//===- Tokens.h - collect tokens from preprocessing --------------*- C++-*-===//

//

// 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

//

//===----------------------------------------------------------------------===//

// Record tokens that a preprocessor emits and define operations to map between

// the tokens written in a file and tokens produced by the preprocessor.

//

// When running the compiler, there are two token streams we are interested in:

//   - "spelled" tokens directly correspond to a substring written in some

//     source file.

//   - "expanded" tokens represent the result of preprocessing, parses consumes

//     this token stream to produce the AST.

//

// Expanded tokens correspond directly to locations found in the AST, allowing

// to find subranges of the token stream covered by various AST nodes. Spelled

// tokens correspond directly to the source code written by the user.

//

// To allow composing these two use-cases, we also define operations that map

// between expanded and spelled tokens that produced them (macro calls,

// directives, etc).

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_TOOLING_SYNTAX_TOKENS_H

#define LLVM_CLANG_TOOLING_SYNTAX_TOKENS_H

#include "clang/Basic/FileManager.h"

#include "clang/Basic/LangOptions.h"

#include "clang/Basic/SourceLocation.h"

#include "clang/Basic/SourceManager.h"

#include "clang/Basic/TokenKinds.h"

#include "clang/Lex/Token.h"

#include "llvm/ADT/ArrayRef.h"

#include "llvm/ADT/Optional.h"

#include "llvm/ADT/StringRef.h"

#include "llvm/Support/Compiler.h"

#include "llvm/Support/raw_ostream.h"

#include <cstdint>

#include <tuple>

namespace clang {

class Preprocessor;

namespace syntax {

/// A half-open character range inside a particular file, the start offset is

/// included and the end offset is excluded from the range.

struct FileRange {

  /// EXPECTS: File.isValid() && Begin <= End.

  FileRange(FileID File, unsigned BeginOffset, unsigned EndOffset);

  /// EXPECTS: BeginLoc.isValid() && BeginLoc.isFileID().

  FileRange(const SourceManager &SM, SourceLocation BeginLoc, unsigned Length);

  /// EXPECTS: BeginLoc.isValid() && BeginLoc.isFileID(), Begin <= End and files

  ///          are the same.

  FileRange(const SourceManager &SM, SourceLocation BeginLoc,

            SourceLocation EndLoc);

  FileID file() const { return File; }

  /// Start is a start offset (inclusive) in the corresponding file.

  unsigned beginOffset() const { return Begin; }

  /// End offset (exclusive) in the corresponding file.

  unsigned endOffset() const { return End; }

  unsigned length() const { return End - Begin; }

  /// Check if \p Offset is inside the range.

  bool contains(unsigned Offset) const {

    return Begin <= Offset && Offset < End;

  }

  /// Check \p Offset is inside the range or equal to its endpoint.

  bool touches(unsigned Offset) const {

    return Begin <= Offset && Offset <= End;

  }

  /// Gets the substring that this FileRange refers to.

  llvm::StringRef text(const SourceManager &SM) const;

  /// Convert to the clang range. The returned range is always a char range,

  /// never a token range.

  CharSourceRange toCharRange(const SourceManager &SM) const;

  friend bool operator==(const FileRange &L, const FileRange &R) {

    return std::tie(L.File, L.Begin, L.End) == std::tie(R.File, R.Begin, R.End);

  }

  friend bool operator!=(const FileRange &L, const FileRange &R) {

    return !(L == R);

  }

private:

  FileID File;

  unsigned Begin;

  unsigned End;

};

/// For debugging purposes.

llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const FileRange &R);

/// A token coming directly from a file or from a macro invocation. Has just

/// enough information to locate the token in the source code.

/// Can represent both expanded and spelled tokens.

class Token {

public:

  Token(SourceLocation Location, unsigned Length, tok::TokenKind Kind);

  /// EXPECTS: clang::Token is not an annotation token.

  explicit Token(const clang::Token &T);

  tok::TokenKind kind() const { return Kind; }

  /// Location of the first character of a token.

