gecko-dev/lib/libmsg/newsset.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 */

#include "msg.h"
#include "newsset.h"
#include "newshost.h"

extern "C" {
	extern int MK_OUT_OF_MEMORY;
}


/* A compressed encoding for sets of article.  This is usually for lines from
   the newsrc, which have article lists like

   1-29627,29635,29658,32861-32863

   so the data has these properties:

   - strictly increasing
   - large subsequences of monotonically increasing ranges
   - gaps in the set are usually small, but not always
   - consecutive ranges tend to be large

   The biggest win is to run-length encode the data, storing ranges as two
   numbers (start+length or start,end). We could also store each number as a
   delta from the previous number for further compression, but that gets kind
   of tricky, since there are no guarentees about the sizes of the gaps, and
   we'd have to store variable-length words.

   Current data format:

   DATA := SIZE [ CHUNK ]*
   CHUNK := [ RANGE | VALUE ]
   RANGE := -LENGTH START
   START := VALUE
   LENGTH := int32
   VALUE := a literal positive integer, for now
   it could also be an offset from the previous value.
   LENGTH could also perhaps be a less-than-32-bit quantity,
   at least most of the time.

   Lengths of CHUNKs are stored negative to distinguish the beginning of
   a chunk from a literal: negative means two-word sequence, positive
   means one-word sequence.

   0 represents a literal 0, but should not occur, and should never occur
   except in the first position.

   A length of -1 won't occur either, except temporarily - a sequence of
   two elements is represented as two literals, since they take up the same
   space.

   Another optimization we make is to notice that we typically ask the
   question ``is N a member of the set'' for increasing values of N. So the
   set holds a cache of the last value asked for, and can simply resume the
   search from there.  */



msg_NewsArtSet::msg_NewsArtSet(MSG_NewsHost* host)
{
	m_cached_value = -1;
	m_cached_value_index = 0;
	m_length = 0;
	m_data_size = 10;
	m_data = (int32 *) XP_ALLOC (sizeof (int32) * m_data_size);
	m_host = host;
}


msg_NewsArtSet::~msg_NewsArtSet()
{
	FREEIF(m_data);
}


XP_Bool msg_NewsArtSet::Grow()
{
	int32 new_size;
	int32 *new_data;
	new_size = m_data_size * 2;
	new_data = (int32 *) XP_REALLOC (m_data, sizeof (int32) * new_size);
	if (! new_data)
		return FALSE;
	m_data_size = new_size;
	m_data = new_data;
	return TRUE;
}


msg_NewsArtSet::msg_NewsArtSet(const char* numbers, MSG_NewsHost* host)
{
	int32 *head, *tail, *end;

	m_host = host;
	m_cached_value = -1;
	m_cached_value_index = 0;
	m_length = 0;
	m_data_size = 10;
	m_data = (int32 *) XP_ALLOC (sizeof (int32) * m_data_size);
	if (!m_data) return;

	head = m_data;
	tail = head;
	end = head + m_data_size;

	if(!numbers) {
		return;
	}

	while (isspace (*numbers)) numbers++;
	while (*numbers) {
		int32 from = 0;
		int32 to;

		if (tail >= end - 4) {
			/* out of room! */
			int32 tailo = tail - head;
			if (!Grow()) {
				FREEIF(m_data);
				return;
			}
			/* data may have been relocated */
			head = m_data;
			tail = head + tailo;
			end = head + m_data_size;
		}

		while (isspace(*numbers)) numbers++;
		if (*numbers && !isdigit(*numbers)) {
			break;			/* illegal character */
		}
		while (isdigit (*numbers)) {
			from = (from * 10) + (*numbers++ - '0');
		}
		while (isspace (*numbers)) numbers++;
		if (*numbers != '-') {
			to = from;
		} else {
			to = 0;
			numbers++;
			while (*numbers >= '0' && *numbers <= '9')
				to = (to * 10) + (*numbers++ - '0');
			while (isspace (*numbers)) numbers++;
		}

		if (to < from) to = from; /* illegal */

		/* This is a hack - if the newsrc file specifies a range 1-x as
		   being read, we internally pretend that article 0 is read as well.
		   (But if only 2-x are read, then 0 is not read.)  This is needed
		   because some servers think that article 0 is an article (I think)
		   but some news readers (including Netscape 1.1) choke if the .newsrc
		   file has lines beginning with 0...   ### */
		if (from == 1) from = 0;

		if (to == from) {
			/* Write it as a literal */
			*tail = from;
			tail++;
		} else /* Write it as a range. */ {
			*tail = -(to - from);
			tail++;
			*tail = from;
			tail++;
		}

