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165 lines
5.7 KiB
Plaintext
165 lines
5.7 KiB
Plaintext
/**
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\mainpage
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\section _intro Introduction
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<a HREF="http://www.json.org/">JSON (JavaScript Object Notation)</a>
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is a lightweight data-interchange format.
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Here is an example of JSON data:
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\verbatim
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{
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"encoding" : "UTF-8",
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"plug-ins" : [
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"python",
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"c++",
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"ruby"
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],
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"indent" : { "length" : 3, "use_space": true }
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}
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\endverbatim
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<b>JsonCpp</b> supports comments as <i>meta-data</i>:
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\code
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// Configuration options
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{
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// Default encoding for text
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"encoding" : "UTF-8",
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// Plug-ins loaded at start-up
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"plug-ins" : [
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"python",
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"c++", // trailing comment
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"ruby"
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],
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// Tab indent size
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// (multi-line comment)
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"indent" : { /*embedded comment*/ "length" : 3, "use_space": true }
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}
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\endcode
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\section _features Features
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- read and write JSON document
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- attach C++ style comments to element during parsing
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- rewrite JSON document preserving original comments
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Notes: Comments used to be supported in JSON but were removed for
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portability (C like comments are not supported in Python). Since
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comments are useful in configuration/input file, this feature was
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preserved.
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\section _example Code example
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\code
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Json::Value root; // 'root' will contain the root value after parsing.
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std::cin >> root;
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// You can also read into a particular sub-value.
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std::cin >> root["subtree"];
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// Get the value of the member of root named 'encoding',
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// and return 'UTF-8' if there is no such member.
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std::string encoding = root.get("encoding", "UTF-8" ).asString();
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// Get the value of the member of root named 'plug-ins'; return a 'null' value if
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// there is no such member.
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const Json::Value plugins = root["plug-ins"];
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// Iterate over the sequence elements.
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for ( int index = 0; index < plugins.size(); ++index )
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loadPlugIn( plugins[index].asString() );
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// Try other datatypes. Some are auto-convertible to others.
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foo::setIndentLength( root["indent"].get("length", 3).asInt() );
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foo::setIndentUseSpace( root["indent"].get("use_space", true).asBool() );
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// Since Json::Value has an implicit constructor for all value types, it is not
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// necessary to explicitly construct the Json::Value object.
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root["encoding"] = foo::getCurrentEncoding();
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root["indent"]["length"] = foo::getCurrentIndentLength();
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root["indent"]["use_space"] = foo::getCurrentIndentUseSpace();
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// If you like the defaults, you can insert directly into a stream.
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std::cout << root;
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// Of course, you can write to `std::ostringstream` if you prefer.
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// If desired, remember to add a linefeed and flush.
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std::cout << std::endl;
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\endcode
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\section _advanced Advanced usage
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Configure *builders* to create *readers* and *writers*. For
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configuration, we use our own `Json::Value` (rather than
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standard setters/getters) so that we can add
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features without losing binary-compatibility.
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\code
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// For convenience, use `writeString()` with a specialized builder.
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Json::StreamWriterBuilder wbuilder;
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wbuilder["indentation"] = "\t";
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std::string document = Json::writeString(wbuilder, root);
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// Here, using a specialized Builder, we discard comments and
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// record errors as we parse.
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Json::CharReaderBuilder rbuilder;
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rbuilder["collectComments"] = false;
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std::string errs;
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bool ok = Json::parseFromStream(rbuilder, std::cin, &root, &errs);
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\endcode
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Yes, compile-time configuration-checking would be helpful,
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but `Json::Value` lets you
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write and read the builder configuration, which is better! In other words,
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you can configure your JSON parser using JSON.
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CharReaders and StreamWriters are not thread-safe, but they are re-usable.
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\code
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Json::CharReaderBuilder rbuilder;
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cfg >> rbuilder.settings_;
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std::unique_ptr<Json::CharReader> const reader(rbuilder.newCharReader());
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reader->parse(start, stop, &value1, &errs);
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// ...
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reader->parse(start, stop, &value2, &errs);
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// etc.
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\endcode
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\section _pbuild Build instructions
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The build instructions are located in the file
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<a HREF="https://github.com/open-source-parsers/jsoncpp/blob/master/README.md">README.md</a> in the top-directory of the project.
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The latest version of the source is available in the project's GitHub repository:
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<a HREF="https://github.com/open-source-parsers/jsoncpp/">
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jsoncpp</a>
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\section _news What's New?
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The description of latest changes can be found in
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<a HREF="https://github.com/open-source-parsers/jsoncpp/wiki/NEWS">
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the NEWS wiki
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</a>.
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\section _rlinks Related links
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- <a HREF="http://www.json.org/">JSON</a> Specification and alternate language implementations.
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- <a HREF="http://www.yaml.org/">YAML</a> A data format designed for human readability.
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- <a HREF="http://www.cl.cam.ac.uk/~mgk25/unicode.html">UTF-8 and Unicode FAQ</a>.
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\section _plinks Old project links
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- <a href="https://sourceforge.net/projects/jsoncpp/">https://sourceforge.net/projects/jsoncpp/</a>
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- <a href="http://jsoncpp.sourceforge.net">http://jsoncpp.sourceforge.net</a>
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- <a href="http://sourceforge.net/projects/jsoncpp/files/">http://sourceforge.net/projects/jsoncpp/files/</a>
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- <a href="http://jsoncpp.svn.sourceforge.net/svnroot/jsoncpp/trunk/">http://jsoncpp.svn.sourceforge.net/svnroot/jsoncpp/trunk/</a>
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- <a href="http://jsoncpp.sourceforge.net/old.html">http://jsoncpp.sourceforge.net/old.html</a>
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\section _license License
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See file <a href="https://github.com/open-source-parsers/jsoncpp/blob/master/LICENSE"><code>LICENSE</code></a> in the top-directory of the project.
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Basically JsonCpp is licensed under MIT license, or public domain if desired
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and recognized in your jurisdiction.
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\author Baptiste Lepilleur <blep@users.sourceforge.net> (originator)
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\author Christopher Dunn <cdunn2001@gmail.com> (primary maintainer)
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\version \include version
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We make strong guarantees about binary-compatibility, consistent with
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<a href="http://apr.apache.org/versioning.html">the Apache versioning scheme</a>.
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\sa version.h
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*/
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