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Diffstat (limited to 'utils/text/templates.cpp')
| -rw-r--r-- | utils/text/templates.cpp | 764 |
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diff --git a/utils/text/templates.cpp b/utils/text/templates.cpp new file mode 100644 index 000000000000..13cb27b1cce2 --- /dev/null +++ b/utils/text/templates.cpp @@ -0,0 +1,764 @@ +// 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/text/templates.hpp" + +#include <algorithm> +#include <fstream> +#include <sstream> +#include <stack> + +#include "utils/format/macros.hpp" +#include "utils/fs/path.hpp" +#include "utils/noncopyable.hpp" +#include "utils/sanity.hpp" +#include "utils/text/exceptions.hpp" +#include "utils/text/operations.ipp" + +namespace text = utils::text; + + +namespace { + + +/// Definition of a template statement. +/// +/// A template statement is a particular line in the input file that is +/// preceeded by a template marker. This class provides a high-level +/// representation of the contents of such statement and a mechanism to parse +/// the textual line into this high-level representation. +class statement_def { +public: + /// Types of the known statements. + enum statement_type { + /// Alternative clause of a conditional. + /// + /// Takes no arguments. + type_else, + + /// End of conditional marker. + /// + /// Takes no arguments. + type_endif, + + /// End of loop marker. + /// + /// Takes no arguments. + type_endloop, + + /// Beginning of a conditional. + /// + /// Takes a single argument, which denotes the name of the variable or + /// vector to check for existence. This is the only expression + /// supported. + type_if, + + /// Beginning of a loop over all the elements of a vector. + /// + /// Takes two arguments: the name of the vector over which to iterate + /// and the name of the iterator to later index this vector. + type_loop, + }; + +private: + /// Internal data describing the structure of a particular statement type. + struct type_descriptor { + /// The native type of the statement. + statement_type type; + + /// The expected number of arguments. + unsigned int n_arguments; + + /// Constructs a new type descriptor. + /// + /// \param type_ The native type of the statement. + /// \param n_arguments_ The expected number of arguments. + type_descriptor(const statement_type type_, + const unsigned int n_arguments_) + : type(type_), n_arguments(n_arguments_) + { + } + }; + + /// Mapping of statement type names to their definitions. + typedef std::map< std::string, type_descriptor > types_map; + + /// Description of the different statement types. + /// + /// This static map is initialized once and reused later for any statement + /// lookup. Unfortunately, we cannot perform this initialization in a + /// static manner without C++11. + static types_map _types; + + /// Generates a new types definition map. + /// + /// \return A new types definition map, to be assigned to _types. + static types_map + generate_types_map(void) + { + // If you change this, please edit the comments in the enum above. + types_map types; + types.insert(types_map::value_type( + "else", type_descriptor(type_else, 0))); + types.insert(types_map::value_type( + "endif", type_descriptor(type_endif, 0))); + types.insert(types_map::value_type( + "endloop", type_descriptor(type_endloop, 0))); + types.insert(types_map::value_type( + "if", type_descriptor(type_if, 1))); + types.insert(types_map::value_type( + "loop", type_descriptor(type_loop, 2))); + return types; + } + +public: + /// The type of the statement. + statement_type type; + + /// The arguments to the statement, in textual form. + const std::vector< std::string > arguments; + + /// Creates a new statement. + /// + /// \param type_ The type of the statement. + /// \param arguments_ The arguments to the statement. + statement_def(const statement_type& type_, + const std::vector< std::string >& arguments_) : + type(type_), arguments(arguments_) + { +#if !defined(NDEBUG) + for (types_map::const_iterator iter = _types.begin(); + iter != _types.end(); ++iter) { + const type_descriptor& descriptor = (*iter).second; + if (descriptor.type == type_) { + PRE(descriptor.n_arguments == arguments_.size()); + return; + } + } + UNREACHABLE; +#endif + } + + /// Parses a statement. + /// + /// \param line The textual representation of the statement without any + /// prefix. + /// + /// \return The parsed statement. + /// + /// \throw