TokenLexer.h source code [clang_source_code/include/clang/Lex/TokenLexer.h]

1	//===- TokenLexer.h - Lex from a token buffer -------------------- C++ --===//
2	//
3	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4	// See https://llvm.org/LICENSE.txt for license information.
5	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6	//
7	//===----------------------------------------------------------------------===//
8	//
9	// This file defines the TokenLexer interface.
10	//
11	//===----------------------------------------------------------------------===//
12
13	#ifndef LLVM_CLANG_LEX_TOKENLEXER_H
14	#define LLVM_CLANG_LEX_TOKENLEXER_H
15
16	#include "clang/Basic/SourceLocation.h"
17	#include "llvm/ADT/ArrayRef.h"
18
19	namespace clang {
20
21	class MacroArgs;
22	class MacroInfo;
23	class Preprocessor;
24	class Token;
25	class VAOptExpansionContext;
26
27	/// TokenLexer - This implements a lexer that returns tokens from a macro body
28	/// or token stream instead of lexing from a character buffer. This is used for
29	/// macro expansion and _Pragma handling, for example.
30	class TokenLexer {
31	friend class Preprocessor;
32
33	/// The macro we are expanding from. This is null if expanding a token stream.
34	MacroInfo *Macro = nullptr;
35
36	/// The actual arguments specified for a function-like macro, or null. The
37	/// TokenLexer owns the pointed-to object.
38	MacroArgs *ActualArgs = nullptr;
39
40	/// The current preprocessor object we are expanding for.
41	Preprocessor &PP;
42
43	/// This is the pointer to an array of tokens that the macro is
44	/// defined to, with arguments expanded for function-like macros. If this is
45	/// a token stream, these are the tokens we are returning. This points into
46	/// the macro definition we are lexing from, a cache buffer that is owned by
47	/// the preprocessor, or some other buffer that we may or may not own
48	/// (depending on OwnsTokens).
49	/// Note that if it points into Preprocessor's cache buffer, the Preprocessor
50	/// may update the pointer as needed.
51	const Token *Tokens;
52
53	/// This is the length of the Tokens array.
54	unsigned NumTokens;
55
56	/// This is the index of the next token that Lex will return.
57	unsigned CurTokenIdx;
58
59	/// The source location range where this macro was expanded.
60	SourceLocation ExpandLocStart, ExpandLocEnd;
61
62	/// Source location pointing at the source location entry chunk that
63	/// was reserved for the current macro expansion.
64	SourceLocation MacroExpansionStart;
65
66	/// The offset of the macro expansion in the
67	/// "source location address space".
68	unsigned MacroStartSLocOffset;
69
70	/// Location of the macro definition.
71	SourceLocation MacroDefStart;
72
73	/// Length of the macro definition.
74	unsigned MacroDefLength;
75
76	/// Lexical information about the expansion point of the macro: the identifier
77	/// that the macro expanded from had these properties.
78	bool AtStartOfLine : 1;
79	bool HasLeadingSpace : 1;
80
81	// When this is true, the next token appended to the
82	// output list during function argument expansion will get a leading space,
83	// regardless of whether it had one to begin with or not. This is used for
84	// placemarker support. If still true after function argument expansion, the
85	// leading space will be applied to the first token following the macro
86	// expansion.
87	bool NextTokGetsSpace : 1;
88
89	/// This is true if this TokenLexer allocated the Tokens
90	/// array, and thus needs to free it when destroyed. For simple object-like
91	/// macros (for example) we just point into the token buffer of the macro
92	/// definition, we don't make a copy of it.
93	bool OwnsTokens : 1;
94
95	/// This is true when tokens lexed from the TokenLexer
96	/// should not be subject to further macro expansion.
97	bool DisableMacroExpansion : 1;
98
99	public:
100	/// Create a TokenLexer for the specified macro with the specified actual
101	/// arguments. Note that this ctor takes ownership of the ActualArgs pointer.
102	/// ILEnd specifies the location of the ')' for a function-like macro or the
103	/// identifier for an object-like macro.
104	TokenLexer(Token &Tok, SourceLocation ILEnd, MacroInfo *MI,
105	MacroArgs *ActualArgs, Preprocessor &pp)
106	: PP(pp), OwnsTokens(false) {
107	Init(Tok, ILEnd, MI, ActualArgs);
108	}
109
110	/// Create a TokenLexer for the specified token stream. If 'OwnsTokens' is
111	/// specified, this takes ownership of the tokens and delete[]'s them when
112	/// the token lexer is empty.
113	TokenLexer(const Token *TokArray, unsigned NumToks, bool DisableExpansion,
114	bool ownsTokens, Preprocessor &pp)
115	: PP(pp), OwnsTokens(false) {
116	Init(TokArray, NumToks, DisableExpansion, ownsTokens);
117	}
118
119	TokenLexer(const TokenLexer &) = delete;
120	TokenLexer &operator=(const TokenLexer &) = delete;
121	~TokenLexer() { destroy(); }
122
123	/// Initialize this TokenLexer to expand from the specified macro
124	/// with the specified argument information. Note that this ctor takes
125	/// ownership of the ActualArgs pointer. ILEnd specifies the location of the
126	/// ')' for a function-like macro or the identifier for an object-like macro.