		while (*numbers == ',' || isspace (*numbers)) {
			numbers++;
		}
	}

	m_length = tail - head; /* size of data */
}



msg_NewsArtSet*
msg_NewsArtSet::Create(MSG_NewsHost* host)
{
	msg_NewsArtSet* set = new msg_NewsArtSet(host);
	if (set && set->m_data == NULL) {
		delete set;
		set = NULL;
	}
	return set;
}


msg_NewsArtSet*
msg_NewsArtSet::Create(const char* value, MSG_NewsHost* host)
{
	msg_NewsArtSet* set = new msg_NewsArtSet(value, host);
	if (set && set->m_data == NULL) {
		delete set;
		set = NULL;
	}
	return set;
}



/* Returns the lowest non-member of the set greater than 0.
 */
int32
msg_NewsArtSet::FirstNonMember ()
{
	if (m_length <= 0) {
		return 1;
	} else if(m_data[0] < 0 && m_data[1] != 1 && m_data[1] != 0) {
		/* first range not equal to 0 or 1, always return 1 */
		return 1;
	} else if (m_data[0] < 0) {
		/* it's a range */
		/* If there is a range [N-M] we can presume that M+1 is not in the
		   set. */
		return (m_data[1] - m_data[0] + 1);
	} else {
		/* it's a literal */
		if (m_data[0] == 1) {
			/* handle "1,..." */
			if (m_length > 1 && m_data[1] == 2) {
				/* This is "1,2,M-N,..." or "1,2,M,..."  where M >= 4.  Note
				   that M will never be 3, because in that case we would have
				   started with a range: "1-3,..." */
				return 3;
			} else {
				return 2;              /* handle "1,M-N,.." or "1,M,..."
										  where M >= 3; */
			}
		}
		else if (m_data[0] == 0) {
			/* handle "0,..." */
			if (m_length > 1 && m_data[1] == 1) {
				/* this is 0,1, (see above) */
				return 2;
			}
			else {
				return 1;
			}

		} else {
			/* handle "M,..." where M >= 2. */
			return 1;
		}
	}
}


char *
msg_NewsArtSet::Output()
{
	int32 size;
	int32 *head;
	int32 *tail;
	int32 *end;
	int32 s_size;
	char *s_head;
	char *s, *s_end;
	int32 last_art = -1;

	size = m_length;
	head = m_data;
	tail = head;
	end = head + size;

	s_size = (size * 12) + 10;	// dmb - try to make this allocation get used at least once.
	s_head = new char [s_size];
	s_head[0] = '\0';			// otherwise, s_head will contain garbage.
	s = s_head;
	s_end = s + s_size;

	if (! s) return 0;

	while (tail < end) {
		int32 from;
		int32 to;

		if (s > (s_end - (12 * 2 + 10))) { /* 12 bytes for each number (enough
											  for "2147483647" aka 2^31-1),
											  plus 10 bytes of slop. */
			int32 so = s - s_head;
			s_size += 200;
			char* tmp = new char[s_size];
			if (tmp) XP_STRCPY(tmp, s_head);
			delete [] s_head;
			s_head = tmp;
			if (!s_head) return 0;
			s = s_head + so;
			s_end = s_head + s_size;
		}

		if (*tail < 0) {
			/* it's a range */
			from = tail[1];
			to = from + (-(tail[0]));
			tail += 2;
		}
		else /* it's a literal */
			{
				from = *tail;
				to = from;
				tail++;
			}
		if (from == 0) {
			from = 1;				/* See 'hack' comment above  ### */
		}
		if (from <= last_art) from = last_art + 1;
		if (from <= to) {
			if (from < to) {
				PR_snprintf(s, s_end - s, "%lu-%lu,", from, to);
			} else {
				PR_snprintf(s, s_end - s, "%lu,", from);
			}
			s += XP_STRLEN(s);
			last_art = to;
		}
	}
	if (last_art >= 0) {
		s--;							/* Strip off the last ',' */
	}

