Create a CharSetConverter class with both iconv and icu support.

Author: abhina-sree

llvm/cmake/config-ix.cmake

@@ -257,6 +257,22 @@ else()
   set(LLVM_ENABLE_TERMINFO 0)
 endif()
 
+#Check for icu.
+find_package(ICU COMPONENTS uc i18n)
+if(ICU_FOUND)
+  set(HAVE_ICU 1)
+else()
+  set(HAVE_ICU 0)
+endif()
+
+# Check for iconv.
+find_package(Iconv)
+if(Iconv_FOUND)
+  set(HAVE_ICONV 1)
+else()
+  set(HAVE_ICONV 0)
+endif()
+
 # function checks
 check_symbol_exists(arc4random "stdlib.h" HAVE_DECL_ARC4RANDOM)
 find_package(Backtrace)

llvm/include/llvm/Config/config.h.cmake

@@ -281,6 +281,12 @@
 /* Have host's ___chkstk_ms */
 #cmakedefine HAVE____CHKSTK_MS ${HAVE____CHKSTK_MS}
 
+/* Define if icu library is available */
+#cmakedefine HAVE_ICU ${HAVE_ICU}
+
+/* Define if iconv library is available */
+#cmakedefine HAVE_ICONV ${HAVE_ICONV}
+
 /* Linker version detected at compile time. */
 #cmakedefine HOST_LINK_VERSION "${HOST_LINK_VERSION}"
 

