Line data Source code
1 : // Protocol Buffers - Google's data interchange format
2 : // Copyright 2008 Google Inc. All rights reserved.
3 : // https://developers.google.com/protocol-buffers/
4 : //
5 : // Redistribution and use in source and binary forms, with or without
6 : // modification, are permitted provided that the following conditions are
7 : // met:
8 : //
9 : // * Redistributions of source code must retain the above copyright
10 : // notice, this list of conditions and the following disclaimer.
11 : // * Redistributions in binary form must reproduce the above
12 : // copyright notice, this list of conditions and the following disclaimer
13 : // in the documentation and/or other materials provided with the
14 : // distribution.
15 : // * Neither the name of Google Inc. nor the names of its
16 : // contributors may be used to endorse or promote products derived from
17 : // this software without specific prior written permission.
18 : //
19 : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 :
31 : // Author: kenton@google.com (Kenton Varda)
32 : // Based on original Protocol Buffers design by
33 : // Sanjay Ghemawat, Jeff Dean, and others.
34 : //
35 : // Class for parsing tokenized text from a ZeroCopyInputStream.
36 :
37 : #ifndef GOOGLE_PROTOBUF_IO_TOKENIZER_H__
38 : #define GOOGLE_PROTOBUF_IO_TOKENIZER_H__
39 :
40 : #include <string>
41 : #include <vector>
42 : #include <google/protobuf/stubs/common.h>
43 :
44 : namespace google {
45 : namespace protobuf {
46 : namespace io {
47 :
48 : class ZeroCopyInputStream; // zero_copy_stream.h
49 :
50 : // Defined in this file.
51 : class ErrorCollector;
52 : class Tokenizer;
53 :
54 : // Abstract interface for an object which collects the errors that occur
55 : // during parsing. A typical implementation might simply print the errors
56 : // to stdout.
57 : class LIBPROTOBUF_EXPORT ErrorCollector {
58 : public:
59 0 : inline ErrorCollector() {}
60 : virtual ~ErrorCollector();
61 :
62 : // Indicates that there was an error in the input at the given line and
63 : // column numbers. The numbers are zero-based, so you may want to add
64 : // 1 to each before printing them.
65 : virtual void AddError(int line, int column, const string& message) = 0;
66 :
67 : // Indicates that there was a warning in the input at the given line and
68 : // column numbers. The numbers are zero-based, so you may want to add
69 : // 1 to each before printing them.
70 0 : virtual void AddWarning(int /* line */, int /* column */,
71 0 : const string& /* message */) { }
72 :
73 : private:
74 : GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ErrorCollector);
75 : };
76 :
77 : // This class converts a stream of raw text into a stream of tokens for
78 : // the protocol definition parser to parse. The tokens recognized are
79 : // similar to those that make up the C language; see the TokenType enum for
80 : // precise descriptions. Whitespace and comments are skipped. By default,
81 : // C- and C++-style comments are recognized, but other styles can be used by
82 : // calling set_comment_style().
83 : class LIBPROTOBUF_EXPORT Tokenizer {
84 : public:
85 : // Construct a Tokenizer that reads and tokenizes text from the given
86 : // input stream and writes errors to the given error_collector.
87 : // The caller keeps ownership of input and error_collector.
88 : Tokenizer(ZeroCopyInputStream* input, ErrorCollector* error_collector);
89 : ~Tokenizer();
90 :
91 : enum TokenType {
92 : TYPE_START, // Next() has not yet been called.
93 : TYPE_END, // End of input reached. "text" is empty.
94 :
95 : TYPE_IDENTIFIER, // A sequence of letters, digits, and underscores, not
96 : // starting with a digit. It is an error for a number
97 : // to be followed by an identifier with no space in
98 : // between.
99 : TYPE_INTEGER, // A sequence of digits representing an integer. Normally
100 : // the digits are decimal, but a prefix of "0x" indicates
101 : // a hex number and a leading zero indicates octal, just
102 : // like with C numeric literals. A leading negative sign
103 : // is NOT included in the token; it's up to the parser to
104 : // interpret the unary minus operator on its own.
