Backend_Memory works: desired behaviour implented.

Author: cnngimenez

src/libraries/apagerlib/apagerlib-backend.adb

@@ -19,6 +19,8 @@
 
 -------------------------------------------------------------------------
 
+with Ada.Exceptions;
+use Ada.Exceptions;
 with Ada.Characters.Latin_1;
 
 package body Apagerlib.Backend is
@@ -68,7 +70,10 @@ package body Apagerlib.Backend is
         end loop;
 
         exception
-        when No_More_Char => raise No_Line_Found;
+        when Exc : No_More_Char =>
+            Raise_Exception (No_Line_Found'Identity,
+                "Next_Line could not find new line because: " &
+                Exception_Message (Exc));
     end Next_Line;
 
     function Next_Line_Position (Stream : in out Backend_Stream'Class;
@@ -103,13 +108,15 @@ package body Apagerlib.Backend is
             raise No_Line_Found;
         end if;
 
-        while Stream.Current_Position > 1 and then C /= LF and then C /= CR
-        loop
+        while C /= LF and then C /= CR loop
             C := Stream.Previous_Char;
         end loop;
 
         exception
-        when No_More_Char => return;
+        when Exc : No_More_Char =>
+            Raise_Exception (No_Line_Found'Identity,
+                "Could not find previous line beacuse: "
+                & Exception_Message (Exc));
     end Previous_Line;
 
     function Previous_Line_Position (Stream : in out Backend_Stream'Class;

src/libraries/apagerlib/apagerlib-memories.adb

@@ -262,7 +262,8 @@ package body Apagerlib.Memories is
                 Memory.Current_BIP := Page_Limit;
             else
                 --  No previous page!
-                raise No_Byte_Found;
+                Raise_Exception (No_More_Char'Identity,
+                    "Could not find previous character at first position.");
             end if;
         end if;
     end Previous_Char;

src/tools/apager_backend_test.adb

@@ -19,6 +19,8 @@
 
 -------------------------------------------------------------------------
 
+with Ada.Exceptions;
+use Ada.Exceptions;
 with Ada.Text_IO; use Ada.Text_IO;
 with Ada.Command_Line; use Ada.Command_Line;
 with Apagerlib.Backend; use Apagerlib.Backend;
@@ -61,6 +63,15 @@ procedure Apager_Backend_Test is
             Memory.Next_Line;
             Put (Memory.Current_Position'Image);
         end loop;
+
+        exception
+        when Exc : Apagerlib.Backend.No_Line_Found =>
+            Put (" ");
+            if Memory.End_Of_File then
+                Put_Line ("No new line character at end of file.");
+            else
+                Put_Line (Exception_Message (Exc));
+            end if;
     end Print_Next_Line;
 
     procedure Print_Next_Line_Function is
@@ -76,10 +87,20 @@ procedure Apager_Backend_Test is
     begin
         Memory.End_Position;
 
+        --  Beware: if the End_Position is a new line it will not be printed.
         while Memory.Current_Position > 1 loop
             Memory.Previous_Line;
             Put (Memory.Current_Position'Image);
         end loop;
+
+        exception
+        when Exc : Apagerlib.Backend.No_Line_Found =>
+            Put (" ");
+            if Memory.Current_Position = 1 then
+                Put_Line ("No new line character at beginning of file.");
+            else
+                Put_Line (Exception_Message (Exc));
+            end if;
     end Print_Previous_Line;
 
     procedure Print_Previous_Line_Function is