gecko-dev/xpcom/ds/nsCharSeparatedTokenizer.h

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef __nsCharSeparatedTokenizer_h
#define __nsCharSeparatedTokenizer_h
#include "nsDependentSubstring.h"
#include "nsCRT.h"
/**
* This parses a SeparatorChar-separated string into tokens.
* Whitespace surrounding tokens is not treated as part of tokens, however
* whitespace inside a token is. If the final token is the empty string, it is
* not returned.
*
* Some examples, with SeparatorChar = ',':
*
* "foo, bar, baz" -> "foo" "bar" "baz"
* "foo,bar,baz" -> "foo" "bar" "baz"
* "foo , bar hi , baz" -> "foo" "bar hi" "baz"
* "foo, ,bar,baz" -> "foo" "" "bar" "baz"
* "foo,,bar,baz" -> "foo" "" "bar" "baz"
* "foo,bar,baz," -> "foo" "bar" "baz"
*
* The function used for whitespace detection is a template argument.
* By default, it is NS_IsAsciiWhitespace.
*/
template<bool IsWhitespace(PRUnichar) = NS_IsAsciiWhitespace>
class nsCharSeparatedTokenizerTemplate
{
public:
// Flags -- only one for now. If we need more, they should be defined to
// be 1<<1, 1<<2, etc. (They're masks, and aFlags/mFlags are bitfields.)
enum {
SEPARATOR_OPTIONAL = 1
};
nsCharSeparatedTokenizerTemplate(const nsSubstring& aSource,
PRUnichar aSeparatorChar,
uint32_t aFlags = 0)
: mFirstTokenBeganWithWhitespace(false),
mLastTokenEndedWithWhitespace(false),
mLastTokenEndedWithSeparator(false),
mSeparatorChar(aSeparatorChar),
mFlags(aFlags)
{
aSource.BeginReading(mIter);
aSource.EndReading(mEnd);
// Skip initial whitespace
while (mIter != mEnd && IsWhitespace(*mIter)) {
mFirstTokenBeganWithWhitespace = true;
++mIter;
}
}
/**
* Checks if any more tokens are available.
*/
bool hasMoreTokens()
{
NS_ASSERTION(mIter == mEnd || !IsWhitespace(*mIter),
"Should be at beginning of token if there is one");
return mIter != mEnd;
}
bool firstTokenBeganWithWhitespace() const
{
return mFirstTokenBeganWithWhitespace;
}
bool lastTokenEndedWithSeparator() const
{
return mLastTokenEndedWithSeparator;
}
bool lastTokenEndedWithWhitespace() const
{
return mLastTokenEndedWithWhitespace;
}
/**
* Returns the next token.
*/
const nsDependentSubstring nextToken()
{
nsSubstring::const_char_iterator end = mIter, begin = mIter;
NS_ASSERTION(mIter == mEnd || !IsWhitespace(*mIter),
"Should be at beginning of token if there is one");
// Search until we hit separator or end (or whitespace, if separator
// isn't required -- see clause with 'break' below).
while (mIter != mEnd && *mIter != mSeparatorChar) {
// Skip to end of current word.
while (mIter != mEnd &&
!IsWhitespace(*mIter) && *mIter != mSeparatorChar) {
++mIter;
}
end = mIter;
// Skip whitespace after current word.
mLastTokenEndedWithWhitespace = false;
while (mIter != mEnd && IsWhitespace(*mIter)) {
mLastTokenEndedWithWhitespace = true;
++mIter;
}
if (mFlags & SEPARATOR_OPTIONAL) {
// We've hit (and skipped) whitespace, and that's sufficient to end
// our token, regardless of whether we've reached a SeparatorChar.
break;
} // (else, we'll keep looping until we hit mEnd or SeparatorChar)
}
mLastTokenEndedWithSeparator = (mIter != mEnd &&
*mIter == mSeparatorChar);
NS_ASSERTION((mFlags & SEPARATOR_OPTIONAL) ||
(mLastTokenEndedWithSeparator == (mIter != mEnd)),
"If we require a separator and haven't hit the end of "
"our string, then we shouldn't have left the loop "
"unless we hit a separator");
// Skip separator (and any whitespace after it), if we're at one.
if (mLastTokenEndedWithSeparator) {
++mIter;
while (mIter != mEnd && IsWhitespace(*mIter)) {
++mIter;
}
}
return Substring(begin, end);
}
private:
nsSubstring::const_char_iterator mIter, mEnd;
bool mFirstTokenBeganWithWhitespace;
bool mLastTokenEndedWithWhitespace;
bool mLastTokenEndedWithSeparator;
PRUnichar mSeparatorChar;
uint32_t mFlags;
};
class nsCharSeparatedTokenizer: public nsCharSeparatedTokenizerTemplate<>
{
public:
nsCharSeparatedTokenizer(const nsSubstring& aSource,
PRUnichar aSeparatorChar,
uint32_t aFlags = 0)
: nsCharSeparatedTokenizerTemplate<>(aSource, aSeparatorChar, aFlags)
{
}
};
class nsCCharSeparatedTokenizer
{
public:
nsCCharSeparatedTokenizer(const nsCSubstring& aSource,
char aSeparatorChar)
: mSeparatorChar(aSeparatorChar)
{
aSource.BeginReading(mIter);
aSource.EndReading(mEnd);
while (mIter != mEnd && isWhitespace(*mIter)) {
++mIter;
}
}
/**
* Checks if any more tokens are available.
*/
bool hasMoreTokens()
{
return mIter != mEnd;
}
/**
* Returns the next token.
*/
const nsDependentCSubstring nextToken()
{
nsCSubstring::const_char_iterator end = mIter, begin = mIter;
// Search until we hit separator or end.
while (mIter != mEnd && *mIter != mSeparatorChar) {
while (mIter != mEnd &&
!isWhitespace(*mIter) && *mIter != mSeparatorChar) {
++mIter;
}
end = mIter;
while (mIter != mEnd && isWhitespace(*mIter)) {
++mIter;
}
}
// Skip separator (and any whitespace after it).
if (mIter != mEnd) {
NS_ASSERTION(*mIter == mSeparatorChar, "Ended loop too soon");
++mIter;
while (mIter != mEnd && isWhitespace(*mIter)) {
++mIter;
}
}
return Substring(begin, end);
}
private:
nsCSubstring::const_char_iterator mIter, mEnd;
char mSeparatorChar;
bool isWhitespace(unsigned char aChar)
{
return aChar <= ' ' &&
(aChar == ' ' || aChar == '\n' ||
aChar == '\r'|| aChar == '\t');
}
};
#endif /* __nsCharSeparatedTokenizer_h */