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package body Packrat.Lexer.Combinators is
function Sequence
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result
is
Result : Combinator_Result := Create_Result (0, Success, Empty_Array);
Position : Positive := Start;
begin
if Start > Input'Last then
return Empty_Fail;
end if;
for C of Params loop
if Position > Input'Last then
Result.Status := Needs_More;
exit;
end if;
Result := Result.Join (C (Input, Position));
exit when Result.Status = Failure;
Position := Start + Result.Length;
end loop;
return Result;
end Sequence;
function Count
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result
is
Result : Combinator_Result := Create_Result (0, Success, Empty_Array);
Position : Positive := Start;
begin
if Start > Input'Last then
return Empty_Fail;
end if;
for I in Integer range 1 .. Number loop
if Position > Input'Last then
Result.Status := Needs_More;
exit;
end if;
Result := Result.Join (Param (Input, Position));
exit when Result.Status = Failure;
Position := Start + Result.Length;
end loop;
return Result;
end Count;
function Many
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result
is
Result : Combinator_Result := Create_Result (0, Success, Empty_Array);
Temp : Combinator_Result;
Position : Positive := Start;
Counter : Natural := 0;
begin
if Start > Input'Last then
return Empty_Fail;
end if;
loop
Temp := Param (Input, Position);
exit when Temp.Status = Failure;
if Temp.Status = Needs_More then
Result.Status := Optional_More;
exit;
end if;
Result := Result.Join (Temp);
Counter := Counter + 1;
Position := Start + Result.Length;
if Position > Input'Last then
Result.Status := Optional_More;
exit;
end if;
end loop;
if Counter < Minimum then
if Result.Status = Optional_More then
Result.Status := Needs_More;
else
Result.Status := Failure;
end if;
end if;
return Result;
end Many;
function Many_Until
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result is
begin
return Empty_Fail;
end Many_Until;
function Satisfy
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result is
begin
if Start > Input'Last then
return Empty_Fail;
elsif Test (Input (Start)) then
return Create_Result (1, Success, (1 => Input (Start)));
else
return Empty_Fail;
end if;
end Satisfy;
function Satisfy_With
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result is
begin
if Start > Input'Last then
return Empty_Fail;
elsif Test (Change (Input (Start))) then
return Create_Result (1, Success, (1 => Input (Start)));
else
return Empty_Fail;
end if;
end Satisfy_With;
function Match
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result is
begin
if Start > Input'Last then
return Empty_Fail;
elsif Input (Start) = Item then
return Create_Result (1, Success, (1 => Item));
else
return Empty_Fail;
end if;
end Match;
function Match_With
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result is
begin
if Start > Input'Last then
return Empty_Fail;
elsif Change (Input (Start)) = Item then
return Create_Result (1, Success, (1 => Input (Start)));
else
return Empty_Fail;
end if;
end Match_With;
function Multimatch
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result
is
Current_Offset : Natural := 0;
begin
if Items'Length = 0 then
return Create_Result (0, Success, Empty_Array);
end if;
if Input'Last - Start + 1 <= 0 then
return Empty_Fail;
end if;
while Input (Start + Current_Offset) = Items (Items'First + Current_Offset) loop
if Items'First + Current_Offset = Items'Last then
return Create_Result (Current_Offset + 1, Success, Items);
elsif Start + Current_Offset = Input'Last then
return Create_Result (Current_Offset + 1, Needs_More, Input (Start .. Input'Last));
end if;
Current_Offset := Current_Offset + 1;
end loop;
return Create_Result (Current_Offset, Failure, Input (Start .. Start + Current_Offset - 1));
end Multimatch;
function Take
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result is
begin
if Start > Input'Last then
return Empty_Fail;
elsif Start + Number - 1 > Input'Last then
return Create_Result (Input'Last - Start + 1, Needs_More, Input (Start .. Input'Last));
else
return Create_Result (Number, Success, Input (Start .. Start + Number - 1));
end if;
end Take;
function Take_While
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result
is
Finish : Positive := Start;
Status : Result_Status;
begin
if Start > Input'Last or else not Test (Input (Start)) then
return Empty_Fail;
end if;
while Finish <= Input'Last and then Test (Input (Finish)) loop
Finish := Finish + 1;
end loop;
if Finish > Input'Last then
Status := Optional_More;
else
Status := Success;
end if;
return Create_Result (Finish - Start, Status, Input (Start .. Finish - 1));
end Take_While;
function Take_Until
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result
is
Finish : Positive := Start;
Status : Result_Status;
begin
if Start > Input'Last or else Test (Input (Start)) then
return Empty_Fail;
end if;
while Finish <= Input'Last and then not Test (Input (Finish)) loop
Finish := Finish + 1;
end loop;
if Finish > Input'Last then
Status := Optional_More;
else
Status := Success;
end if;
return Create_Result (Finish - Start, Status, Input (Start .. Finish - 1));
end Take_Until;
function Line_End
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result is
begin
if Start > Input'Last then
return Empty_Fail;
elsif Input (Start) = EOL_Item then
return Create_Result (1, Success, (1 => EOL_Item));
else
return Empty_Fail;
end if;
end Line_End;
function Input_End
(Input : in Element_Array;
Start : in Positive)
return Combinator_Result is
begin
if Start > Input'Last then
return Empty_Fail;
elsif Input (Start) = EOF_Item then
return Create_Result (1, Success, (1 => EOF_Item));
else
return Empty_Fail;
end if;
end Input_End;
end Packrat.Lexer.Combinators;
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