StringTemplate.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Misc/AssertionMacros.h"
#include "Containers/UnrealString.h"
#include "Containers/StringView.h"
#include "Containers/Array.h"
#include "Containers/Map.h"
 
class FStringTemplate
{
public:
    struct FErrorInfo
    {
        FStringView Message;
 
        int32 Line;
 
        int32 Offset;
    };
 
public:
    FStringTemplate();
 
    bool Load(FString TemplateString, FErrorInfo& Errorinfo);
 
    const FString& GetTemplateString() const { return TemplateString; }
 
    int32 GetNumNamedParameters() const { return NumNamedParameters; }
 
    void GetParameters(TArray<FStringView>& OutParams) const;
 
private:
    struct FChunk
    {
        FStringView Text;
 
        bool bIsParameter;
    };
 
    FString TemplateString;
 
    TArray<FChunk> Chunks;
 
    int32 NumNamedParameters = 0;
 
    friend class FStringTemplateResolver;
};
 
class FStringTemplateResolver
{
public:
    FStringTemplateResolver(const FStringTemplate& Template, uint32 ResolvedStringSizeHint = 0);
 
    const FStringTemplate& GetTemplate() const { return Template; }
 
    void SetParameterMap(const TMap<FString, FString>* Parameters)
    {
        NamedParameters = Parameters;
    }
 
    void Advance(FStringView NextNamelessParameterValue);
 
    FString Finalize(uint32 ResolvedStringSizeHint = 0);
    
private:
    const FStringTemplate& Template;
 
    int32 ChunkIndex = 0;
 
    const TMap<FString, FString>* NamedParameters = nullptr;
 
    FString ResolvedString;
};