llvm/include/llvm/Support/CharSet.h

@@ -0,0 +1,160 @@
+//===-- CharSet.h - Utility class to convert between char sets ----*- C++ -*-=//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides a utility class to convert between different character
+/// set encodings.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_CHARSET_H
+#define LLVM_SUPPORT_CHARSET_H
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Config/config.h"
+#include "llvm/Support/ErrorOr.h"
+
+#include <functional>
+#include <string>
+#include <system_error>
+
+namespace llvm {
+
+template <typename T> class SmallVectorImpl;
+
+namespace details {
+class CharSetConverterImplBase {
+public:
+  virtual ~CharSetConverterImplBase() = default;
+
+  /// Converts a string.
+  /// \param[in] Source source string
+  /// \param[in,out] Result container for converted string
+  /// \param[in] ShouldAutoFlush Append shift-back sequence after conversion
+  /// for multi-byte encodings iff true.
+  /// \return error code in case something went wrong
+  ///
+  /// The following error codes can occur, among others:
+  ///   - std::errc::argument_list_too_long: The result requires more than
+  ///     std::numeric_limits<size_t>::max() bytes.
+  ///   - std::errc::illegal_byte_sequence: The input contains an invalid
+  ///     multibyte sequence.
+  ///   - std::errc::invalid_argument: The input contains an incomplete
+  ///     multibyte sequence.
+  ///
+  /// In case of an error, the result string contains the successfully converted
+  /// part of the input string.
+  ///
+
+  virtual std::error_code convert(StringRef Source,
+                                  SmallVectorImpl<char> &Result,
+                                  bool ShouldAutoFlush) const = 0;
+
+  /// Restore the conversion to the original state.
+  /// \return error code in case something went wrong
+  ///
+  /// If the original character set or the destination character set
+  /// are multi-byte character sets, set the shift state to the initial
+  /// state. Otherwise this is a no-op.
+  virtual std::error_code flush() const = 0;
+
+  virtual std::error_code flush(SmallVectorImpl<char> &Result) const = 0;
+};
+} // namespace details
+
+// Names inspired by https://wg21.link/p1885.
+namespace text_encoding {
+enum class id {
+  /// UTF-8 character set encoding.
+  UTF8,
+
+  /// IBM EBCDIC 1047 character set encoding.
+  IBM1047
+};
+} // end namespace text_encoding
+
+/// Utility class to convert between different character set encodings.
+/// The class always supports converting between EBCDIC 1047 and Latin-1/UTF-8.
+class CharSetConverter {
+  // details::CharSetConverterImplBase *Converter;
+  std::unique_ptr<details::CharSetConverterImplBase> Converter;
+
+  CharSetConverter(std::unique_ptr<details::CharSetConverterImplBase> Converter)
+      : Converter(std::move(Converter)) {}
+
+public:
+  /// Creates a CharSetConverter instance.
+  /// \param[in] CSFrom name of the source character encoding
+  /// \param[in] CSTo name of the target character encoding
+  /// \return a CharSetConverter instance
+  static CharSetConverter create(text_encoding::id CSFrom,
+                                 text_encoding::id CSTo);
+
+  /// Creates a CharSetConverter instance.
+  /// Returns std::errc::invalid_argument in case the requested conversion is
+  /// not supported.
+  /// \param[in] CPFrom name of the source character encoding
+  /// \param[in] CPTo name of the target character encoding
+  /// \return a CharSetConverter instance or an error code
+  static ErrorOr<CharSetConverter> create(StringRef CPFrom, StringRef CPTo);
+
+  CharSetConverter(const CharSetConverter &) = delete;
+  CharSetConverter &operator=(const CharSetConverter &) = delete;
+
+  CharSetConverter(CharSetConverter &&Other) {
+    Converter = std::move(Other.Converter);
+  }
+
+  CharSetConverter &operator=(CharSetConverter &&Other) {
+    if (this != &Other)
+      Converter = std::move(Other.Converter);
+    return *this;
+  }
+
+  ~CharSetConverter() = default;
+
+  /// Converts a string.
+  /// \param[in] Source source string
+  /// \param[in,out] Result container for converted string
+  /// \param[in] ShouldAutoFlush Append shift-back sequence after conversion
+  /// for multi-byte encodings.
+  /// \return error code in case something went wrong
+  std::error_code convert(StringRef Source, SmallVectorImpl<char> &Result,
+                          bool ShouldAutoFlush = true) const {
+    return Converter->convert(Source, Result, ShouldAutoFlush);
+  }
+
+  char convert(char SingleChar) const {
+    SmallString<1> Result;
+    Converter->convert(StringRef(&SingleChar, 1), Result, false);
+    return Result[0];
+  }
+
+  /// Converts a string.
+  /// \param[in] Source source string
+  /// \param[in,out] Result container for converted string
+  /// \param[in] ShouldAutoFlush Append shift-back sequence after conversion
+  /// for multi-byte encodings iff true.
+  /// \return error code in case something went wrong
+  std::error_code convert(const std::string &Source,
+                          SmallVectorImpl<char> &Result,
+                          bool ShouldAutoFlush = true) const {
+    return convert(StringRef(Source), Result, ShouldAutoFlush);
+  }
+
+  std::error_code flush() const { return Converter->flush(); }
+
+  std::error_code flush(SmallVectorImpl<char> &Result) const {
+    return Converter->flush(Result);
+  }
+};
+
+} // namespace llvm
+
+#endif

llvm/lib/Support/CMakeLists.txt

@@ -153,6 +153,7 @@ add_llvm_component_library(LLVMSupport
   CachePruning.cpp
   Caching.cpp
   circular_raw_ostream.cpp
+  CharSet.cpp
   Chrono.cpp
   COM.cpp
   CodeGenCoverage.cpp
@@ -292,6 +293,22 @@ add_llvm_component_library(LLVMSupport
   Demangle
   )
 
+# Link icu library if it is an external library.
+if(ICU_FOUND)
+  target_link_libraries(LLVMSupport
+  PRIVATE
+  ${ICU_LIBRARIES}
+  )
+else()
+  # Link iconv library if it is an external library.
+  if(Iconv_FOUND AND NOT Iconv_IS_BUILT_IN)
+    target_link_libraries(LLVMSupport
+    PRIVATE
+    ${Iconv_LIBRARIES}
+    )
+  endif()
+endif()
+
 set(llvm_system_libs ${system_libs})
 
 # This block is only needed for llvm-config. When we deprecate llvm-config and