	*s = 0;

	return s_head;
}

int32 
msg_NewsArtSet::GetLastMember()
{
	if (m_length > 1)
	{
		int32 nextToLast = m_data[m_length - 2];
		if (nextToLast < 0)	// is range at end?
		{
			int32 last = m_data[m_length - 1];
			return (-nextToLast + last - 1);
		}
		else	// no, so last number must be last member
		{
			return m_data[m_length - 1];
		}
	}
	else if (m_length == 1)
		return m_data[0];	// must be only 1 read.
	else
		return 0;
}

void msg_NewsArtSet::SetLastMember(int32 newHighWaterMark)
{
	if (newHighWaterMark < GetLastMember())
	{
		while (TRUE)
		{
			if (m_length > 1)
			{
				int32 nextToLast = m_data[m_length - 2];
				int32 curHighWater;
				if (nextToLast < 0)	// is range at end?
				{
					int32 rangeStart = m_data[m_length - 1];
					int32 rangeLength = -nextToLast;
					curHighWater = (rangeLength + rangeStart - 1);
					if (curHighWater > newHighWaterMark)
					{
						if (rangeStart > newHighWaterMark)	
						{
							m_length -= 2;	// throw away whole range
						}
						else if (rangeStart == newHighWaterMark)
						{
							// turn range into single element.
							m_data[m_length - 2] = newHighWaterMark;
							m_length--;
							break;
						}
						else	// just shorten range
						{
							m_data[m_length - 2] = -(newHighWaterMark - rangeStart);
							break;
						}
					}	
				}
				else if (m_data[m_length - 1] > newHighWaterMark)	// no, so last number must be last member
				{
					m_length--;
				}
				else
					break;
			}
			else 
				break;
		}
		// well, the whole range is probably invalid, because the server probably re-ordered ids, 
		// but what can you do?
		if (m_host) 
			m_host->MarkDirty();
	}
}

int32 
msg_NewsArtSet::GetFirstMember()
{
	if (m_length > 1)
	{
		int32 first = m_data[0];
		if (first < 0)	// is range at start?
		{
			int32 second = m_data[1];
			return (second);
		}
		else	// no, so first number must be first member
		{
			return m_data[0];
		}
	}
	else if (m_length == 1)
		return m_data[0];	// must be only 1 read.
	else
		return 0;
}

/* Re-compresses a `msg_NewsArtSet' object.

   The assumption is made that the `msg_NewsArtSet' is syntactically correct
   (all ranges have a length of at least 1, and all values are non-
   decreasing) but will optimize the compression, for example, merging
   consecutive literals or ranges into one range.

   Returns TRUE if successful, FALSE if there wasn't enough memory to
   allocate scratch space.

   #### This should be changed to modify the buffer in place.

   Also note that we never call Optimize() unless we actually changed
   something, so it's a great place to tell the MSG_NewsHost* that something
   changed.
   */
XP_Bool
msg_NewsArtSet::Optimize()
{
	int32 input_size;
	int32 output_size;
	int32 *input_tail;
	int32 *output_data;
	int32 *output_tail;
	int32 *input_end;
	int32 *output_end;

	input_size = m_length;
	output_size = input_size + 1;
	input_tail = m_data;
	output_data = (int32 *) XP_ALLOC (sizeof (int32) * output_size);
	output_tail = output_data;
	input_end = input_tail + input_size;
	output_end = output_data + output_size;

	if (!output_data) return FALSE;

	/* We're going to modify the set, so invalidate the cache. */
	m_cached_value = -1;

	while (input_tail < input_end) {
		int32 from, to;
		XP_Bool range_p = (*input_tail < 0);

		if (range_p) {
			/* it's a range */
			from = input_tail[1];
			to = from + (-(input_tail[0]));

			/* Copy it over */
			*output_tail++ = *input_tail++;
			*output_tail++ = *input_tail++;				
		} else {
			/* it's a literal */
			from = *input_tail;
			to = from;

			/* Copy it over */
			*output_tail++ = *input_tail++;
		}
		XP_ASSERT(output_tail < output_end);
		if (output_tail >= output_end) {
			XP_FREE(output_data);
			return FALSE;
		}

		/* As long as this chunk is followed by consecutive chunks,
		   keep extending it. */
		while (input_tail < input_end &&
			   ((*input_tail > 0 && /* literal... */
				 *input_tail == to + 1) || /* ...and consecutive, or */
				(*input_tail <= 0 && /* range... */
				 input_tail[1] == to + 1)) /* ...and consecutive. */
			   ) {
			if (! range_p) {
				/* convert the literal to a range. */
				output_tail++;
				output_tail [-2] = 0;
				output_tail [-1] = from;
				range_p = TRUE;
			}

			if (*input_tail > 0) { /* literal */
				output_tail[-2]--; /* increase length by 1 */
				to++;
				input_tail++;
			} else {
				int32 L2 = (- *input_tail) + 1;
				output_tail[-2] -= L2; /* increase length by N */
				to += L2;
				input_tail += 2;
			}
		}
	}

	XP_FREE (m_data);
	m_data = output_data;
	m_data_size = output_size;
	m_length = output_tail - output_data;

