1// Copyright 2012 The Kyua Authors.
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3//
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16//
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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/fs/path.hpp"
40#include "utils/logging/macros.hpp"
41#include "utils/noncopyable.hpp"
42
43namespace config = utils::config;
44
45
46// History of configuration file versions:
47//
48// 2 - Changed the syntax() call to take only a version number, instead of the
49//     word 'config' as the first argument and the version as the second one.
50//     Files now start with syntax(2) instead of syntax('config', 1).
51//
52// 1 - Initial version.
53
54
55/// Internal implementation of the parser.
56struct utils::config::parser::impl : utils::noncopyable {
57    /// Pointer to the parent parser.  Needed for callbacks.
58    parser* _parent;
59
60    /// The Lua state used by this parser to process the configuration file.
61    lutok::state _state;
62
63    /// The tree to be filed in by the configuration parameters, as provided by
64    /// the caller.
65    config::tree& _tree;
66
67    /// Whether syntax() has been called or not.
68    bool _syntax_called;
69
70    /// Constructs a new implementation.
71    ///
72    /// \param parent_ Pointer to the class being constructed.
73    /// \param config_tree_ The configuration tree provided by the user.
74    impl(parser* const parent_, tree& config_tree_) :
75        _parent(parent_), _tree(config_tree_), _syntax_called(false)
76    {
77    }
78
79    friend void lua_syntax(lutok::state&);
80
81    /// Callback executed by the Lua syntax() function.
82    ///
83    /// \param syntax_version The syntax format version as provided by the
84    ///     configuration file in the call to syntax().
85    void
86    syntax_callback(const int syntax_version)
87    {
88        if (_syntax_called)
89            throw syntax_error("syntax() can only be called once");
90        _syntax_called = true;
91
92        // Allow the parser caller to populate the tree with its own schema
93        // depending on the format/version combination.
94        _parent->setup(_tree, syntax_version);
95
96        // Export the config module to the Lua state so that all global variable
97        // accesses are redirected to the configuration tree.
98        config::redirect(_state, _tree);
99    }
100};
101
102
103namespace {
104
105
106static int
107lua_syntax(lutok::state& state)
108{
109    if (!state.is_number(-1))
110        throw config::value_error("Last argument to syntax must be a number");
111    const int syntax_version = state.to_integer(-1);
112
113    if (syntax_version == 1) {
114        if (state.get_top() != 2)
115            throw config::value_error("Version 1 files need two arguments to "
116                                      "syntax()");
117        if (!state.is_string(-2) || state.to_string(-2) != "config")
118            throw config::value_error("First argument to syntax must be "
119                                      "'config' for version 1 files");
120    } else {
121        if (state.get_top() != 1)
122            throw config::value_error("syntax() only takes one argument");
123    }
124
125    state.get_global("_config_parser");
126    config::parser::impl* impl =
127        *state.to_userdata< config::parser::impl* >(-1);
128    state.pop(1);
129
130    impl->syntax_callback(syntax_version);
131
132    return 0;
133}
134
135
136}  // anonymous namespace
137
138
139/// Constructs a new parser.
140///
141/// \param [in,out] config_tree The configuration tree into which the values set
142///     in the configuration file will be stored.
143config::parser::parser(tree& config_tree) :
144    _pimpl(new impl(this, config_tree))
145{
146    lutok::stack_cleaner cleaner(_pimpl->_state);
147
148    _pimpl->_state.push_cxx_function(lua_syntax);
149    _pimpl->_state.set_global("syntax");
150    *_pimpl->_state.new_userdata< config::parser::impl* >() = _pimpl.get();
151    _pimpl->_state.set_global("_config_parser");
152}
153
154
155/// Destructor.
156config::parser::~parser(void)
157{
158}
159
160
161/// Parses a configuration file.
162///
163/// \post The tree registered during the construction of this class is updated
164/// to contain the values read from the configuration file.  If the processing
165/// fails, the state of the output tree is undefined.
166///
167/// \param file The path to the file to process.
168///
169/// \throw syntax_error If there is any problem processing the file.
170void
171config::parser::parse(const fs::path& file)
172{
173    try {
174        lutok::do_file(_pimpl->_state, file.str(), 0, 0, 0);
175    } catch (const lutok::error& e) {
176        throw syntax_error(e.what());
177    }
178
179    if (!_pimpl->_syntax_called)
180        throw syntax_error("No syntax defined (no call to syntax() found)");
181}
182