Inverted index: Difference between revisions
Added Delphi example
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Enter a word to search for: (q to quit): q
quitting.</pre>
=={{header|Delphi}}==
{{libheader| System.SysUtils}}
{{libheader| system.Generics.Collections}}
{{libheader| SYstem.IOUtils}}
<lang Delphi>
program Inverted_index;
{$APPTYPE CONSOLE}
uses
System.SysUtils,
system.Generics.Collections,
SYstem.IOUtils;
type
TIndex = class
private
FFileNames: TArray<string>;
FIndexs: TDictionary<string, string>;
class function SplitWords(Text: string): TArray<string>; static;
function StoreFileName(FileName: TFileName): string;
procedure StoreLine(Line, Id: string);
procedure StoreWord(aWord, Id: string);
function DecodeFileName(Indexed: string): string;
public
procedure AddFile(FileName: TFileName);
constructor Create;
destructor Destroy; override;
function Search(aWord: string): string;
property Index[aWord: string]: string read Search; default;
end;
{ TIndex }
constructor TIndex.Create;
begin
FIndexs := TDictionary<string, string>.Create();
SetLength(FFileNames, 0);
end;
function TIndex.DecodeFileName(Indexed: string): string;
var
f: string;
i: integer;
begin
Result := Indexed;
if Length(FFileNames) > 0 then
for i := 0 to High(FFileNames) do
begin
f := FFileNames[i];
Result := Result.Replace(format('(%x)', [i]), f);
end;
end;
destructor TIndex.Destroy;
begin
FIndexs.Free;
inherited;
end;
function TIndex.Search(aWord: string): string;
begin
aWord := AnsiLowerCase(aWord);
if FIndexs.ContainsKey(aWord) then
Result := 'found in ' + DecodeFileName(FIndexs[aWord])
else
Result := 'not found';
end;
class function TIndex.SplitWords(Text: string): TArray<string>;
const
WORD_CHARSET: set of char = (['a'..'z', 'A'..'Z', 'á', 'é', 'í', 'ó', 'ú', 'ã',
'õ', 'à', 'è', 'ì', 'ò', 'ù', 'Á', 'É', 'Í', 'Ó', 'Ú', 'Ã', 'Õ', 'À', 'È',
'Ì', 'Ò', 'Ù', 'ä', 'ë', 'ï', 'ö', 'ü', 'ç', 'Ç', '_', '0'..'9']);
procedure Append(var value: string);
begin
if not value.IsEmpty then
begin
SetLength(result, length(result) + 1);
result[high(result)] := value;
value := '';
end;
end;
var
c: Char;
inWord, isWordChar: boolean;
w: string;
begin
inWord := False;
w := '';
SetLength(result, 0);
for c in Text do
begin
isWordChar := (c in WORD_CHARSET);
if inWord then
if isWordChar then
w := w + c
else
begin
Append(w);
inWord := false;
Continue;
end;
if not inWord and isWordChar then
begin
inWord := True;
w := c;
end;
end;
if inWord then
Append(w);
end;
function TIndex.StoreFileName(FileName: TFileName): string;
begin
SetLength(FFileNames, length(FFileNames) + 1);
FFileNames[High(FFileNames)] := FileName;
Result := format('"(%x)"', [High(FFileNames)]);
end;
procedure TIndex.StoreLine(Line, Id: string);
var
Words: TArray<string>;
w: string;
begin
Words := SplitWords(Line);
for w in Words do
StoreWord(w, Id);
end;
procedure TIndex.StoreWord(aWord, Id: string);
begin
aWord := AnsiLowercase(aWord);
if FIndexs.ContainsKey(aWord) then
begin
if (FIndexs[aWord].IndexOf(Id) = -1) then
FIndexs[aWord] := FIndexs[aWord] + ', ' + Id;
end
else
FIndexs.Add(aWord, Id);
end;
procedure TIndex.AddFile(FileName: TFileName);
var
Lines: TArray<string>;
Line: string;
Id: string;
begin
if not FileExists(FileName) then
exit;
Lines := TFile.ReadAllLines(FileName);
if length(Lines) = 0 then
exit;
// Remove this line if you want full filename
FileName := ExtractFileName(FileName);
Id := StoreFileName(FileName);
for Line in Lines do
StoreLine(Line, Id);
end;
var
Index: TIndex;
FileNames: TArray<TFileName> = ['file1.txt', 'file2.txt', 'file3.txt'];
FileName: TFileName;
Querys: TArray<string> = ['Cat', 'is', 'banana', 'it', 'what'];
Query, Found: string;
begin
Index := TIndex.Create;
for FileName in FileNames do
Index.AddFile(FileName);
for Query in Querys do
Writeln(format('"%s" %s'#10, [Query, Index[Query]]));
repeat
Writeln('Enter a word to search for: (q to quit)');
Readln(Query);
if Query = 'q' then
Break;
Writeln(format('"%s" %s'#10, [Query, Index[Query]]));
until False;
Index.Free;
end.</lang>
Input: Same of [[#D|D]].
{{out}}
<pre>"Cat" not found
"is" found in "file1.txt", "file2.txt", "file3.txt"
"banana" found in "file3.txt"
"it" found in "file1.txt", "file2.txt", "file3.txt"
"what" found in "file1.txt", "file2.txt"
Enter a word to search for: (q to quit):
q</pre>
=={{header|EchoLisp}}==
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