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//===--- Extract.cpp - Clang refactoring library --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Implements the "extract" refactoring that can pull code into
/// new functions, methods or declare new variables.
///
//===----------------------------------------------------------------------===//
#include "clang/Tooling/Refactoring/Extract/Extract.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprObjC.h"
#include "clang/Rewrite/Core/Rewriter.h"
#include "clang/Tooling/Refactoring/Extract/SourceExtraction.h"
namespace clang {
namespace tooling {
namespace {
/// Returns true if \c E is a simple literal or a reference expression that
/// should not be extracted.
bool isSimpleExpression(const Expr *E) {
if (!E)
return false;
switch (E->IgnoreParenCasts()->getStmtClass()) {
case Stmt::DeclRefExprClass:
case Stmt::PredefinedExprClass:
case Stmt::IntegerLiteralClass:
case Stmt::FloatingLiteralClass:
case Stmt::ImaginaryLiteralClass:
case Stmt::CharacterLiteralClass:
case Stmt::StringLiteralClass:
return true;
default:
return false;
}
}
SourceLocation computeFunctionExtractionLocation(const Decl *D) {
if (isa<CXXMethodDecl>(D)) {
// Code from method that is defined in class body should be extracted to a
// function defined just before the class.
while (const auto *RD = dyn_cast<CXXRecordDecl>(D->getLexicalDeclContext()))
D = RD;
}
return D->getBeginLoc();
}
} // end anonymous namespace
const RefactoringDescriptor &ExtractFunction::describe() {
static const RefactoringDescriptor Descriptor = {
"extract-function",
"Extract Function",
"(WIP action; use with caution!) Extracts code into a new function",
};
return Descriptor;
}
Expected<ExtractFunction>
ExtractFunction::initiate(RefactoringRuleContext &Context,
CodeRangeASTSelection Code,
Optional<std::string> DeclName) {
// We would like to extract code out of functions/methods/blocks.
// Prohibit extraction from things like global variable / field
// initializers and other top-level expressions.
if (!Code.isInFunctionLikeBodyOfCode())
return Context.createDiagnosticError(
diag::err_refactor_code_outside_of_function);
if (Code.size() == 1) {
// Avoid extraction of simple literals and references.
if (isSimpleExpression(dyn_cast<Expr>(Code[0])))
return Context.createDiagnosticError(
diag::err_refactor_extract_simple_expression);
// Property setters can't be extracted.
if (const auto *PRE = dyn_cast<ObjCPropertyRefExpr>(Code[0])) {
if (!PRE->isMessagingGetter())
return Context.createDiagnosticError(
diag::err_refactor_extract_prohibited_expression);
}
}
return ExtractFunction(std::move(Code), DeclName);
}
// FIXME: Support C++ method extraction.
// FIXME: Support Objective-C method extraction.
Expected<AtomicChanges>
ExtractFunction::createSourceReplacements(RefactoringRuleContext &Context) {
const Decl *ParentDecl = Code.getFunctionLikeNearestParent();
assert(ParentDecl && "missing parent");
// Compute the source range of the code that should be extracted.
SourceRange ExtractedRange(Code[0]->getBeginLoc(),
Code[Code.size() - 1]->getEndLoc());
// FIXME (Alex L): Add code that accounts for macro locations.
ASTContext &AST = Context.getASTContext();
SourceManager &SM = AST.getSourceManager();
const LangOptions &LangOpts = AST.getLangOpts();
Rewriter ExtractedCodeRewriter(SM, LangOpts);
// FIXME: Capture used variables.
// Compute the return type.
QualType ReturnType = AST.VoidTy;
// FIXME (Alex L): Account for the return statement in extracted code.
// FIXME (Alex L): Check for lexical expression instead.
bool IsExpr = Code.size() == 1 && isa<Expr>(Code[0]);
if (IsExpr) {
// FIXME (Alex L): Get a more user-friendly type if needed.
ReturnType = cast<Expr>(Code[0])->getType();
}
// FIXME: Rewrite the extracted code performing any required adjustments.
// FIXME: Capture any field if necessary (method -> function extraction).
// FIXME: Sort captured variables by name.
// FIXME: Capture 'this' / 'self' if necessary.
// FIXME: Compute the actual parameter types.
// Compute the location of the extracted declaration.
SourceLocation ExtractedDeclLocation =
computeFunctionExtractionLocation(ParentDecl);
// FIXME: Adjust the location to account for any preceding comments.
// FIXME: Adjust with PP awareness like in Sema to get correct 'bool'
// treatment.
PrintingPolicy PP = AST.getPrintingPolicy();
// FIXME: PP.UseStdFunctionForLambda = true;
PP.SuppressStrongLifetime = true;
PP.SuppressLifetimeQualifiers = true;
PP.SuppressUnwrittenScope = true;
ExtractionSemicolonPolicy Semicolons = ExtractionSemicolonPolicy::compute(
Code[Code.size() - 1], ExtractedRange, SM, LangOpts);
AtomicChange Change(SM, ExtractedDeclLocation);
// Create the replacement for the extracted declaration.
{
std::string ExtractedCode;
llvm::raw_string_ostream OS(ExtractedCode);
// FIXME: Use 'inline' in header.
OS << "static ";
ReturnType.print(OS, PP, DeclName);
OS << '(';
// FIXME: Arguments.
OS << ')';
// Function body.
OS << " {\n";
if (IsExpr && !ReturnType->isVoidType())
OS << "return ";
OS << ExtractedCodeRewriter.getRewrittenText(ExtractedRange);
if (Semicolons.isNeededInExtractedFunction())
OS << ';';
OS << "\n}\n\n";
auto Err = Change.insert(SM, ExtractedDeclLocation, OS.str());
if (Err)
return std::move(Err);
}
// Create the replacement for the call to the extracted declaration.
{
std::string ReplacedCode;
llvm::raw_string_ostream OS(ReplacedCode);
OS << DeclName << '(';
// FIXME: Forward arguments.
OS << ')';
if (Semicolons.isNeededInOriginalFunction())
OS << ';';
auto Err = Change.replace(
SM, CharSourceRange::getTokenRange(ExtractedRange), OS.str());
if (Err)
return std::move(Err);
}
// FIXME: Add support for assocciated symbol location to AtomicChange to mark
// the ranges of the name of the extracted declaration.
return AtomicChanges{std::move(Change)};
}
} // end namespace tooling
} // end namespace clang
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