diff options
Diffstat (limited to 'src/libutil')
| -rw-r--r-- | src/libutil/args.cc | 9 | ||||
| -rw-r--r-- | src/libutil/error.cc | 7 | ||||
| -rw-r--r-- | src/libutil/error.hh | 8 | ||||
| -rw-r--r-- | src/libutil/suggestions.cc | 111 | ||||
| -rw-r--r-- | src/libutil/suggestions.hh | 41 |
5 files changed, 174 insertions, 2 deletions
diff --git a/src/libutil/args.cc b/src/libutil/args.cc index f970c0e9e..69aa0d094 100644 --- a/src/libutil/args.cc +++ b/src/libutil/args.cc @@ -328,8 +328,13 @@ MultiCommand::MultiCommand(const Commands & commands_) completions->add(name); } auto i = commands.find(s); - if (i == commands.end()) - throw UsageError("'%s' is not a recognised command", s); + if (i == commands.end()) { + std::set<std::string> commandNames; + for (auto & [name, _] : commands) + commandNames.insert(name); + auto suggestions = Suggestions::bestMatches(commandNames, s); + throw UsageError(suggestions, "'%s' is not a recognised command", s); + } command = {s, i->second()}; command->second->parent = this; }} diff --git a/src/libutil/error.cc b/src/libutil/error.cc index dcd2f82a5..15ae7a759 100644 --- a/src/libutil/error.cc +++ b/src/libutil/error.cc @@ -282,6 +282,13 @@ std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool s } } + auto suggestions = einfo.suggestions.trim(); + if (! suggestions.suggestions.empty()){ + oss << "Did you mean " << + suggestions.trim().pretty_print() << + "?" << std::endl; + } + // traces if (showTrace && !einfo.traces.empty()) { for (auto iter = einfo.traces.rbegin(); iter != einfo.traces.rend(); ++iter) { diff --git a/src/libutil/error.hh b/src/libutil/error.hh index d55e1d701..600e94888 100644 --- a/src/libutil/error.hh +++ b/src/libutil/error.hh @@ -1,5 +1,6 @@ #pragma once +#include "suggestions.hh" #include "ref.hh" #include "types.hh" #include "fmt.hh" @@ -112,6 +113,8 @@ struct ErrorInfo { std::optional<ErrPos> errPos; std::list<Trace> traces; + Suggestions suggestions; + static std::optional<std::string> programName; }; @@ -141,6 +144,11 @@ public: : err { .level = lvlError, .msg = hintfmt(fs, args...) } { } + template<typename... Args> + BaseError(const Suggestions & sug, const Args & ... args) + : err { .level = lvlError, .msg = hintfmt(args...), .suggestions = sug } + { } + BaseError(hintformat hint) : err { .level = lvlError, .msg = hint } { } diff --git a/src/libutil/suggestions.cc b/src/libutil/suggestions.cc new file mode 100644 index 000000000..96b48416b --- /dev/null +++ b/src/libutil/suggestions.cc @@ -0,0 +1,111 @@ +#include "suggestions.hh" +#include "ansicolor.hh" +#include "util.hh" +#include <algorithm> + +namespace nix { + +/** + * Return `some(distance)` where distance is an integer representing some + * notion of distance between both arguments. + * + * If the distance is too big, return none + */ +int distanceBetween(std::string_view first, std::string_view second) +{ + // Levenshtein distance. + // Implementation borrowed from + // https://en.wikipedia.org/wiki/Levenshtein_distance#Iterative_with_two_matrix_rows + + int m = first.size(); + int n = second.size(); + + auto v0 = std::vector<int>(n+1); + auto v1 = std::vector<int>(n+1); + + for (auto i = 0; i <= n; i++) + v0[i] = i; + + for (auto i = 0; i < m; i++) { + v1[0] = i+1; + + for (auto j = 0; j < n; j++) { + auto deletionCost = v0[j+1] + 1; + auto insertionCost = v1[j] + 1; + auto substitutionCost = first[i] == second[j] ? v0[j] : v0[j] + 1; + v1[j+1] = std::min({deletionCost, insertionCost, substitutionCost}); + } + + std::swap(v0, v1); + } + + return v0[n]; +} + +Suggestions Suggestions::bestMatches ( + std::set<std::string> allMatches, + std::string query) +{ + std::set<Suggestion> res; + for (const auto & possibleMatch : allMatches) { + res.insert(Suggestion { + .distance = distanceBetween(query, possibleMatch), + .suggestion = possibleMatch, + }); + } + return Suggestions { res }; +} + +Suggestions Suggestions::trim(int limit, int maxDistance) const +{ + std::set<Suggestion> res; + + int count = 0; + + for (auto & elt : suggestions) { + if (count >= limit || elt.distance >= maxDistance) + break; + count++; + res.insert(elt); + } + + return Suggestions{res}; +} + +std::string Suggestion::pretty_print() const +{ + return ANSI_WARNING + filterANSIEscapes(suggestion) + ANSI_NORMAL; +} + +std::string Suggestions::pretty_print() const +{ + switch (suggestions.size()) { + case 0: + return ""; + case 1: + return suggestions.begin()->pretty_print(); + default: { + std::string res = "one of "; + auto iter = suggestions.begin(); + res += iter->pretty_print(); // Iter can’t be end() because the container isn’t null + iter++; + auto last = suggestions.end(); last--; + for ( ; iter != suggestions.end() ; iter++) { + res += (iter == last) ? " or " : ", "; + res += iter->pretty_print(); + } + return res; + } + } +} + +Suggestions & Suggestions::operator+=(const Suggestions & other) +{ + suggestions.insert( + other.suggestions.begin(), + other.suggestions.end() + ); + return *this; +} + +} diff --git a/src/libutil/suggestions.hh b/src/libutil/suggestions.hh new file mode 100644 index 000000000..3caed487a --- /dev/null +++ b/src/libutil/suggestions.hh @@ -0,0 +1,41 @@ +#pragma once + +#include "comparator.hh" +#include "types.hh" +#include <set> + +namespace nix { + +/** + * A potential suggestion for the cli interface. + */ +class Suggestion { +public: + int distance; // The smaller the better + std::string suggestion; + + std::string pretty_print() const; + + GENERATE_CMP(Suggestion, me->distance, me->suggestion) +}; + +class Suggestions { +public: + std::set<Suggestion> suggestions; + + std::string pretty_print() const; + + Suggestions trim( + int limit = 5, + int maxDistance = 2 + ) const; + + static Suggestions bestMatches ( + std::set<std::string> allMatches, + std::string query + ); + + Suggestions& operator+=(const Suggestions & other); +}; + +} |