text::syntax_error If the statement is not correctly defined. + static statement_def + parse(const std::string& line) + { + if (_types.empty()) + _types = generate_types_map(); + + const std::vector< std::string > words = text::split(line, ' '); + if (words.empty()) + throw text::syntax_error("Empty statement"); + + const types_map::const_iterator iter = _types.find(words[0]); + if (iter == _types.end()) + throw text::syntax_error(F("Unknown statement '%s'") % words[0]); + const type_descriptor& descriptor = (*iter).second; + + if (words.size() - 1 != descriptor.n_arguments) + throw text::syntax_error(F("Invalid number of arguments for " + "statement '%s'") % words[0]); + + std::vector< std::string > new_arguments; + new_arguments.resize(words.size() - 1); + std::copy(words.begin() + 1, words.end(), new_arguments.begin()); + + return statement_def(descriptor.type, new_arguments); + } +}; + + +statement_def::types_map statement_def::_types; + + +/// Definition of a loop. +/// +/// This simple structure is used to keep track of the parameters of a loop. +struct loop_def { + /// The name of the vector over which this loop is iterating. + std::string vector; + + /// The name of the iterator defined by this loop. + std::string iterator; + + /// Position in the input to which to rewind to on looping. + /// + /// This position points to the line after the loop statement, not the loop + /// itself. This is one of the reasons why we have this structure, so that + /// we can maintain the data about the loop without having to re-process it. + std::istream::pos_type position; + + /// Constructs a new loop definition. + /// + /// \param vector_ The name of the vector (first argument). + /// \param iterator_ The name of the iterator (second argumnet). + /// \param position_ Position of the next line after the loop statement. + loop_def(const std::string& vector_, const std::string& iterator_, + const std::istream::pos_type position_) : + vector(vector_), iterator(iterator_), position(position_) + { + } +}; + + +/// Stateful class to instantiate the templates in an input stream. +/// +/// The goal of this parser is to scan the input once and not buffer anything in +/// memory. The only exception are loops: loops are reinterpreted on every +/// iteration from the same input file by rewidining the stream to the +/// appropriate position. +class templates_parser : utils::noncopyable { + /// The templates to apply. + /// + /// Note that this is not const because the parser has to have write access + /// to the templates. In particular, it needs to be able to define the + /// iterators as regular variables. + text::templates_def _templates; + + /// Prefix that marks a line as a statement. + const std::string _prefix; + + /// Delimiter to surround an expression instantiation. + const std::string _delimiter; + + /// Whether to skip incoming lines or not. + /// + /// The top of the stack is true whenever we encounter a conditional that + /// evaluates to false or a loop that does not have any iterations left. + /// Under these circumstances, we need to continue scanning the input stream + /// until we find the matching closing endif or endloop construct. + /// + /// This is a stack rather than a plain boolean to allow us deal with + /// if-else clauses. + std::stack< bool > _skip; + + /// Current count of nested conditionals. + unsigned int _if_level; + + /// Level of the top-most conditional that evaluated to false. + unsigned int _exit_if_level; + + /// Current count of nested loops. + unsigned int _loop_level; + + /// Level of the top-most loop that does not have any iterations left. + unsigned int _exit_loop_level; + + /// Information about all the nested loops up to the current point. + std::stack< loop_def > _loops; + + /// Checks if a line is a statement or not. + /// + /// \param line The line to validate. + /// + /// \return True if the line looks like a statement, which is determined by + /// checking if the line starts by the predefined prefix. + bool + is_statement(const std::string& line) + { + return ((line.length() >= _prefix.length() && + line.substr(0, _prefix.length()) == _prefix) && + (line.length() < _delimiter.length() || + line.substr(0, _delimiter.length()) != _delimiter)); + } + + /// Parses a given statement line into a statement definition. + /// + /// \param line The line to validate; it must be a valid statement. + /// + /// \return The parsed statement. + /// + /// \throw