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1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef CHROME_COMMON_LIBXML_UTILS_H__ | |
6 #define CHROME_COMMON_LIBXML_UTILS_H__ | |
7 #pragma once | |
8 | |
9 #include <string> | |
10 | |
11 #include "libxml/xmlreader.h" | |
12 #include "libxml/xmlwriter.h" | |
13 | |
14 class FilePath; | |
15 | |
16 // Converts a libxml xmlChar* into a UTF-8 std::string. | |
17 // NULL inputs produce an empty string. | |
18 std::string XmlStringToStdString(const xmlChar* xmlstring); | |
19 | |
20 // libxml uses a global error function pointer for reporting errors. | |
21 // A ScopedXmlErrorFunc object lets you change the global error pointer | |
22 // for the duration of the object's lifetime. | |
23 class ScopedXmlErrorFunc { | |
24 public: | |
25 ScopedXmlErrorFunc(void* context, xmlGenericErrorFunc func) { | |
26 old_error_func_ = xmlGenericError; | |
27 old_error_context_ = xmlGenericErrorContext; | |
28 xmlSetGenericErrorFunc(context, func); | |
29 } | |
30 ~ScopedXmlErrorFunc() { | |
31 xmlSetGenericErrorFunc(old_error_context_, old_error_func_); | |
32 } | |
33 | |
34 private: | |
35 xmlGenericErrorFunc old_error_func_; | |
36 void* old_error_context_; | |
37 }; | |
38 | |
39 // XmlReader is a wrapper class around libxml's xmlReader, | |
40 // providing a simplified C++ API. | |
41 class XmlReader { | |
42 public: | |
43 XmlReader(); | |
44 ~XmlReader(); | |
45 | |
46 // Load a document into the reader from memory. |input| must be UTF-8 and | |
47 // exist for the lifetime of this object. Returns false on error. | |
48 // TODO(evanm): handle encodings other than UTF-8? | |
49 bool Load(const std::string& input); | |
50 | |
51 // Load a document into the reader from a file. Returns false on error. | |
52 bool LoadFile(const FilePath& file_path); | |
53 | |
54 // Wrappers around libxml functions ----------------------------------------- | |
55 | |
56 // Read() advances to the next node. Returns false on EOF or error. | |
57 bool Read() { return xmlTextReaderRead(reader_) == 1; } | |
58 | |
59 // Next(), when pointing at an opening tag, advances to the node after | |
60 // the matching closing tag. Returns false on EOF or error. | |
61 bool Next() { return xmlTextReaderNext(reader_) == 1; } | |
62 | |
63 // Return the depth in the tree of the current node. | |
64 int Depth() { return xmlTextReaderDepth(reader_); } | |
65 | |
66 // Returns the "local" name of the current node. | |
67 // For a tag like <foo:bar>, this is the string "foo:bar". | |
68 std::string NodeName() { | |
69 return XmlStringToStdString(xmlTextReaderConstLocalName(reader_)); | |
70 } | |
71 | |
72 // When pointing at a tag, retrieves the value of an attribute. | |
73 // Returns false on failure. | |
74 // E.g. for <foo bar:baz="a">, NodeAttribute("bar:baz", &value) | |
75 // returns true and |value| is set to "a". | |
76 bool NodeAttribute(const char* name, std::string* value); | |
77 | |
78 // Helper functions not provided by libxml ---------------------------------- | |
79 | |
80 // Return the string content within an element. | |
81 // "<foo>bar</foo>" is a sequence of three nodes: | |
82 // (1) open tag, (2) text, (3) close tag. | |
83 // With the reader currently at (1), this returns the text of (2), | |
84 // and advances past (3). | |
85 // Returns false on error. | |
86 bool ReadElementContent(std::string* content); | |
87 | |
88 // Skip to the next opening tag, returning false if we reach a closing | |
89 // tag or EOF first. | |
90 // If currently on an opening tag, doesn't advance at all. | |
91 bool SkipToElement(); | |
92 | |
93 // Returns the errors reported by libxml, if any. | |
94 // (libxml normally just dumps these errors to stderr.) | |