105 : TYPE_FLOAT, // A floating point literal, with a fractional part and/or
106 : // an exponent. Always in decimal. Again, never
107 : // negative.
108 : TYPE_STRING, // A quoted sequence of escaped characters. Either single
109 : // or double quotes can be used, but they must match.
110 : // A string literal cannot cross a line break.
111 : TYPE_SYMBOL, // Any other printable character, like '!' or '+'.
112 : // Symbols are always a single character, so "!+$%" is
113 : // four tokens.
114 : };
115 :
116 : // Structure representing a token read from the token stream.
117 0 : struct Token {
118 : TokenType type;
119 : string text; // The exact text of the token as it appeared in
120 : // the input. e.g. tokens of TYPE_STRING will still
121 : // be escaped and in quotes.
122 :
123 : // "line" and "column" specify the position of the first character of
124 : // the token within the input stream. They are zero-based.
125 : int line;
126 : int column;
127 : int end_column;
128 : };
129 :
130 : // Get the current token. This is updated when Next() is called. Before
131 : // the first call to Next(), current() has type TYPE_START and no contents.
132 : const Token& current();
133 :
134 : // Return the previous token -- i.e. what current() returned before the
135 : // previous call to Next().
136 : const Token& previous();
137 :
138 : // Advance to the next token. Returns false if the end of the input is
139 : // reached.
140 : bool Next();
141 :
142 : // Like Next(), but also collects comments which appear between the previous
143 : // and next tokens.
144 : //
145 : // Comments which appear to be attached to the previous token are stored
146 : // in *prev_tailing_comments. Comments which appear to be attached to the
147 : // next token are stored in *next_leading_comments. Comments appearing in
148 : // between which do not appear to be attached to either will be added to
149 : // detached_comments. Any of these parameters can be NULL to simply discard
150 : // the comments.
151 : //
152 : // A series of line comments appearing on consecutive lines, with no other
153 : // tokens appearing on those lines, will be treated as a single comment.
154 : //
155 : // Only the comment content is returned; comment markers (e.g. //) are
156 : // stripped out. For block comments, leading whitespace and an asterisk will
157 : // be stripped from the beginning of each line other than the first. Newlines
158 : // are included in the output.
159 : //
160 : // Examples:
161 : //
162 : // optional int32 foo = 1; // Comment attached to foo.
163 : // // Comment attached to bar.
164 : // optional int32 bar = 2;
165 : //
166 : // optional string baz = 3;
167 : // // Comment attached to baz.
168 : // // Another line attached to baz.
169 : //
170 : // // Comment attached to qux.
171 : // //
172 : // // Another line attached to qux.
173 : // optional double qux = 4;
174 : //
175 : // // Detached comment. This is not attached to qux or corge
176 : // // because there are blank lines separating it from both.
177 : //
178 : // optional string corge = 5;
179 : // /* Block comment attached
180 : // * to corge. Leading asterisks
181 : // * will be removed. */
182 : // /* Block comment attached to
183 : // * grault. */
184 : // optional int32 grault = 6;
185 : bool NextWithComments(string* prev_trailing_comments,
186 : vector<string>* detached_comments,
187 : string* next_leading_comments);
188 :
189 : // Parse helpers ---------------------------------------------------
190 :
191 : // Parses a TYPE_FLOAT token. This never fails, so long as the text actually
192 : // comes from a TYPE_FLOAT token parsed by Tokenizer. If it doesn't, the
193 : // result is undefined (possibly an assert failure).
194 : static double ParseFloat(const string& text);
195 :
196 : // Parses a TYPE_STRING token. This never fails, so long as the text actually
197 : // comes from a TYPE_STRING token parsed by Tokenizer. If it doesn't, the
198 : // result is undefined (possibly an assert failure).
