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Basic source code snippet system (#98)

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This commit is contained in:
Jeremy Rifkin 2024-02-28 23:29:24 -06:00 committed by GitHub
parent 736643358b
commit d99f1745d2
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8 changed files with 221 additions and 13 deletions
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1
CMakeLists.txt
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@ -221,6 +221,7 @@ target_sources(
src/unwind/unwind_with_unwind.cpp
src/unwind/unwind_with_winapi.cpp
src/unwind/unwind_with_dbghelp.cpp
src/snippets/snippet.cpp
)
target_include_directories(

9
README.md
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@ -251,6 +251,9 @@ namespace cpptrace {
`cpptrace::demangle` provides a helper function for name demangling, since it has to implement that helper internally
anyways.
`cpptrace::get_snippet` gets a text snippet, if possible, from for the given source file for +/- `context_size` lines
around `line`.
`cpptrace::isatty` and the fileno definitions are useful for deciding whether to use color when printing stack traces.
`cpptrace::register_terminate_handler()` is a helper function to set a custom `std::terminate` handler that prints a
@ -259,6 +262,12 @@ stack trace from a cpptrace exception (more info below) and otherwise behaves li
```cpp
namespace cpptrace {
std::string demangle(const std::string& name);
std::string get_snippet(
const std::string& path,
std::size_t line,
std::size_t context_size,
bool color = false
);
bool isatty(int fd);
extern const int stdin_fileno;

10
include/cpptrace/cpptrace.hpp
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@ -179,6 +179,9 @@ namespace cpptrace {
void print() const;
void print(std::ostream& stream) const;
void print(std::ostream& stream, bool color) const;
void print_with_snippets() const;
void print_with_snippets(std::ostream& stream) const;
void print_with_snippets(std::ostream& stream, bool color) const;
void clear();
bool empty() const noexcept;
std::string to_string(bool color = false) const;
@ -194,6 +197,7 @@ namespace cpptrace {
inline const_iterator cend() const noexcept { return frames.cend(); }
private:
void print(std::ostream& stream, bool color, bool newline_at_end, const char* header) const;
void print_with_snippets(std::ostream& stream, bool color, bool newline_at_end, const char* header) const;
friend void print_terminate_trace();
};
@ -236,6 +240,12 @@ namespace cpptrace {
// utilities:
CPPTRACE_EXPORT std::string demangle(const std::string& name);
CPPTRACE_EXPORT std::string get_snippet(
const std::string& path,
std::size_t line,
std::size_t context_size,
bool color = false
);
CPPTRACE_EXPORT bool isatty(int fd);
CPPTRACE_EXPORT extern const int stdin_fileno;

61
src/cpptrace.cpp
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@ -20,15 +20,7 @@
#include "utils/utils.hpp"
#include "binary/object.hpp"
#include "binary/safe_dl.hpp"
#define ESC "\033["
#define RESET ESC "0m"
#define RED ESC "31m"
#define GREEN ESC "32m"
#define YELLOW ESC "33m"
#define BLUE ESC "34m"
#define MAGENTA ESC "35m"
#define CYAN ESC "36m"
#include "snippets/snippet.hpp"
namespace cpptrace {
CPPTRACE_FORCE_NO_INLINE
@ -173,10 +165,10 @@ namespace cpptrace {
std::size_t counter,
const stacktrace_frame& frame
) {
const auto reset = color ? ESC "0m" : "";
const auto green = color ? ESC "32m" : "";
const auto yellow = color ? ESC "33m" : "";
const auto blue = color ? ESC "34m" : "";
const auto reset = color ? RESET : "";
const auto green = color ? GREEN : "";
const auto yellow = color ? YELLOW : "";
const auto blue = color ? BLUE : "";
stream
<< '#'
<< std::setw(static_cast<int>(frame_number_width))
@ -253,6 +245,45 @@ namespace cpptrace {
}
}
void stacktrace::print_with_snippets() const {
print_with_snippets(std::cerr, true);
}
void stacktrace::print_with_snippets(std::ostream& stream) const {
print_with_snippets(stream, true);
}
void stacktrace::print_with_snippets(std::ostream& stream, bool color) const {
print_with_snippets(stream, color, true, nullptr);
}
void stacktrace::print_with_snippets(std::ostream& stream, bool color, bool newline_at_end, const char* header) const {
if(
color && (
(&stream == &std::cout && isatty(stdout_fileno)) || (&stream == &std::cerr && isatty(stderr_fileno))
)
) {
detail::enable_virtual_terminal_processing_if_needed();
}
stream<<(header ? header : "Stack trace (most recent call first):") << '\n';
std::size_t counter = 0;
if(frames.empty()) {
stream<<"<empty trace>" << '\n';
return;
}
const auto frame_number_width = detail::n_digits(static_cast<int>(frames.size()) - 1);
for(const auto& frame : frames) {
print_frame(stream, color, frame_number_width, counter, frame);
if(newline_at_end || &frame != &frames.back()) {
stream << '\n';
