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      1 //===- OptionalDiagnostic.h - An optional diagnostic ------------*- C++ -*-===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 //
      9 /// \file
     10 /// Implements a partial diagnostic which may not be emitted.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_CLANG_AST_OPTIONALDIAGNOSTIC_H
     15 #define LLVM_CLANG_AST_OPTIONALDIAGNOSTIC_H
     16 
     17 #include "clang/AST/APValue.h"
     18 #include "clang/Basic/PartialDiagnostic.h"
     19 #include "llvm/ADT/APFloat.h"
     20 #include "llvm/ADT/APSInt.h"
     21 #include "llvm/ADT/SmallVector.h"
     22 #include "llvm/ADT/StringRef.h"
     23 
     24 namespace clang {
     25 
     26 /// A partial diagnostic which we might know in advance that we are not going
     27 /// to emit.
     28 class OptionalDiagnostic {
     29   PartialDiagnostic *Diag;
     30 
     31 public:
     32   explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr) : Diag(Diag) {}
     33 
     34   template <typename T> OptionalDiagnostic &operator<<(const T &v) {
     35     if (Diag)
     36       *Diag << v;
     37     return *this;
     38   }
     39 
     40   OptionalDiagnostic &operator<<(const llvm::APSInt &I) {
     41     if (Diag) {
     42       SmallVector<char, 32> Buffer;
     43       I.toString(Buffer);
     44       *Diag << StringRef(Buffer.data(), Buffer.size());
     45     }
     46     return *this;
     47   }
     48 
     49   OptionalDiagnostic &operator<<(const llvm::APFloat &F) {
     50     if (Diag) {
     51       // FIXME: Force the precision of the source value down so we don't
     52       // print digits which are usually useless (we don't really care here if
     53       // we truncate a digit by accident in edge cases).  Ideally,
     54       // APFloat::toString would automatically print the shortest
     55       // representation which rounds to the correct value, but it's a bit
     56       // tricky to implement. Could use std::to_chars.
     57       unsigned precision = llvm::APFloat::semanticsPrecision(F.getSemantics());
     58       precision = (precision * 59 + 195) / 196;
     59       SmallVector<char, 32> Buffer;
     60       F.toString(Buffer, precision);
     61       *Diag << StringRef(Buffer.data(), Buffer.size());
     62     }
     63     return *this;
     64   }
     65 
     66   OptionalDiagnostic &operator<<(const llvm::APFixedPoint &FX) {
     67     if (Diag) {
     68       SmallVector<char, 32> Buffer;
     69       FX.toString(Buffer);
     70       *Diag << StringRef(Buffer.data(), Buffer.size());
     71     }
     72     return *this;
     73   }
     74 };
     75 
     76 } // namespace clang
     77 
     78 #endif
     79