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{
This file is part of the Free Pascal Run time library.
Copyright (c) 2021 by Michael Van Canneyt (michael@freepascal.org)
This file contains a Mustache DB context, getting data from a dataset
See the File COPYING.FPC, included in this distribution,
for details about the copyright.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
**********************************************************************}
unit fpdbmustache;
{$mode ObjFPC}{$H+}
interface
uses
Classes, SysUtils, db, fpMustache;
Type
{ TDatasetCollectionItem }
TDatasetCollectionItem = Class(TCollectionItem)
private
FDataset: TDataSet;
FSection: String;
Public
Property Dataset : TDataSet Read FDataset Write FDataset;
Property SectionName : String Read FSection Write FSection;
end;
TDatasetCollection = Class(TCollection)
private
function GetDS(aIndex : Integer): TDatasetCollectionItem;
Public
Function IndexOfDataset(aDataset : TDataset) : Integer;
Function IndexOfSection(aSection : String) : Integer;
Property Datasets[aIndex : Integer] : TDatasetCollectionItem Read GetDS; default;
end;
{ TMustacheDBContext }
TMustacheDBContext = Class(TMustacheContext)
Private
Type
TPair = Record
atStart : Boolean;
Value : TDataset;
end;
Private
FStack : Array of TPair;
FCount : Integer;
FStaticValues: TStrings;
FDatasets : TDatasetCollection;
Function FindField(Const aName : TMustacheString) : TField;
function GetDataset(aIndex : Integer): TDatasetCollectionItem;
function GetDatasetCount: INteger;
procedure SetStaticValues(AValue: TStrings);
Public
Constructor Create(aCallback : TGetTextValueEvent); override;
Destructor destroy; override;
Procedure Clear;
Function MoveNextSectionItem(Const aName : TMustacheString) : Boolean; override;
Function PushSection(Const aName : TMustacheString) : TMustacheSectionType; override;
Procedure PopSection(Const aName : TMustacheString); override;
Function GetTextValue(Const aName : TMustacheString) : TMustacheString; override;
Procedure AddDataset(aDataset : TDataset; aSectionName : String = '');
Procedure RemoveDataset(aDataset : TDataset);
Property StaticValues : TStrings Read FStaticValues Write SetStaticValues;
Property Datasets[aIndex : Integer] : TDatasetCollectionItem Read GetDataset;
Property DatasetCount : INteger Read GetDatasetCount;
end;
implementation
uses StrUtils;
Resourcestring
SErrPopSectionNoPush = 'PopSection %s without push';
SErrDatasetNameEmpty = 'Dataset name and section cannot both be empty';
SErrDatasetEmpty = 'Dataset is Nil';
SErrDuplicateDataSetName = 'Duplicate dataset name: %s';
{ TMustacheDBContext }
function TMustacheDBContext.FindField(const aName: TMustacheString): TField;
Var
aCount : Integer;
begin
Result:=Nil;
aCount:=FCount-1;
While (Result=Nil) and (aCount>=0) do
begin
Result:=FStack[aCount].Value.FieldByName(aName);
Dec(aCount);
end;
end;
function TMustacheDBContext.GetDataset(aIndex : Integer
): TDatasetCollectionItem;
begin
Result:=FDatasets[aIndex];
end;
function TMustacheDBContext.GetDatasetCount: INteger;
begin
Result:=FDatasets.Count;
end;
procedure TMustacheDBContext.SetStaticValues(AValue: TStrings);
begin
if FStaticValues=AValue then Exit;
FStaticValues.Assign(AValue);
end;
constructor TMustacheDBContext.Create(aCallback: TGetTextValueEvent);
begin
inherited Create(aCallback);
FDatasets:=TDatasetCollection.Create(TDatasetCollectionItem);
FStaticValues:=TStringList.Create;
SetLength(FStack,JSONListGrowCount);
FCount:=0;
end;
destructor TMustacheDBContext.destroy;
begin
FreeAndNil(FStaticValues);
FreeAndNil(FDatasets);
inherited destroy;
end;
procedure TMustacheDBContext.Clear;
begin
FStaticValues.Clear;
FDatasets.Clear;
end;
function TMustacheDBContext.MoveNextSectionItem(const aName: TMustacheString
): Boolean;
begin
if FStack[FCount-1].atStart then
FStack[FCount-1].atStart:=False
else
FStack[FCount-1].Value.Next;
Result:=Not FStack[FCount-1].Value.EOF;
end;
function TMustacheDBContext.PushSection(const aName: TMustacheString
): TMustacheSectionType;
Var
aDS : TDataset;
Idx : Integer;
begin
Result:=mstNone;
Idx:=FDatasets.IndexOfSection(aName);
if Idx=-1 then
Exit;
aDS:=FDatasets[Idx].Dataset;
if aDS.IsEmpty then
exit;
if FCount=Length(FStack) then
SetLength(FStack,FCount+JSONListGrowCount);
FStack[FCount].Value:=aDS;
FStack[FCount].atStart:=True;
Inc(FCount,1);
Result:=mstList;
end;
procedure TMustacheDBContext.PopSection(const aName: TMustacheString);
begin
if FCount<1 then
Raise EMustache.CreateFmt(SErrPopSectionNoPush,[aName]);
Dec(FCount,1);
end;
function TMustacheDBContext.GetTextValue(const aName: TMustacheString
): TMustacheString;
Var
F : TField;
idx : Integer;
begin
F:=Nil;
if Pos('.',aName)=0 then
F:=FindField(aName)
else if WordCount(aName,['.'])=2 then
begin
Idx:=FDatasets.IndexOfSection(ExtractWord(1,aName,['.']));
if (Idx<>-1) then
F:=FDatasets[Idx].Dataset.FindField(ExtractWord(2,aName,['.']));
end;
If Assigned(F) then
Result:=F.AsString
else
begin
Idx:=FStaticValues.IndexOfName(aName);
if Idx<>-1 then
Result:=FStaticValues.ValueFromIndex[Idx]
else
Result:=Inherited GetTextValue(aName);
end;
end;
procedure TMustacheDBContext.AddDataset(aDataset: TDataset; aSectionName: String);
Var
DCI : TDatasetCollectionItem;
aName : String;
begin
aName:=aSectionName;
if aName='' then
aName:=aDataset.Name;
if aName='' then
raise EMustache.Create(SErrDatasetNameEmpty);
if aDataset=Nil then
raise EMustache.Create(SErrDatasetEmpty);
if FDatasets.IndexOfSection(aName)<>-1 then
raise EMustache.CreateFmt(SErrDuplicateDataSetName, [aName]);
DCI:=FDatasets.Add as TDatasetCollectionItem;
DCI.Dataset:=aDataset;
DCI.SectionName:=aName;
end;
procedure TMustacheDBContext.RemoveDataset(aDataset: TDataset);
Var
Idx : Integer;
begin
Idx:=FDatasets.IndexOfDataset(aDataset);
if Idx<>-1 then
FDatasets.Delete(Idx);
end;
{ TDatasetCollection }
function TDatasetCollection.GetDS(aIndex : Integer): TDatasetCollectionItem;
begin
Result:=Items[aIndex] as TDatasetCollectionItem;
end;
function TDatasetCollection.IndexOfDataset(aDataset: TDataset): Integer;
begin
Result:=Count-1;
While (Result>=0) and (GetDS(Result).Dataset<>ADataset) do
Dec(Result);
end;
function TDatasetCollection.IndexOfSection(aSection: String): Integer;
begin
Result:=Count-1;
While (Result>=0) and not SameText(GetDS(Result).SectionName,ASection) do
Dec(Result);
end;
end.
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