Merge pull request #615 from miloyip/example

Add filterkey and filterkeydom examples

example/CMakeLists.txt

@@ -7,6 +7,8 @@ endif()
 set(EXAMPLES
     capitalize
     condense
+    filterkey
+    filterkeydom
     jsonx
     messagereader
     parsebyparts

example/filterkey/filterkey.cpp

@@ -0,0 +1,135 @@
+// JSON filterkey example with SAX-style API.
+
+// This example parses JSON text from stdin with validation.
+// During parsing, specified key will be filtered using a SAX handler.
+// It re-output the JSON content to stdout without whitespace.
+
+#include "rapidjson/reader.h"
+#include "rapidjson/writer.h"
+#include "rapidjson/filereadstream.h"
+#include "rapidjson/filewritestream.h"
+#include "rapidjson/error/en.h"
+#include <stack>
+
+using namespace rapidjson;
+
+// This handler forwards event into an output handler, with filtering the descendent events of specified key.
+template <typename OutputHandler>
+class FilterKeyHandler {
+public:
+    typedef char Ch;
+
+    FilterKeyHandler(OutputHandler& outputHandler, const Ch* keyString, SizeType keyLength) : 
+        outputHandler_(outputHandler), keyString_(keyString), keyLength_(keyLength), filterValueDepth_(), filteredKeyCount_()
+    {}
+
+    bool Null()             { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Null()    && EndValue(); }
+    bool Bool(bool b)       { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Bool(b)   && EndValue(); }
+    bool Int(int i)         { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Int(i)    && EndValue(); }
+    bool Uint(unsigned u)   { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Uint(u)   && EndValue(); }
+    bool Int64(int64_t i)   { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Int64(i)  && EndValue(); }
+    bool Uint64(uint64_t u) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Uint64(u) && EndValue(); }
+    bool Double(double d)   { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Double(d) && EndValue(); }
+    bool RawNumber(const Ch* str, SizeType len, bool copy) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.RawNumber(str, len, copy) && EndValue(); }
+    bool String   (const Ch* str, SizeType len, bool copy) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.String   (str, len, copy) && EndValue(); }
+    
+    bool StartObject() { 
+        if (filterValueDepth_ > 0) {
+            filterValueDepth_++;
+            return true;
+        }
+        else {
+            filteredKeyCount_.push(0);
+            return outputHandler_.StartObject();
+        }
+    }
+    
+    bool Key(const Ch* str, SizeType len, bool copy) { 
+        if (filterValueDepth_ > 0) 
+            return true;
+        else if (len == keyLength_ && std::memcmp(str, keyString_, len) == 0) {
+            filterValueDepth_ = 1;
+            return true;
+        }
+        else {
+            ++filteredKeyCount_.top();
+            return outputHandler_.Key(str, len, copy);
+        }
+    }
+
+    bool EndObject(SizeType) {
+        if (filterValueDepth_ > 0) {
+            filterValueDepth_--;
+            return EndValue();
+        }
+        else {
+            // Use our own filtered memberCount
+            SizeType memberCount = filteredKeyCount_.top();
+            filteredKeyCount_.pop();
+            return outputHandler_.EndObject(memberCount) && EndValue();
+        }
+    }
+
+    bool StartArray() {
+        if (filterValueDepth_ > 0) {
+            filterValueDepth_++;
+            return true;
+        }
+        else
+            return outputHandler_.StartArray();
+    }
+
+    bool EndArray(SizeType elementCount) {
+        if (filterValueDepth_ > 0) {
+            filterValueDepth_--;
+            return EndValue();
+        }
+        else
+            return outputHandler_.EndArray(elementCount) && EndValue();
+    }
+
+private:
+    FilterKeyHandler(const FilterKeyHandler&);
+    FilterKeyHandler& operator=(const FilterKeyHandler&);
+
+    bool EndValue() {
+        if (filterValueDepth_ == 1) // Just at the end of value after filtered key
+            filterValueDepth_ = 0;
+        return true;
+    }
+    
+    OutputHandler& outputHandler_;
+    const char* keyString_;
+    const SizeType keyLength_;
+    unsigned filterValueDepth_;
+    std::stack<SizeType> filteredKeyCount_;
+};
+
+int main(int argc, char* argv[]) {
+    if (argc != 2) {
+        fprintf(stderr, "filterkey key < input.json > output.json\n");
+        return 1;
+    }
+
+    // Prepare JSON reader and input stream.
+    Reader reader;
+    char readBuffer[65536];
+    FileReadStream is(stdin, readBuffer, sizeof(readBuffer));
+
+    // Prepare JSON writer and output stream.
+    char writeBuffer[65536];
+    FileWriteStream os(stdout, writeBuffer, sizeof(writeBuffer));
+    Writer<FileWriteStream> writer(os);
+
+    // Prepare Filter
+    FilterKeyHandler<Writer<FileWriteStream> > filter(writer, argv[1], static_cast<SizeType>(strlen(argv[1])));
+
+    // JSON reader parse from the input stream, filter handler filters the events, and forward to writer.
+    // i.e. the events flow is: reader -> filter -> writer
+    if (!reader.Parse(is, filter)) {
+        fprintf(stderr, "\nError(%u): %s\n", static_cast<unsigned>(reader.GetErrorOffset()), GetParseError_En(reader.GetParseErrorCode()));
+        return 1;
+    }
+
+    return 0;
+}