  SourceLocation location() const { return Location; }

  /// Location right after the last character of a token.

  SourceLocation endLocation() const {

    return Location.getLocWithOffset(Length);

  }

  unsigned length() const { return Length; }

  /// Get the substring covered by the token. Note that will include all

  /// digraphs, newline continuations, etc. E.g. tokens for 'int' and

  ///    in\

  ///    t

  /// both have the same kind tok::kw_int, but results of text() are different.

  llvm::StringRef text(const SourceManager &SM) const;

  /// Gets a range of this token.

  /// EXPECTS: token comes from a file, not from a macro expansion.

  FileRange range(const SourceManager &SM) const;

  /// Given two tokens inside the same file, returns a file range that starts at

  /// \p First and ends at \p Last.

  /// EXPECTS: First and Last are file tokens from the same file, Last starts

  ///          after First.

  static FileRange range(const SourceManager &SM, const syntax::Token &First,

                         const syntax::Token &Last);

  std::string dumpForTests(const SourceManager &SM) const;

  /// For debugging purposes.

  std::string str() const;

private:

  SourceLocation Location;

  unsigned Length;

  tok::TokenKind Kind;

};

/// For debugging purposes. Equivalent to a call to Token::str().

llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Token &T);

/// A list of tokens obtained by preprocessing a text buffer and operations to

/// map between the expanded and spelled tokens, i.e. TokenBuffer has

/// information about two token streams:

///    1. Expanded tokens: tokens produced by the preprocessor after all macro

///       replacements,

///    2. Spelled tokens: corresponding directly to the source code of a file

///       before any macro replacements occurred.

/// Here's an example to illustrate a difference between those two:

///     #define FOO 10

///     int a = FOO;

///

/// Spelled tokens are {'#','define','FOO','10','int','a','=','FOO',';'}.

/// Expanded tokens are {'int','a','=','10',';','eof'}.

///

/// Note that the expanded token stream has a tok::eof token at the end, the

/// spelled tokens never store a 'eof' token.

///

/// The full list expanded tokens can be obtained with expandedTokens(). Spelled

/// tokens for each of the files can be obtained via spelledTokens(FileID).

///

/// To map between the expanded and spelled tokens use findSpelledByExpanded().

///

/// To build a token buffer use the TokenCollector class. You can also compute

/// the spelled tokens of a file using the tokenize() helper.

///

/// FIXME: allow to map from spelled to expanded tokens when use-case shows up.

/// FIXME: allow mappings into macro arguments.

class TokenBuffer {

public:

  TokenBuffer(const SourceManager &SourceMgr) : SourceMgr(&SourceMgr) {}

  /// All tokens produced by the preprocessor after all macro replacements,

  /// directives, etc. Source locations found in the clang AST will always

  /// point to one of these tokens.

  /// Tokens are in TU order (per SourceManager::isBeforeInTranslationUnit()).

  /// FIXME: figure out how to handle token splitting, e.g. '>>' can be split

  ///        into two '>' tokens by the parser. However, TokenBuffer currently

  ///        keeps it as a single '>>' token.

  llvm::ArrayRef<syntax::Token> expandedTokens() const {

    return ExpandedTokens;

  }

  /// Returns the subrange of expandedTokens() corresponding to the closed

  /// token range R.

  llvm::ArrayRef<syntax::Token> expandedTokens(SourceRange R) const;

  /// Find the subrange of spelled tokens that produced the corresponding \p

  /// Expanded tokens.

  ///

  /// EXPECTS: \p Expanded is a subrange of expandedTokens().

  ///

  /// Will fail if the expanded tokens do not correspond to a

  /// sequence of spelled tokens. E.g. for the following example:

  ///

  ///   #define FIRST f1 f2 f3

  ///   #define SECOND s1 s2 s3

  ///

  ///   a FIRST b SECOND c // expanded tokens are: a f1 f2 f3 b s1 s2 s3 c

  ///

  /// the results would be:

  ///   expanded   => spelled

  ///   ------------------------

  ///            a => a

  ///     s1 s2 s3 => SECOND

  ///   a f1 f2 f3 => a FIRST

  ///         a f1 => can't map

  ///        s1 s2 => can't map

  ///

  /// If \p Expanded is empty, the returned value is llvm::None.