text::syntax_error If the input is not a valid statement. + statement_def + parse_statement(const std::string& line) + { + PRE(is_statement(line)); + return statement_def::parse(line.substr(_prefix.length())); + } + + /// Processes a line from the input when not in skip mode. + /// + /// \param line The line to be processed. + /// \param input The input stream from which the line was read. The current + /// position in the stream must be after the line being processed. + /// \param output The output stream into which to write the results. + /// + /// \throw text::syntax_error If the input is not valid. + void + handle_normal(const std::string& line, std::istream& input, + std::ostream& output) + { + if (!is_statement(line)) { + // Fast path. Mostly to avoid an indentation level for the big + // chunk of code below. + output << line << '\n'; + return; + } + + const statement_def statement = parse_statement(line); + + switch (statement.type) { + case statement_def::type_else: + _skip.top() = !_skip.top(); + break; + + case statement_def::type_endif: + _if_level--; + break; + + case statement_def::type_endloop: { + PRE(_loops.size() == _loop_level); + loop_def& loop = _loops.top(); + + const std::size_t next_index = 1 + text::to_type< std::size_t >( + _templates.get_variable(loop.iterator)); + + if (next_index < _templates.get_vector(loop.vector).size()) { + _templates.add_variable(loop.iterator, F("%s") % next_index); + input.seekg(loop.position); + } else { + _loop_level--; + _loops.pop(); + _templates.remove_variable(loop.iterator); + } + } break; + + case statement_def::type_if: { + _if_level++; + const std::string value = _templates.evaluate( + statement.arguments[0]); + if (value.empty() || value == "0" || value == "false") { + _exit_if_level = _if_level; + _skip.push(true); + } else { + _skip.push(false); + } + } break; + + case statement_def::type_loop: { + _loop_level++; + + const loop_def loop(statement.arguments[0], statement.arguments[1], + input.tellg()); + if (_templates.get_vector(loop.vector).empty()) { + _exit_loop_level = _loop_level; + _skip.push(true); + } else { + _templates.add_variable(loop.iterator, "0"); + _loops.push(loop); + _skip.push(false); + } + } break; + } + } + + /// Processes a line from the input when in skip mode. + /// + /// \param line The line to be processed. + /// + /// \throw text::syntax_error If the input is not valid. + void + handle_skip(const std::string& line) + { + PRE(_skip.top()); + + if (!is_statement(line)) + return; + + const statement_def statement = parse_statement(line); + switch (statement.type) { + case statement_def::type_else: + if (_exit_if_level == _if_level) + _skip.top() = !_skip.top(); + break; + + case statement_def::type_endif: + INV(_if_level >= _exit_if_level); + if (_if_level == _exit_if_level) + _skip.top() = false; + _if_level--; + _skip.pop(); + break; + + case statement_def::type_endloop: + INV(_loop_level >= _exit_loop_level); + if (_loop_level == _exit_loop_level) + _skip.top() = false; + _loop_level--; + _skip.pop(); + break; + + case statement_def::type_if: + _if_level++; + _skip.push(true); + break; + + case statement_def::type_loop: + _loop_level++; + _skip.push(true); + break; + + default: + break; + } + } + + /// Evaluates expressions on a given input line. + /// + /// An expression is surrounded by _delimiter on both sides. We scan the + /// string from left to right finding any expressions that may appear, yank + /// them out and call templates_def::evaluate() to get their value. + /// + /// Lonely or unbalanced appearances of _delimiter on the input line are + /// not considered an error, given that the user may actually want to supply + /// that character sequence without being interpreted as a template. + /// + /// \param in_line The input line from which to evaluate expressions. + /// + /// \return The evaluated line. + /// + /// \throw text::syntax_error If the expressions in the line are malformed. + std::string + evaluate(const std::string& in_line) + { + std::string out_line; + + std::string::size_type last_pos = 0; + while (last_pos != std::string::npos) { + const std::string::size_type open_pos = in_line.find( + _delimiter, last_pos); + if (open_pos == std::string::npos) { + out_line += in_line.substr(last_pos); + last_pos = std::string::npos; + } else { + const std::string::size_type close_pos = in_line.find( + _delimiter, open_pos + _delimiter.length()); + if (close_pos == std::string::npos) { + out_line += in_line.substr(last_pos); + last_pos = std::string::npos; + } else { + out_line += in_line.substr(last_pos, open_pos - last_pos); + out_line += _templates.evaluate(in_line.substr( + open_pos + _delimiter.length(), + close_pos - open_pos - _delimiter.length())); + last_pos = close_pos + _delimiter.length(); + } + } + } + + return out_line; + } + +public: + /// Constructs a new template parser. + /// + /// \param templates_ The templates to apply to the processed file. + /// \param prefix_ The prefix that identifies lines as statements. + /// \param delimiter_ Delimiter to surround a variable instantiation. + templates_parser(const text::templates_def& templates_, + const std::string& prefix_, + const std::string& delimiter_) : + _templates(templates_), + _prefix(prefix_), + _delimiter(delimiter_), + _if_level(0), + _exit_if_level(0), + _loop_level(0), + _exit_loop_level(0) + { + } + + /// Applies the templates to a given input. + /// + /// \param input The stream to which to apply the templates. + /// \param output The stream into which to write the results. + /// + /// \throw text::syntax_error If the input is not valid. Note that the + /// is not guaranteed to be unmodified on exit if an error is + /// encountered. + void + instantiate(std::istream& input, std::ostream& output) + { + std::string line; + while (std::getline(input, line).good()) { + if (!_skip.empty() && _skip.top()) + handle_skip(line); + else + handle_normal(evaluate(line), input, output); + } + } +}; + + +} // anonymous namespace + + +/// Constructs an empty templates definition. +text::templates_def::templates_def(void) +{ +} + + +/// Sets a string variable in the templates. +/// +/// If the variable already exists, its value is replaced. This behavior is +/// required to implement iterators, but client code should really not be +/// redefining variables. +/// +/// \pre The variable must not already exist as a vector. +/// +/// \param name The name of the variable to set. +/// \param value The value to set the given variable to. +void +text::templates_def::add_variable(const std::string& name, + const std::string& value) +{ + PRE(_vectors.find(name) == _vectors.end()); + _variables[name] = value; +} + + +/// Unsets a string variable from the templates. +/// +/// Client code has no reason to use this. This is only required to implement +/// proper scoping of loop iterators. +/// +/// \pre The variable must exist. +/// +/// \param name The name of the variable to remove from the templates. +void +text::templates_def::remove_variable(const std::string& name) +{ + PRE(_variables.find(name) != _variables.end()); + _variables.erase(_variables.find(name)); +} + + +/// Creates a new vector in the templates. +/// +/// If the vector already exists, it is cleared. Client code should really not +/// be redefining variables. +/// +/// \pre The vector must not already exist as a variable. +/// +/// \param name The name of the vector to set. +void +text::templates_def::add_vector(const std::string& name) +{ + PRE(_variables.find(name) == _variables.end()); + _vectors[name] = strings_vector(); +} + + +/// Adds a value to an existing vector in the templates. +/// +/// \pre name The vector must exist. +/// +/// \param name The name of the vector to append the value to. +/// \param value The textual value to append to the vector. +void +text::templates_def::add_to_vector(const std::string& name, + const std::string& value) +{ + PRE(_variables.find(name) == _variables.end()); + PRE(_vectors.find(name) != _vectors.end()); + _vectors[name].push_back(value); +} + + +/// Checks whether a given identifier exists as a variable or a vector. +/// +/// This is used to implement the evaluation of conditions in if clauses. +/// +/// \param name The name of the variable or vector. +/// +/// \return True if the given name exists as a variable or a vector; false +/// otherwise. +bool +text::templates_def::exists(const std::string& name) const +{ + return (_variables.find(name) != _variables.end() || + _vectors.find(name) != _vectors.end()); +} + + +/// Gets the value of a variable. +/// +/// \param name The name of the variable. +/// +/// \return The value of the requested variable. +/// +/// \throw text::syntax_error If the variable does not exist. +const std::string& +text::templates_def::get_variable(const std::string& name) const +{ + const variables_map::const_iterator iter = _variables.find(name); + if (iter == _variables.end()) + throw