flutter_flutter/sky/engine/platform/text/BidiTestHarness.h

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#ifndef SKY_ENGINE_PLATFORM_TEXT_BIDITESTHARNESS_H_
#define SKY_ENGINE_PLATFORM_TEXT_BIDITESTHARNESS_H_

#include <stdio.h>
#include <istream>
#include <map>
#include <string>
#include <vector>

// FIXME: We don't have any business owning this code. We should try to
// upstream this to unicode.org if possible (for other implementations to use).
// Unicode.org provides a reference implmentation, including parser:
// http://www.unicode.org/Public/PROGRAMS/BidiReferenceC/6.3.0/source/brtest.c
// But it, like the other implementations I've found, is rather tied to
// the algorithms it is testing. This file seeks to only implement the parser
// bits.

// Other C/C++ implementations of this parser:
// https://github.com/googlei18n/fribidi-vs-unicode/blob/master/test.c
// http://source.icu-project.org/repos/icu/icu/trunk/source/test/intltest/bidiconf.cpp
// Both of those are too tied to their respective projects to be use to Blink.

// There are non-C implmentations to parse BidiTest.txt as well, including:
// https://github.com/twitter/twitter-cldr-rb/blob/master/spec/bidi/bidi_spec.rb

// NOTE: None of this file is currently written to be thread-safe.

namespace bidi_test {

enum ParagraphDirection {
  DirectionAutoLTR = 1,
  DirectionLTR = 2,
  DirectionRTL = 4,
};
const int kMaxParagraphDirection =
    DirectionAutoLTR | DirectionLTR | DirectionRTL;

// For error printing:
std::string nameFromParagraphDirection(ParagraphDirection paragraphDirection) {
  switch (paragraphDirection) {
    case bidi_test::DirectionAutoLTR:
      return "Auto-LTR";
    case bidi_test::DirectionLTR:
      return "LTR";
    case bidi_test::DirectionRTL:
      return "RTL";
  }
  // This should never be reached.
  return "";
}

template <class Runner>
class Harness {
 public:
  Harness(Runner& runner) : m_runner(runner) {}
  void parse(std::istream& bidiTestFile);

 private:
  Runner& m_runner;
};

// We could use boost::trim, but no other part of Blink uses boost yet.
inline void ltrim(std::string& s) {
  static const std::string separators(" \t");
  s.erase(0, s.find_first_not_of(separators));
}

inline void rtrim(std::string& s) {
  static const std::string separators(" \t");
  size_t lastNonSpace = s.find_last_not_of(separators);
  if (lastNonSpace == std::string::npos) {
    s.erase();
    return;
  }
  size_t firstSpaceAtEndOfString = lastNonSpace + 1;
  if (firstSpaceAtEndOfString >= s.size())
    return;  // lastNonSpace was the last char.
  s.erase(firstSpaceAtEndOfString,
          std::string::npos);  // erase to the end of the string.
}

inline void trim(std::string& s) {
  rtrim(s);
  ltrim(s);
}

static std::vector<std::string> parseStringList(const std::string& str) {
  std::vector<std::string> strings;
  static const std::string separators(" \t");
  size_t lastPos = str.find_first_not_of(separators);   // skip leading spaces
  size_t pos = str.find_first_of(separators, lastPos);  // find next space

  while (std::string::npos != pos || std::string::npos != lastPos) {
    strings.push_back(str.substr(lastPos, pos - lastPos));
    lastPos = str.find_first_not_of(separators, pos);
    pos = str.find_first_of(separators, lastPos);
  }
  return strings;
}

static std::vector<int> parseIntList(const std::string& str) {
  std::vector<int> ints;
  std::vector<std::string> strings = parseStringList(str);
  for (size_t x = 0; x < strings.size(); x++) {
    int i = atoi(strings[x].c_str());
    ints.push_back(i);
  }
  return ints;
}

static std::vector<int> parseLevels(const std::string& line) {
  std::vector<int> levels;
  std::vector<std::string> strings = parseStringList(line);
  for (size_t x = 0; x < strings.size(); x++) {
    const std::string& levelString = strings[x];
    int i;
    if (levelString == "x")
      i = -1;
    else
      i = atoi(levelString.c_str());
    levels.push_back(i);
  }
  return levels;
}