95 const std::string& errors() const { return errors_; } | |
96 | |
97 private: | |
98 // A callback for libxml to report errors. | |
99 static void GenericErrorCallback(void* context, const char* msg, ...); | |
100 | |
101 // Returns the libxml node type of the current node. | |
102 int NodeType() { return xmlTextReaderNodeType(reader_); } | |
103 | |
104 // The underlying libxml xmlTextReader. | |
105 xmlTextReaderPtr reader_; | |
106 | |
107 // error_func_ is used to reassign libxml's global error function | |
108 // to report errors into |errors_| for the lifetime of this object. | |
109 ScopedXmlErrorFunc error_func_; | |
110 std::string errors_; | |
111 }; | |
112 | |
113 // XmlWriter is a wrapper class around libxml's xmlWriter, | |
114 // providing a simplified C++ API. | |
115 // StartWriting must be called before other methods, and StopWriting | |
116 // must be called before GetWrittenString() will return results. | |
117 class XmlWriter { | |
118 public: | |
119 XmlWriter(); | |
120 ~XmlWriter(); | |
121 | |
122 // Allocates the xmlTextWriter and an xmlBuffer and starts an XML document. | |
123 // This must be called before any other functions. By default, indenting is | |
124 // set to true. | |
125 void StartWriting(); | |
126 | |
127 // Ends the XML document and frees the xmlTextWriter. | |
128 // This must be called before GetWrittenString() is called. | |
129 void StopWriting(); | |
130 // Wrappers around libxml functions ----------------------------------------- | |
131 | |
132 // All following elements will be indented to match their depth. | |
133 void StartIndenting() { xmlTextWriterSetIndent(writer_, 1); } | |
134 | |
135 // All follow elements will not be indented. | |
136 void StopIndenting() { xmlTextWriterSetIndent(writer_, 0); } | |
137 | |
138 // Start an element with the given name. All future elements added will be | |
139 // children of this element, until it is ended. Returns false on error. | |
140 bool StartElement(const std::string& element_name) { | |
141 return xmlTextWriterStartElement(writer_, | |
142 BAD_CAST element_name.c_str()) >= 0; | |
143 } | |
144 | |
145 // Ends the current open element. Returns false on error. | |
146 bool EndElement() { | |
147 return xmlTextWriterEndElement(writer_) >= 0; | |
148 } | |
149 | |
150 // Adds an attribute to the current open element. Returns false on error. | |
151 bool AddAttribute(const std::string& attribute_name, | |
152 const std::string& attribute_value) { | |
153 return xmlTextWriterWriteAttribute(writer_, | |
154 BAD_CAST attribute_name.c_str(), | |
155 BAD_CAST attribute_value.c_str()) >= 0; | |
156 } | |
157 | |
158 // Adds a new element with name |element_name| and content |content| | |
159 // to the buffer. Example: <|element_name|>|content|</|element_name|> | |
160 // Returns false on errors. | |
161 bool WriteElement(const std::string& element_name, | |
162 const std::string& content) { | |
163 return xmlTextWriterWriteElement(writer_, | |
164 BAD_CAST element_name.c_str(), | |
165 BAD_CAST content.c_str()) >= 0; | |
166 } | |
167 | |
168 // Helper functions not provided by xmlTextWriter --------------------------- | |
169 | |
170 // Returns the string that has been written to the buffer. | |
171 std::string GetWrittenString() { | |
172 if (buffer_ == NULL) | |
173 return ""; | |
174 return XmlStringToStdString(buffer_->content); | |
175 } | |
176 | |
177 private: | |
178 // The underlying libxml xmlTextWriter. | |
179 xmlTextWriterPtr writer_; | |
180 | |
181 // Stores the output. | |
182 xmlBufferPtr buffer_; | |
183 }; | |
184 | |
185 #endif // CHROME_COMMON_LIBXML_UTILS_H__ | |
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