example/filterkeydom/filterkeydom.cpp

@@ -0,0 +1,170 @@
+// JSON filterkey example which populates filtered SAX events into a Document.
+
+// This example parses JSON text from stdin with validation.
+// During parsing, specified key will be filtered using a SAX handler.
+// And finally the filtered events are used to populate a Document.
+// As an example, the document is written to standard output.
+
+#include "rapidjson/document.h"
+#include "rapidjson/writer.h"
+#include "rapidjson/filereadstream.h"
+#include "rapidjson/filewritestream.h"
+#include "rapidjson/error/en.h"
+#include <stack>
+
+using namespace rapidjson;
+
+// This handler forwards event into an output handler, with filtering the descendent events of specified key.
+template <typename OutputHandler>
+class FilterKeyHandler {
+public:
+    typedef char Ch;
+
+    FilterKeyHandler(OutputHandler& outputHandler, const Ch* keyString, SizeType keyLength) : 
+        outputHandler_(outputHandler), keyString_(keyString), keyLength_(keyLength), filterValueDepth_(), filteredKeyCount_()
+    {}
+
+    bool Null()             { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Null()    && EndValue(); }
+    bool Bool(bool b)       { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Bool(b)   && EndValue(); }
+    bool Int(int i)         { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Int(i)    && EndValue(); }
+    bool Uint(unsigned u)   { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Uint(u)   && EndValue(); }
+    bool Int64(int64_t i)   { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Int64(i)  && EndValue(); }
+    bool Uint64(uint64_t u) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Uint64(u) && EndValue(); }
+    bool Double(double d)   { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.Double(d) && EndValue(); }
+    bool RawNumber(const Ch* str, SizeType len, bool copy) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.RawNumber(str, len, copy) && EndValue(); }
+    bool String   (const Ch* str, SizeType len, bool copy) { return filterValueDepth_ > 0 ? EndValue() : outputHandler_.String   (str, len, copy) && EndValue(); }
+    
+    bool StartObject() { 
+        if (filterValueDepth_ > 0) {
+            filterValueDepth_++;
+            return true;
+        }
+        else {
+            filteredKeyCount_.push(0);
+            return outputHandler_.StartObject();
+        }
+    }
+    
+    bool Key(const Ch* str, SizeType len, bool copy) { 
+        if (filterValueDepth_ > 0) 
+            return true;
+        else if (len == keyLength_ && std::memcmp(str, keyString_, len) == 0) {
+            filterValueDepth_ = 1;
+            return true;
+        }
+        else {
+            ++filteredKeyCount_.top();
+            return outputHandler_.Key(str, len, copy);
+        }
+    }
+
+    bool EndObject(SizeType) {
+        if (filterValueDepth_ > 0) {
+            filterValueDepth_--;
+            return EndValue();
+        }
+        else {
+            // Use our own filtered memberCount
+            SizeType memberCount = filteredKeyCount_.top();
+            filteredKeyCount_.pop();
+            return outputHandler_.EndObject(memberCount) && EndValue();
+        }
+    }
+
+    bool StartArray() {
+        if (filterValueDepth_ > 0) {
+            filterValueDepth_++;
+            return true;
+        }
+        else
+            return outputHandler_.StartArray();
+    }
+
+    bool EndArray(SizeType elementCount) {
+        if (filterValueDepth_ > 0) {
+            filterValueDepth_--;
+            return EndValue();
+        }
+        else
+            return outputHandler_.EndArray(elementCount) && EndValue();
+    }
+
+private:
+    FilterKeyHandler(const FilterKeyHandler&);
+    FilterKeyHandler& operator=(const FilterKeyHandler&);
+
+    bool EndValue() {
+        if (filterValueDepth_ == 1) // Just at the end of value after filtered key
+            filterValueDepth_ = 0;
+        return true;
+    }
+
+    OutputHandler& outputHandler_;
+    const char* keyString_;
+    const SizeType keyLength_;
+    unsigned filterValueDepth_;
+    std::stack<SizeType> filteredKeyCount_;
+};
+
+// Implements a generator for Document::Populate()
+template <typename InputStream>
+class FilterKeyReader {
+public:
+    typedef char Ch;
+
+    FilterKeyReader(InputStream& is, const Ch* keyString, SizeType keyLength) : 
+        is_(is), keyString_(keyString), keyLength_(keyLength), parseResult_()
+    {}
+
+    // SAX event flow: reader -> filter -> handler
+    template <typename Handler>
+    bool operator()(Handler& handler) {
+        FilterKeyHandler<Handler> filter(handler, keyString_, keyLength_);
+        Reader reader;
+        parseResult_ = reader.Parse(is_, filter);
+        return parseResult_;
+    }
+
+    const ParseResult& GetParseResult() const { return parseResult_; }
+
+private:
+    FilterKeyReader(const FilterKeyReader&);
+    FilterKeyReader& operator=(const FilterKeyReader&);
+
+    InputStream& is_;
+    const char* keyString_;
+    const SizeType keyLength_;
+    ParseResult parseResult_;
+};
+
+int main(int argc, char* argv[]) {
+    if (argc != 2) {
+        fprintf(stderr, "filterkeydom key < input.json > output.json\n");
+        return 1;
+    }
+
+    // Prepare input stream.
+    char readBuffer[65536];
+    FileReadStream is(stdin, readBuffer, sizeof(readBuffer));
+
+    // Prepare Filter
+    FilterKeyReader<FileReadStream> reader(is, argv[1], static_cast<SizeType>(strlen(argv[1])));
+
+    // Populates the filtered events from reader
+    Document document;
+    document.Populate(reader);
+    ParseResult pr = reader.GetParseResult();
+    if (!pr) {
+        fprintf(stderr, "\nError(%u): %s\n", static_cast<unsigned>(pr.Offset()), GetParseError_En(pr.Code()));
+        return 1;
+    }
+
+    // Prepare JSON writer and output stream.
+    char writeBuffer[65536];
+    FileWriteStream os(stdout, writeBuffer, sizeof(writeBuffer));
+    Writer<FileWriteStream> writer(os);
+
+    // Write the document to standard output
+    document.Accept(writer);
+    return 0;
+}

