llvm-project/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.h

//===-- ClangUserExpression.h -----------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef liblldb_ClangUserExpression_h_
#define liblldb_ClangUserExpression_h_

// C Includes
// C++ Includes
#include <vector>

// Other libraries and framework includes
// Project includes
#include "ASTStructExtractor.h"
#include "ASTResultSynthesizer.h"
#include "ClangExpressionDeclMap.h"
#include "ClangExpressionHelper.h"
#include "ClangExpressionVariable.h"
#include "IRForTarget.h"

#include "lldb/lldb-forward.h"
#include "lldb/lldb-private.h"
#include "lldb/Core/Address.h"
#include "lldb/Core/ClangForward.h"
#include "lldb/Expression/LLVMUserExpression.h"
#include "lldb/Expression/Materializer.h"
#include "lldb/Target/ExecutionContext.h"

namespace lldb_private
{

//----------------------------------------------------------------------
/// @class ClangUserExpression ClangUserExpression.h "lldb/Expression/ClangUserExpression.h"
/// @brief Encapsulates a single expression for use with Clang
///
/// LLDB uses expressions for various purposes, notably to call functions
/// and as a backend for the expr command.  ClangUserExpression encapsulates
/// the objects needed to parse and interpret or JIT an expression.  It
/// uses the Clang parser to produce LLVM IR from the expression.
//----------------------------------------------------------------------
class ClangUserExpression : public LLVMUserExpression
{
public:
    enum { kDefaultTimeout = 500000u };

    class ClangUserExpressionHelper : public ClangExpressionHelper
    {
    public:
        ClangUserExpressionHelper (Target &target) :
            m_target(target)
        {
        }
        
        ~ClangUserExpressionHelper() override = default;
        
        //------------------------------------------------------------------
        /// Return the object that the parser should use when resolving external
        /// values.  May be NULL if everything should be self-contained.
        //------------------------------------------------------------------
        ClangExpressionDeclMap *
        DeclMap() override
        {
            return m_expr_decl_map_up.get();
        }
        
        void
        ResetDeclMap()
        {
            m_expr_decl_map_up.reset();
        }
        
        void
        ResetDeclMap (ExecutionContext & exe_ctx, Materializer::PersistentVariableDelegate &result_delegate, bool keep_result_in_memory);
        
        //------------------------------------------------------------------
        /// Return the object that the parser should allow to access ASTs.
        /// May be NULL if the ASTs do not need to be transformed.
        ///
        /// @param[in] passthrough
        ///     The ASTConsumer that the returned transformer should send
        ///     the ASTs to after transformation.
        //------------------------------------------------------------------
        clang::ASTConsumer *
        ASTTransformer(clang::ASTConsumer *passthrough) override;

    private:
        Target                                  &m_target;
        std::unique_ptr<ClangExpressionDeclMap> m_expr_decl_map_up;
        std::unique_ptr<ASTStructExtractor> m_struct_extractor_up;         ///< The class that generates the argument struct layout.
        std::unique_ptr<ASTResultSynthesizer> m_result_synthesizer_up;
    };

    //------------------------------------------------------------------
    /// Constructor
    ///
    /// @param[in] expr
    ///     The expression to parse.
    ///
    /// @param[in] expr_prefix
    ///     If non-NULL, a C string containing translation-unit level
    ///     definitions to be included when the expression is parsed.
    ///
    /// @param[in] language
    ///     If not eLanguageTypeUnknown, a language to use when parsing
    ///     the expression.  Currently restricted to those languages
    ///     supported by Clang.
    ///
    /// @param[in] desired_type
    ///     If not eResultTypeAny, the type to use for the expression
    ///     result.
    //------------------------------------------------------------------
    ClangUserExpression (ExecutionContextScope &exe_scope,
                         const char *expr,
                         const char *expr_prefix,
                         lldb::LanguageType language,
                         ResultType desired_type,
                         const EvaluateExpressionOptions &options);

    ~ClangUserExpression() override;

    //------------------------------------------------------------------
    /// Parse the expression
    ///
    /// @param[in] error_stream
    ///     A stream to print parse errors and warnings to.
    ///
    /// @param[in] exe_ctx
    ///     The execution context to use when looking up entities that
    ///     are needed for parsing (locations of functions, types of
    ///     variables, persistent variables, etc.)
    ///
    /// @param[in] execution_policy
    ///     Determines whether interpretation is possible or mandatory.
    ///
    /// @param[in] keep_result_in_memory
    ///     True if the resulting persistent variable should reside in
    ///     target memory, if applicable.
    ///
    /// @return
    ///     True on success (no errors); false otherwise.
    //------------------------------------------------------------------
    bool
    Parse (Stream &error_stream,
           ExecutionContext &exe_ctx,
           lldb_private::ExecutionPolicy execution_policy,
           bool keep_result_in_memory,
           bool generate_debug_info) override;

    ExpressionTypeSystemHelper *
    GetTypeSystemHelper () override
    {
        return &m_type_system_helper;
    }
    
    ClangExpressionDeclMap *
    DeclMap ()
    {
        return m_type_system_helper.DeclMap();
    }
    
    void
    ResetDeclMap ()
    {
        m_type_system_helper.ResetDeclMap();
    }
    
    void
    ResetDeclMap (ExecutionContext & exe_ctx, Materializer::PersistentVariableDelegate &result_delegate, bool keep_result_in_memory)
    {
        m_type_system_helper.ResetDeclMap(exe_ctx, result_delegate, keep_result_in_memory);
    }

    lldb::ExpressionVariableSP
    GetResultAfterDematerialization(ExecutionContextScope *exe_scope) override;
    
private:
    //------------------------------------------------------------------
    /// Populate m_in_cplusplus_method and m_in_objectivec_method based on the environment.
    //------------------------------------------------------------------

    void
    ScanContext (ExecutionContext &exe_ctx,
                 lldb_private::Error &err) override;

    bool
    AddInitialArguments (ExecutionContext &exe_ctx,
                         std::vector<lldb::addr_t> &args,
                         Stream &error_stream) override;
    
    ClangUserExpressionHelper   m_type_system_helper;
    
    class ResultDelegate : public Materializer::PersistentVariableDelegate
    {
    public:
        ResultDelegate();
        ConstString GetName() override;
        void DidDematerialize(lldb::ExpressionVariableSP &variable) override;
        
        void RegisterPersistentState(PersistentExpressionState *persistent_state);
        lldb::ExpressionVariableSP &GetVariable();

    private:
        PersistentExpressionState *m_persistent_state;
        lldb::ExpressionVariableSP m_variable;
    };
    
    ResultDelegate                                          m_result_delegate;
};

} // namespace lldb_private

#endif // liblldb_ClangUserExpression_h_