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Unit TextSearchQuery;
{$mode objfpc}{$H+}
// NewView - a new OS/2 Help Viewer
// Copyright 2003 Aaron Lawrence (aaronl at consultant dot com)
// This software is released under the Gnu Public License - see readme.txt
Interface
// Encapsulates a parsed search query.
uses
Classes, SysUtils;
Type
ESearchSyntaxError = class( Exception )
end;
TSearchTermCombineMethod =
(
cmOptional,
cmRequired,
cmExcluded
);
TSearchTerm = class(TObject)
public
Text: string;
Parts: TStringList;
CombineMethod: TSearchTermCombineMethod;
constructor Create( const TheText: string;
const TheCombineMethod: TSearchTermCombineMethod );
destructor Destroy; override;
end;
TTextSearchQuery = class(TObject)
protected
Terms: TList;
function GetTerm( Index: longint ): TSearchTerm;
function GetTermCount: longint;
public
constructor Create( const SearchString: string );
destructor Destroy; override;
property Term[ Index: longint ]: TSearchTerm read GetTerm;
property TermCount: longint read GetTermCount;
end;
implementation
uses
nvUtilities
,ACLStringUtility
;
const
QueryErrorMissingWord1 = 'No search word given after';
QueryErrorMissingWord2 = ' before ';
constructor TTextSearchQuery.Create( const SearchString: string );
var
TermText: string;
CombineMethod: TSearchTermCombineMethod;
lTerm: TSearchTerm;
tmpTerms : TStrings;
i : integer;
begin
inherited Create;
Terms := TList.Create;
try
tmpTerms := TStringList.Create;
StrExtractStringsQuoted(tmpTerms, SearchString);
for i := 0 to tmpTerms.count-1 do
begin
TermText := tmpTerms[i];
// Check for modifiers:
// + word must be matched
// - word must not be matched
case TermText[ 1 ] of
'+':
CombineMethod := cmRequired;
'-':
CombineMethod := cmExcluded;
else
CombineMethod := cmOptional;
end;
if CombineMethod <> cmOptional then
begin
// delete + or -
if Length( TermText ) = 1 then
if (i < tmpTerms.count-1) then
raise ESearchSyntaxError.Create( QueryErrorMissingWord1
+ StrInDoubleQuotes(TermText)
+ QueryErrorMissingWord2
+ StrInDoubleQuotes(tmpTerms[i+1]) )
else
raise ESearchSyntaxError.Create( QueryErrorMissingWord1
+ StrInDoubleQuotes(TermText));
Delete( TermText, 1, 1 );
end;
lTerm := TSearchTerm.Create( TermText,
CombineMethod );
Terms.Add( lTerm );
end;
tmpTerms.Free;
except
while Terms.Count > 0 do
begin
lTerm := TSearchTerm(Terms.Last);
Terms.Remove(lTerm);
lTerm.Free;
end;
Terms.Free;
raise; // reraise exception
end;
end;
destructor TTextSearchQuery.Destroy;
begin
DestroyListObjects( Terms );
Terms.Free;
inherited Destroy;
end;
function TTextSearchQuery.GetTerm( index: longint ): TSearchTerm;
begin
Result := TSearchTerm(Terms[ Index ]);
end;
function TTextSearchQuery.GetTermCount: longint;
begin
Result := Terms.Count;
end;
constructor TSearchTerm.Create( const TheText: string;
const TheCombineMethod: TSearchTermCombineMethod );
var
TermParseIndex: longint;
TermChar: char;
TermPart: string;
begin
Parts := TStringList.Create;
Text := TheText;
CombineMethod := TheCombineMethod;
// Break out each part of the term as IPF does:
// consecutive alphanumeric chars become a "word"
// but each symbol is a separate word, and symbols break
// up alphanumerics into multiple words. e.g.
// CAKE_SAUSAGE becomes three words in IPF,
// one each for "CAKE" "_" and "SAUSAGE"
TermParseIndex := 1;
while TermParseIndex <= Length( Text ) do
begin
// collect alphanumeric chars
TermPart := '';
while TermParseIndex <= Length( Text ) do
begin
TermChar := Text[ TermParseIndex ];
if ( IsAlpha( TermChar )
or IsDigit( TermChar ) ) then
begin
// alpha numeric, collect it
TermPart := TermPart + TermChar;
inc( TermParseIndex );
end
else
begin
// not alpha numeric, so stop
break;
end;
end;
if Length( TermPart ) > 0 then
begin
Parts.Add( TermPart ); // add collected alphanumeric part
end;
if TermParseIndex <= Length( Text ) then
begin
// must be a symbol,
// each symbol (excluding space) is an individual item
if Text[ TermParseIndex ] <> ' ' then
Parts.Add( Text[ TermParseIndex ] );
inc( TermParseIndex );
end;
end;
end;
destructor TSearchTerm.Destroy;
begin
Parts.Free;
inherited Destroy;
end;
end.
|
