nix-super/src/libexpr/print.cc

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#include <limits>
#include <unordered_set>
#include "print.hh"
#include "ansicolor.hh"
#include "signals.hh"
#include "store-api.hh"
#include "terminal.hh"
#include "english.hh"
#include "eval.hh"
namespace nix {
void printElided(
std::ostream & output,
unsigned int value,
const std::string_view single,
const std::string_view plural,
bool ansiColors)
{
if (ansiColors)
output << ANSI_FAINT;
output << "«";
pluralize(output, value, single, plural);
output << " elided»";
if (ansiColors)
output << ANSI_NORMAL;
}
std::ostream &
printLiteralString(std::ostream & str, const std::string_view string, size_t maxLength, bool ansiColors)
{
size_t charsPrinted = 0;
if (ansiColors)
str << ANSI_MAGENTA;
str << "\"";
for (auto i = string.begin(); i != string.end(); ++i) {
if (charsPrinted >= maxLength) {
str << "\" ";
printElided(str, string.length() - charsPrinted, "byte", "bytes", ansiColors);
return str;
}
if (*i == '\"' || *i == '\\') str << "\\" << *i;
else if (*i == '\n') str << "\\n";
else if (*i == '\r') str << "\\r";
else if (*i == '\t') str << "\\t";
else if (*i == '$' && *(i+1) == '{') str << "\\" << *i;
else str << *i;
charsPrinted++;
}
str << "\"";
if (ansiColors)
str << ANSI_NORMAL;
return str;
}
std::ostream &
printLiteralString(std::ostream & str, const std::string_view string)
{
return printLiteralString(str, string, std::numeric_limits<size_t>::max(), false);
}
std::ostream &
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printLiteralBool(std::ostream & str, bool boolean)
{
str << (boolean ? "true" : "false");
return str;
}
// Returns `true' is a string is a reserved keyword which requires quotation
// when printing attribute set field names.
//
// This list should generally be kept in sync with `./lexer.l'.
// You can test if a keyword needs to be added by running:
// $ nix eval --expr '{ <KEYWORD> = 1; }'
// For example `or' doesn't need to be quoted.
bool isReservedKeyword(const std::string_view str)
{
static const std::unordered_set<std::string_view> reservedKeywords = {
"if", "then", "else", "assert", "with", "let", "in", "rec", "inherit"
};
return reservedKeywords.contains(str);
}
std::ostream &
printIdentifier(std::ostream & str, std::string_view s) {
if (s.empty())
str << "\"\"";
else if (isReservedKeyword(s))
str << '"' << s << '"';
else {
char c = s[0];
if (!((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_')) {
printLiteralString(str, s);
return str;
}
for (auto c : s)
if (!((c >= 'a' && c <= 'z') ||
(c >= 'A' && c <= 'Z') ||
(c >= '0' && c <= '9') ||
c == '_' || c == '\'' || c == '-')) {
printLiteralString(str, s);
return str;
}
str << s;
}
return str;
}
static bool isVarName(std::string_view s)
{
if (s.size() == 0) return false;
if (isReservedKeyword(s)) return false;
char c = s[0];
if ((c >= '0' && c <= '9') || c == '-' || c == '\'') return false;
for (auto & i : s)
if (!((i >= 'a' && i <= 'z') ||
(i >= 'A' && i <= 'Z') ||
(i >= '0' && i <= '9') ||
i == '_' || i == '-' || i == '\''))
return false;
return true;
}
std::ostream &
printAttributeName(std::ostream & str, std::string_view name) {
if (isVarName(name))
str << name;
else
printLiteralString(str, name);
return str;
}
bool isImportantAttrName(const std::string& attrName)
{
return attrName == "type" || attrName == "_type";
}
typedef std::pair<std::string, Value *> AttrPair;
struct ImportantFirstAttrNameCmp
{
bool operator()(const AttrPair& lhs, const AttrPair& rhs) const
{
auto lhsIsImportant = isImportantAttrName(lhs.first);
auto rhsIsImportant = isImportantAttrName(rhs.first);
return std::forward_as_tuple(!lhsIsImportant, lhs.first)
< std::forward_as_tuple(!rhsIsImportant, rhs.first);
}
};
typedef std::set<const void *> ValuesSeen;
typedef std::vector<std::pair<std::string, Value *>> AttrVec;
class Printer
{
private:
std::ostream & output;
EvalState & state;
PrintOptions options;
std::optional<ValuesSeen> seen;
size_t attrsPrinted = 0;
size_t listItemsPrinted = 0;
std::string indent;
void increaseIndent()
{
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if (options.shouldPrettyPrint()) {
indent.append(options.prettyIndent, ' ');
}
}
void decreaseIndent()
{
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if (options.shouldPrettyPrint()) {
assert(indent.size() >= options.prettyIndent);
indent.resize(indent.size() - options.prettyIndent);
}
}
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/**
* Print a space (for separating items or attributes).
