Implementation of JSON Streaming Parser
This change will introduce a streaming parser capability to Haiku. The existing functionality of writing the JSON data to a BMessage in-memory model is retained. The new parser implements a SAX-style listener based interface where the listener accepts parse events. Unit tests have been supplied for the JSON parser as well.
This commit is contained in:
Andrew Lindesay
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/*
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* Copyright 2017, Andrew Lindesay <[email protected]>
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* Distributed under the terms of the MIT License.
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*/
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#include "JsonErrorHandlingTest.h"
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#include <AutoDeleter.h>
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#include <Json.h>
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#include <JsonEventListener.h>
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#include <cppunit/TestCaller.h>
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#include <cppunit/TestSuite.h>
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#include "JsonSamples.h"
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using namespace BPrivate;
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class ErrorCapturingListener : public BJsonEventListener {
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public:
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ErrorCapturingListener();
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virtual ~ErrorCapturingListener();
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bool Handle(const BJsonEvent& event);
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void HandleError(status_t status, int32 line,
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const char* message);
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void Complete() {};
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status_t ErrorStatus();
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int32 GetErrorLine();
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BString GetErrorMessage();
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bool HasEventsAfterError();
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json_event_type FirstEventTypeAfterError();
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private:
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status_t fErrorStatus;
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int32 fErrorLine;
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BString fErrorMessage;
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json_event_type fFirstEventTypeAfterError;
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int32 fEventCountAfterError;
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};
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/*! This DataIO concrete implementation is designed to open and then to fail
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in order to simulate what might happen if there were an IO problem when
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parsing some JSON.
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*/
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class FailingDataIO : public BDataIO {
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public:
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FailingDataIO();
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virtual ~FailingDataIO();
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ssize_t Read(void* buffer, size_t size);
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ssize_t Write(const void* buffer, size_t size);
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status_t Flush();
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};
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// #pragma mark - FailingDataIO
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FailingDataIO::FailingDataIO()
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{
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}
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FailingDataIO::~FailingDataIO()
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{
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}
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ssize_t
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FailingDataIO::Read(void* buffer, size_t size)
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{
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return B_IO_ERROR;
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}
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ssize_t
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FailingDataIO::Write(const void* buffer, size_t size)
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{
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fprintf(stdout, "attempt to write");
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return B_IO_ERROR;
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}
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status_t
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FailingDataIO::Flush()
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{
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return B_IO_ERROR;
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}
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// #pragma mark - ErrorCapturingListener
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ErrorCapturingListener::ErrorCapturingListener()
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{
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fErrorStatus = B_OK;
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fFirstEventTypeAfterError = B_JSON_NULL; // least likely
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fEventCountAfterError = 0;
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}
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ErrorCapturingListener::~ErrorCapturingListener()
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{
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}
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bool
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ErrorCapturingListener::Handle(const BJsonEvent& event)
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{
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if (fErrorStatus != B_OK) {
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if (fEventCountAfterError == 0)
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fFirstEventTypeAfterError = event.EventType();
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fEventCountAfterError++;
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}
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return true; // keep going.
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}
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void
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ErrorCapturingListener::HandleError(status_t status, int32 line,
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const char *message)
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{
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fErrorStatus = status;
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fErrorLine = line;
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if (message != NULL)
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fErrorMessage = BString(message);
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else
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fErrorMessage = BString();
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}
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status_t
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ErrorCapturingListener::ErrorStatus()
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{
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return fErrorStatus;
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}
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int32
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ErrorCapturingListener::GetErrorLine()
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{
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return fErrorLine;
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}
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BString
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ErrorCapturingListener::GetErrorMessage()
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{
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return fErrorMessage;
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}
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json_event_type
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ErrorCapturingListener::FirstEventTypeAfterError()
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{
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return fFirstEventTypeAfterError;
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}
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bool
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ErrorCapturingListener::HasEventsAfterError()
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{
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return fEventCountAfterError > 0;
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}
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JsonErrorHandlingTest::JsonErrorHandlingTest()
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{
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}
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JsonErrorHandlingTest::~JsonErrorHandlingTest()
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{
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}
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void
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JsonErrorHandlingTest::TestParseWithBadStringEscape(const char* input,
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int32 line, status_t expectedStatus, char expectedBadEscapeChar)
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{
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BString expectedMessage;
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expectedMessage.SetToFormat("unexpected escaped character [%c] "
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"in string parsing", expectedBadEscapeChar);
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TestParseWithErrorMessage(input, line, expectedStatus,
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expectedMessage.String());