readme.md

@@ -146,3 +146,5 @@ More [examples](https://github.com/miloyip/rapidjson/tree/master/example) are av
 * Advanced
  * [prettyauto](https://github.com/miloyip/rapidjson/blob/master/example/prettyauto/prettyauto.cpp): A modified version of [pretty](https://github.com/miloyip/rapidjson/blob/master/example/pretty/pretty.cpp) to automatically handle JSON with any UTF encodings.
  * [parsebyparts](https://github.com/miloyip/rapidjson/blob/master/example/parsebyparts/parsebyparts.cpp): Implements an `AsyncDocumentParser` which can parse JSON in parts, using C++11 thread.
+ * [filterkey](https://github.com/miloyip/rapidjson/blob/master/example/filterkey/filterkey.cpp): A command line tool to remove all values with user-specified key.
+ * [filterkeydom](https://github.com/miloyip/rapidjson/blob/master/example/filterkey/filterkey.cpp): Same tool as above, but it demonstrates how to use a generator to populate a `Document`.

readme.zh-cn.md

@@ -138,3 +138,5 @@ int main() {
 * 进阶
  * [prettyauto](https://github.com/miloyip/rapidjson/blob/master/example/prettyauto/prettyauto.cpp): [pretty](https://github.com/miloyip/rapidjson/blob/master/example/pretty/pretty.cpp) 的修改版本，可自动处理任何 UTF 编码的 JSON。
  * [parsebyparts](https://github.com/miloyip/rapidjson/blob/master/example/parsebyparts/parsebyparts.cpp): 这例子中的 `AsyncDocumentParser` 类使用 C++ 线程来逐段解析 JSON。
+ * [filterkey](https://github.com/miloyip/rapidjson/blob/master/example/filterkey/filterkey.cpp): 移取使用者指定的键值的命令行工具。
+ * [filterkeydom](https://github.com/miloyip/rapidjson/blob/master/example/filterkey/filterkey.cpp): 如上的工具，但展示如何使用生成器（generator）去填充一个 `Document`。