Annotation of embedaddon/pcre/pcre_scanner.h, revision 1.1.1.1
1.1 misho 1: // Copyright (c) 2005, Google Inc.
2: // All rights reserved.
3: //
4: // Redistribution and use in source and binary forms, with or without
5: // modification, are permitted provided that the following conditions are
6: // met:
7: //
8: // * Redistributions of source code must retain the above copyright
9: // notice, this list of conditions and the following disclaimer.
10: // * Redistributions in binary form must reproduce the above
11: // copyright notice, this list of conditions and the following disclaimer
12: // in the documentation and/or other materials provided with the
13: // distribution.
14: // * Neither the name of Google Inc. nor the names of its
15: // contributors may be used to endorse or promote products derived from
16: // this software without specific prior written permission.
17: //
18: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29: //
30: // Author: Sanjay Ghemawat
31: //
32: // Regular-expression based scanner for parsing an input stream.
33: //
34: // Example 1: parse a sequence of "var = number" entries from input:
35: //
36: // Scanner scanner(input);
37: // string var;
38: // int number;
39: // scanner.SetSkipExpression("\\s+"); // Skip any white space we encounter
40: // while (scanner.Consume("(\\w+) = (\\d+)", &var, &number)) {
41: // ...;
42: // }
43:
44: #ifndef _PCRE_SCANNER_H
45: #define _PCRE_SCANNER_H
46:
47: #include <assert.h>
48: #include <string>
49: #include <vector>
50:
51: #include <pcrecpp.h>
52: #include <pcre_stringpiece.h>
53:
54: namespace pcrecpp {
55:
56: class PCRECPP_EXP_DEFN Scanner {
57: public:
58: Scanner();
59: explicit Scanner(const std::string& input);
60: ~Scanner();
61:
62: // Return current line number. The returned line-number is
63: // one-based. I.e. it returns 1 + the number of consumed newlines.
64: //
65: // Note: this method may be slow. It may take time proportional to
66: // the size of the input.
67: int LineNumber() const;
68:
69: // Return the byte-offset that the scanner is looking in the
70: // input data;
71: int Offset() const;
72:
73: // Return true iff the start of the remaining input matches "re"
74: bool LookingAt(const RE& re) const;
75:
76: // Return true iff all of the following are true
77: // a. the start of the remaining input matches "re",
78: // b. if any arguments are supplied, matched sub-patterns can be
79: // parsed and stored into the arguments.
80: // If it returns true, it skips over the matched input and any
81: // following input that matches the "skip" regular expression.
82: bool Consume(const RE& re,
83: const Arg& arg0 = RE::no_arg,
84: const Arg& arg1 = RE::no_arg,
85: const Arg& arg2 = RE::no_arg
86: // TODO: Allow more arguments?
87: );
88:
89: // Set the "skip" regular expression. If after consuming some data,
90: // a prefix of the input matches this RE, it is automatically
91: // skipped. For example, a programming language scanner would use
92: // a skip RE that matches white space and comments.
93: //
94: // scanner.SetSkipExpression("\\s+|//.*|/[*](.|\n)*?[*]/");
95: //
96: // Skipping repeats as long as it succeeds. We used to let people do
97: // this by writing "(...)*" in the regular expression, but that added
98: // up to lots of recursive calls within the pcre library, so now we
99: // control repetition explicitly via the function call API.
100: //
101: // You can pass NULL for "re" if you do not want any data to be skipped.
102: void Skip(const char* re); // DEPRECATED; does *not* repeat
103: void SetSkipExpression(const char* re);
104:
105: // Temporarily pause "skip"ing. This
106: // Skip("Foo"); code ; DisableSkip(); code; EnableSkip()
107: // is similar to
108: // Skip("Foo"); code ; Skip(NULL); code ; Skip("Foo");
109: // but avoids creating/deleting new RE objects.
110: void DisableSkip();
111:
112: // Reenable previously paused skipping. Any prefix of the input
113: // that matches the skip pattern is immediately dropped.
114: void EnableSkip();
115:
116: /***** Special wrappers around SetSkip() for some common idioms *****/
117:
118: // Arranges to skip whitespace, C comments, C++ comments.
119: // The overall RE is a disjunction of the following REs:
120: // \\s whitespace
121: // //.*\n C++ comment
122: // /[*](.|\n)*?[*]/ C comment (x*? means minimal repetitions of x)
123: // We get repetition via the semantics of SetSkipExpression, not by using *
124: void SkipCXXComments() {
125: SetSkipExpression("\\s|//.*\n|/[*](?:\n|.)*?[*]/");
126: }
127:
128: void set_save_comments(bool comments) {
129: save_comments_ = comments;
130: }
131:
132: bool save_comments() {
133: return save_comments_;
134: }
135:
136: // Append to vector ranges the comments found in the
137: // byte range [start,end] (inclusive) of the input data.
138: // Only comments that were extracted entirely within that
139: // range are returned: no range splitting of atomically-extracted
140: // comments is performed.
141: void GetComments(int start, int end, std::vector<StringPiece> *ranges);
142:
143: // Append to vector ranges the comments added
144: // since the last time this was called. This
145: // functionality is provided for efficiency when
146: // interleaving scanning with parsing.
147: void GetNextComments(std::vector<StringPiece> *ranges);
148:
149: private:
150: std::string data_; // All the input data
151: StringPiece input_; // Unprocessed input
152: RE* skip_; // If non-NULL, RE for skipping input
153: bool should_skip_; // If true, use skip_
154: bool skip_repeat_; // If true, repeat skip_ as long as it works
155: bool save_comments_; // If true, aggregate the skip expression
156:
157: // the skipped comments
158: // TODO: later consider requiring that the StringPieces be added
159: // in order by their start position
160: std::vector<StringPiece> *comments_;
161:
162: // the offset into comments_ that has been returned by GetNextComments
163: int comments_offset_;
164:
165: // helper function to consume *skip_ and honour
166: // save_comments_
167: void ConsumeSkip();
168: };
169:
170: } // namespace pcrecpp
171:
172: #endif /* _PCRE_SCANNER_H */
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