	/* One last pass to turn [N - N+1] into [N, N+1]. */
	output_tail = output_data;
	output_end = output_tail + m_length;
	while (output_tail < output_end) {
		if (*output_tail < 0) {
			/* it's a range */
			if (output_tail[0] == -1) {
				output_tail[0] = output_tail[1];
				output_tail[1]++;
			}
			output_tail += 2;
		} else {
			/* it's a literal */
			output_tail++;
		}
	}

	if (m_host) m_host->MarkDirty();
	return TRUE;
}



XP_Bool
msg_NewsArtSet::IsMember(int32 number)
{
	XP_Bool value = FALSE;
	int32 size;
	int32 *head;
	int32 *tail;
	int32 *end;

	size = m_length;
	head = m_data;
	tail = head;
	end = head + size;

	/* If there is a value cached, and that value is smaller than the
	   value we're looking for, skip forward that far. */
	if (m_cached_value > 0 &&
		m_cached_value < number) {
		tail += m_cached_value_index;
	}

	while (tail < end) {
		if (*tail < 0) {
			/* it's a range */
			int32 from = tail[1];
			int32 to = from + (-(tail[0]));
			if (from > number) {
				/* This range begins after the number - we've passed it. */
				value = FALSE;
				goto DONE;
			} else if (to >= number) {
				/* In range. */
				value = TRUE;
				goto DONE;
			} else {
				tail += 2;
			}
		}
		else {
			/* it's a literal */
			if (*tail == number) {
				/* bang */
				value = TRUE;
				goto DONE;
			} else if (*tail > number) {
				/* This literal is after the number - we've passed it. */
				value = FALSE;
				goto DONE;
			} else {
				tail++;
			}
		}
	}

DONE:
	/* Store the position of this chunk for next time. */
	m_cached_value = number;
	m_cached_value_index = tail - head;

	return value;
}


int
msg_NewsArtSet::Add(int32 number)
{
	int32 size;
	int32 *head;
	int32 *tail;
	int32 *end;

	size = m_length;
	head = m_data;
	tail = head;
	end = head + size;

	XP_ASSERT (number >= 0);
	if (number < 0)
		return 0;

	/* We're going to modify the set, so invalidate the cache. */
	m_cached_value = -1;

	while (tail < end) {
		if (*tail < 0) {
			/* it's a range */
			int32 from = tail[1];
			int32 to = from + (-(tail[0]));

			if (from <= number && to >= number) {
				/* This number is already present - we don't need to do
				   anything. */
				return 0;
			}

			if (to > number) {
				/* We have found the point before which the new number
				   should be inserted. */
				break;
			}

			tail += 2;
		} else {
			/* it's a literal */
			if (*tail == number) {
				/* This number is already present - we don't need to do
				   anything. */
				return 0;
			}

			if (*tail > number) {
				/* We have found the point before which the new number
				   should be inserted. */
				break;
			}

			tail++;
		}
	}

	/* At this point, `tail' points to a position in the set which represents
	   a value greater than `new'; or it is at `end'. In the interest of
	   avoiding massive duplication of code, simply insert a literal here and
	   then run the optimizer.
	   */
	int mid = (tail - head); 

	if (m_data_size <= m_length + 1) {
		int endo = end - head;
		if (!Grow()) {
			return MK_OUT_OF_MEMORY;
		}
		head = m_data;
		end = head + endo;
	}

	if (tail == end) {
		/* at the end */
		/* Add a literal to the end. */
		m_data[m_length++] = number;
	} else {
		/* need to insert (or edit) in the middle */
		int32 i;
		for (i = size; i > mid; i--) {
			m_data[i] = m_data[i-1];
		}
		m_data[i] = number;
		m_length++;
	}

	Optimize();
	return 1;
}



int
msg_NewsArtSet::Remove(int32 number)
{
	int32 size;
	int32 *head;
	int32 *tail;
	int32 *end;

	size = m_length;
	head = m_data;
	tail = head;
	end = head + size;

	// **** I am not sure this is a right thing to comment the following
	// statements out. The reason for this is due to the implementation of
	// offline save draft and template. We use faked UIDs (negative ids) for
	// offline draft and template in order to distinguish them from real
	// UID. David I need your help here. **** jt

