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//===-- FunctionSizeCheck.cpp - clang-tidy --------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "FunctionSizeCheck.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "llvm/ADT/BitVector.h"
using namespace clang::ast_matchers;
namespace clang::tidy::readability {
namespace {
class FunctionASTVisitor : public RecursiveASTVisitor<FunctionASTVisitor> {
using Base = RecursiveASTVisitor<FunctionASTVisitor>;
public:
bool VisitVarDecl(VarDecl *VD) {
// Do not count function params.
// Do not count decomposition declarations (C++17's structured bindings).
if (StructNesting == 0 &&
!(isa<ParmVarDecl>(VD) || isa<DecompositionDecl>(VD)))
++Info.Variables;
return true;
}
bool VisitBindingDecl(BindingDecl *BD) {
// Do count each of the bindings (in the decomposition declaration).
if (StructNesting == 0)
++Info.Variables;
return true;
}
bool TraverseStmt(Stmt *Node) {
if (!Node)
return Base::TraverseStmt(Node);
if (TrackedParent.back() && !isa<CompoundStmt>(Node))
++Info.Statements;
switch (Node->getStmtClass()) {
case Stmt::IfStmtClass:
case Stmt::WhileStmtClass:
case Stmt::DoStmtClass:
case Stmt::CXXForRangeStmtClass:
case Stmt::ForStmtClass:
case Stmt::SwitchStmtClass:
++Info.Branches;
[[fallthrough]];
case Stmt::CompoundStmtClass:
TrackedParent.push_back(true);
break;
default:
TrackedParent.push_back(false);
break;
}
Base::TraverseStmt(Node);
TrackedParent.pop_back();
return true;
}
bool TraverseCompoundStmt(CompoundStmt *Node) {
// If this new compound statement is located in a compound statement, which
// is already nested NestingThreshold levels deep, record the start location
// of this new compound statement.
if (CurrentNestingLevel == Info.NestingThreshold)
Info.NestingThresholders.push_back(Node->getBeginLoc());
++CurrentNestingLevel;
Base::TraverseCompoundStmt(Node);
--CurrentNestingLevel;
return true;
}
bool TraverseDecl(Decl *Node) {
TrackedParent.push_back(false);
Base::TraverseDecl(Node);
TrackedParent.pop_back();
return true;
}
bool TraverseLambdaExpr(LambdaExpr *Node) {
++StructNesting;
Base::TraverseLambdaExpr(Node);
--StructNesting;
return true;
}
bool TraverseCXXRecordDecl(CXXRecordDecl *Node) {
++StructNesting;
Base::TraverseCXXRecordDecl(Node);
--StructNesting;
return true;
}
bool TraverseStmtExpr(StmtExpr *SE) {
++StructNesting;
Base::TraverseStmtExpr(SE);
--StructNesting;
return true;
}
struct FunctionInfo {
unsigned Lines = 0;
unsigned Statements = 0;
unsigned Branches = 0;
unsigned NestingThreshold = 0;
unsigned Variables = 0;
std::vector<SourceLocation> NestingThresholders;
};
FunctionInfo Info;
llvm::BitVector TrackedParent;
unsigned StructNesting = 0;
unsigned CurrentNestingLevel = 0;
};
} // namespace
FunctionSizeCheck::FunctionSizeCheck(StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
LineThreshold(Options.get("LineThreshold", -1U)),
StatementThreshold(Options.get("StatementThreshold", 800U)),
BranchThreshold(Options.get("BranchThreshold", -1U)),
ParameterThreshold(Options.get("ParameterThreshold", -1U)),
NestingThreshold(Options.get("NestingThreshold", -1U)),
VariableThreshold(Options.get("VariableThreshold", -1U)) {}
void FunctionSizeCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "LineThreshold", LineThreshold);
Options.store(Opts, "StatementThreshold", StatementThreshold);
Options.store(Opts, "BranchThreshold", BranchThreshold);
Options.store(Opts, "ParameterThreshold", ParameterThreshold);
Options.store(Opts, "NestingThreshold", NestingThreshold);
Options.store(Opts, "VariableThreshold", VariableThreshold);
}
void FunctionSizeCheck::registerMatchers(MatchFinder *Finder) {
// Lambdas ignored - historically considered part of enclosing function.
// FIXME: include them instead? Top-level lambdas are currently never counted.
Finder->addMatcher(functionDecl(unless(isInstantiated()),
unless(cxxMethodDecl(ofClass(isLambda()))))
.bind("func"),
this);
}
void FunctionSizeCheck::check(const MatchFinder::MatchResult &Result) {
const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func");
FunctionASTVisitor Visitor;
Visitor.Info.NestingThreshold = NestingThreshold;
Visitor.TraverseDecl(const_cast<FunctionDecl *>(Func));
auto &FI = Visitor.Info;
if (FI.Statements == 0)
return;
// Count the lines including whitespace and comments. Really simple.
if (const Stmt *Body = Func->getBody()) {
SourceManager *SM = Result.SourceManager;
if (SM->isWrittenInSameFile(Body->getBeginLoc(), Body->getEndLoc())) {
FI.Lines = SM->getSpellingLineNumber(Body->getEndLoc()) -
SM->getSpellingLineNumber(Body->getBeginLoc());
}
}
unsigned ActualNumberParameters = Func->getNumParams();
if (FI.Lines > LineThreshold || FI.Statements > StatementThreshold ||
FI.Branches > BranchThreshold ||
ActualNumberParameters > ParameterThreshold ||
!FI.NestingThresholders.empty() || FI.Variables > VariableThreshold) {
diag(Func->getLocation(),
"function %0 exceeds recommended size/complexity thresholds")
<< Func;
}
if (FI.Lines > LineThreshold) {
diag(Func->getLocation(),
"%0 lines including whitespace and comments (threshold %1)",
DiagnosticIDs::Note)
<< FI.Lines << LineThreshold;
}
if (FI.Statements > StatementThreshold) {
diag(Func->getLocation(), "%0 statements (threshold %1)",
DiagnosticIDs::Note)
<< FI.Statements << StatementThreshold;
}
if (FI.Branches > BranchThreshold) {
diag(Func->getLocation(), "%0 branches (threshold %1)", DiagnosticIDs::Note)
<< FI.Branches << BranchThreshold;
}
if (ActualNumberParameters > ParameterThreshold) {
diag(Func->getLocation(), "%0 parameters (threshold %1)",
DiagnosticIDs::Note)
<< ActualNumberParameters << ParameterThreshold;
}
for (const auto &CSPos : FI.NestingThresholders) {
diag(CSPos, "nesting level %0 starts here (threshold %1)",
DiagnosticIDs::Note)
<< NestingThreshold + 1 << NestingThreshold;
}
if (FI.Variables > VariableThreshold) {
diag(Func->getLocation(), "%0 variables (threshold %1)",
DiagnosticIDs::Note)
<< FI.Variables << VariableThreshold;
}
}
} // namespace clang::tidy::readability
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