3 files changed, 201 insertions, 0 deletions
diff --git a/src/packrat-errors.adb b/src/packrat-errors.adb
new file mode 100644
index 0000000..44b9202
--- /dev/null
+++ b/src/packrat-errors.adb
@@ -0,0 +1,105 @@
+
+
+separate (Packrat)
+package body Errors is
+
+
+    package SU renames Ada.Strings.Unbounded;
+
+
+
+
+
+    function Valid_Identifier
+           (Check : in String)
+        return Boolean is
+    begin
+        return True;
+    end Valid_Identifier;
+
+
+    function Valid_Identifier
+           (Check : in SU.Unbounded_String)
+        return Boolean is
+    begin
+        return True;
+    end Valid_Identifier;
+
+
+    function Valid_Identifier_Array
+           (Check : in Error_Info_Array)
+        return Boolean is
+    begin
+        return True;
+    end Valid_Identifier_Array;
+
+
+    function Valid_Message
+           (Check : in String)
+        return Boolean is
+    begin
+        return True;
+    end Valid_Message;
+
+
+
+
+
+    function Join
+           (Left, Right : in Error_Message)
+        return Error_Message is
+    begin
+        return "";
+    end Join;
+
+
+
+
+
+    function Encode
+           (Name : in String;
+            Pos  : in Natural)
+        return Error_Message is
+    begin
+        return "";
+    end Encode;
+
+
+    function Encode
+           (Name : in SU.Unbounded_String;
+            Pos  : in Natural)
+        return Error_Message is
+    begin
+        return "";
+    end Encode;
+
+
+    function Encode
+           (Info : in Error_Info)
+        return Error_Message is
+    begin
+        return "";
+    end Encode;
+
+
+    function Encode_Array
+           (Info : in Error_Info_Array)
+        return Error_Message is
+    begin
+        return "";
+    end Encode_Array;
+
+
+    function Decode
+           (Msg : in Error_Message)
+        return Error_Info_Array
+    is
+        Result : Error_Info_Array (1 .. 0);
+    begin
+        return Result;
+    end Decode;
+
+
+end Errors;
+
+
diff --git a/src/packrat.adb b/src/packrat.adb
new file mode 100644
index 0000000..e78d0ae
--- /dev/null
+++ b/src/packrat.adb
@@ -0,0 +1,11 @@
+
+
+package body Packrat is
+
+
+    package body Errors is separate;
+
+
+end Packrat;
+
+
diff --git a/src/packrat.ads b/src/packrat.ads
index 36410d5..628923f 100644
--- a/src/packrat.ads
+++ b/src/packrat.ads
@@ -1,8 +1,93 @@
 
 
+with
+
+    Ada.Strings.Unbounded;
+
+
 package Packrat is
 
 
+    Parse_Error : exception;
+
+
+
+
+    package Errors is
+
+
+        subtype Error_Message is String
+            with Dynamic_Predicate => Valid_Message (Error_Message);
+
+        type Error_Info is record
+            Symbol   : Ada.Strings.Unbounded.Unbounded_String;
+            Position : Natural;
+        end record;
+
+        type Error_Info_Array is array (Positive range <>) of Error_Info;
+
+
+        --  Note: No consideration is given to ordering of Error_Info items
+        --        encoded into an Error_Message string.
+
+        --  Note: Using "&" to join two Valid Error_Messages together
+        --        will result in an Error_Message that is also Valid,
+        --        but for best results Join should be used instead to
+        --        prevent duplication of Error_Info in the message.
+
+
+        function Valid_Identifier
+               (Check : in String)
+            return Boolean;
+
+        function Valid_Identifier
+               (Check : in Ada.Strings.Unbounded.Unbounded_String)
+            return Boolean;
+
+        function Valid_Identifier_Array
+               (Check : in Error_Info_Array)
+            return Boolean;
+
+        function Valid_Message
+               (Check : in String)
+            return Boolean;
+
+
+        function Join
+               (Left, Right : in Error_Message)
+            return Error_Message;
+
+
+        function Encode
+               (Name : in String;
+                Pos  : in Natural)
+            return Error_Message
+            with Pre => Valid_Identifier (Name);
+
+        function Encode
+               (Name : in Ada.Strings.Unbounded.Unbounded_String;
+                Pos  : in Natural)
+            return Error_Message
+            with Pre => Valid_Identifier (Name);
+
+        function Encode
+               (Info : in Error_Info)
+            return Error_Message
+            with Pre => Valid_Identifier (Info.Symbol);
+
+        function Encode_Array
+               (Info : in Error_Info_Array)
+            return Error_Message
+            with Pre => Valid_Identifier_Array (Info);
+
+        function Decode
+               (Msg : in Error_Message)
+            return Error_Info_Array;
+
+
+    end Errors;
+
+
 private