	// XP_ASSERT(number >= 0);
	// if (number < 0) {
	//	return -1;
	/// }

	/* We're going to modify the set, so invalidate the cache. */
	m_cached_value = -1;

	while (tail < end) {
		int32 mid = (tail - m_data);

		if (*tail < 0) {
			/* it's a range */
			int32 from = tail[1];
			int32 to = from + (-(tail[0]));

			if (number < from || number > to) {
				/* Not this range */
				tail += 2;
				continue;
			}

			if (to == from + 1) {
				/* If this is a range [N - N+1] and we are removing M
				   (which must be either N or N+1) replace it with a
				   literal. This reduces the length by 1. */
				m_data[mid] = (number == from ? to : from);
				while (++mid < m_length) {
					m_data[mid] = m_data[mid+1];
				}
				m_length--;
				Optimize();
				return 1;
			} else if (to == from + 2) {
				/* If this is a range [N - N+2] and we are removing M,
				   replace it with the literals L,M (that is, either
				   (N, N+1), (N, N+2), or (N+1, N+2). The overall
				   length remains the same. */
				m_data[mid] = from;
				m_data[mid+1] = to;
				if (from == number) {
					m_data[mid] = from+1;
				} else if (to == number) {
					m_data[mid+1] = to-1;
				}
				Optimize();
				return 1;
			} else if (from == number) {
				/* This number is at the beginning of a long range (meaning a
				   range which will still be long enough to remain a range.)
				   Increase start and reduce length of the range. */
				m_data[mid]++;
				m_data[mid+1]++;
				Optimize();
				return 1;
			} else if (to == number) {
				/* This number is at the end of a long range (meaning a range
				   which will still be long enough to remain a range.)
				   Just decrease the length of the range. */
				m_data[mid]++;
				Optimize();
				return 1;
			} else {
				/* The number being deleted is in the middle of a range which
				   must be split. This increases overall length by 2.
				   */
				int32 i;
				int endo = end - head;
				if (m_data_size - m_length <= 2) {
					if (!Grow()) return MK_OUT_OF_MEMORY;
				}
				head = m_data;
				end = head + endo;

				for (i = m_length + 2; i > mid + 2; i--) {
					m_data[i] = m_data[i-2];
				}

				m_data[mid] = (- (number - from - 1));
				m_data[mid+1] = from;
				m_data[mid+2] = (- (to - number - 1));
				m_data[mid+3] = number + 1;
				m_length += 2;

				/* Oops, if we've ended up with a range with a 0 length,
				   which is illegal, convert it to a literal, which reduces
				   the overall length by 1. */
				if (m_data[mid] == 0) {
					/* first range */
					m_data[mid] = m_data[mid+1];
					for (i = mid + 1; i < m_length; i++) {
						m_data[i] = m_data[i+1];
					}
					m_length--;
				}
				if (m_data[mid+2] == 0) {
					/* second range */
					m_data[mid+2] = m_data[mid+3];
					for (i = mid + 3; i < m_length; i++) {
						m_data[i] = m_data[i+1];
					}
					m_length--;
				}
				Optimize();
				return 1;
			}
		} else {
			/* it's a literal */
			if (*tail != number) {
				/* Not this literal */
				tail++;
				continue;
			}

			/* Excise this literal. */
			m_length--;
			while (mid < m_length) {
				m_data[mid] = m_data[mid+1];
				mid++;
			}
			Optimize();
			return 1;
		}
	}

	/* It wasn't here at all. */
	return 0;
}


static int32*
msg_emit_range(int32* tmp, int32 a, int32 b)
{
	if (a == b) {
		*tmp++ = a;
	} else {
		XP_ASSERT(a < b && a >= 0);
		*tmp++ = -(b - a);
		*tmp++ = a;
	}
	return tmp;
}


int
msg_NewsArtSet::AddRange(int32 start, int32 end)
{
	int32 tmplength;
	int32* tmp;
	int32* in;
	int32* out;
	int32* tail;
	int32 a;
	int32 b;
	XP_Bool didit = FALSE;

	/* We're going to modify the set, so invalidate the cache. */
	m_cached_value = -1;

	XP_ASSERT(start <= end);
	if (start > end) return -1;

	if (start == end) {
		return Add(start);
	}

	tmplength = m_length + 2;
	tmp = (int32*) XP_ALLOC(sizeof(int32) * tmplength);

	if (!tmp) return MK_OUT_OF_MEMORY;

	in = m_data;
	out = tmp;
	tail = in + m_length;

#define EMIT(x, y) out = msg_emit_range(out, x, y)

	while (in < tail) {
		// Set [a,b] to be this range.
		if (*in < 0) {
			b = - *in++;
			a = *in++;
			b += a;
		} else {
			a = b = *in++;
		}

		if (a <= start && b >= end) {
			// We already have the entire range marked.
			XP_FREE(tmp);
			return 0;
		}
		if (start > b + 1) {
			// No overlap yet.
			EMIT(a, b);
		} else if (end < a - 1) {
			// No overlap, and we passed it.
			EMIT(start, end);
			EMIT(a, b);
			didit = TRUE;
			break;
		} else {
			// The ranges overlap.  Suck this range into our new range, and
			// keep looking for other ranges that might overlap.
			start = start < a ? start : a;
			end = end > b ? end : b;
		}
	}
	if (!didit) EMIT(start, end);
	while (in < tail) {
		*out++ = *in++;
	}

