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Diffstat (limited to 'utils/config/lua_module.cpp')
| -rw-r--r-- | utils/config/lua_module.cpp | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/utils/config/lua_module.cpp b/utils/config/lua_module.cpp new file mode 100644 index 000000000000..891f07302e0a --- /dev/null +++ b/utils/config/lua_module.cpp @@ -0,0 +1,282 @@ +// Copyright 2012 The Kyua Authors. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in the +// documentation and/or other materials provided with the distribution. +// * Neither the name of Google Inc. nor the names of its contributors +// may be used to endorse or promote products derived from this software +// without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#include "utils/config/lua_module.hpp" + +#include <lutok/stack_cleaner.hpp> +#include <lutok/state.ipp> + +#include "utils/config/exceptions.hpp" +#include "utils/config/keys.hpp" +#include "utils/config/tree.ipp" + +namespace config = utils::config; +namespace detail = utils::config::detail; + + +namespace { + + +/// Gets the tree singleton stored in the Lua state. +/// +/// \param state The Lua state. The registry must contain a key named +/// "tree" with a pointer to the singleton. +/// +/// \return A reference to the tree associated with the Lua state. +/// +/// \throw syntax_error If the tree cannot be located. +config::tree& +get_global_tree(lutok::state& state) +{ + lutok::stack_cleaner cleaner(state); + + state.push_value(lutok::registry_index); + state.push_string("tree"); + state.get_table(-2); + if (state.is_nil(-1)) + throw config::syntax_error("Cannot find tree singleton; global state " + "corrupted?"); + config::tree& tree = **state.to_userdata< config::tree* >(-1); + state.pop(1); + return tree; +} + + +/// Gets a fully-qualified tree key from the state. +/// +/// \param state The Lua state. +/// \param table_index An index to the Lua stack pointing to the table being +/// accessed. If this table contains a tree_key metadata property, this is +/// considered to be the prefix of the tree key. +/// \param field_index An index to the Lua stack pointing to the entry +/// containing the name of the field being indexed. +/// +/// \return A dotted key. +/// +/// \throw invalid_key_error If the name of the key is invalid. +static std::string +get_tree_key(lutok::state& state, const int table_index, const int field_index) +{ + PRE(state.is_string(field_index)); + const std::string field = state.to_string(field_index); + if (!field.empty() && field[0] == '_') + throw config::invalid_key_error( + F("Configuration key cannot have an underscore as a prefix; " + "found %s") % field); + + std::string tree_key; + if (state.get_metafield(table_index, "tree_key")) { + tree_key = state.to_string(-1) + "." + state.to_string(field_index - 1); + state.pop(1); + } else + tree_key = state.to_string(field_index); + return tree_key; +} + + +static int redirect_newindex(lutok::state&); +static int redirect_index(lutok::state&); + + +/// Creates a table for a new configuration inner node. +/// +/// \post state(-1) Contains the new table. +/// +/// \param state The Lua state in which to push the table. +/// \param tree_key The key to which the new table corresponds. +static void +new_table_for_key(lutok::state& state, const std::string& tree_key) +{ + state.new_table(); + { + state.new_table(); + { + state.push_string("__index"); + state.push_cxx_function(redirect_index); + state.set_table(-3); + + state.push_string("__newindex"); + state.push_cxx_function(redirect_newindex); + state.set_table(-3); + + state.push_string("tree_key"); + state.push_string(tree_key); + state.set_table(-3); + } + state.set_metatable(-2); + } +} + + +/// Sets the value of an configuration node. +/// +/// \pre state(-3) The table to index. If this is not _G, then the table +/// metadata must contain a tree_key property describing the path to +/// current level. +/// \pre state(-2) The field to index into the table. Must be a string. +/// \pre state(-1) The value to set the indexed table field to. +/// +/// \param state The Lua state in which to operate. +/// +/// \return The number of result values on the Lua stack; always 0. +/// +/// \throw invalid_key_error If the provided key is invalid. +/// \throw