Execute a Markov algorithm: Difference between revisions
added Pascal example
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000000A000000
00011H1111000
</pre>
=={{header|Pascal}}==
{{works with|FPC}}
<syntaxhighlight lang="pascal">
program InterpretMA;
{$mode objfpc}{$h+}{$j-}{$b-}
uses
SysUtils;
type
TRule = record
Pattern, Replacement: string;
Terminating: Boolean;
end;
TRules = array of TRule;
function ParseMA(const aScheme: string; out aRules: TRules): Boolean;
function ParseLine(const s: string; out r: TRule): Boolean;
var
Terms: TStringArray;
begin
Terms := s.Split([' -> ']);
if Length(Terms) <> 2 then exit(False);
r.Pattern := Terms[0].TrimRight;
if r.Pattern = '' then exit(False);
r.Replacement := Terms[1].TrimLeft;
r.Terminating := False;
if (r.Replacement <> '') and (r.Replacement[1] = '.') then begin
r.Terminating := True;
Delete(r.Replacement, 1, 1);
end;
Result := True;
end;
var
Lines: TStringArray;
s: string;
I: Integer;
begin
aRules := nil;
if aScheme = '' then exit(False);
Lines := aScheme.Split([LineEnding], TStringSplitOptions.ExcludeEmpty);
if Lines = nil then exit(False);
SetLength(aRules, Length(Lines));
I := 0;
for s in Lines do begin
if s[1] = '#' then continue;
if not ParseLine(s, aRules[I]) then exit(False);
Inc(I);
end;
SetLength(aRules, I);
Result := True;
end;
function ExecuteMA(const aScheme, aInput: string): string;
var
Rules: TRules;
r: TRule;
Applied: Boolean;
begin
if not ParseMA(aScheme.Replace(#9, ' ', [rfReplaceAll]), Rules) then
exit('Error while parsing MA scheme');
Result := aInput;
repeat
Applied := False;
for r in Rules do
if Result.IndexOf(r.Pattern) >= 0 then begin
Result := Result.Replace(r.Pattern, r.Replacement);
if r.Terminating then exit;
Applied := True;
break;
end;
until not Applied;
end;
type
TTestEntry = record
Scheme, Input, Output: string;
end;
const
LE = LineEnding;
TestSet: array[1..5] of TTestEntry = (
(Scheme:
'# This rules file is extracted from Wikipedia: ' +LE+
'# http://en.wikipedia.org/wiki/Markov_Algorithm' +LE+
'A -> apple' +LE+
'B -> bag' +LE+
'S -> shop' +LE+
'T -> the' +LE+
'the shop -> my brother' +LE+
'a never used -> .terminating rule';
Input: 'I bought a B of As from T S.'; Output: 'I bought a bag of apples from my brother.'),
(Scheme:
'# Slightly modified from the rules on Wikipedia' +LE+
'A -> apple' +LE+
'B -> bag' +LE+
'S -> .shop' +LE+
'T -> the' +LE+
'the shop -> my brother' +LE+
'a never used -> .terminating rule';
Input: 'I bought a B of As from T S.'; Output: 'I bought a bag of apples from T shop.'),
(Scheme:
'# BNF Syntax testing rules' +LE+
'A -> apple' +LE+
'WWWW -> with' +LE+
'Bgage -> ->.*' +LE+
'B -> bag' +LE+
'->.* -> money' +LE+
'W -> WW' +LE+
'S -> .shop' +LE+
'T -> the' +LE+
'the shop -> my brother' +LE+
'a never used -> .terminating rule';
Input: 'I bought a B of As W my Bgage from T S.'; Output: 'I bought a bag of apples with my money from T shop.'),
(Scheme:
'### Unary Multiplication Engine, for testing Markov Algorithm implementations' +LE+
'### By Donal Fellows.' +LE+
'# Unary addition engine' +LE+
'_+1 -> _1+' +LE+
'1+1 -> 11+' +LE+
'# Pass for converting from the splitting of multiplication into ordinary' +LE+
'# addition' +LE+
'1! -> !1' +LE+
',! -> !+' +LE+
'_! -> _' +LE+
'# Unary multiplication by duplicating left side, right side times' +LE+
'1*1 -> x,@y' +LE+
'1x -> xX' +LE+
'X, -> 1,1' +LE+
'X1 -> 1X' +LE+
'_x -> _X' +LE+
',x -> ,X' +LE+
'y1 -> 1y' +LE+
'y_ -> _' +LE+
'# Next phase of applying' +LE+
'1@1 -> x,@y' +LE+
'1@_ -> @_' +LE+
',@_ -> !_' +LE+
'++ -> +' +LE+
'# Termination cleanup for addition' +LE+
'_1 -> 1' +LE+
'1+_ -> 1' +LE+
'_+_ -> ';
Input: '_1111*11111_'; Output: '11111111111111111111'),
(Scheme:
'# Turing machine: three-state busy beaver' +LE+
'#' +LE+
'# state A, symbol 0 => write 1, move right, new state B' +LE+
'A0 -> 1B' +LE+
'# state A, symbol 1 => write 1, move left, new state C' +LE+
'0A1 -> C01' +LE+
'1A1 -> C11' +LE+
'# state B, symbol 0 => write 1, move left, new state A' +LE+
'0B0 -> A01' +LE+
'1B0 -> A11' +LE+
'# state B, symbol 1 => write 1, move right, new state B' +LE+
'B1 -> 1B' +LE+
'# state C, symbol 0 => write 1, move left, new state B' +LE+
'0C0 -> B01' +LE+
'1C0 -> B11' +LE+
'# state C, symbol 1 => write 1, move left, halt' +LE+
'0C1 -> H01' +LE+
'1C1 -> H11';
Input: '000000A000000'; Output: '00011H1111000')
);
E_FMT = 'test #%d: expected "%s", but got "%s"';
var
e: TTestEntry;
Result: string;
I: Integer = 1;
Failed: Integer = 0;
begin
for e in TestSet do begin
Result := ExecuteMA(e.Scheme, e.Input);
if Result <> e.Output then begin
WriteLn(Format(E_FMT, [I, e.Output, Result]));
Inc(Failed);
end;
Inc(I);
end;
WriteLn('tests completed: ', Length(TestSet), ', failed: ', Failed);
end.
</syntaxhighlight>
{{out}}
<pre>
tests completed: 5, failed: 0
</pre>
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