lix/src/libexpr/print.cc
Alex Ameen b72bc4a972
libexpr: quote reserved keys when printing
This fixes a bug in commands like `nix eval' which would emit invalid attribute
sets if they contained reserved keywords such as "assert", "let", etc.

These keywords will not be quoted when printed, making them valid expressions.
All keywords recognized by the lexer are quoted except "or", which does not
require quotation.
2023-05-09 09:45:12 -05:00

95 lines
2.6 KiB
C++

#include "print.hh"
#include <unordered_set>
namespace nix {
std::ostream &
printLiteralString(std::ostream & str, const std::string_view string)
{
str << "\"";
for (auto i = string.begin(); i != string.end(); ++i) {
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;
}
str << "\"";
return str;
}
std::ostream &
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;
}
}