199 : static void ParseString(const string& text, string* output);
200 :
201 : // Identical to ParseString, but appends to output.
202 : static void ParseStringAppend(const string& text, string* output);
203 :
204 : // Parses a TYPE_INTEGER token. Returns false if the result would be
205 : // greater than max_value. Otherwise, returns true and sets *output to the
206 : // result. If the text is not from a Token of type TYPE_INTEGER originally
207 : // parsed by a Tokenizer, the result is undefined (possibly an assert
208 : // failure).
209 : static bool ParseInteger(const string& text, uint64 max_value,
210 : uint64* output);
211 :
212 : // Options ---------------------------------------------------------
213 :
214 : // Set true to allow floats to be suffixed with the letter 'f'. Tokens
215 : // which would otherwise be integers but which have the 'f' suffix will be
216 : // forced to be interpreted as floats. For all other purposes, the 'f' is
217 : // ignored.
218 0 : void set_allow_f_after_float(bool value) { allow_f_after_float_ = value; }
219 :
220 : // Valid values for set_comment_style().
221 : enum CommentStyle {
222 : // Line comments begin with "//", block comments are delimited by "/*" and
223 : // "*/".
224 : CPP_COMMENT_STYLE,
225 : // Line comments begin with "#". No way to write block comments.
226 : SH_COMMENT_STYLE
227 : };
228 :
229 : // Sets the comment style.
230 0 : void set_comment_style(CommentStyle style) { comment_style_ = style; }
231 :
232 : // Whether to require whitespace between a number and a field name.
233 : // Default is true. Do not use this; for Google-internal cleanup only.
234 0 : void set_require_space_after_number(bool require) {
235 0 : require_space_after_number_ = require;
236 0 : }
237 :
238 : // Whether to allow string literals to span multiple lines. Default is false.
239 : // Do not use this; for Google-internal cleanup only.
240 0 : void set_allow_multiline_strings(bool allow) {
241 0 : allow_multiline_strings_ = allow;
242 0 : }
243 :
244 : // External helper: validate an identifier.
245 : static bool IsIdentifier(const string& text);
246 :
247 : // -----------------------------------------------------------------
248 : private:
249 : GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Tokenizer);
250 :
251 : Token current_; // Returned by current().
252 : Token previous_; // Returned by previous().
253 :
254 : ZeroCopyInputStream* input_;
255 : ErrorCollector* error_collector_;
256 :
257 : char current_char_; // == buffer_[buffer_pos_], updated by NextChar().
258 : const char* buffer_; // Current buffer returned from input_.
259 : int buffer_size_; // Size of buffer_.
260 : int buffer_pos_; // Current position within the buffer.
261 : bool read_error_; // Did we previously encounter a read error?
262 :
263 : // Line and column number of current_char_ within the whole input stream.
264 : int line_;
265 : int column_;
266 :
267 : // String to which text should be appended as we advance through it.
268 : // Call RecordTo(&str) to start recording and StopRecording() to stop.
269 : // E.g. StartToken() calls RecordTo(¤t_.text). record_start_ is the
270 : // position within the current buffer where recording started.
271 : string* record_target_;
272 : int record_start_;
273 :
274 : // Options.
275 : bool allow_f_after_float_;
276 : CommentStyle comment_style_;
277 : bool require_space_after_number_;
278 : bool allow_multiline_strings_;
279 :
280 : // Since we count columns we need to interpret tabs somehow. We'll take
281 : // the standard 8-character definition for lack of any way to do better.
282 : static const int kTabWidth = 8;
283 :
284 : // -----------------------------------------------------------------
285 : // Helper methods.
286 :
287 : // Consume this character and advance to the next one.
288 : void NextChar();
289 :
290 : // Read a new buffer from the input.
291 : void Refresh();
292 :
293 : inline void RecordTo(string* target);
294 : inline void StopRecording();
295 :
296 : // Called when the current character is the first character of a new
297 : // token (not including whitespace or comments).
