1 // Copyright 2012 Google Inc.
2 // All rights reserved.
3 //
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5 // modification, are permitted provided that the following conditions are
6 // met:
7 //
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10 // * Redistributions in binary form must reproduce the above copyright
11 // notice, this list of conditions and the following disclaimer in the
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13 // * Neither the name of Google Inc. nor the names of its contributors
14 // may be used to endorse or promote products derived from this software
15 // without specific prior written permission.
16 //
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
29 #include "utils/config/parser.hpp"
30
31 #include <lutok/exceptions.hpp>
32 #include <lutok/operations.hpp>
33 #include <lutok/stack_cleaner.hpp>
34 #include <lutok/state.ipp>
35
36 #include "utils/config/exceptions.hpp"
37 #include "utils/config/lua_module.hpp"
38 #include "utils/config/tree.ipp"
39 #include "utils/logging/macros.hpp"
40 #include "utils/noncopyable.hpp"
41
42 namespace config = utils::config;
43
44
45 // History of configuration file versions:
46 //
47 // 2 - Changed the syntax() call to take only a version number, instead of the
48 // word 'config' as the first argument and the version as the second one.
49 // Files now start with syntax(2) instead of syntax('config', 1).
50 //
51 // 1 - Initial version.
52
53
54 /// Internal implementation of the parser.
55 struct utils::config::parser::impl : utils::noncopyable {
56 /// Pointer to the parent parser. Needed for callbacks.
57 parser* _parent;
58
59 /// The Lua state used by this parser to process the configuration file.
60 lutok::state _state;
61
62 /// The tree to be filed in by the configuration parameters, as provided by
63 /// the caller.
64 config::tree& _tree;
65
66 /// Whether syntax() has been called or not.
67 bool _syntax_called;
68
69 /// Constructs a new implementation.
70 ///
71 /// \param parent_ Pointer to the class being constructed.
72 /// \param config_tree_ The configuration tree provided by the user.
implutils::config::parser::impl73 impl(parser* const parent_, tree& config_tree_) :
74 _parent(parent_), _tree(config_tree_), _syntax_called(false)
75 {
76 }
77
78 friend void lua_syntax(lutok::state&);
79
80 /// Callback executed by the Lua syntax() function.
81 ///
82 /// \param syntax_version The syntax format version as provided by the
83 /// configuration file in the call to syntax().
84 void
syntax_callbackutils::config::parser::impl85 syntax_callback(const int syntax_version)
86 {
87 if (_syntax_called)
88 throw syntax_error("syntax() can only be called once");
89 _syntax_called = true;
90
91 // Allow the parser caller to populate the tree with its own schema
92 // depending on the format/version combination.
93 _parent->setup(_tree, syntax_version);
94
95 // Export the config module to the Lua state so that all global variable
96 // accesses are redirected to the configuration tree.
97 config::redirect(_state, _tree);
98 }
99 };
100
101
102 namespace {
103
104
105 /// Implementation of the Lua syntax() function.
106 ///
107 /// The syntax() function has to be called by configuration files as the very
108 /// first thing they do. Once called, this function populates the configuration
109 /// tree based on the syntax version and then continues to process the rest of
110 /// the file.
111 ///
112 /// \pre state(-2) The syntax format name, if a v1 file.
113 /// \pre state(-1) The syntax format version.
114 ///
115 /// \param state The Lua state to operate in.
116 ///
117 /// \return The number of results pushed onto the stack; always 0.
118 static int
lua_syntax(lutok::state & state)119 lua_syntax(lutok::state& state)
120 {
121 if (!state.is_number(-1))
122 throw config::value_error("Last argument to syntax must be a number");
123 const int syntax_version = state.to_integer(-1);
124
125 if (syntax_version == 1) {
126 if (state.get_top() != 2)
127 throw config::value_error("Version 1 files need two arguments to "
128 "syntax()");
129 if (!state.is_string(-2) || state.to_string(-2) != "config")
130 throw config::value_error("First argument to syntax must be "
131 "'config' for version 1 files");
132 } else {
133 if (state.get_top() != 1)
134 throw config::value_error("syntax() only takes one argument");
135 }
136
137 state.get_global("_config_parser");
138 config::parser::impl* impl = *state.to_userdata< config::parser::impl* >();
139 state.pop(1);
140
141 impl->syntax_callback(syntax_version);
142
143 return 0;
144 }
145
146
147 } // anonymous namespace
148
149
150 /// Constructs a new parser.
151 ///
152 /// \param [in,out] config_tree The configuration tree into which the values set
153 /// in the configuration file will be stored.
parser(tree & config_tree)154 config::parser::parser(tree& config_tree) :
155 _pimpl(new impl(this, config_tree))
156 {
157 lutok::stack_cleaner cleaner(_pimpl->_state);
158
159 _pimpl->_state.push_cxx_function(lua_syntax);
160 _pimpl->_state.set_global("syntax");
161 *_pimpl->_state.new_userdata< config::parser::impl* >() = _pimpl.get();
162 _pimpl->_state.set_global("_config_parser");
163 }
164
165
166 /// Destructor.
~parser(void)167 config::parser::~parser(void)
168 {
169 }
170
171
172 /// Parses a configuration file.
173 ///
174 /// \post The tree registered during the construction of this class is updated
175 /// to contain the values read from the configuration file. If the processing
176 /// fails, the state of the output tree is undefined.
177 ///
178 /// \param file The path to the file to process.
179 ///
180 /// \throw syntax_error If there is any problem processing the file.
181 void
parse(const fs::path & file)182 config::parser::parse(const fs::path& file)
183 {
184 try {
185 lutok::do_file(_pimpl->_state, file.str());
186 } catch (const lutok::error& e) {
187 throw syntax_error(e.what());
188 }
189
190 if (!_pimpl->_syntax_called)
191 throw syntax_error("No syntax defined (no call to syntax() found)");
192 }
193