*
* If pretty-printing is enabled, a newline and the current `indent` is
* printed instead.
*/
void printSpace(bool prettyPrint)
{
if (prettyPrint) {
output << "\n" << indent;
} else {
output << " ";
}
}
void printRepeated()
{
if (options.ansiColors)
output << ANSI_MAGENTA;
output << "«repeated»";
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printNullptr()
{
if (options.ansiColors)
output << ANSI_MAGENTA;
output << "«nullptr»";
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printElided(unsigned int value, const std::string_view single, const std::string_view plural)
{
::nix::printElided(output, value, single, plural, options.ansiColors);
}
void printInt(Value & v)
{
if (options.ansiColors)
output << ANSI_CYAN;
output << v.integer;
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printFloat(Value & v)
{
if (options.ansiColors)
output << ANSI_CYAN;
output << v.fpoint;
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printBool(Value & v)
{
if (options.ansiColors)
output << ANSI_CYAN;
printLiteralBool(output, v.boolean);
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printString(Value & v)
{
printLiteralString(output, v.string_view(), options.maxStringLength, options.ansiColors);
}
void printPath(Value & v)
{
if (options.ansiColors)
output << ANSI_GREEN;
output << v.path().to_string(); // !!! escaping?
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printNull()
{
if (options.ansiColors)
output << ANSI_CYAN;
output << "null";
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printDerivation(Value & v)
{
try {
Bindings::iterator i = v.attrs->find(state.sDrvPath);
NixStringContext context;
std::string storePath;
if (i != v.attrs->end())
storePath = state.store->printStorePath(state.coerceToStorePath(i->pos, *i->value, context, "while evaluating the drvPath of a derivation"));
if (options.ansiColors)
output << ANSI_GREEN;
output << "«derivation";
if (!storePath.empty()) {
output << " " << storePath;
}
output << "»";
if (options.ansiColors)
output << ANSI_NORMAL;
} catch (Error & e) {
printError_(e);
}
}
bool shouldPrettyPrintAttrs(AttrVec & v)
{
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if (!options.shouldPrettyPrint() || v.empty()) {
return false;
}
// Pretty-print attrsets with more than one item.
if (v.size() > 1) {
return true;
}
auto item = v[0].second;
if (!item) {
return true;
}
// Pretty-print single-item attrsets only if they contain nested
// structures.
auto itemType = item->type();
return itemType == nList || itemType == nAttrs || itemType == nThunk;
}
void printAttrs(Value & v, size_t depth)
{
if (seen && !seen->insert(v.attrs).second) {
printRepeated();
return;
}
if (options.force && options.derivationPaths && state.isDerivation(v)) {
printDerivation(v);
} else if (depth < options.maxDepth) {
increaseIndent();
output << "{";
AttrVec sorted;
for (auto & i : *v.attrs)
sorted.emplace_back(std::pair(state.symbols[i.name], i.value));
if (options.maxAttrs == std::numeric_limits<size_t>::max())
std::sort(sorted.begin(), sorted.end());
else
std::sort(sorted.begin(), sorted.end(), ImportantFirstAttrNameCmp());
auto prettyPrint = shouldPrettyPrintAttrs(sorted);
for (auto & i : sorted) {
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printSpace(prettyPrint);
if (attrsPrinted >= options.maxAttrs) {
printElided(sorted.size() - attrsPrinted, "attribute", "attributes");
break;
}
printAttributeName(output, i.first);
output << " = ";
print(*i.second, depth + 1);
output << ";";
attrsPrinted++;
}
decreaseIndent();
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printSpace(prettyPrint);
output << "}";
} else {
output << "{ ... }";
}
}
bool shouldPrettyPrintList(std::span<Value * const> list)
{
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if (!options.shouldPrettyPrint() || list.empty()) {
return false;
}
// Pretty-print lists with more than one item.
if (list.size() > 1) {
return true;
}
auto item = list[0];
if (!item) {
return true;
}
// Pretty-print single-item lists only if they contain nested
// structures.