  /// Complexity is logarithmic.

  llvm::Optional<llvm::ArrayRef<syntax::Token>>

  spelledForExpanded(llvm::ArrayRef<syntax::Token> Expanded) const;

  /// An expansion produced by the preprocessor, includes macro expansions and

  /// preprocessor directives. Preprocessor always maps a non-empty range of

  /// spelled tokens to a (possibly empty) range of expanded tokens. Here is a

  /// few examples of expansions:

  ///    #pragma once      // Expands to an empty range.

  ///    #define FOO 1 2 3 // Expands an empty range.

  ///    FOO               // Expands to "1 2 3".

  /// FIXME(ibiryukov): implement this, currently #include expansions are empty.

  ///    #include <vector> // Expands to tokens produced by the include.

  struct Expansion {

    llvm::ArrayRef<syntax::Token> Spelled;

    llvm::ArrayRef<syntax::Token> Expanded;

  };

  /// If \p Spelled starts a mapping (e.g. if it's a macro name or '#' starting

  /// a preprocessor directive) return the subrange of expanded tokens that the

  /// macro expands to.

  llvm::Optional<Expansion>

  expansionStartingAt(const syntax::Token *Spelled) const;

  /// Lexed tokens of a file before preprocessing. E.g. for the following input

  ///     #define DECL(name) int name = 10

  ///     DECL(a);

  /// spelledTokens() returns

  ///    {"#", "define", "DECL", "(", "name", ")", "int", "name", "=", "10",

  ///     "DECL", "(", "a", ")", ";"}

  llvm::ArrayRef<syntax::Token> spelledTokens(FileID FID) const;

  /// Get all tokens that expand a macro in \p FID. For the following input

  ///     #define FOO B

  ///     #define FOO2(X) int X

  ///     FOO2(XY)

  ///     int B;

  ///     FOO;

  /// macroExpansions() returns {"FOO2", "FOO"} (from line 3 and 5

  /// respecitvely).

  std::vector<const syntax::Token *> macroExpansions(FileID FID) const;

  const SourceManager &sourceManager() const { return *SourceMgr; }

  std::string dumpForTests() const;

private:

  /// Describes a mapping between a continuous subrange of spelled tokens and

  /// expanded tokens. Represents macro expansions, preprocessor directives,

  /// conditionally disabled pp regions, etc.

  ///   #define FOO 1+2

  ///   #define BAR(a) a + 1

  ///   FOO    // invocation #1, tokens = {'1','+','2'}, macroTokens = {'FOO'}.

  ///   BAR(1) // invocation #2, tokens = {'a', '+', '1'},

  ///                            macroTokens = {'BAR', '(', '1', ')'}.

  struct Mapping {

    // Positions in the corresponding spelled token stream. The corresponding

    // range is never empty.

    unsigned BeginSpelled = 0;

    unsigned EndSpelled = 0;

    // Positions in the expanded token stream. The corresponding range can be

    // empty.

    unsigned BeginExpanded = 0;

    unsigned EndExpanded = 0;

    /// For debugging purposes.

    std::string str() const;

  };

  /// Spelled tokens of the file with information about the subranges.

  struct MarkedFile {

    /// Lexed, but not preprocessed, tokens of the file. These map directly to

    /// text in the corresponding files and include tokens of all preprocessor

    /// directives.