// This is not thread-safe as written.
static std::basic_string<UChar> parseTestString(const std::string& line) {
  std::basic_string<UChar> testString;
  static std::map<std::string, UChar> charClassExamples;
  if (charClassExamples.empty()) {
    // FIXME: Explicit make_pair is ugly, but required for C++98 compat.
    charClassExamples.insert(std::make_pair("L", 0x6c));     // 'l' for L
    charClassExamples.insert(std::make_pair("R", 0x05D0));   // HEBREW ALEF
    charClassExamples.insert(std::make_pair("EN", 0x33));    // '3' for EN
    charClassExamples.insert(std::make_pair("ES", 0x2d));    // '-' for ES
    charClassExamples.insert(std::make_pair("ET", 0x25));    // '%' for ET
    charClassExamples.insert(std::make_pair("AN", 0x0660));  // arabic 0
    charClassExamples.insert(std::make_pair("CS", 0x2c));    // ',' for CS
    charClassExamples.insert(std::make_pair("B", 0x0A));     // <control-000A>
    charClassExamples.insert(std::make_pair("S", 0x09));     // <control-0009>
    charClassExamples.insert(std::make_pair("WS", 0x20));    // ' ' for WS
    charClassExamples.insert(std::make_pair("ON", 0x3d));    // '=' for ON
    charClassExamples.insert(
        std::make_pair("NSM", 0x05BF));  // HEBREW POINT RAFE
    charClassExamples.insert(std::make_pair("AL", 0x0608));  // ARABIC RAY
    charClassExamples.insert(std::make_pair("BN", 0x00AD));  // SOFT HYPHEN
    charClassExamples.insert(std::make_pair("LRE", 0x202A));
    charClassExamples.insert(std::make_pair("RLE", 0x202B));
    charClassExamples.insert(std::make_pair("PDF", 0x202C));
    charClassExamples.insert(std::make_pair("LRO", 0x202D));
    charClassExamples.insert(std::make_pair("RLO", 0x202E));
    charClassExamples.insert(std::make_pair("LRI", 0x2066));
    charClassExamples.insert(std::make_pair("RLI", 0x2067));
    charClassExamples.insert(std::make_pair("FSI", 0x2068));
    charClassExamples.insert(std::make_pair("PDI", 0x2069));
  }

  std::vector<std::string> charClasses = parseStringList(line);
  for (size_t i = 0; i < charClasses.size(); i++) {
    // FIXME: If the lookup failed we could return false for a parse error.
    testString.push_back(charClassExamples.find(charClasses[i])->second);
  }
  return testString;
}

static bool parseParagraphDirectionMask(const std::string& line,
                                        int& modeMask) {
  modeMask = atoi(line.c_str());
  return modeMask >= 1 && modeMask <= kMaxParagraphDirection;
}

static void parseError(const std::string& line, size_t lineNumber) {
  // Use printf to avoid the expense of std::cout.
  printf("Parse error, line %zu : %s\n", lineNumber, line.c_str());
}

template <class Runner>
void Harness<Runner>::parse(std::istream& bidiTestFile) {
  static const std::string levelsPrefix("@Levels");
  static const std::string reorderPrefix("@Reorder");

  // FIXME: UChar is an ICU type and cheating a bit to use here.
  // uint16_t might be more portable.
  std::basic_string<UChar> testString;
  std::vector<int> levels;
  std::vector<int> reorder;
  int paragraphDirectionMask;

  std::string line;
  size_t lineNumber = 0;
  while (std::getline(bidiTestFile, line)) {
    lineNumber++;
    const std::string originalLine = line;
    size_t commentStart = line.find_first_of('#');
    if (commentStart != std::string::npos)
      line = line.substr(0, commentStart);
    trim(line);
    if (line.empty())
      continue;
    if (line[0] == '@') {
      if (!line.find(levelsPrefix)) {
        levels = parseLevels(line.substr(levelsPrefix.length() + 1));
        continue;
      }
      if (!line.find(reorderPrefix)) {
        reorder = parseIntList(line.substr(reorderPrefix.length() + 1));
        continue;
      }
    } else {
      // Assume it's a data line.
      size_t seperatorIndex = line.find_first_of(';');
      if (seperatorIndex == std::string::npos) {
        parseError(originalLine, lineNumber);
        continue;
      }
      testString = parseTestString(line.substr(0, seperatorIndex));
      if (!parseParagraphDirectionMask(line.substr(seperatorIndex + 1),
                                       paragraphDirectionMask)) {
        parseError(originalLine, lineNumber);
        continue;
      }

      if (paragraphDirectionMask & DirectionAutoLTR)
        m_runner.runTest(testString, reorder, levels, DirectionAutoLTR,
                         originalLine, lineNumber);
      if (paragraphDirectionMask & DirectionLTR)
        m_runner.runTest(testString, reorder, levels, DirectionLTR,
                         originalLine, lineNumber);
      if (paragraphDirectionMask & DirectionRTL)
        m_runner.runTest(testString, reorder, levels, DirectionRTL,
                         originalLine, lineNumber);
    }
  }
}

}  // namespace bidi_test

#endif  // SKY_ENGINE_PLATFORM_TEXT_BIDITESTHARNESS_H_