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-- This source is licensed under the Sunset License v1.0
with
Ada.Text_IO,
Ada.Strings.Unbounded,
Ada.Strings.Maps,
Ada.Command_Line,
Packrat.Standard,
Packrat.Utilities;
use
Ada.Text_IO;
procedure Simple_Calc is
type Lexer_Labels is (Whitespace, Number, Operator);
type Parser_Labels is (Sum, Factor);
package My_Rat is new Packrat.Standard
(Lexer_Labels, Parser_Labels, Character, String);
-- Lexer Grammar
-- <number> ::= <digits>
-- <digits> ::= <zerotonine> <digits> | <zerotonine>
-- <zerotonine> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
function Is_Operator is new Packrat.Utilities.In_Set
(Ada.Strings.Maps.To_Set ("+-"));
function Sat_Operator is new My_Rat.Lexers.Satisfy (Is_Operator);
function Operator is new My_Rat.Lexers.Stamp (Operator, Sat_Operator);
function Sat_Digit is new My_Rat.Lexers.Satisfy (Packrat.Utilities.Is_Digit);
function Some_Digits is new My_Rat.Lexers.Many (Sat_Digit, 1);
function Number is new My_Rat.Lexers.Stamp (Number, Some_Digits);
function Sat_Blank is new My_Rat.Lexers.Satisfy (Packrat.Utilities.Is_Whitespace);
function Many_Blank is new My_Rat.Lexers.Many (Sat_Blank, 1);
function Whitespace is new My_Rat.Lexers.Discard (Whitespace, Many_Blank);
package Scanner is new My_Rat.Lexers.Scan_Once
((Whitespace'Access, Number'Access, Operator'Access));
-- Parser Grammar
-- <expr> ::= <sum> <endofinput>
-- <sum> ::= <sum> + <factor> | <sum> - <factor> | <factor>
-- <factor> ::= <number>
package Sum_Redir is new My_Rat.Parsers.Redirect;
function Is_Number is new My_Rat.Lexer_Tokens.Is_Label (Number);
function Sat_Number is new My_Rat.Parsers.Satisfy (Is_Number);
function Factor is new My_Rat.Parsers.Stamp (Factor, Sat_Number);
function Is_Minus is new My_Rat.Lexer_Tokens.Is_Value ("-");
function Sat_Minus is new My_Rat.Parsers.Satisfy (Is_Minus);
function Is_Plus is new My_Rat.Lexer_Tokens.Is_Value ("+");
function Sat_Plus is new My_Rat.Parsers.Satisfy (Is_Plus);
function Sum_Plus is new My_Rat.Parsers.Sequence
((Sum_Redir.Call'Access, Sat_Plus'Access, Factor'Access));
function Sum_Minus is new My_Rat.Parsers.Sequence
((Sum_Redir.Call'Access, Sat_Minus'Access, Factor'Access));
function Sum_Choice is new My_Rat.Parsers.Choice
((Sum_Plus'Access, Sum_Minus'Access, Factor'Access));
function Sum is new My_Rat.Parsers.Stamp (Sum, Sum_Choice);
function Expr is new My_Rat.Parsers.Sequence_2 (Sum, My_Rat.Parsers.End_Of_Input);
package Parser is new My_Rat.Parsers.Parse_Once (Expr);
type Calc_Result is delta 10.0**(-9) digits 18;
function Value
(Tok : in My_Rat.Parser_Tokens.Finished_Token_Type)
return String
is
Lexed : My_Rat.Lexer_Tokens.Token_Array :=
My_Rat.Parser_Tokens.Value (Tok.Token);
begin
if Lexed'Length = 0 then
return "";
else
return My_Rat.Lexer_Tokens.Value (Lexed (Lexed'First));
end if;
end Value;
function Element
(Subs : in My_Rat.Parse_Graphs.Token_Group_Array;
Ind : in Positive)
return My_Rat.Parser_Tokens.Finished_Token_Type is
begin
return My_Rat.Parse_Graphs.Element (Subs (Subs'First), Ind);
end Element;
function Evaluate
(Graph : in My_Rat.Parser_Result;
Position : in My_Rat.Parser_Tokens.Finished_Token_Type)
return Calc_Result
is
Subgroups : My_Rat.Parse_Graphs.Token_Group_Array := Graph.Subgroups (Position);
begin
case My_Rat.Parser_Tokens.Label (Position.Token) is
when Sum =>
if Value (Position) = "+" then
return Evaluate (Graph, Element (Subgroups, 1)) +
Evaluate (Graph, Element (Subgroups, 2));
elsif Value (Position) = "-" then
return Evaluate (Graph, Element (Subgroups, 1)) -
Evaluate (Graph, Element (Subgroups, 2));
else
return Evaluate (Graph, Element (Subgroups, 1));
end if;
when Factor =>
return Calc_Result (Integer'Value (Value (Position)));
end case;
end Evaluate;
function Image
(Val : in Calc_Result)
return String is
begin
return Val'Image;
end Image;
package SU renames Ada.Strings.Unbounded;
package Comlin renames Ada.Command_Line;
Comlin_Input : SU.Unbounded_String;
Silent_Running : Boolean := False;
Real_Arg_Count : Natural := 0;
begin
Sum_Redir.Set (Sum'Access);
for I in 1 .. Comlin.Argument_Count loop
if Comlin.Argument (I) /= "--silent" then
Real_Arg_Count := Real_Arg_Count + 1;
end if;
end loop;
if Real_Arg_Count = 0 then
Put_Line ("Simplified Command Line Calculator");
New_Line;
Put_Line ("This program calculates elementary mathematical");
Put_Line ("expressions it receives as command line arguments.");
Put_Line ("Naturally, it needs you to supply arguments for that.");
Put_Line ("You may have to use quotes to ensure the shell doesn't mess with input.");
New_Line;
Put_Line ("Accepted operators are + -");
Put_Line ("Please ensure all numbers are positive integers.");
New_Line;
Put_Line ("If you do not want to see any output beyond the answer,");
Put_Line ("then use the --silent switch.");
return;
end if;
for I in 1 .. Comlin.Argument_Count loop
if Comlin.Argument (I) = "--silent" then
Silent_Running := True;
else
SU.Append (Comlin_Input, Comlin.Argument (I) & " ");
end if;
end loop;
SU.Delete (Comlin_Input, SU.Length (Comlin_Input), SU.Length (Comlin_Input));
declare
Input : String := SU.To_String (Comlin_Input);
Lexed_Tokens : My_Rat.Lexer_Result := Scanner.Scan (Input);
Result_Graph : My_Rat.Parser_Result := Parser.Parse (Lexed_Tokens);
Calculated : Calc_Result := Evaluate (Result_Graph, Result_Graph.Root_Elements (1));
begin
if Silent_Running then
Put_Line (Image (Calculated));
return;
end if;
Put_Line ("Input:");
Put_Line (Input);
New_Line;
Put_Line ("Lexer token output:");
for T of Lexed_Tokens loop
Put (My_Rat.Lexer_Tokens.Debug_String (T));
end loop;
New_Line;
Put_Line ("Parser graph output:");
Put_Line (My_Rat.Parse_Graphs.Debug_String (Result_Graph));
New_Line;
Put_Line ("Root tokens:");
for T of Result_Graph.Root_Elements loop
Put (My_Rat.Parser_Tokens.Debug_String (T));
end loop;
New_Line;
Put_Line ("Calculated result:");
Put_Line (Image (Calculated));
end;
end Simple_Calc;
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