    /// FIXME: spelled tokens don't change across FileID that map to the same

    ///        FileEntry. We could consider deduplicating them to save memory.

    std::vector<syntax::Token> SpelledTokens;

    /// A sorted list to convert between the spelled and expanded token streams.

    std::vector<Mapping> Mappings;

    /// The first expanded token produced for this FileID.

    unsigned BeginExpanded = 0;

    unsigned EndExpanded = 0;

  };

  friend class TokenCollector;

  /// Maps a single expanded token to its spelled counterpart or a mapping that

  /// produced it.

  std::pair<const syntax::Token *, const Mapping *>

  spelledForExpandedToken(const syntax::Token *Expanded) const;

  /// Token stream produced after preprocessing, conceputally this captures the

  /// same stream as 'clang -E' (excluding the preprocessor directives like

  /// #file, etc.).

  std::vector<syntax::Token> ExpandedTokens;

  llvm::DenseMap<FileID, MarkedFile> Files;

  // The value is never null, pointer instead of reference to avoid disabling

  // implicit assignment operator.

  const SourceManager *SourceMgr;

};

/// The spelled tokens that overlap or touch a spelling location Loc.

/// This always returns 0-2 tokens.

llvm::ArrayRef<syntax::Token>

spelledTokensTouching(SourceLocation Loc, const syntax::TokenBuffer &Tokens);

llvm::ArrayRef<syntax::Token>

spelledTokensTouching(SourceLocation Loc, llvm::ArrayRef<syntax::Token> Tokens);

/// The identifier token that overlaps or touches a spelling location Loc.

/// If there is none, returns nullptr.

const syntax::Token *

spelledIdentifierTouching(SourceLocation Loc,

                          llvm::ArrayRef<syntax::Token> Tokens);

const syntax::Token *

spelledIdentifierTouching(SourceLocation Loc,

                          const syntax::TokenBuffer &Tokens);

/// Lex the text buffer, corresponding to \p FID, in raw mode and record the

/// resulting spelled tokens. Does minimal post-processing on raw identifiers,

/// setting the appropriate token kind (instead of the raw_identifier reported

/// by lexer in raw mode). This is a very low-level function, most users should

/// prefer to use TokenCollector. Lexing in raw mode produces wildly different

/// results from what one might expect when running a C++ frontend, e.g.

/// preprocessor does not run at all.

/// The result will *not* have a 'eof' token at the end.

std::vector<syntax::Token> tokenize(FileID FID, const SourceManager &SM,

                                    const LangOptions &LO);

/// Collects tokens for the main file while running the frontend action. An

/// instance of this object should be created on

/// FrontendAction::BeginSourceFile() and the results should be consumed after

/// FrontendAction::Execute() finishes.

class TokenCollector {

public:

  /// Adds the hooks to collect the tokens. Should be called before the

  /// preprocessing starts, i.e. as a part of BeginSourceFile() or

  /// CreateASTConsumer().

  TokenCollector(Preprocessor &P);

  /// Finalizes token collection. Should be called after preprocessing is

  /// finished, i.e. after running Execute().

  LLVM_NODISCARD TokenBuffer consume() &&;

private:

  /// Maps from a start to an end spelling location of transformations

  /// performed by the preprocessor. These include:

  ///   1. range from '#' to the last token in the line for PP directives,

  ///   2. macro name and arguments for macro expansions.

  /// Note that we record only top-level macro expansions, intermediate

  /// expansions (e.g. inside macro arguments) are ignored.

  ///

  /// Used to find correct boundaries of macro calls and directives when

  /// building mappings from spelled to expanded tokens.

  ///

  /// Logically, at each point of the preprocessor execution there is a stack of

  /// macro expansions being processed and we could use it to recover the

  /// location information we need. However, the public preprocessor API only

  /// exposes the points when macro expansions start (when we push a macro onto

  /// the stack) and not when they end (when we pop a macro from the stack).

  /// To workaround this limitation, we rely on source location information

  /// stored in this map.

  using PPExpansions = llvm::DenseMap</*SourceLocation*/ int, SourceLocation>;

  class Builder;

  class CollectPPExpansions;

  std::vector<syntax::Token> Expanded;

  // FIXME: we only store macro expansions, also add directives(#pragma, etc.)

  PPExpansions Expansions;

  Preprocessor &PP;

  CollectPPExpansions *Collector;

};

} // namespace syntax

} // namespace clang

#endif