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llvm-mirror/lib/Support/StringExtras.cpp
Michael Kruse 8fc32bf8f9 [ADT] Replace std::isprint by llvm::isPrint.
The standard library functions ::isprint/std::isprint have platform-
and locale-dependent behavior which makes LLVM's output less
predictable. In particular, regression tests my fail depending on the
implementation of these functions.

Implement llvm::isPrint in StringExtras.h with a standard behavior and
replace all uses of ::isprint/std::isprint by a call it llvm::isPrint.
The function is inlined and does not look up language settings so it
should perform better than the standard library's version.

Such a replacement has already been done for isdigit, isalpha, isxdigit
in r314883. gtest does the same in gtest-printers.cc using the following
justification:

    // Returns true if c is a printable ASCII character.  We test the
    // value of c directly instead of calling isprint(), which is buggy on
    // Windows Mobile.
    inline bool IsPrintableAscii(wchar_t c) {
      return 0x20 <= c && c <= 0x7E;
    }

Similar issues have also been encountered by Julia:
https://github.com/JuliaLang/julia/issues/7416

I noticed the problem myself when on Windows isprint('\t') started to
evaluate to true (see https://stackoverflow.com/questions/51435249) and
thus caused several unit tests to fail. The result of isprint doesn't
seem to be well-defined even for ASCII characters. Therefore I suggest
to replace isprint by a platform-independent version.

Differential Revision: https://reviews.llvm.org/D49680

llvm-svn: 338034
2018-07-26 15:31:41 +00:00

92 lines
3.1 KiB
C++

//===-- StringExtras.cpp - Implement the StringExtras header --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the StringExtras.h header
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
/// StrInStrNoCase - Portable version of strcasestr. Locates the first
/// occurrence of string 's1' in string 's2', ignoring case. Returns
/// the offset of s2 in s1 or npos if s2 cannot be found.
StringRef::size_type llvm::StrInStrNoCase(StringRef s1, StringRef s2) {
size_t N = s2.size(), M = s1.size();
if (N > M)
return StringRef::npos;
for (size_t i = 0, e = M - N + 1; i != e; ++i)
if (s1.substr(i, N).equals_lower(s2))
return i;
return StringRef::npos;
}
/// getToken - This function extracts one token from source, ignoring any
/// leading characters that appear in the Delimiters string, and ending the
/// token at any of the characters that appear in the Delimiters string. If
/// there are no tokens in the source string, an empty string is returned.
/// The function returns a pair containing the extracted token and the
/// remaining tail string.
std::pair<StringRef, StringRef> llvm::getToken(StringRef Source,
StringRef Delimiters) {
// Figure out where the token starts.
StringRef::size_type Start = Source.find_first_not_of(Delimiters);
// Find the next occurrence of the delimiter.
StringRef::size_type End = Source.find_first_of(Delimiters, Start);
return std::make_pair(Source.slice(Start, End), Source.substr(End));
}
/// SplitString - Split up the specified string according to the specified
/// delimiters, appending the result fragments to the output list.
void llvm::SplitString(StringRef Source,
SmallVectorImpl<StringRef> &OutFragments,
StringRef Delimiters) {
std::pair<StringRef, StringRef> S = getToken(Source, Delimiters);
while (!S.first.empty()) {
OutFragments.push_back(S.first);
S = getToken(S.second, Delimiters);
}
}
void llvm::printEscapedString(StringRef Name, raw_ostream &Out) {
for (unsigned i = 0, e = Name.size(); i != e; ++i) {
unsigned char C = Name[i];
if (isPrint(C) && C != '\\' && C != '"')
Out << C;
else
Out << '\\' << hexdigit(C >> 4) << hexdigit(C & 0x0F);
}
}
void llvm::printHTMLEscaped(StringRef String, raw_ostream &Out) {
for (char C : String) {
if (C == '&')
Out << "&amp;";
else if (C == '<')
Out << "&lt;";
else if (C == '>')
Out << "&gt;";
else if (C == '\"')
Out << "&quot;";
else if (C == '\'')
Out << "&apos;";
else
Out << C;
}
}
void llvm::printLowerCase(StringRef String, raw_ostream &Out) {
for (const char C : String)
Out << toLower(C);
}