127	void Init(Token &Tok, SourceLocation ELEnd, MacroInfo *MI,
128	MacroArgs *Actuals);
129
130	/// Initialize this TokenLexer with the specified token stream.
131	/// This does not take ownership of the specified token vector.
132	///
133	/// DisableExpansion is true when macro expansion of tokens lexed from this
134	/// stream should be disabled.
135	void Init(const Token *TokArray, unsigned NumToks,
136	bool DisableMacroExpansion, bool OwnsTokens);
137
138	/// If the next token lexed will pop this macro off the
139	/// expansion stack, return 2. If the next unexpanded token is a '(', return
140	/// 1, otherwise return 0.
141	unsigned isNextTokenLParen() const;
142
143	/// Lex and return a token from this macro stream.
144	bool Lex(Token &Tok);
145
146	/// isParsingPreprocessorDirective - Return true if we are in the middle of a
147	/// preprocessor directive.
148	bool isParsingPreprocessorDirective() const;
149
150	private:
151	void destroy();
152
153	/// Return true if the next lex call will pop this macro off the include
154	/// stack.
155	bool isAtEnd() const {
156	return CurTokenIdx == NumTokens;
157	}
158
159	/// Concatenates the next (sub-)sequence of \p Tokens separated by '##'
160	/// starting with LHSTok - stopping when we encounter a token that is neither
161	/// '##' nor preceded by '##'. Places the result back into \p LHSTok and sets
162	/// \p CurIdx to point to the token following the last one that was pasted.
163	///
164	/// Also performs the MSVC extension wide-literal token pasting involved with:
165	/// \code L #macro-arg. \endcode
166	///
167	/// \param[in,out] LHSTok - Contains the token to the left of '##' in \p
168	/// Tokens upon entry and will contain the resulting concatenated Token upon
169	/// exit.
170	///
171	/// \param[in] TokenStream - The stream of Tokens we are lexing from.
172	///
173	/// \param[in,out] CurIdx - Upon entry, \pTokens[\pCurIdx] must equal '##'
174	/// (with the exception of the MSVC extension mentioned above). Upon exit, it
175	/// is set to the index of the token following the last token that was
176	/// concatenated together.
177	///
178	/// \returns If this returns true, the caller should immediately return the
179	/// token.
180	bool pasteTokens(Token &LHSTok, ArrayRef<Token> TokenStream,
181	unsigned int &CurIdx);
182
183	/// Calls pasteTokens above, passing in the '*this' object's Tokens and
184	/// CurTokenIdx data members.
185	bool pasteTokens(Token &Tok);
186
187
188	/// Takes the tail sequence of tokens within ReplacementToks that represent
189	/// the just expanded __VA_OPT__ tokens (possibly zero tokens) and transforms
190	/// them into a string. \p VCtx is used to determine which token represents
191	/// the first __VA_OPT__ replacement token.
192	///
193	/// \param[in,out] ResultToks - Contains the current Replacement Tokens
194	/// (prior to rescanning and token pasting), the tail end of which represents
195	/// the tokens just expanded through __VA_OPT__ processing. These (sub)
196	/// sequence of tokens are folded into one stringified token.
197	///
198	/// \param[in] VCtx - contains relevant contextual information about the
199	/// state of the tokens around and including the __VA_OPT__ token, necessary
200	/// for stringification.
201	void stringifyVAOPTContents(SmallVectorImpl<Token> &ResultToks,
202	const VAOptExpansionContext &VCtx,
203	SourceLocation VAOPTClosingParenLoc);
204
205	/// Expand the arguments of a function-like macro so that we can quickly
206	/// return preexpanded tokens from Tokens.
207	void ExpandFunctionArguments();
208
209	/// In microsoft compatibility mode, /##/ pastes
210	/// together to form a comment that comments out everything in the current
211	/// macro, other active macros, and anything left on the current physical
212	/// source line of the expanded buffer. Handle this by returning the
213	/// first token on the next line.
214	void HandleMicrosoftCommentPaste(Token &Tok, SourceLocation OpLoc);
215
216	/// If \p loc is a FileID and points inside the current macro
217	/// definition, returns the appropriate source location pointing at the
218	/// macro expansion source location entry.
219	SourceLocation getExpansionLocForMacroDefLoc(SourceLocation loc) const;
220
221	/// Creates SLocEntries and updates the locations of macro argument
222	/// tokens to their new expanded locations.
223	///
224	/// \param ArgIdSpellLoc the location of the macro argument id inside the
225	/// macro definition.
226	void updateLocForMacroArgTokens(SourceLocation ArgIdSpellLoc,
227	Token begin_tokens, Token end_tokens);
228
229	/// Remove comma ahead of __VA_ARGS__, if present, according to compiler
230	/// dialect settings. Returns true if the comma is removed.
231	bool MaybeRemoveCommaBeforeVaArgs(SmallVectorImpl<Token> &ResultToks,
232	bool HasPasteOperator,
233	MacroInfo *Macro, unsigned MacroArgNo,
234	Preprocessor &PP);
235
236	void PropagateLineStartLeadingSpaceInfo(Token &Result);
237	};
238
239	} // namespace clang
240
241	#endif // LLVM_CLANG_LEX_TOKENLEXER_H
242