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- // from: http://www.codeproject.com/Articles/1863/Design-by-Contract-Framework
- // Provides support for Design By Contract
- // as described by Bertrand Meyer in his seminal book,
- // Object-Oriented Software Construction (2nd Ed) Prentice Hall 1997
- // (See chapters 11 and 12).
- //
- // See also Building Bug-free O-O Software: An Introduction to Design by Contract
- // http://www.eiffel.com/doc/manuals/technology/contract/
- //
- // The following conditional compilation symbols are supported:
- //
- // These suggestions are based on Bertrand Meyer's Object-Oriented Software Construction (2nd Ed) p393
- //
- // DBC_CHECK_ALL - Check assertions - implies checking preconditions, postconditions and invariants
- // DBC_CHECK_INVARIANT - Check invariants - implies checking preconditions and postconditions
- // DBC_CHECK_POSTCONDITION - Check postconditions - implies checking preconditions
- // DBC_CHECK_PRECONDITION - Check preconditions only, e.g., in Release build
- //
- // A suggested default usage scenario is the following:
- //
- // #if DEBUG
- // #define DBC_CHECK_ALL
- // #else
- // #define DBC_CHECK_PRECONDITION
- // #endif
- //
- // Alternatively, you can define these in the project properties dialog.
-
- #if DEBUG && !PROFILER
- #define DBC_CHECK_ALL
- #endif
-
- using System;
- using System.Diagnostics;
-
- namespace DesignByContract
- {
- /// <summary>
- /// Design By Contract Checks.
- ///
- /// Each method generates an exception or
- /// a trace assertion statement if the contract is broken.
- /// </summary>
- /// <remarks>
- /// This example shows how to call the Require method.
- /// Assume DBC_CHECK_PRECONDITION is defined.
- /// <code>
- /// public void Test(int x)
- /// {
- /// try
- /// {
- /// Check.Require(x > 1, "x must be > 1");
- /// }
- /// catch (System.Exception ex)
- /// {
- /// Console.WriteLine(ex.ToString());
- /// }
- /// }
- /// </code>
- /// If you wish to use trace assertion statements, intended for Debug scenarios,
- /// rather than exception handling then set
- ///
- /// <code>Check.UseAssertions = true</code>
- ///
- /// You can specify this in your application entry point and maybe make it
- /// dependent on conditional compilation flags or configuration file settings, e.g.,
- /// <code>
- /// #if DBC_USE_ASSERTIONS
- /// Check.UseAssertions = true;
- /// #endif
- /// </code>
- /// You can direct output to a Trace listener. For example, you could insert
- /// <code>
- /// Trace.Listeners.Clear();
- /// Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
- /// </code>
- ///
- /// or direct output to a file or the Event Log.
- ///
- /// (Note: For ASP.NET clients use the Listeners collection
- /// of the Debug, not the Trace, object and, for a Release build, only exception-handling
- /// is possible.)
- /// </remarks>
- ///
- public sealed class Check
- {
- #region Interface
-
- /// <summary>
- /// Precondition check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT"),
- Conditional("DBC_CHECK_POSTCONDITION"),
- Conditional("DBC_CHECK_PRECONDITION")]
- public static void Require(bool assertion, string message)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new PreconditionException(message);
- }
- else
- {
- Trace.Assert(assertion, "Precondition: " + message);
- }
- }
-
- /// <summary>
- /// Precondition check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT"),
- Conditional("DBC_CHECK_POSTCONDITION"),
- Conditional("DBC_CHECK_PRECONDITION")]
- public static void Require(bool assertion, string message, Exception inner)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new PreconditionException(message, inner);
- }
- else
- {
- Trace.Assert(assertion, "Precondition: " + message);
- }
- }
-
- /// <summary>
- /// Precondition check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT"),
- Conditional("DBC_CHECK_POSTCONDITION"),
- Conditional("DBC_CHECK_PRECONDITION")]
- public static void Require(bool assertion)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new PreconditionException("Precondition failed.");
- }
- else
- {
- Trace.Assert(assertion, "Precondition failed.");
- }
- }
-
- /// <summary>
- /// Postcondition check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT"),
- Conditional("DBC_CHECK_POSTCONDITION")]
- public static void Ensure(bool assertion, string message)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new PostconditionException(message);
- }
- else
- {
- Trace.Assert(assertion, "Postcondition: " + message);
- }
- }
-
- /// <summary>
- /// Postcondition check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT"),
- Conditional("DBC_CHECK_POSTCONDITION")]
- public static void Ensure(bool assertion, string message, Exception inner)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new PostconditionException(message, inner);
- }
- else
- {
- Trace.Assert(assertion, "Postcondition: " + message);
- }
- }
-
- /// <summary>
- /// Postcondition check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT"),
- Conditional("DBC_CHECK_POSTCONDITION")]
- public static void Ensure(bool assertion)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new PostconditionException("Postcondition failed.");
- }
- else
- {
- Trace.Assert(assertion, "Postcondition failed.");
- }
- }
-
- /// <summary>
- /// Invariant check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT")]
- public static void Invariant(bool assertion, string message)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new InvariantException(message);
- }
- else
- {
- Trace.Assert(assertion, "Invariant: " + message);
- }
- }
-
- /// <summary>
- /// Invariant check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT")]
- public static void Invariant(bool assertion, string message, Exception inner)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new InvariantException(message, inner);
- }
- else
- {
- Trace.Assert(assertion, "Invariant: " + message);
- }
- }
-
- /// <summary>
- /// Invariant check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL"),
- Conditional("DBC_CHECK_INVARIANT")]
- public static void Invariant(bool assertion)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new InvariantException("Invariant failed.");
- }
- else
- {
- Trace.Assert(assertion, "Invariant failed.");
- }
- }
-
- /// <summary>
- /// Assertion check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL")]
- public static void Assert(bool assertion, string message)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new AssertionException(message);
- }
- else
- {
- Trace.Assert(assertion, "Assertion: " + message);
- }
- }
-
- /// <summary>
- /// Assertion check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL")]
- public static void Assert(bool assertion, string message, Exception inner)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new AssertionException(message, inner);
- }
- else
- {
- Trace.Assert(assertion, "Assertion: " + message);
- }
- }
-
- /// <summary>
- /// Assertion check.
