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#ifndef ERRORSTACK_HH
#define ERRORSTACK_HH
#include <QList>
#include <QString>
#include <QTextStream>
/** Implements a stack of error messages to provide a pretty formatted error traceback.
*
* This class is intended to be used like:
* @code
* class MyClass: public ErrorStack
* {
*
* // [...]
*
* bool someMethod(const ErrorStack &err=ErrorStack()) {
* // [...]
* if (someError) {
* errMsg() << "Some error happened!";
* return false;
* }
* // [...]
* }
*
* // [...]
* }
* @endcode
*
* The error message can then be obtained using the public methods. E.g.,
* @code
* // [...]
* MyClass instance;
* ErrorStack err;
*
* if (! instance.someMethod(err)) {
* QString msg = err.formatErrorMessages();
* // []
* }
* @endcode
* @ingroup log */
class ErrorStack
{
public:
class Stack;
/** Represents a single error message. That is, a tuple of file, line and message. */
class Message
{
public:
/** Empty constructor. */
Message();
/** Constructor from file, line and message. */
Message(const QString &file, unsigned line, const QString &message);
/** Returns the file name. */
const QString &file() const;
/** Returns the line within the file. */
unsigned line() const;
/** Returns the error message. */
const QString &message() const;
/** Formats the error messaege. */
QString format() const;
protected:
/** Holds the file path. */
QString _file;
/** Holds the line. */
unsigned _line;
/** Holds the error message. */
QString _message;
};
/** A helper class to assemble error messages as streams. Use the @c errorMessage macro. */
class MessageStream: public QTextStream
{
public:
/** Constructor. */
MessageStream(const ErrorStack &stack, const QString &file, unsigned line);
/** Destructor, puts the message on the stack. */
virtual ~MessageStream();
protected:
/** Holds a weak reference to the error stack to put the message on. */
const ErrorStack &_stack;
/** The file path. */
QString _file;
/** The line number. */
unsigned _line;
/** The message buffer. */
QString _message;
};
/** The actual error message stack. */
class Stack
{
public:
/** Empty constructor. */
Stack() noexcept;
public:
/** Returns @c true if there are any error messages. */
bool isEmpty() const;
/** Returns the number of error messages. */
unsigned count() const;
/** Returns a specific error message. */
const Message &message(unsigned i) const;
/** Returns a formatted string of error messages. */
QString format(const QString &indent=" ") const;
/** Adds an error message to the stack. */
void push(const Message &msg);
/** Adds the error messages from another stack. */
void push(const Stack &other);
/** Clears the error stack. */
void clear();
/** Returns a new reference to the stack. */
Stack *ref();
/** Dereferences a stack, this decreases the ref count. When 0 is reached, the stack is
* destroyed. */
void unref();
private:
/** Reference counter. */
unsigned _refcount;
/** Holds the stack of error messages. */
QList<Message> _errorMessageStack;
};
public:
/** Default constructor. */
ErrorStack() noexcept;
/** Copy constructor. */
ErrorStack(const ErrorStack &other);
/** Destructor. */
~ErrorStack();
/** Copy assignment. */
ErrorStack &operator= (const ErrorStack &other);
/** Returns @c true, if the stack is empty. */
bool isEmpty() const;
/** Returns the number of elements on the stack. */
unsigned count() const;
/** Returns the i-th message from the stack. */
const Message &message(unsigned i) const;
/** Pushes a message on the stack. */
void push(const Message &msg) const;
/** Takes all messages from the other stack. */
void take(const ErrorStack &other) const;
/** Returns a formatted string of error messages. */
QString format(const QString &indent=" ") const;
protected:
/** A reference to the actual message stack. */
Stack *_stack;
};
/** Utility macro to assemble a message stream. */
#define errMsg(stack) (ErrorStack::MessageStream(stack, __FILE__, __LINE__))
#endif // ERRORSTACK_HH
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