unknown_key_error If the key cannot be located. +/// \throw value_error If the value has an unsupported type or cannot be +/// set on the key, or if the input table or index are invalid. +static int +redirect_newindex(lutok::state& state) +{ + if (!state.is_table(-3)) + throw config::value_error("Indexed object is not a table"); + if (!state.is_string(-2)) + throw config::value_error("Invalid field in configuration object " + "reference; must be a string"); + + const std::string dotted_key = get_tree_key(state, -3, -2); + try { + config::tree& tree = get_global_tree(state); + tree.set_lua(dotted_key, state, -1); + } catch (const config::value_error& e) { + throw config::invalid_key_value(detail::parse_key(dotted_key), + e.what()); + } + + // Now really set the key in the Lua table, but prevent direct accesses from + // the user by prefixing it. We do this to ensure that re-setting the same + // key of the tree results in a call to __newindex instead of __index. + state.push_string("_" + state.to_string(-2)); + state.push_value(-2); + state.raw_set(-5); + + return 0; +} + + +/// Indexes a configuration node. +/// +/// \pre state(-3) The table to index. If this is not _G, then the table +/// metadata must contain a tree_key property describing the path to +/// current level. If the field does not exist, a new table is created. +/// \pre state(-1) The field to index into the table. Must be a string. +/// +/// \param state The Lua state in which to operate. +/// +/// \return The number of result values on the Lua stack; always 1. +/// +/// \throw value_error If the input table or index are invalid. +static int +redirect_index(lutok::state& state) +{ + if (!state.is_table(-2)) + throw config::value_error("Indexed object is not a table"); + if (!state.is_string(-1)) + throw config::value_error("Invalid field in configuration object " + "reference; must be a string"); + + // Query if the key has already been set by a call to redirect_newindex. + state.push_string("_" + state.to_string(-1)); + state.raw_get(-3); + if (!state.is_nil(-1)) + return 1; + state.pop(1); + + state.push_value(-1); // Duplicate the field name. + state.raw_get(-3); // Get table[field] to see if it's defined. + if (state.is_nil(-1)) { + state.pop(1); + + // The stack is now the same as when we entered the function, but we + // know that the field is undefined and thus have to create a new + // configuration table. + INV(state.is_table(-2)); + INV(state.is_string(-1)); + + const config::tree& tree = get_global_tree(state); + const std::string tree_key = get_tree_key(state, -2, -1); + if (tree.is_set(tree_key)) { + // Publish the pre-recorded value in the tree to the Lua state, + // instead of considering this table key a new inner node. + tree.push_lua(tree_key, state); + } else { + state.push_string("_" + state.to_string(-1)); + state.insert(-2); + state.pop(1); + + new_table_for_key(state, tree_key); + + // Duplicate the newly created table and place it deep in the stack + // so that the raw_set below leaves us with the return value of this + // function at the top of the stack. + state.push_value(-1); + state.insert(-4); + + state.raw_set(-3); + state.pop(1); + } + } + return 1; +} + + +} // anonymous namespace + + +/// Install wrappers for globals to set values in the configuration tree. +/// +/// This function installs wrappers to capture all accesses to global variables. +/// Such wrappers redirect the reads and writes to the out_tree, which is the +/// entity that defines what configuration variables exist. +/// +/// \param state The Lua state into which to install the wrappers. +/// \param out_tree The tree with the layout definition and where the +/// configuration settings will be collected. +void +config::redirect(lutok::state& state, tree& out_tree) +{ + lutok::stack_cleaner cleaner(state); + + state.get_global_table(); + { + state.push_string("__index"); + state.push_cxx_function(redirect_index); + state.set_table(-3); + + state.push_string("__newindex"); + state.push_cxx_function(redirect_newindex); + state.set_table(-3); + } + state.set_metatable(-1); + + state.push_value(lutok::registry_index); + state.push_string("tree"); + config::tree** tree = state.new_userdata< config::tree* >(); + *tree = &out_tree; + state.set_table(-3); + state.pop(1); +} |