- /// </summary>
- [Conditional("DBC_CHECK_ALL")]
- public static void Assert(bool assertion)
- {
- if (UseExceptions)
- {
- if (!assertion)
- throw new AssertionException("Assertion failed.");
- }
- else
- {
- Trace.Assert(assertion, "Assertion failed.");
- }
- }
-
- /// <summary>
- /// Set this if you wish to use Trace Assert statements
- /// instead of exception handling.
- /// (The Check class uses exception handling by default.)
- /// </summary>
- public static bool UseAssertions
- {
- get
- {
- return useAssertions;
- }
- set
- {
- useAssertions = value;
- }
- }
-
- #endregion // Interface
-
- #region Implementation
-
- // No creation
- private Check() {}
-
- /// <summary>
- /// Is exception handling being used?
- /// </summary>
- private static bool UseExceptions
- {
- get
- {
- return !useAssertions;
- }
- }
-
- // Are trace assertion statements being used?
- // Default is to use exception handling.
- private static bool useAssertions = false;
-
- #endregion // Implementation
-
- } // End Check
-
- internal class Trace
- {
- internal static void Assert(bool assertion, string v)
- {
- #if NETFX_CORE
- System.Diagnostics.Contracts.Contract.Assert(assertion, v);
- #else
- System.Diagnostics.Trace.Assert(assertion, v);
- #endif
- }
- }
-
- #region Exceptions
-
- /// <summary>
- /// Exception raised when a contract is broken.
- /// Catch this exception type if you wish to differentiate between
- /// any DesignByContract exception and other runtime exceptions.
- ///
- /// </summary>
- public class DesignByContractException : ApplicationException
- {
- protected DesignByContractException() {}
- protected DesignByContractException(string message) : base(message) {}
- protected DesignByContractException(string message, Exception inner) : base(message, inner) {}
- }
-
- /// <summary>
- /// Exception raised when a precondition fails.
- /// </summary>
- public class PreconditionException : DesignByContractException
- {
- /// <summary>
- /// Precondition Exception.
- /// </summary>
- public PreconditionException() {}
- /// <summary>
- /// Precondition Exception.
- /// </summary>
- public PreconditionException(string message) : base(message) {}
- /// <summary>
- /// Precondition Exception.
- /// </summary>
- public PreconditionException(string message, Exception inner) : base(message, inner) {}
- }
-
- /// <summary>
- /// Exception raised when a postcondition fails.
- /// </summary>
- public class PostconditionException : DesignByContractException
- {
- /// <summary>
- /// Postcondition Exception.
- /// </summary>
- public PostconditionException() {}
- /// <summary>
- /// Postcondition Exception.
- /// </summary>
- public PostconditionException(string message) : base(message) {}
- /// <summary>
- /// Postcondition Exception.
- /// </summary>
- public PostconditionException(string message, Exception inner) : base(message, inner) {}
- }
-
- /// <summary>
- /// Exception raised when an invariant fails.
- /// </summary>
- public class InvariantException : DesignByContractException
- {
- /// <summary>
- /// Invariant Exception.
- /// </summary>
- public InvariantException() {}
- /// <summary>
- /// Invariant Exception.
- /// </summary>
- public InvariantException(string message) : base(message) {}
- /// <summary>
- /// Invariant Exception.
- /// </summary>
- public InvariantException(string message, Exception inner) : base(message, inner) {}
- }
-
- /// <summary>
- /// Exception raised when an assertion fails.
- /// </summary>
- public class AssertionException : DesignByContractException
- {
- /// <summary>
- /// Assertion Exception.
- /// </summary>
- public AssertionException() {}
- /// <summary>
- /// Assertion Exception.
- /// </summary>
- public AssertionException(string message) : base(message) {}
- /// <summary>
- /// Assertion Exception.
- /// </summary>
- public AssertionException(string message, Exception inner) : base(message, inner) {}
- }
-
- #endregion // Exception classes
-
- } // End Design By Contract
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