[m-rev.] For review: Added cdr command to interactive term browser

[Ian MacLarty]

For review by anyone.

Estimated hours taken: 1
Branches: main

Added a `cdr' command to the interactive term browser.  This repeatedly cd's
into a path and is useful for accessing deep structures (like long lists).

browser/browse.m
	Rewrote simplify_dirs predicate which removes redundant `..' 
	directories.  The previous method was too inefficient and caused
	commands like `cdr 10000 ..' to take a long time.
	Added help text.

browser/parse.m
	Added handler for `cdr' command which is just translated into a `cd'
	command with the path repeated the appropriate number of times.

tests/debugger/browser_test.inp
tests/debugger/browser_test.exp
	Added test for cdr command.

Index: browser/browse.m
===================================================================
RCS file: /home/mercury1/repository/mercury/browser/browse.m,v
retrieving revision 1.44
diff -u -r1.44 browse.m
--- browser/browse.m	9 Aug 2004 03:05:19 -0000	1.44
+++ browser/browse.m	21 Oct 2004 23:58:26 -0000
@@ -556,6 +556,7 @@
 "\t[print|p|ls] [format_options] [path]\n",
 "\t               -- print the specified subterm using the `browse' params\n",
 "\tcd [path]      -- cd to the specified subterm (default is root)\n",
+"\tcdr n path     -- repeatedly cd's into the path n times\n",
 "\tpwd            -- print the path to the current subterm\n",
 "\tset [setting_options] var value\n",
 "\t               -- set a parameter value\n",
@@ -1471,34 +1472,35 @@
 
 	% Remove "/dir/../" sequences from a list of directories to yield
 	% a form that lacks ".." entries.
-	% NB: This can be done more efficiently than simple iteration
-	% to a limit.
+	%
 :- pred simplify_dirs(list(dir)::in, list(dir)::out) is det.
 
 simplify_dirs(Dirs, SimpleDirs) :-
-	util__limit(simplify, Dirs, SimpleDirs).
+	list.reverse(Dirs, RevDirs),
+	simplify_rev_dirs(RevDirs, 0, [], SimpleDirs).
 
-	% If possible, remove a single occurence of
-	% either:
-	%	- "dir/../"
-	% or:
-	%	- "/.." (parent of root is root)
+	% simplify_rev_dirs(RevDirs, N, SoFar, SimpleDirs).
+	% Assumes a reverse list of directories and removes redundant `..'
+	% entries by scanning from the bottom most directory to the top,
+	% counting how many `..' occured (N) and removing entries accordingly.
+	% SoFar accumulates the simplified dirs processed so far so we can be
+	% tail recursive.
 	%
-:- pred simplify(list(dir)::in, list(dir)::out) is det.
+:- pred simplify_rev_dirs(list(dir)::in, int::in, list(dir)::in, 
+	list(dir)::out) is det.
 
-simplify([], []).
-simplify([First | Rest], Simplified) :-
-	( First = parent ->
-		Simplified = Rest
-	; Rest = [] ->
-		Simplified = [First]
-	; Rest = [parent | Tail] ->
-		Simplified = Tail
+simplify_rev_dirs([], _, SimpleDirs, SimpleDirs).
+simplify_rev_dirs([Dir | Dirs], N, SoFar, SimpleDirs) :-
+	( Dir = parent ->
+		simplify_rev_dirs(Dirs, N+1, SoFar, SimpleDirs)
 	;
-		simplify(Rest, SimplifiedRest),
-		Simplified = [First | SimplifiedRest]
+		( N > 0 ->
+			simplify_rev_dirs(Dirs, N-1, SoFar, SimpleDirs)
+		;
+			simplify_rev_dirs(Dirs, N, [Dir | SoFar], SimpleDirs)
+		)
 	).
-
+	
 :- func dir_to_string(dir) = string.
 
 dir_to_string(parent) = "..".
Index: browser/parse.m
===================================================================
RCS file: /home/mercury1/repository/mercury/browser/parse.m,v
retrieving revision 1.19
diff -u -r1.19 parse.m
--- browser/parse.m	2 Sep 2004 04:03:50 -0000	1.19
+++ browser/parse.m	21 Oct 2004 14:11:29 -0000
@@ -347,6 +347,14 @@
 			Command = cd(Path)
 		)
 	;
+		CmdToken = name("cdr")
+	->
+		ArgTokens = [num(Repetitions) | TokenPath],
+		list.duplicate(Repetitions, TokenPath, DupTokenPath),
+		list.condense(DupTokenPath, RepeatedTokenPath),
+		parse_path(RepeatedTokenPath, RepeatedPath),
+		Command = cd(RepeatedPath)
+	;
 		CmdToken = name("pwd")
 	->
 		ArgTokens = [],
Index: tests/debugger/browser_test.exp
===================================================================
RCS file: /home/mercury1/repository/tests/debugger/browser_test.exp,v
retrieving revision 1.17
diff -u -r1.17 browser_test.exp
--- tests/debugger/browser_test.exp	13 May 2004 08:50:31 -0000	1.17
+++ tests/debugger/browser_test.exp	21 Oct 2004 23:45:04 -0000
@@ -94,6 +94,15 @@
   big(big(small, 1, small), 2, small), 
   3, 
   big(big(small, 4, big(small, 5, small)), 6, small))
+browser> cdr 3 1
+browser> ls
+small
+browser> cdr 3 ../1/..
+browser> ls
+big(
+  big(big(small, 1, small), 2, small), 
+  3, 
+  big(big(small, 4, big(small, 5, small)), 6, small))
 browser> quit
 mdb> set -A -f depth 1
 mdb> print *
Index: tests/debugger/browser_test.inp
===================================================================
RCS file: /home/mercury1/repository/tests/debugger/browser_test.inp,v
retrieving revision 1.9
diff -u -r1.9 browser_test.inp
--- tests/debugger/browser_test.inp	13 May 2004 08:50:31 -0000	1.9
+++ tests/debugger/browser_test.inp	21 Oct 2004 14:17:02 -0000
@@ -30,6 +30,10 @@
 ls
 cd
 ls
+cdr 3 1
+ls
+cdr 3 ../1/..
+ls
 quit
 set -A -f depth 1
 print *
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