1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef AAPT_XML_PULL_PARSER_H
18#define AAPT_XML_PULL_PARSER_H
19
20#include <algorithm>
21#include <ostream>
22#include <string>
23#include <vector>
24
25#include "StringPiece.h"
26
27namespace aapt {
28
29class XmlPullParser {
30public:
31    enum class Event {
32        kBadDocument,
33        kStartDocument,
34        kEndDocument,
35
36        kStartNamespace,
37        kEndNamespace,
38        kStartElement,
39        kEndElement,
40        kText,
41        kComment,
42    };
43
44    static void skipCurrentElement(XmlPullParser* parser);
45    static bool isGoodEvent(Event event);
46
47    virtual ~XmlPullParser() {}
48
49    /**
50     * Returns the current event that is being processed.
51     */
52    virtual Event getEvent() const = 0;
53
54    virtual const std::string& getLastError() const = 0;
55
56    /**
57     * Note, unlike XmlPullParser, the first call to next() will return
58     * StartElement of the first element.
59     */
60    virtual Event next() = 0;
61
62    //
63    // These are available for all nodes.
64    //
65
66    virtual const std::u16string& getComment() const = 0;
67    virtual size_t getLineNumber() const = 0;
68    virtual size_t getDepth() const = 0;
69
70    /**
71     * Returns the character data for a Text event.
72     */
73    virtual const std::u16string& getText() const = 0;
74
75    //
76    // Namespace prefix and URI are available for StartNamespace and EndNamespace.
77    //
78
79    virtual const std::u16string& getNamespacePrefix() const = 0;
80    virtual const std::u16string& getNamespaceUri() const = 0;
81
82    /*
83     * Uses the current stack of namespaces to resolve the package. Eg:
84     * xmlns:app = "http://schemas.android.com/apk/res/com.android.app"
85     * ...
86     * android:text="@app:string/message"
87     *
88     * In this case, 'app' will be converted to 'com.android.app'.
89     *
90     * If xmlns:app="http://schemas.android.com/apk/res-auto", then
91     * 'package' will be set to 'defaultPackage'.
92     */
93    virtual bool applyPackageAlias(std::u16string* package,
94                                   const std::u16string& defaultPackage) const = 0;
95
96    //
97    // These are available for StartElement and EndElement.
98    //
99
100    virtual const std::u16string& getElementNamespace() const = 0;
101    virtual const std::u16string& getElementName() const = 0;
102
103    //
104    // Remaining methods are for retrieving information about attributes
105    // associated with a StartElement.
106    //
107    // Attributes must be in sorted order (according to the less than operator
108    // of struct Attribute).
109    //
110
111    struct Attribute {
112        std::u16string namespaceUri;
113        std::u16string name;
114        std::u16string value;
115
116        int compare(const Attribute& rhs) const;
117        bool operator<(const Attribute& rhs) const;
118        bool operator==(const Attribute& rhs) const;
119        bool operator!=(const Attribute& rhs) const;
120    };
121
122    using const_iterator = std::vector<Attribute>::const_iterator;
123
124    virtual const_iterator beginAttributes() const = 0;
125    virtual const_iterator endAttributes() const = 0;
126    virtual size_t getAttributeCount() const = 0;
127    const_iterator findAttribute(StringPiece16 namespaceUri, StringPiece16 name) const;
128};
129
130//
131// Implementation
132//
133
134inline ::std::ostream& operator<<(::std::ostream& out, XmlPullParser::Event event) {
135    switch (event) {
136        case XmlPullParser::Event::kBadDocument: return out << "BadDocument";
137        case XmlPullParser::Event::kStartDocument: return out << "StartDocument";
138        case XmlPullParser::Event::kEndDocument: return out << "EndDocument";
139        case XmlPullParser::Event::kStartNamespace: return out << "StartNamespace";
140        case XmlPullParser::Event::kEndNamespace: return out << "EndNamespace";
141        case XmlPullParser::Event::kStartElement: return out << "StartElement";
142        case XmlPullParser::Event::kEndElement: return out << "EndElement";
143        case XmlPullParser::Event::kText: return out << "Text";
144        case XmlPullParser::Event::kComment: return out << "Comment";
145    }
146    return out;
147}
148
149inline void XmlPullParser::skipCurrentElement(XmlPullParser* parser) {
150    int depth = 1;
151    while (depth > 0) {
152        switch (parser->next()) {
153            case Event::kEndDocument:
154            case Event::kBadDocument:
155                return;
156            case Event::kStartElement:
157                depth++;
158                break;
159            case Event::kEndElement:
160                depth--;
161                break;
162            default:
163                break;
164        }
165    }
166}
167
168inline bool XmlPullParser::isGoodEvent(XmlPullParser::Event event) {
169    return event != Event::kBadDocument && event != Event::kEndDocument;
170}
171
172inline int XmlPullParser::Attribute::compare(const Attribute& rhs) const {
173    int cmp = namespaceUri.compare(rhs.namespaceUri);
174    if (cmp != 0) return cmp;
175    return name.compare(rhs.name);
176}
177
178inline bool XmlPullParser::Attribute::operator<(const Attribute& rhs) const {
179    return compare(rhs) < 0;
180}
181
182inline bool XmlPullParser::Attribute::operator==(const Attribute& rhs) const {
183    return compare(rhs) == 0;
184}
185
186inline bool XmlPullParser::Attribute::operator!=(const Attribute& rhs) const {
187    return compare(rhs) != 0;
188}
189
190inline XmlPullParser::const_iterator XmlPullParser::findAttribute(StringPiece16 namespaceUri,
191                                                                  StringPiece16 name) const {
192    const auto endIter = endAttributes();
193    const auto iter = std::lower_bound(beginAttributes(), endIter,
194            std::pair<StringPiece16, StringPiece16>(namespaceUri, name),
195            [](const Attribute& attr, const std::pair<StringPiece16, StringPiece16>& rhs) -> bool {
196                int cmp = attr.namespaceUri.compare(0, attr.namespaceUri.size(),
197                        rhs.first.data(), rhs.first.size());
198                if (cmp < 0) return true;
199                if (cmp > 0) return false;
200                cmp = attr.name.compare(0, attr.name.size(), rhs.second.data(), rhs.second.size());
201                if (cmp < 0) return true;
202                return false;
203            }
204    );
205
206    if (iter != endIter && namespaceUri == iter->namespaceUri && name == iter->name) {
207        return iter;
208    }
209    return endIter;
210}
211
212} // namespace aapt
213
214#endif // AAPT_XML_PULL_PARSER_H
215