#undef EMIT

	XP_FREE(m_data);
	m_data = tmp;
	m_length = out - tmp;
	m_data_size = tmplength;
	if (m_host) m_host->MarkDirty();
	return 1;
}

int32
msg_NewsArtSet::CountMissingInRange(int32 range_start, int32 range_end)
{
	int32 count;
	int32 *head;
	int32 *tail;
	int32 *end;

	XP_ASSERT (range_start >= 0 && range_end >= 0 && range_end >= range_start);
	if (range_start < 0 || range_end < 0 || range_end < range_start) return -1;

	head = m_data;
	tail = head;
	end = head + m_length;

	count = range_end - range_start + 1;

	while (tail < end) {
		if (*tail < 0) {
			/* it's a range */
			int32 from = tail[1];
			int32 to = from + (-(tail[0]));
			if (from < range_start) from = range_start;
			if (to > range_end) to = range_end;

			if (to >= from)
				count -= (to - from + 1);

			tail += 2;
		} else {
			/* it's a literal */
			if (*tail >= range_start && *tail <= range_end) count--;
			tail++;
		}
		XP_ASSERT (count >= 0);
	}
	return count;
}


int 
msg_NewsArtSet::FirstMissingRange(int32 min, int32 max,
								  int32* first, int32* last)
{
	int32 size;
	int32 *head;
	int32 *tail;
	int32 *end;
	int32 from = 0;
	int32 to = 0;
	int32 a;
	int32 b;

	XP_ASSERT(first && last);
	if (!first || !last) return -1;

	*first = *last = 0;

	XP_ASSERT(min <= max && min > 0);
	if (min > max || min <= 0) return -1;

	size = m_length;
	head = m_data;
	tail = head;
	end = head + size;

	while (tail < end) {
		a = to + 1;
		if (*tail < 0) {			/* We got a range. */
			from = tail[1];
			to = from + (-(tail[0]));
			tail += 2;
		} else {
			from = to = tail[0];
			tail++;
		}
		b = from - 1;
		/* At this point, [a,b] is the range of unread articles just before
		   the current range of read articles [from,to].  See if this range
		   intersects the [min,max] range we were given. */
		if (a > max) return 0;	/* It's hopeless; there are none. */
		if (a <= b && b >= min) {
			/* Ah-hah!  We found an intersection. */
			*first = a > min ? a : min;
			*last = b < max ? b : max;
			return 0;
		}
	} 
	/* We found no holes in the newsrc that overlaps the range, nor did we hit
	   something read beyond the end of the range.  So, the great infinite
	   range of unread articles at the end of any newsrc line intersects the
	   range we want, and we just need to return that. */
	a = to + 1;
	*first = a > min ? a : min;
	*last = max;
	return 0;
}

// I'm guessing we didn't include this because we didn't think we're going
// to need it. I'm not so sure. I'm putting it in for now.
int 
msg_NewsArtSet::LastMissingRange(int32 min, int32 max,
								  int32* first, int32* last)
{
  int32 size;
  int32 *head;
  int32 *tail;
  int32 *end;
  int32 from = 0;
  int32 to = 0;
  int32 a;
  int32 b;

  XP_ASSERT(first && last);
  if (!first || !last) return -1;

  *first = *last = 0;


  XP_ASSERT(min <= max && min > 0);
  if (min > max || min <= 0) return -1;

  size = m_length;
  head = m_data;
  tail = head;
  end = head + size;

  while (tail < end) {
	a = to + 1;
	if (*tail < 0) {			/* We got a range. */
	  from = tail[1];
	  to = from + (-(tail[0]));
	  tail += 2;
	} else {
	  from = to = tail[0];
	  tail++;
	}
	b = from - 1;
	/* At this point, [a,b] is the range of unread articles just before
	   the current range of read articles [from,to].  See if this range
	   intersects the [min,max] range we were given. */
	if (a > max) return 0;	/* We're done.  If we found something, it's already
							   sitting in [*first,*last]. */
	if (a <= b && b >= min) {
	  /* Ah-hah!  We found an intersection. */
	  *first = a > min ? a : min;
	  *last = b < max ? b : max;
	  /* Continue on, looking for a later range. */
	}
  }
  if (to < max) {
	/* The great infinite range of unread articles at the end of any newsrc
	   line intersects the range we want, and we just need to return that. */
	a = to + 1;
	*first = a > min ? a : min;
	*last = max;
  }
  return 0;
}