298 : inline void StartToken();
299 : // Called when the current character is the first character after the
300 : // end of the last token. After this returns, current_.text will
301 : // contain all text consumed since StartToken() was called.
302 : inline void EndToken();
303 :
304 : // Convenience method to add an error at the current line and column.
305 0 : void AddError(const string& message) {
306 0 : error_collector_->AddError(line_, column_, message);
307 0 : }
308 :
309 : // -----------------------------------------------------------------
310 : // The following four methods are used to consume tokens of specific
311 : // types. They are actually used to consume all characters *after*
312 : // the first, since the calling function consumes the first character
313 : // in order to decide what kind of token is being read.
314 :
315 : // Read and consume a string, ending when the given delimiter is
316 : // consumed.
317 : void ConsumeString(char delimiter);
318 :
319 : // Read and consume a number, returning TYPE_FLOAT or TYPE_INTEGER
320 : // depending on what was read. This needs to know if the first
321 : // character was a zero in order to correctly recognize hex and octal
322 : // numbers.
323 : // It also needs to know if the first characted was a . to parse floating
324 : // point correctly.
325 : TokenType ConsumeNumber(bool started_with_zero, bool started_with_dot);
326 :
327 : // Consume the rest of a line.
328 : void ConsumeLineComment(string* content);
329 : // Consume until "*/".
330 : void ConsumeBlockComment(string* content);
331 :
332 : enum NextCommentStatus {
333 : // Started a line comment.
334 : LINE_COMMENT,
335 :
336 : // Started a block comment.
337 : BLOCK_COMMENT,
338 :
339 : // Consumed a slash, then realized it wasn't a comment. current_ has
340 : // been filled in with a slash token. The caller should return it.
341 : SLASH_NOT_COMMENT,
342 :
343 : // We do not appear to be starting a comment here.
344 : NO_COMMENT
345 : };
346 :
347 : // If we're at the start of a new comment, consume it and return what kind
348 : // of comment it is.
349 : NextCommentStatus TryConsumeCommentStart();
350 :
351 : // -----------------------------------------------------------------
352 : // These helper methods make the parsing code more readable. The
353 : // "character classes" refered to are defined at the top of the .cc file.
354 : // Basically it is a C++ class with one method:
355 : // static bool InClass(char c);
356 : // The method returns true if c is a member of this "class", like "Letter"
357 : // or "Digit".
358 :
359 : // Returns true if the current character is of the given character
360 : // class, but does not consume anything.
361 : template<typename CharacterClass>
362 : inline bool LookingAt();
363 :
364 : // If the current character is in the given class, consume it and return
365 : // true. Otherwise return false.
366 : // e.g. TryConsumeOne<Letter>()
367 : template<typename CharacterClass>
368 : inline bool TryConsumeOne();
369 :
370 : // Like above, but try to consume the specific character indicated.
371 : inline bool TryConsume(char c);
372 :
373 : // Consume zero or more of the given character class.
374 : template<typename CharacterClass>
375 : inline void ConsumeZeroOrMore();
376 :
377 : // Consume one or more of the given character class or log the given
378 : // error message.
379 : // e.g. ConsumeOneOrMore<Digit>("Expected digits.");
380 : template<typename CharacterClass>
381 : inline void ConsumeOneOrMore(const char* error);
382 : };
383 :
384 : // inline methods ====================================================
385 0 : inline const Tokenizer::Token& Tokenizer::current() {
386 0 : return current_;
387 : }
388 :
389 : inline const Tokenizer::Token& Tokenizer::previous() {
390 : return previous_;
391 : }
392 :
393 : inline void Tokenizer::ParseString(const string& text, string* output) {
394 : output->clear();
395 : ParseStringAppend(text, output);
396 : }
397 :
398 : } // namespace io
399 : } // namespace protobuf
400 :
401 : } // namespace google
402 : #endif // GOOGLE_PROTOBUF_IO_TOKENIZER_H__
|
