/// <summary>
/// Creates an automaton for validating the correctness of argument placeholders for a given argument.
/// </summary>
/// <param name="argToValidateIndex">The index of the argument to validate.</param>
/// <param name="argNames">The names of all arguments.</param>
/// <returns>The created automaton.</returns>
private static StringAutomaton GetArgumentValidatingAutomaton(int argToValidateIndex, IReadOnlyList <string> argNames)
{
Debug.Assert(
argNames != null && argNames.All(name => !string.IsNullOrEmpty(name)),
"A valid array of argument names must be provided.");
Debug.Assert(
argToValidateIndex >= 0 && argToValidateIndex < argNames.Count,
"The provided argument index must be a valid index in the argument name array.");
string argListKey = ArgumentListToDictionaryKey(argToValidateIndex, argNames);
StringAutomaton result;
if (ArgsToValidatingAutomaton.TryGetValue(argListKey, out result))
{
return(result);
}
// Accepts placeholder for the current argument
StringAutomaton checkBracesForCurrentArg = StringAutomaton.ConstantOn(1.0, "{" + argNames[argToValidateIndex] + "}");
StringAutomaton checkBracesForOtherArgs = DisallowBracesAutomaton.Clone();
if (argNames.Count > 1)
{
// Skips placeholders for every argument except the current one
StringAutomaton skipOtherArgs = StringAutomaton.ConstantOnElement(1.0, '{')
.Append(StringAutomaton.ConstantOn(1.0, argNames.Where((arg, index) => index != argToValidateIndex)))
.Append(StringAutomaton.ConstantOnElement(1.0, '}'));
// Accepts placeholders for arguments other than current, with arbitrary intermediate text
checkBracesForOtherArgs = checkBracesForOtherArgs.Append(skipOtherArgs);
checkBracesForOtherArgs = StringAutomaton.Repeat(checkBracesForOtherArgs, minTimes: 0)
.Append(DisallowBracesAutomaton);
}
// Checks the placeholder for the current argument, then skips placeholders for other arguments
StringAutomaton validateArgumentThenOtherArguments = checkBracesForCurrentArg.Append(checkBracesForOtherArgs);
if (!RequirePlaceholderForEveryArgument)
{
// Make this block optional
validateArgumentThenOtherArguments = StringAutomaton.Sum(
validateArgumentThenOtherArguments,
StringAutomaton.ConstantOn(1.0, string.Empty));
}
// Accepts placeholders for arguments other then current, then for the current argument, then again other placeholders
result = checkBracesForOtherArgs.Append(validateArgumentThenOtherArguments);
result = result.TryDeterminize();
ArgsToValidatingAutomaton[argListKey] = result;
return(result);
}
/// <summary>
/// An implementation of <see cref="FormatAverageConditional(StringDistribution, IReadOnlyList{StringDistribution}, IReadOnlyList{string})"/>
/// specialized for some cases for performance reasons.
/// </summary>
/// <param name="str">The message from <c>str</c>.</param>
/// <param name="allowedArgs">The message from <c>args</c>, truncated to allowed values and converted to automata.</param>
/// <param name="argNames">The names of the arguments.</param>
/// <param name="resultDist">The computed result.</param>
/// <returns>
/// <see langword="true"/> if there is an optimized implementation available for the provided parameters,
/// and <paramref name="resultDist"/> has been computed using it.
/// <see langword="false"/> otherwise.
/// </returns>
/// <remarks>
/// Supports the case of point mass <paramref name="str"/> and <paramref name="allowedArgs"/>,
/// where each of the arguments is present in <paramref name="str"/> at most once and the occurrences
/// are non-overlapping.
/// </remarks>
private static bool TryOptimizedFormatAverageConditionalImpl(
StringDistribution str, IReadOnlyList <StringAutomaton> allowedArgs, IReadOnlyList <string> argNames, out StringDistribution resultDist)
{
resultDist = null;
string[] allowedArgPoints = Util.ArrayInit(allowedArgs.Count, i => allowedArgs[i].TryComputePoint());
if (!str.IsPointMass || !allowedArgPoints.All(argPoint => argPoint != null && SubstringOccurrencesCount(str.Point, argPoint) <= 1))
{
// Fall back to the general case
return(false);
}
// Obtain arguments present in 'str' (ordered by position)
var argPositions =
allowedArgPoints.Select((arg, argIndex) => Tuple.Create(argIndex, str.Point.IndexOf(arg, StringComparison.Ordinal)))
.Where(t => t.Item2 != -1)
.OrderBy(t => t.Item2)
.ToList();
if (RequirePlaceholderForEveryArgument && argPositions.Count != allowedArgs.Count)
{
// Some argument is not in 'str'
resultDist = StringDistribution.Zero();
return(true);
}
StringAutomaton result = StringAutomaton.ConstantOn(1.0, string.Empty);
int curArgumentIndex = -1;
int curArgumentPos = -1;
int curArgumentLength = 1;
for (int i = 0; i < argPositions.Count; ++i)
{
int prevArgumentIndex = curArgumentIndex;
int prevArgumentPos = curArgumentPos;
int prevArgumentLength = curArgumentLength;
curArgumentIndex = argPositions[i].Item1;
curArgumentPos = argPositions[i].Item2;
curArgumentLength = allowedArgPoints[curArgumentIndex].Length;
if (prevArgumentIndex != -1 && curArgumentPos < prevArgumentPos + prevArgumentLength)
{
// It's easier to fall back to the general case in case of overlapping arguments
return(false);
}
// Append the contents of 'str' preceeding the current argument
result = result.Append(str.Point.Substring(prevArgumentPos + prevArgumentLength, curArgumentPos - prevArgumentPos - prevArgumentLength));
// The format may have included either the text ot the placeholder
string argName = "{" + argNames[curArgumentIndex] + "}";
if (RequirePlaceholderForEveryArgument)
{
result = result.Append(StringAutomaton.ConstantOn(1.0, argName));
}
else
{
result = result.Append(StringAutomaton.ConstantOn(1.0, argName, allowedArgPoints[curArgumentIndex]));
}
}
// Append the rest of 'str'
result = result.Append(str.Point.Substring(curArgumentPos + curArgumentLength, str.Point.Length - curArgumentPos - curArgumentLength));
resultDist = StringDistribution.FromWeightFunction(result);
return(true);
}
