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-rw-r--r--src/libcmd/installables.cc11
-rw-r--r--src/libexpr/attr-path.cc10
-rw-r--r--src/libutil/args.cc9
-rw-r--r--src/libutil/error.cc7
-rw-r--r--src/libutil/error.hh8
-rw-r--r--src/libutil/suggestions.cc111
-rw-r--r--src/libutil/suggestions.hh41
7 files changed, 191 insertions, 6 deletions
diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 3209456bf..888d863ff 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -610,17 +610,24 @@ std::pair<Value *, Pos> InstallableFlake::toValue(EvalState & state)
auto emptyArgs = state.allocBindings(0);
+ Suggestions suggestions;
+
for (auto & attrPath : getActualAttrPaths()) {
try {
auto [v, pos] = findAlongAttrPath(state, attrPath, *emptyArgs, *vOutputs);
state.forceValue(*v, pos);
return {v, pos};
} catch (AttrPathNotFound & e) {
+ suggestions += e.info().suggestions;
}
}
- throw Error("flake '%s' does not provide attribute %s",
- flakeRef, showAttrPaths(getActualAttrPaths()));
+ throw Error(
+ suggestions,
+ "flake '%s' does not provide attribute %s",
+ flakeRef,
+ showAttrPaths(getActualAttrPaths())
+ );
}
std::vector<std::pair<std::shared_ptr<eval_cache::AttrCursor>, std::string>>
diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index eb0e706c7..32deecfae 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -74,8 +74,14 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const std::string &
throw Error("empty attribute name in selection path '%1%'", attrPath);
Bindings::iterator a = v->attrs->find(state.symbols.create(attr));
- if (a == v->attrs->end())
- throw AttrPathNotFound("attribute '%1%' in selection path '%2%' not found", attr, attrPath);
+ if (a == v->attrs->end()) {
+ std::set<std::string> attrNames;
+ for (auto & attr : *v->attrs)
+ attrNames.insert(attr.name);
+
+ auto suggestions = Suggestions::bestMatches(attrNames, attr);
+ throw AttrPathNotFound(suggestions, "attribute '%1%' in selection path '%2%' not found", attr, attrPath);
+ }
v = &*a->value;
pos = *a->pos;
}
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);
+};
+
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 16:19:29 +0000