#ifdef DEBUG /* A lot of test cases for the above */

#define countof(x) (sizeof(x) / sizeof(*(x)))

void
msg_NewsArtSet::test_decoder (const char *string)
{
	msg_NewsArtSet set(string, NULL);
	char* tmp = set.Output();
	printf ("\t\"%s\"\t--> \"%s\"\n", string, tmp);
	delete [] tmp;
}


#define START(STRING) \
  string = STRING;	  \
  if (!(set = msg_NewsArtSet::Create(string))) abort ()

#define FROB(N,PUSHP)									\
  i = N;												\
  if (!(s = set->Output())) abort ();					\
  printf ("%3lu: %-58s %c %3lu =\n", set->m_length, s,	\
		  (PUSHP ? '+' : '-'), i);						\
  delete [] s;											\
  if (PUSHP												\
	  ? set->Add(i) < 0									\
	  : set->Remove(i) < 0)								\
	abort ();											\
  if (! (s = set->Output())) abort ();					\
  printf ("%3lu: %-58s optimized =\n", set->m_length, s);	\
  XP_FREE (s);											\

#define END()							   \
  if (!(s = set->Output())) abort ();	   \
  printf ("%3lu: %s\n\n", set->m_length, s); \
  delete [] s;							   \
  delete set;							   \



void
msg_NewsArtSet::test_adder (void)
{
  char *string;
  msg_NewsArtSet *set;
  char *s;
  int32 i;

  START("0-70,72-99,105,107,110-111,117-200");

  FROB(205, TRUE);
  FROB(206, TRUE);
  FROB(207, TRUE);
  FROB(208, TRUE);
  FROB(208, TRUE);
  FROB(109, TRUE);
  FROB(72, TRUE);

  FROB(205, FALSE);
  FROB(206, FALSE);
  FROB(207, FALSE);
  FROB(208, FALSE);
  FROB(208, FALSE);
  FROB(109, FALSE);
  FROB(72, FALSE);

  FROB(72, TRUE);
  FROB(109, TRUE);
  FROB(208, TRUE);
  FROB(208, TRUE);
  FROB(207, TRUE);
  FROB(206, TRUE);
  FROB(205, TRUE);

  FROB(205, FALSE);
  FROB(206, FALSE);
  FROB(207, FALSE);
  FROB(208, FALSE);
  FROB(208, FALSE);
  FROB(109, FALSE);
  FROB(72, FALSE);

  FROB(100, TRUE);
  FROB(101, TRUE);
  FROB(102, TRUE);
  FROB(103, TRUE);
  FROB(106, TRUE);
  FROB(104, TRUE);
  FROB(109, TRUE);
  FROB(108, TRUE);
  END();

  START("1-6"); FROB(7, FALSE); END();
  START("1-6"); FROB(6, FALSE); END();
  START("1-6"); FROB(5, FALSE); END();
  START("1-6"); FROB(4, FALSE); END();
  START("1-6"); FROB(3, FALSE); END();
  START("1-6"); FROB(2, FALSE); END();
  START("1-6"); FROB(1, FALSE); END();
  START("1-6"); FROB(0, FALSE); END();

  START("1-3"); FROB(1, FALSE); END();
  START("1-3"); FROB(2, FALSE); END();
  START("1-3"); FROB(3, FALSE); END();

  START("1,3,5-7,9,10"); FROB(5, FALSE); END();
  START("1,3,5-7,9,10"); FROB(6, FALSE); END();
  START("1,3,5-7,9,10"); FROB(7, FALSE); FROB(7, TRUE); FROB(8, TRUE);
  FROB (4, TRUE); FROB (2, FALSE); FROB (2, TRUE);

  FROB (4, FALSE); FROB (5, FALSE); FROB (6, FALSE); FROB (7, FALSE);
  FROB (8, FALSE); FROB (9, FALSE); FROB (10, FALSE); FROB (3, FALSE);
  FROB (2, FALSE); FROB (1, FALSE); FROB (1, FALSE); FROB (0, FALSE);
  END();
}

#undef START
#undef FROB
#undef END



#define START(STRING) \
  string = STRING;	  \
  if (!(set = msg_NewsArtSet::Create(string))) abort ()

#define FROB(N,M)												\
  i = N;														\
  j = M;														\
  if (!(s = set->Output())) abort ();							\
  printf ("%3lu: %-58s + %3lu-%3lu =\n", set->m_length, s, i, j);	\
  delete [] s;													\
  switch (set->AddRange(i, j)) {								\
  case 0:														\
	printf("(no-op)\n");										\
	break;														\
  case 1:														\
	break;														\
  default:														\
	abort();													\
  }																\
  if (!(s = set->Output())) abort ();							\
  printf ("%3lu: %-58s\n", set->m_length, s);						\
  XP_FREE (s);													\