text::syntax_error(F("Unknown variable '%s'") % name); + return (*iter).second; +} + + +/// Gets a vector. +/// +/// \param name The name of the vector. +/// +/// \return A reference to the requested vector. +/// +/// \throw text::syntax_error If the vector does not exist. +const text::templates_def::strings_vector& +text::templates_def::get_vector(const std::string& name) const +{ + const vectors_map::const_iterator iter = _vectors.find(name); + if (iter == _vectors.end()) + throw text::syntax_error(F("Unknown vector '%s'") % name); + return (*iter).second; +} + + +/// Indexes a vector and gets the value. +/// +/// \param name The name of the vector to index. +/// \param index_name The name of a variable representing the index to use. +/// This must be convertible to a natural. +/// +/// \return The value of the vector at the given index. +/// +/// \throw text::syntax_error If the vector does not existor if the index is out +/// of range. +const std::string& +text::templates_def::get_vector(const std::string& name, + const std::string& index_name) const +{ + const strings_vector& vector = get_vector(name); + const std::string& index_str = get_variable(index_name); + + std::size_t index; + try { + index = text::to_type< std::size_t >(index_str); + } catch (const text::syntax_error& e) { + throw text::syntax_error(F("Index '%s' not an integer, value '%s'") % + index_name % index_str); + } + if (index >= vector.size()) + throw text::syntax_error(F("Index '%s' out of range at position '%s'") % + index_name % index); + + return vector[index]; +} + + +/// Evaluates a expression using these templates. +/// +/// An expression is a query on the current templates to fetch a particular +/// value. The value is always returned as a string, as this is how templates +/// are internally stored. +/// +/// \param expression The expression to evaluate. This should not include any +/// of the delimiters used in the user input, as otherwise the expression +/// will not be evaluated properly. +/// +/// \return The result of the expression evaluation as a string. +/// +/// \throw text::syntax_error If there is any problem while evaluating the +/// expression. +std::string +text::templates_def::evaluate(const std::string& expression) const +{ + const std::string::size_type paren_open = expression.find('('); + if (paren_open == std::string::npos) { + return get_variable(expression); + } else { + const std::string::size_type paren_close = expression.find( + ')', paren_open); + if (paren_close == std::string::npos) + throw text::syntax_error(F("Expected ')' in expression '%s')") % + expression); + if (paren_close != expression.length() - 1) + throw text::syntax_error(F("Unexpected text found after ')' in " + "expression '%s'") % expression); + + const std::string arg0 = expression.substr(0, paren_open); + const std::string arg1 = expression.substr( + paren_open + 1, paren_close - paren_open - 1); + if (arg0 == "defined") { + return exists(arg1) ? "true" : "false"; + } else if (arg0 == "length") { + return F("%s") % get_vector(arg1).size(); + } else { + return get_vector(arg0, arg1); + } + } +} + + +/// Applies a set of templates to an input stream. +/// +/// \param templates The templates to use. +/// \param input The input to process. +/// \param output The stream to which to write the processed text. +/// +/// \throw text::syntax_error If there is any problem processing the input. +void +text::instantiate(const templates_def& templates, + std::istream& input, std::ostream& output) +{ + templates_parser parser(templates, "%", "%%"); + parser.instantiate(input, output); +} + + +/// Applies a set of templates to an input file and writes an output file. +/// +/// \param templates The templates to use. +/// \param input_file The path to the input to process. +/// \param output_file The path to the file into which to write the output. +/// +/// \throw text::error If the input or output files cannot be opened. +/// \throw text::syntax_error If there is any problem processing the input. +void +text::instantiate(const templates_def& templates, + const fs::path& input_file, const fs::path& output_file) +{ + std::ifstream input(input_file.c_str()); + if (!input) + throw text::error(F("Failed to open %s for read") % input_file); + + std::ofstream output(output_file.c_str()); + if (!output) + throw text::error(F("Failed to open %s for write") % output_file); + + instantiate(templates, input, output); +} |