auto itemType = item->type();
return itemType == nList || itemType == nAttrs || itemType == nThunk;
}
void printList(Value & v, size_t depth)
{
if (seen && v.listSize() && !seen->insert(&v).second) {
printRepeated();
return;
}
if (depth < options.maxDepth) {
increaseIndent();
output << "[";
auto listItems = v.listItems();
auto prettyPrint = shouldPrettyPrintList(listItems);
for (auto elem : listItems) {
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printSpace(prettyPrint);
if (listItemsPrinted >= options.maxListItems) {
printElided(listItems.size() - listItemsPrinted, "item", "items");
break;
}
if (elem) {
print(*elem, depth + 1);
} else {
printNullptr();
}
listItemsPrinted++;
}
decreaseIndent();
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printSpace(prettyPrint);
output << "]";
} else {
output << "[ ... ]";
}
}
void printFunction(Value & v)
{
if (options.ansiColors)
output << ANSI_BLUE;
output << "«";
if (v.isLambda()) {
output << "lambda";
if (v.lambda.fun) {
if (v.lambda.fun->name) {
output << " " << state.symbols[v.lambda.fun->name];
}
std::ostringstream s;
s << state.positions[v.lambda.fun->pos];
output << " @ " << filterANSIEscapes(s.str());
}
} else if (v.isPrimOp()) {
if (v.primOp)
output << *v.primOp;
else
output << "primop";
} else if (v.isPrimOpApp()) {
output << "partially applied ";
auto primOp = v.primOpAppPrimOp();
if (primOp)
output << *primOp;
else
output << "primop";
} else {
abort();
}
output << "»";
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printThunk(Value & v)
{
if (v.isBlackhole()) {
// Although we know for sure that it's going to be an infinite recursion
// when this value is accessed _in the current context_, it's likely
// that the user will misinterpret a simpler «infinite recursion» output
// as a definitive statement about the value, while in fact it may be
// a valid value after `builtins.trace` and perhaps some other steps
// have completed.
if (options.ansiColors)
output << ANSI_RED;
output << "«potential infinite recursion»";
if (options.ansiColors)
output << ANSI_NORMAL;
} else if (v.isThunk() || v.isApp()) {
if (options.ansiColors)
output << ANSI_MAGENTA;
output << "«thunk»";
if (options.ansiColors)
output << ANSI_NORMAL;
} else {
abort();
}
}
void printExternal(Value & v)
{
v.external->print(output);
}
void printUnknown()
{
if (options.ansiColors)
output << ANSI_RED;
output << "«unknown»";
if (options.ansiColors)
output << ANSI_NORMAL;
}
void printError_(Error & e)
{
if (options.ansiColors)
output << ANSI_RED;
output << "«error: " << filterANSIEscapes(e.info().msg.str(), true) << "»";
if (options.ansiColors)
output << ANSI_NORMAL;
}
void print(Value & v, size_t depth)
{
output.flush();
checkInterrupt();
if (options.force) {
try {
state.forceValue(v, v.determinePos(noPos));
} catch (Error & e) {
printError_(e);
return;
}
}
switch (v.type()) {
case nInt:
printInt(v);
break;
case nFloat:
printFloat(v);
break;
case nBool:
printBool(v);
break;
case nString:
printString(v);
break;
case nPath:
printPath(v);
break;
case nNull:
printNull();
break;
case nAttrs:
printAttrs(v, depth);
break;
case nList:
printList(v, depth);
break;
case nFunction:
printFunction(v);
break;
case nThunk:
printThunk(v);
break;
case nExternal:
printExternal(v);
break;
default:
printUnknown();
break;
}
}
public:
Printer(std::ostream & output, EvalState & state, PrintOptions options)
: output(output), state(state), options(options) { }
void print(Value & v)
{
attrsPrinted = 0;
listItemsPrinted = 0;
indent.clear();
if (options.trackRepeated) {
seen.emplace();
} else {
seen.reset();
}
ValuesSeen seen;
print(v, 0);
}
};
void printValue(EvalState & state, std::ostream & output, Value & v, PrintOptions options)
{
Printer(output, state, options).print(v);
}
std::ostream & operator<<(std::ostream & output, const ValuePrinter & printer)
{
printValue(printer.state, output, printer.value, printer.options);
return output;
}
template<>
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HintFmt & HintFmt::operator%(const ValuePrinter & value)
{
fmt % value;
return *this;
}
}