[m-rev.] diff: implement concat_string_list for .NET

[Fergus Henderson]

On 14-Feb-2003, Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> On 14-Feb-2003, Zoltan Somogyi <zs at cs.mu.OZ.AU> wrote:
> > On 13-Feb-2003, Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> 
> > > +% This version is only used if there is no matching foreign_proc version.
> > > +% XXX why is this implemented in C anyway?  Why not just use Mercury?
> > > +concat_string_list(StringsList, _Len, String) :-
> > > +	String = string__append_list(StringsList).
> > 
> > This Mercury implementation therefore has a very subtle bug.
> 
> Well, actually that code will work fine on .NET and Java,
> since on those platforms, strings can contain embedded NUL characters.

Sorry, I was wrong about that.  I didn't realize that `concat_string_list'
doesn't just concatenate the strings, it also includes their terminating
nulls.  So the diff that I posted earlier won't work.  But I have a new
version that will -- see below.  I've also modified the code so that
it checks if the Mercury string representation can support embedded
nulls, and calls sorry/1 if it can't.

I'm going to go ahead and commit this.

----------

Estimated hours taken: 2
Branches: main

compiler/stack_layout.m:
	Implement concat_strings in Mercury.

compiler/layout.m:
compiler/layout_out.m:
compiler/stack_layout.m:
	Use a separate type `string_with_0s' rather than `string'
	for strings which may contain null characters.

Workspace: /home/fjh/ws/hermes
Index: compiler/layout.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/layout.m,v
retrieving revision 1.10
diff -u -d -r1.10 layout.m
--- compiler/layout.m	15 Nov 2002 04:50:22 -0000	1.10
+++ compiler/layout.m	16 Feb 2003 01:54:44 -0000
@@ -39,6 +39,9 @@
 :- import_module libs__trace_params.
 :- import_module bool, std_util, list, assoc_list.
 
+	% This type is for strings which may contain embedded null characters.
+:- type string_with_0s ---> string_with_0s(string).
+
 :- type layout_data
 	--->	label_layout_data(		% defines MR_Label_Layout
 			label			:: label,
@@ -56,7 +59,7 @@
 	;	module_layout_data(		% defines MR_Module_Layout
 			module_name		:: module_name,
 			string_table_size	:: int,
-			string_table		:: string,
+			string_table		:: string_with_0s,
 			proc_layout_names	:: list(layout_name),
 			file_layouts		:: list(file_layout_data),
 			trace_level		:: trace_level,
Index: compiler/layout_out.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/layout_out.m,v
retrieving revision 1.17
diff -u -d -r1.17 layout_out.m
--- compiler/layout_out.m	15 Nov 2002 04:50:22 -0000	1.17
+++ compiler/layout_out.m	16 Feb 2003 01:54:44 -0000
@@ -931,7 +931,7 @@
 %-----------------------------------------------------------------------------%
 
 :- pred output_module_layout_data_defn(module_name::in, int::in,
-	string::in, list(layout_name)::in, list(file_layout_data)::in,
+	string_with_0s::in, list(layout_name)::in, list(file_layout_data)::in,
 	trace_level::in, int::in, decl_set::in, decl_set::out,
 	io__state::di, io__state::uo) is det.
 
@@ -1006,7 +1006,7 @@
 	% empty string.
 
 :- pred output_module_string_table(module_name::in,
-	int::in, string::in, decl_set::in, decl_set::out,
+	int::in, string_with_0s::in, decl_set::in, decl_set::out,
 	io__state::di, io__state::uo) is det.
 
 output_module_string_table(ModuleName, StringTableSize, StringTable,
@@ -1020,15 +1020,16 @@
 	{ decl_set_insert(DeclSet0, data_addr(layout_addr(TableName)),
 		DeclSet) }.
 
-:- pred output_module_string_table_chars(int::in, int::in, string::in,
+:- pred output_module_string_table_chars(int::in, int::in, string_with_0s::in,
 	io__state::di, io__state::uo) is det.
 
-output_module_string_table_chars(CurIndex, MaxIndex, String) -->
+output_module_string_table_chars(CurIndex, MaxIndex, StringWithNulls) -->
 	( { CurIndex mod 16 = 0 } ->
 		io__write_string("\n\t")
 	;
 		[]
 	),
+	{ StringWithNulls = string_with_0s(String) },
 	{ string__unsafe_index(String, CurIndex, Char) },
 	io__write_char(''''),
 	c_util__output_quoted_char(Char),
@@ -1036,7 +1037,7 @@
 	( { CurIndex < MaxIndex } ->
 		io__write_string(", "),
 		output_module_string_table_chars(CurIndex + 1, MaxIndex,
-			String)
+			StringWithNulls)
 	;
 		[]
 	).
Index: compiler/stack_layout.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/stack_layout.m,v
retrieving revision 1.73
diff -u -d -r1.73 stack_layout.m
--- compiler/stack_layout.m	15 Nov 2002 04:50:28 -0000	1.73
+++ compiler/stack_layout.m	16 Feb 2003 01:54:44 -0000
@@ -58,7 +58,7 @@
 :- import_module backend_libs__rtti, ll_backend__layout.
 :- import_module ll_backend__ll_pseudo_type_info, (parse_tree__inst).
 :- import_module ll_backend__code_util.
-:- import_module assoc_list, bool, string, int, require.
+:- import_module assoc_list, bool, char, string, int, require.
 :- import_module map, term, set, varset.
 
 %---------------------------------------------------------------------------%
@@ -151,8 +151,11 @@
 
 %---------------------------------------------------------------------------%
 
+	% concat_string_list appends a list of strings together,
+	% appending a null character after each string.
+	% The resulting string will contain embedded null characters.
 :- pred stack_layout__concat_string_list(list(string)::in, int::in,
-	string::out) is det.
+	string_with_0s::out) is det.
 
 :- pragma c_header_code("
 	#include ""mercury_tags.h""	/* for MR_list_*() */
@@ -192,6 +195,25 @@
 		MR_fatal_error(msg);
 	}
 }").
+
+% This version is only used if there is no matching foreign_proc version.
+% Note that this version only works if the Mercury implementation's
+% string representation allows strings to contain embedded null
+% characters.  So we check that.
+concat_string_list(StringsList, _Len, string_with_0s(StringWithNulls)) :-
+	(	
+		char__to_int(NullChar, 0),
+		NullCharString = string__char_to_string(NullChar),
+		string__length(NullCharString, 1)
+	->
+		StringsWithNullsList = list__map(func(S) = S ++ NullCharString,
+			StringsList),
+		StringWithNulls = string__append_list(StringsWithNullsList)
+	;
+		% the Mercury implementation's string representation
+		% doesn't support strings containing null characters
+		private_builtin.sorry("stack_layout.concat_string_list")
+	).
 
 %---------------------------------------------------------------------------%
 

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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