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mercury/doc/squeeze
Zoltan Somogyi d9122a1b30 Document I/O tabling, after cleaning it up for public use.
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Document I/O tabling, after cleaning it up for public use.

We have previously implemented two forms of I/O tabling. One tables
only the output arguments of each primitive; this allows transparent
retries across I/O. The other tables all the arguments and the name
of the predicate; this allows transparent retries across I/O, the
declarative debugging of code that does I/O, and the printing of tabled
I/O actions. Since we now support declarative debugging in the standard
debugging grades, standardize on the second form of I/O tabling, and
make the first form accessible to implementors only, via a deliberately
undocumented option. This option, --trace-table-io-only-retry, is sort of
the inverse of the old option --trace-table-io-decl, which this change
deletes. (Only "sort of" because --trace-table-io-decl used to turn on
I/O tabling, whereas --trace-table-io-only-retry is consulted only if
I/O tabling is turned on by some other mechanism.)

NEWS:
	Mention I/O tabling.

compiler/options.m:
	Delete --trace-table-io-decl, and add --trace-table-io-only-retry.

	Update documentation.

compiler/table_gen.m:
	Base decisions on --trace-table-io-only-retry, not
	--trace-table-io-decl.

compiler/handle_options.m:
	Delete an implication involving --trace-table-io-decl that is now
	unnecessary.

doc/user_guide.texi:
	Document the idea of I/O tabling, and move the table_io command
	out of the list of developer only commands into a category of its own
	(since it doesn't naturally fit anywhere else).

	Change the old mismatched "table_io start" "table_io end" pair to
	the matched "table_io start" "table_io stop" pair.

	Document the variants of the print and browse commands that print and
	browse I/O actions.

	Be consistent about formatting of categories of mdb commands.

	Comment out some obsolete material in the documentation of retry.

doc/generate_mdb_doc:
	Include the new table_io category in the list of mdb command
	categories.

	Squeeze out repeated blank lines in the automatically generated
	documentation, to make maximum use of screen real estate.

doc/squeeze:
	A new script to do the squeezing.

doc/mdb_categories:
	Include the new table_io category in the list of mdb command
	categories.

runtime/mercury_trace_base.[ch]:
	Add a new global variable MR_io_tabling_allowed. It is initialized
	to TRUE in debugging grades and FALSE in other grades.

trace/mercury_trace_internal.c:
	Accept "table_io begin" and "table_io end" as well as "table_io start"
	and "table_io stop". Consistently use "start" and "stop" in output.

	Make "table_io" print a message saying the executable is not set up
	for I/O tabling unless MR_io_tabling_allowed is set.

	Add a new command, "table allow", that sets MR_io_tabling_allowed to
	TRUE. In debugging grades, this has no effect. In other grades, it
	allows I/O tabling, even though some parts of the program may have
	been compiled with --trace-table-io and some without. This
	inconsistency can yield weird results, which is why this command is
	deliberately undocumented. However, we can use it in a disciplined
	fashion to test I/O tabling even in nondebugging grades, thus spotting
	any regression in this area more quickly than if we tested I/O tabling
	only in debugging grades.

tests/debugger/Mercury.options:
tests/debugger/declarative/Mercury.options:
	Delete all occurrences of --trace-table-io-decl, since its effect is
	now the default.

tests/debugger/mdb_command_test.inp:
	Move the location of the table_io command test in this autogenerated
	file to reflect its move to a new category.

tests/debugger/tabled_read*.{inp,exp}:
tests/debugger/declarative/tabled_read*.{inp,exp}:
	Execute "table_io allow" before trying to turn on I/O tabling, since
	this is now required in non-debugging grades.

	Reflect the change in terminology: expect "stopped", not "ended",
2002-10-22 04:36:26 +00:00

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#!/bin/sh
#---------------------------------------------------------------------------#
# Copyright (C) 2002 The University of Melbourne.
# This file may only be copied under the terms of the GNU General
# Public License - see the file COPYING in the Mercury distribution.
#---------------------------------------------------------------------------#
# Replace any sequence of blank lines in the input with a single blank line.
# If invoked with arguments, the input is the concatenation of the named files;
# if invoked without arguments, the input is standard input.
awk '
$0 ~ /^[ \t]*$/ {
if (empties == 0)
print;
empties++;
}
$0 !~ /^[ \t]*$/ {
empties = 0;
print;
}
' $@