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libexpr: Use int64_t for NixInt
Using a 64bit integer on 32bit systems will come with a bit of a performance overhead, but given that Nix doesn't use a lot of integers compared to other types, I think the overhead is negligible also considering that 32bit systems are in decline. The biggest advantage however is that when we use a consistent integer size across all platforms it's less likely that we miss things that we break due to that. One example would be: https://github.com/NixOS/nixpkgs/pull/44233 On Hydra it will evaluate, because the evaluator runs on a 64bit machine, but when evaluating the same on a 32bit machine it will fail, so using 64bit integers should make that consistent. While the change of the type in value.hh is rather easy to do, we have a few more options available for doing the conversion in the lexer: * Via an #ifdef on the architecture and using strtol() or strtoll() accordingly depending on which architecture we are. For the #ifdef we would need another AX_COMPILE_CHECK_SIZEOF in configure.ac. * Using istringstream, which would involve copying the value. * As we're already using boost, lexical_cast might be a good idea. Spoiler: I went for the latter, first of all because lexical_cast does have an overload for const char* and second of all, because it doesn't involve copying around the input string. Also, because istringstream seems to come with a bigger overhead than boost::lexical_cast: https://www.boost.org/doc/libs/release/doc/html/boost_lexical_cast/performance.html The first method (still using strtol/strtoll) also wasn't something I pursued further, because it is also locale-aware which I doubt is what we want, given that the regex for int is [0-9]+. Signed-off-by: aszlig <aszlig@nix.build> Fixes: #2339
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2 changed files with 7 additions and 3 deletions
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@ -12,6 +12,8 @@
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%{
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#include <boost/lexical_cast.hpp>
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#include "nixexpr.hh"
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#include "parser-tab.hh"
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@ -124,9 +126,11 @@ or { return OR_KW; }
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{ID} { yylval->id = strdup(yytext); return ID; }
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{INT} { errno = 0;
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yylval->n = strtol(yytext, 0, 10);
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if (errno != 0)
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try {
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yylval->n = boost::lexical_cast<int64_t>(yytext);
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} catch (const boost::bad_lexical_cast &) {
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throw ParseError(format("invalid integer '%1%'") % yytext);
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}
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return INT;
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}
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{FLOAT} { errno = 0;
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@ -43,7 +43,7 @@ class XMLWriter;
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class JSONPlaceholder;
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typedef long NixInt;
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typedef int64_t NixInt;
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typedef double NixFloat;
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/* External values must descend from ExternalValueBase, so that
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