TValueOrError<FString, FExpressionError> FStringFormatter::FormatInternal(const TCHAR* InExpression, const TMap<FString, FStringFormatArg>& Args, bool bStrict) const
{
TValueOrError<TArray<FExpressionToken>, FExpressionError> Result = ExpressionParser::Lex(InExpression, bStrict ? StrictNamedDefinitions : NamedDefinitions);
if (!Result.IsValid())
{
return MakeError(Result.StealError());
}
TArray<FExpressionToken>& Tokens = Result.GetValue();
if (Tokens.Num() == 0)
{
return MakeValue(InExpression);
}
// This code deliberately tries to reallocate as little as possible
FString Formatted;
Formatted.Reserve(Tokens.Last().Context.GetTokenEndPos() - InExpression);
for (auto& Token : Tokens)
{
if (const auto* Literal = Token.Node.Cast<FStringLiteral>())
{
Formatted.AppendChars(Literal->String.GetTokenStartPos(), Literal->Len);
}
else if (auto* Escaped = Token.Node.Cast<FEscapedCharacter>())
{
Formatted.AppendChar(Escaped->Character);
}
else if (const auto* FormatToken = Token.Node.Cast<FFormatSpecifier>())
{
const FStringFormatArg* Arg = nullptr;
for (auto& Pair : Args)
{
if (Pair.Key.Len() == FormatToken->Len && FCString::Strnicmp(FormatToken->Identifier.GetTokenStartPos(), *Pair.Key, FormatToken->Len) == 0)
{
Arg = &Pair.Value;
break;
}
}
if (Arg)
{
AppendToString(*Arg, Formatted);
}
else if (bStrict)
{
return MakeError(FText::Format(LOCTEXT("UndefinedFormatSpecifier", "Undefined format token: {0}"), FText::FromString(FormatToken->Identifier.GetString())));
}
else
{
// No replacement found, so just add the original token string
const int32 Length = FormatToken->EntireToken.GetTokenEndPos() - FormatToken->EntireToken.GetTokenStartPos();
Formatted.AppendChars(FormatToken->EntireToken.GetTokenStartPos(), Length);
}
}
}
return MakeValue(Formatted);
}
FExpressionResult Evaluate(const TCHAR* InExpression, const FTokenDefinitions& InTokenDefinitions, const FExpressionGrammar& InGrammar, const IOperatorEvaluationEnvironment& InEnvironment)
{
TValueOrError<TArray<FCompiledToken>, FExpressionError> CompilationResult = Compile(InExpression, InTokenDefinitions, InGrammar);
if (!CompilationResult.IsValid())
{
return MakeError(CompilationResult.GetError());
}
return Evaluate(CompilationResult.GetValue(), InEnvironment);
}
CompileResultType Compile(const TCHAR* InExpression, const FTokenDefinitions& InTokenDefinitions, const FExpressionGrammar& InGrammar)
{
TValueOrError<TArray<FExpressionToken>, FExpressionError> Result = Lex(InExpression, InTokenDefinitions);
if (!Result.IsValid())
{
return MakeError(Result.GetError());
}
return Compile(MoveTemp(Result.GetValue()), InGrammar);
}
TValueOrError<FString, FExpressionError> FStringFormatter::FormatInternal(const TCHAR* InExpression, const TArray<FStringFormatArg>& Args, bool bStrict) const
{
TValueOrError<TArray<FExpressionToken>, FExpressionError> Result = ExpressionParser::Lex(InExpression, bStrict ? StrictOrderedDefinitions : OrderedDefinitions);
if (!Result.IsValid())
{
return MakeError(Result.StealError());
}
TArray<FExpressionToken>& Tokens = Result.GetValue();
if (Tokens.Num() == 0)
{
return MakeValue(InExpression);
}
// This code deliberately tries to reallocate as little as possible
FString Formatted;
Formatted.Reserve(Tokens.Last().Context.GetTokenEndPos() - InExpression);
for (auto& Token : Tokens)
{
if (const auto* Literal = Token.Node.Cast<FStringLiteral>())
{
Formatted.AppendChars(Literal->String.GetTokenStartPos(), Literal->Len);
}
else if (auto* Escaped = Token.Node.Cast<FEscapedCharacter>())
{
Formatted.AppendChar(Escaped->Character);
}
else if (const auto* IndexToken = Token.Node.Cast<FIndexSpecifier>())
{
if (Args.IsValidIndex(IndexToken->Index))
{
AppendToString(Args[IndexToken->Index], Formatted);
}
else if (bStrict)
{
return MakeError(FText::Format(LOCTEXT("InvalidArgumentIndex", "Invalid argument index: {0}"), FText::AsNumber(IndexToken->Index)));
}
else
{
// No replacement found, so just add the original token string
const int32 Length = IndexToken->EntireToken.GetTokenEndPos() - IndexToken->EntireToken.GetTokenStartPos();
Formatted.AppendChars(IndexToken->EntireToken.GetTokenStartPos(), Length);
}
}
}
return MakeValue(Formatted);
}