换函数时，通常也需要这样做" #: :128 #, safe-html, strict-same msgid "" "Consider this example. As was discussed in a previous section, " "<> requires that your key type satisfies " "<>. Now, let's say your keys are not string-like, but " "they do convert to <>. You can make such maps to also convert to " "objects using a context. But if you want to also use another context for " "values, you need a way to pass the full combined context to map elements. " "So, you want the following test to succeed." msgstr "" "考虑以下示例。如前一节所述，<>要求键类型满" "足<>。现在，假设您的键不是类字符串类型，但它们确实" "可以转换为<>。您可以通过上下文使此类映射也转换为对象。但如" "果您想同时为值使用另一个上下文，则需要一种方式将完整的组合上下文传递给映射元" "素。因此，您希望以下测试能够成功。" #: :141 #, safe-html, strict-same msgid "" "For this you will have to use a different overload of `tag_invoke`. This " "time it has to be a function template, and it should have two parameters for " "contexts. The first parameter is the specific context that disambiguates " "that particular overload. The second parameter is the full context passed to " "<> or <>." msgstr "" "为此，您必须使用另一个`tag_invoke`重载。这次，它必须是一个函数模板，并且应包" "含两个上下文参数。第一个参数是用于区分该特定重载的具体上下文；第二个参数是传" "递给 <> 或<>的完整上下文。"