#define END()							   \
  if (!(s = set->Output())) abort ();	   \
  printf ("%3lu: %s\n\n", set->m_length, s); \
  delete [] s;							   \
  delete set;


void
msg_NewsArtSet::test_ranges(void)
{
  char *string;
  msg_NewsArtSet *set;
  char *s;
  int32 i;
  int32 j;

  START("20-40,72-99,105,107,110-111,117-200");

  FROB(205, 208);
  FROB(50, 70);
  FROB(0, 10);
  FROB(112, 113);
  FROB(101, 101);
  FROB(5, 75);
  FROB(103, 109);
  FROB(2, 20);
  FROB(1, 9999);

  END();


#undef START
#undef FROB
#undef END
}




#define TEST(N)									  \
  if (! with_cache) set->m_cached_value = -1;	  \
  if (!(s = set->Output())) abort ();			  \
  printf (" %3d = %s\n", N,						  \
		  (set->IsMember(N) ? "true" : "false")); \
  delete [] s

void
msg_NewsArtSet::test_member(XP_Bool with_cache)
{
  msg_NewsArtSet *set;
  char *s;

  s = "1-70,72-99,105,107,110-111,117-200";
  printf ("\n\nTesting %s (with%s cache)\n", s, with_cache ? "" : "out");
  if (!(set = Create(s))) {
	abort ();
  }

  TEST(-1);
  TEST(0);
  TEST(1);
  TEST(20);
  
  delete set;
  s = "0-70,72-99,105,107,110-111,117-200";
  printf ("\n\nTesting %s (with%s cache)\n", s, with_cache ? "" : "out");
  if (!(set = Create(s))) {
	abort ();
  }
  
  TEST(-1);
  TEST(0);
  TEST(1);
  TEST(20);
  TEST(69);
  TEST(70);
  TEST(71);
  TEST(72);
  TEST(73);
  TEST(74);
  TEST(104);
  TEST(105);
  TEST(106);
  TEST(107);
  TEST(108);
  TEST(109);
  TEST(110);
  TEST(111);
  TEST(112);
  TEST(116);
  TEST(117);
  TEST(118);
  TEST(119);
  TEST(200);
  TEST(201);
  TEST(65535);

  delete set;
}

#undef TEST


// static void
// test_newsrc (char *file)
// {
//   FILE *fp = fopen (file, "r");
//   char buf [1024];
//   if (! fp) abort ();
//   while (fgets (buf, sizeof (buf), fp))
// 	{
// 	  if (!strncmp (buf, "options ", 8))
// 		fwrite (buf, 1, strlen (buf), stdout);
// 	  else
// 		{
// 		  char *sep = buf;
// 		  while (*sep != 0 && *sep != ':' && *sep != '!')
// 			sep++;
// 		  if (*sep) sep++;
// 		  while (isspace (*sep)) sep++;
// 		  fwrite (buf, 1, sep - buf, stdout);
// 		  if (*sep)
// 			{
// 			  char *s;
// 			  msg_NewsRCSet *set = msg_parse_newsrc_set (sep, &allocinfo);
// 			  if (! set)
// 				abort ();
// 			  if (! msg_OptimizeNewsRCSet (set))
// 				abort ();
// 			  if (! ((s = msg_format_newsrc_set (set))))
// 				abort ();
// 			  msg_free_newsrc_set (set, &allocinfo);
// 			  fwrite (s, 1, strlen (s), stdout);
// 			  free (s);
// 			  fwrite ("\n", 1, 1, stdout);
// 			}
// 		}
// 	}
//   fclose (fp);
// }

void
msg_NewsArtSet::RunTests ()
{

  test_decoder ("");
  test_decoder (" ");
  test_decoder ("0");
  test_decoder ("1");
  test_decoder ("123");
  test_decoder (" 123 ");
  test_decoder (" 123 4");
  test_decoder (" 1,2, 3, 4");
  test_decoder ("0-70,72-99,100,101");
  test_decoder (" 0-70 , 72 - 99 ,100,101 ");
  test_decoder ("0 - 268435455");
  /* This one overflows - we can't help it.
	 test_decoder ("0 - 4294967295"); */

  test_adder ();

  test_ranges();

  test_member (FALSE);
  test_member (TRUE);

  // test_newsrc ("/u/montulli/.newsrc");
  /* test_newsrc ("/u/jwz/.newsrc");*/
}

#endif /* DEBUG */