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}
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void
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JsonErrorHandlingTest::TestParseWithUnterminatedElement(const char* input,
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int32 line, status_t expectedStatus)
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{
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BString expectedMessage;
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expectedMessage.SetToFormat("unterminated element");
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TestParseWithErrorMessage(input, line, expectedStatus,
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expectedMessage.String());
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}
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void
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JsonErrorHandlingTest::TestParseWithUnexpectedCharacter(const char* input,
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int32 line, status_t expectedStatus, char expectedChar)
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{
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BString expectedMessage;
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expectedMessage.SetToFormat("unexpected character [%" B_PRIu8
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"] (%c) when parsing element", static_cast<uint8>(expectedChar),
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expectedChar);
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TestParseWithErrorMessage(input, line, expectedStatus,
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expectedMessage.String());
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}
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void
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JsonErrorHandlingTest::TestParseWithErrorMessage(const char* input, int32 line,
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status_t expectedStatus, const char* expectedMessage)
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{
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fprintf(stderr, "in >%s<\n", input);
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BDataIO *inputData = new BMemoryIO(input, strlen(input));
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ObjectDeleter<BDataIO> inputDataDeleter(inputData);
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TestParseWithErrorMessage(inputData, line, expectedStatus, expectedMessage);
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}
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void
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JsonErrorHandlingTest::TestParseWithErrorMessage(BDataIO* inputData, int32 line,
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status_t expectedStatus, const char* expectedMessage)
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{
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ErrorCapturingListener* listener = new ErrorCapturingListener();
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ObjectDeleter<ErrorCapturingListener> listenerDeleter(listener);
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// ----------------------
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BPrivate::BJson::Parse(inputData, listener);
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// ----------------------
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fprintf(stderr, "expected error at line %" B_PRIi32 " - %s : %s\n",
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line,
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strerror(expectedStatus),
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expectedMessage);
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fprintf(stderr, "actual error at line %" B_PRIi32 " - %s : %s\n",
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listener->GetErrorLine(),
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strerror(listener->ErrorStatus()),
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listener->GetErrorMessage().String());
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if (listener->HasEventsAfterError()) {
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fprintf(stderr, "first event after error [%d]\n",
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listener->FirstEventTypeAfterError());
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}
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CPPUNIT_ASSERT(!listener->HasEventsAfterError());
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CPPUNIT_ASSERT_EQUAL(expectedStatus, listener->ErrorStatus());
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CPPUNIT_ASSERT_EQUAL(line, listener->GetErrorLine());
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CPPUNIT_ASSERT(0 == strcmp(expectedMessage,
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listener->GetErrorMessage().String()));
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}
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void
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JsonErrorHandlingTest::TestCompletelyUnknown()
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{
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TestParseWithUnexpectedCharacter(
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JSON_SAMPLE_BROKEN_COMPLETELY_UNKNOWN, 1, B_BAD_DATA, 'z');
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}
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void
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JsonErrorHandlingTest::TestObjectWithPrematureSeparator()
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{
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TestParseWithErrorMessage(JSON_SAMPLE_BROKEN_OBJECT_PREMATURE_SEPARATOR, 1,
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B_BAD_DATA, "unexpected item separator when parsing start of object");
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}
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void
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JsonErrorHandlingTest::TestStringUnterminated()
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{
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TestParseWithErrorMessage(JSON_SAMPLE_BROKEN_UNTERMINATED_STRING, 1,
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B_BAD_DATA, "unexpected end of input");
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}
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void
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JsonErrorHandlingTest::TestBadStringEscape()
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{
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TestParseWithBadStringEscape(
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JSON_SAMPLE_BROKEN_BAD_STRING_ESCAPE, 1, B_BAD_DATA, 'v');
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}
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void
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JsonErrorHandlingTest::TestBadNumber()
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{
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BString expectedMessage;
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expectedMessage.SetToFormat("malformed number",
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JSON_SAMPLE_BROKEN_NUMBER);
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TestParseWithErrorMessage(JSON_SAMPLE_BROKEN_NUMBER, 1, B_BAD_DATA,
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expectedMessage.String());
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}
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void
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JsonErrorHandlingTest::TestIOIssue()
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{
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BDataIO *inputData = new FailingDataIO();
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ObjectDeleter<BDataIO> inputDataDeleter(inputData);
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TestParseWithErrorMessage(inputData, -1, B_IO_ERROR,
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"io related read error");
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}
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/*static*/ void
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JsonErrorHandlingTest::AddTests(BTestSuite& parent)
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{
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CppUnit::TestSuite& suite = *new CppUnit::TestSuite(
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"JsonErrorHandlingTest");
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suite.addTest(new CppUnit::TestCaller<JsonErrorHandlingTest>(
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"JsonErrorHandlingTest::TestCompletelyUnknown",
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&JsonErrorHandlingTest::TestCompletelyUnknown));
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suite.addTest(new CppUnit::TestCaller<JsonErrorHandlingTest>(
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"JsonErrorHandlingTest::TestObjectWithPrematureSeparator",
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&JsonErrorHandlingTest::TestObjectWithPrematureSeparator));
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suite.addTest(new CppUnit::TestCaller<JsonErrorHandlingTest>(
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"JsonErrorHandlingTest::TestStringUnterminated",
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&JsonErrorHandlingTest::TestStringUnterminated));
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suite.addTest(new CppUnit::TestCaller<JsonErrorHandlingTest>(
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"JsonErrorHandlingTest::TestBadStringEscape",
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&JsonErrorHandlingTest::TestBadStringEscape));
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suite.addTest(new CppUnit::TestCaller<JsonErrorHandlingTest>(
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"JsonErrorHandlingTest::TestBadNumber",
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&JsonErrorHandlingTest::TestBadNumber));
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suite.addTest(new CppUnit::TestCaller<JsonErrorHandlingTest>(
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"JsonErrorHandlingTest::TestIOIssue",
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&JsonErrorHandlingTest::TestIOIssue));
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parent.addTest("JsonErrorHandlingTest", &suite);
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}
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