clang-tools  3.8.0
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clang::tidy::readability::SimplifyBooleanExprCheck Class Reference

Looks for boolean expressions involving boolean constants and simplifies them to use the appropriate boolean expression directly. More...

#include <SimplifyBooleanExprCheck.h>

Inheritance diagram for clang::tidy::readability::SimplifyBooleanExprCheck:
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Collaboration diagram for clang::tidy::readability::SimplifyBooleanExprCheck:
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Public Member Functions

 SimplifyBooleanExprCheck (StringRef Name, ClangTidyContext *Context)
 
void storeOptions (ClangTidyOptions::OptionMap &Options) override
 Should store all options supported by this check with their current values or default values for options that haven't been overridden. More...
 
void registerMatchers (ast_matchers::MatchFinder *Finder) override
 Override this to register ASTMatchers with Finder. More...
 
void check (const ast_matchers::MatchFinder::MatchResult &Result) override
 ClangTidyChecks that register ASTMatchers should do the actual work in here. More...
 
- Public Member Functions inherited from clang::tidy::ClangTidyCheck
 ClangTidyCheck (StringRef CheckName, ClangTidyContext *Context)
 Initializes the check with CheckName and Context. More...
 
virtual void registerPPCallbacks (CompilerInstance &Compiler)
 Override this to register PPCallbacks with Compiler. More...
 
DiagnosticBuilder diag (SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
 Add a diagnostic with the check's name. More...
 

Additional Inherited Members

- Protected Member Functions inherited from clang::tidy::ClangTidyCheck
StringRef getCurrentMainFile () const
 Returns the main file name of the current translation unit. More...
 
LangOptions getLangOpts () const
 Returns the language options from the context. More...
 
- Protected Attributes inherited from clang::tidy::ClangTidyCheck
OptionsView Options
 

Detailed Description

Looks for boolean expressions involving boolean constants and simplifies them to use the appropriate boolean expression directly.

Examples:

=========================================== ================ Initial expression Result


if (b == true) if (b) if (b == false) if (!b) if (b && true) if (b) if (b && false) if (false) if (b || true) if (true) if (b || false) if (b) e ? true : false e e ? false : true !e if (true) t(); else f(); t(); if (false) t(); else f(); f(); if (e) return true; else return false; return e; if (e) return false; else return true; return !e; if (e) b = true; else b = false; b = e; if (e) b = false; else b = true; b = !e; if (e) return true; return false; return e; if (e) return false; return true; return !e; =========================================== ================

The resulting expression e is modified as follows:

  1. Unnecessary parentheses around the expression are removed.
  2. Negated applications of ! are eliminated.
  3. Negated applications of comparison operators are changed to use the opposite condition.
  4. Implicit conversions of pointer to bool are replaced with explicit comparisons to nullptr.
  5. Implicit casts to bool are replaced with explicit casts to bool.
  6. Object expressions with explicit operator bool conversion operators are replaced with explicit casts to bool.

Examples:

  1. The ternary assignment bool b = (i < 0) ? true : false; has redundant parentheses and becomes bool b = i < 0;.
  2. The conditional return if (!b) return false; return true; has an implied double negation and becomes return b;.
  3. The conditional return if (i < 0) return false; return true; becomes return i >= 0;.

    The conditional return if (i != 0) return false; return true; becomes return i == 0;.

  4. The conditional return if (p) return true; return false; has an implicit conversion of a pointer to bool and becomes return p != nullptr;.

    The ternary assignment bool b = (i & 1) ? true : false; has an implicit conversion of i & 1 to bool and becomes bool b = static_cast<bool>(i & 1);.

  5. The conditional return if (i & 1) return true; else return false; has an implicit conversion of an integer quantity i & 1 to bool and becomes return static_cast<bool>(i & 1);
  6. Given struct X { explicit operator bool(); };, and an instance x of struct X, the conditional return if (x) return true; return false; becomes return static_cast<bool>(x);

When a conditional boolean return or assignment appears at the end of a chain of if, else if statements, the conditional statement is left unchanged unless the option ChainedConditionalReturn or ChainedConditionalAssignment, respectively, is specified as non-zero. The default value for both options is zero.

Definition at line 91 of file SimplifyBooleanExprCheck.h.

Constructor & Destructor Documentation

clang::tidy::readability::SimplifyBooleanExprCheck::SimplifyBooleanExprCheck ( StringRef  Name,
ClangTidyContext Context 
)

Definition at line 263 of file SimplifyBooleanExprCheck.cpp.

Member Function Documentation

void clang::tidy::readability::SimplifyBooleanExprCheck::check ( const ast_matchers::MatchFinder::MatchResult &  Result)
overridevirtual

ClangTidyChecks that register ASTMatchers should do the actual work in here.

Reimplemented from clang::tidy::ClangTidyCheck.

Definition at line 445 of file SimplifyBooleanExprCheck.cpp.

void clang::tidy::readability::SimplifyBooleanExprCheck::registerMatchers ( ast_matchers::MatchFinder *  Finder)
overridevirtual

Override this to register ASTMatchers with Finder.

This should be used by clang-tidy checks that analyze code properties that dependent on AST knowledge.

You can register as many matchers as necessary with Finder. Usually, "this" will be used as callback, but you can also specify other callback classes. Thereby, different matchers can trigger different callbacks.

If you need to merge information between the different matchers, you can store these as members of the derived class. However, note that all matches occur in the order of the AST traversal.

Reimplemented from clang::tidy::ClangTidyCheck.

Definition at line 408 of file SimplifyBooleanExprCheck.cpp.

void clang::tidy::readability::SimplifyBooleanExprCheck::storeOptions ( ClangTidyOptions::OptionMap Options)
overridevirtual

Should store all options supported by this check with their current values or default values for options that haven't been overridden.

The check should use Options.store() to store each option it supports whether it has the default value or it has been overridden.

Reimplemented from clang::tidy::ClangTidyCheck.

Definition at line 402 of file SimplifyBooleanExprCheck.cpp.

References clang::tidy::ClangTidyCheck::Options, and clang::tidy::OptionsView::store().


The documentation for this class was generated from the following files: