//===--- StringExtras.cpp - String Utilities ------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file implements utilities for working with words and camelCase
// names.
//
//===----------------------------------------------------------------------===//
#include "swift/Basic/StringExtras.h"
#include "clang/Basic/CharInfo.h"
using namespace swift;
using namespace camel_case;

PrepositionKind swift::getPrepositionKind(StringRef word) {
#define DIRECTIONAL_PREPOSITION(Word)           \
  if (word.equals_lower(#Word))                 \
    return PK_Directional;
#define PREPOSITION(Word)                       \
  if (word.equals_lower(#Word))                 \
    return PK_Nondirectional;
#include "Prepositions.def"

  return PK_None;
}

void WordIterator::computeNextPosition() const {
  assert(Position < String.size() && "Already at end of string");

  // Skip over any uppercase letters at the beginning of the word.
  unsigned i = Position, n = String.size();
  while (i < n && clang::isUppercase(String[i]))
    ++i;

  // If there was more than one uppercase letter, this is an
  // acronym.
  if (i - Position > 1) {
    // If we hit the end of the string, that's it. Otherwise, this
    // word ends at the last uppercase letter, so that the next word
    // starts with the last uppercase letter.
    NextPosition = i == n? i : i-1;
    NextPositionValid = true;
    return;
  }

  // Skip non-uppercase letters.
  while (i < n && !clang::isUppercase(String[i]))
    ++i;

  NextPosition = i;
  NextPositionValid = true;
}

void WordIterator::computePrevPosition() const {
  assert(Position > 0 && "Already at beginning of string");

  // While we see non-uppercase letters, keep moving back.
  unsigned i = Position;
  while (i > 0 && !clang::isUppercase(String[i-1]))
    --i;

  // If we found any lowercase letters, this was a normal camel case
  // word (not an acronym).
  if (i < Position) {
    // If we hit the beginning of the string, that's it. Otherwise,
    // this word starts at the uppercase letter that terminated the
    // search above.
    PrevPosition = i == 0 ? 0 : i-1;
    PrevPositionValid = true;
    return;
  }

  // There were no lowercase letters, so this is an acronym. Keep
  // skipping uppercase letters.
  while (i > 0 && clang::isUppercase(String[i-1]))
    --i;

  PrevPosition = i;
  PrevPositionValid = true;
}


StringRef camel_case::getFirstWord(StringRef string) {
  if (string.empty())
    return "";

  return *WordIterator(string, 0);
}

StringRef camel_case::getLastWord(StringRef string) {
  if (string.empty())
    return "";

  return *--WordIterator(string, string.size());
}