}
if(frame.line.has_value() && !frame.filename.empty()) {
stream << detail::get_snippet(frame.filename, frame.line.value(), 2, color);
}
counter++;
}
}
void stacktrace::clear() {
frames.clear();
}
@ -368,6 +399,10 @@ namespace cpptrace {
return detail::demangle(name);
}
std::string get_snippet(const std::string& path, std::size_t line, std::size_t context_size, bool color) {
return detail::get_snippet(path, line, context_size, color);
}
bool isatty(int fd) {
return detail::isatty(fd);
}

129
src/snippets/snippet.cpp Normal file
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@ -0,0 +1,129 @@
#include "snippet.hpp"
#include <algorithm>
#include <cstdint>
#include <mutex>
#include <unordered_map>
#include <vector>
#include <fstream>
#include <iostream>
#include "../utils/common.hpp"
namespace cpptrace {
namespace detail {
constexpr std::int64_t max_size = 1024 * 1024 * 10; // 10 MiB
class snippet_manager {
bool loaded_contents;
std::string contents;
// for index i, gives the index in `contents` of one past the end of the line (i.e. the \n or contents.end())
std::vector<std::size_t> line_table;
public:
snippet_manager(const std::string& path) : loaded_contents(false) {
std::ifstream file;
try {
file.open(path, std::ios::ate);
if(file.is_open()) {
std::ifstream::pos_type size = file.tellg();
if(size == std::ifstream::pos_type(-1) || size > max_size) {
return;
}
// else load file
file.seekg(0, std::ios::beg);
contents.resize(size);
if(!file.read(&contents[0], size)) {
// error ...
}
build_line_table();
loaded_contents = true;
}
} catch(const std::ifstream::failure&) {
// ...
}
}
std::string get_line(std::size_t line) const { // 0-indexed line TODO: reconsider
if(!loaded_contents || line >= line_table.size()) {
return "";
} else if(line == 0) {
return contents.substr(0, line_table[line]);
} else {
return contents.substr(line_table[line - 1] + 1, line_table[line] - line_table[line - 1] - 1);
}
}
std::size_t num_lines() const {
return line_table.size();
}
bool ok() const {
return loaded_contents;
}
private:
void build_line_table() {
std::size_t pos = 0;
while(true) {
std::size_t new_pos = contents.find('\n', pos);
if(new_pos == std::string::npos) {
line_table.push_back(contents.size());
break;
} else {
line_table.push_back(new_pos);
pos = new_pos + 1;
}
}
}
};
std::mutex snippet_manager_mutex;
std::unordered_map<std::string, const snippet_manager> snippet_managers;
const snippet_manager& get_manager(const std::string& path) {
std::unique_lock<std::mutex> lock(snippet_manager_mutex);
auto it = snippet_managers.find(path);
if(it == snippet_managers.end()) {
return snippet_managers.insert({path, snippet_manager(path)}).first->second;
} else {
return it->second;
}
}
std::string get_snippet(const std::string& path, std::size_t target_line, std::size_t context_size, bool color) {
target_line--;
const auto& manager = get_manager(path);
if(!manager.ok()) {
return "";
}
auto begin = target_line <= context_size ? 0 : target_line - context_size;
auto original_begin = begin;
auto end = std::min(target_line + context_size, manager.num_lines() - 1);
std::vector<std::string> lines;
for(auto line = begin; line <= end; line++) {
lines.push_back(manager.get_line(line));
}
// trim blank lines
while(begin < target_line && lines[begin - original_begin].empty()) {
begin++;
}
while(end > target_line && lines[end - original_begin].empty()) {
end--;
}
// make the snippet
std::string snippet;
constexpr std::size_t margin_width = 8;
for(auto line = begin; line <= end; line++) {
if(color && line == target_line) {
snippet += YELLOW;
}
auto line_str = std::to_string(line);
snippet += std::string(margin_width - line_str.size(), ' ') + line_str + ": ";
if(color && line == target_line) {
snippet += RESET;
}
snippet += lines[line - original_begin] + "\n";
}
return snippet;
}
}
}

14
src/snippets/snippet.hpp Normal file
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@ -0,0 +1,14 @@
#ifndef SNIPPET_HPP
#define SNIPPET_HPP
#include <cstddef>
#include <string>
namespace cpptrace {
namespace detail {
// 1-indexed line
std::string get_snippet(const std::string& path, std::size_t line, std::size_t context_size, bool color);
}
}
#endif

9
src/utils/common.hpp
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@ -41,6 +41,15 @@
#include <cpptrace/cpptrace.hpp>
#define ESC "\033["
#define RESET ESC "0m"
#define RED ESC "31m"
#define GREEN ESC "32m"
#define YELLOW ESC "33m"
#define BLUE ESC "34m"
#define MAGENTA ESC "35m"
#define CYAN ESC "36m"
namespace cpptrace {
namespace detail {
// Placed here instead of utils because it's used by error.hpp and utils.hpp

1
test/demo.cpp
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@ -7,6 +7,7 @@
void trace() {
cpptrace::generate_trace().print();
cpptrace::generate_trace().print_with_snippets();
throw cpptrace::logic_error("foobar");
}