lix/src/libexpr/eval.cc

832 lines
24 KiB
C++

#include "eval.hh"
#include "parser.hh"
#include "hash.hh"
#include "util.hh"
#include "store-api.hh"
#include "derivations.hh"
#include "nixexpr-ast.hh"
#include "globals.hh"
#define LocalNoInline(f) static f __attribute__((noinline)); f
#define LocalNoInlineNoReturn(f) static f __attribute__((noinline, noreturn)); f
namespace nix {
EvalState::EvalState()
: normalForms(32768), primOps(128)
{
nrEvaluated = nrCached = 0;
initNixExprHelpers();
addPrimOps();
}
void EvalState::addPrimOp(const string & name,
unsigned int arity, PrimOp primOp)
{
primOps.set(toATerm(name), makePrimOpDef(arity, ATmakeBlob(0, (void *) primOp)));
}
/* Every "format" object (even temporary) takes up a few hundred bytes
of stack space, which is a real killer in the recursive
evaluator. So here are some helper functions for throwing
exceptions. */
LocalNoInlineNoReturn(void throwEvalError(const char * s))
{
throw EvalError(s);
}
LocalNoInlineNoReturn(void throwEvalError(const char * s, const string & s2))
{
throw EvalError(format(s) % s2);
}
LocalNoInlineNoReturn(void throwTypeError(const char * s))
{
throw TypeError(s);
}
LocalNoInlineNoReturn(void throwTypeError(const char * s, const string & s2))
{
throw TypeError(format(s) % s2);
}
LocalNoInline(void addErrorPrefix(Error & e, const char * s))
{
e.addPrefix(s);
}
LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2))
{
e.addPrefix(format(s) % s2);
}
LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2, const string & s3))
{
e.addPrefix(format(s) % s2 % s3);
}
/* Substitute an argument set into the body of a function. */
static Expr substArgs(EvalState & state,
Expr body, ATermList formals, Expr arg)
{
unsigned int nrFormals = ATgetLength(formals);
ATermMap subs(nrFormals);
/* Get the actual arguments and put them in the substitution. */
ATermMap args;
queryAllAttrs(arg, args);
for (ATermMap::const_iterator i = args.begin(); i != args.end(); ++i)
subs.set(i->key, i->value);
/* Get the formal arguments. */
ATermVector defsUsed;
ATermList recAttrs = ATempty;
for (ATermIterator i(formals); i; ++i) {
Expr name, def;
DefaultValue def2;
if (!matchFormal(*i, name, def2)) abort(); /* can't happen */
Expr value = subs[name];
if (value == 0) {
if (!matchDefaultValue(def2, def)) def = 0;
if (def == 0) throw TypeError(format("the argument named `%1%' required by the function is missing")
% aterm2String(name));
value = def;
defsUsed.push_back(name);
recAttrs = ATinsert(recAttrs, makeBind(name, def, makeNoPos()));
}
}
/* Make a recursive attribute set out of the (argument-name,
value) tuples. This is so that we can support default
parameters that refer to each other, e.g. ({x, y ? x + x}: y)
{x = "foo";} evaluates to "foofoo". */
if (defsUsed.size() != 0) {
for (ATermMap::const_iterator i = args.begin(); i != args.end(); ++i)
recAttrs = ATinsert(recAttrs, makeBind(i->key, i->value, makeNoPos()));
Expr rec = makeRec(recAttrs, ATempty);
for (ATermVector::iterator i = defsUsed.begin(); i != defsUsed.end(); ++i)
subs.set(*i, makeSelect(rec, *i));
}
if (subs.size() != nrFormals) {
/* One or more actual arguments were not declared as formal
arguments. Find out which. */
for (ATermIterator i(formals); i; ++i) {
Expr name; ATerm d1;
if (!matchFormal(*i, name, d1)) abort();
subs.remove(name);
}
throw TypeError(format("the function does not expect an argument named `%1%'")
% aterm2String(subs.begin()->key));
}
return substitute(Substitution(0, &subs), body);
}
/* Transform a mutually recursive set into a non-recursive set. Each
attribute is transformed into an expression that has all references
to attributes substituted with selection expressions on the
original set. E.g., e = `rec {x = f x y; y = x;}' becomes `{x = f
(e.x) (e.y); y = e.x;}'. */
LocalNoInline(ATerm expandRec(ATerm e, ATermList rbnds, ATermList nrbnds))
{
ATerm name;
Expr e2;
Pos pos;
/* Create the substitution list. */
ATermMap subs(ATgetLength(rbnds) + ATgetLength(nrbnds));
for (ATermIterator i(rbnds); i; ++i) {
if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */
subs.set(name, makeSelect(e, name));
}
for (ATermIterator i(nrbnds); i; ++i) {
if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */
subs.set(name, e2);
}
Substitution subs_(0, &subs);
/* Create the non-recursive set. */
ATermMap as(ATgetLength(rbnds) + ATgetLength(nrbnds));
for (ATermIterator i(rbnds); i; ++i) {
if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */
as.set(name, makeAttrRHS(substitute(subs_, e2), pos));
}
/* Copy the non-recursive bindings. !!! inefficient */
for (ATermIterator i(nrbnds); i; ++i) {
if (!matchBind(*i, name, e2, pos)) abort(); /* can't happen */
as.set(name, makeAttrRHS(e2, pos));
}
return makeAttrs(as);
}
LocalNoInline(Expr updateAttrs(Expr e1, Expr e2))
{
/* Note: e1 and e2 should be in normal form. */
ATermMap attrs;
queryAllAttrs(e1, attrs, true);
queryAllAttrs(e2, attrs, true);
return makeAttrs(attrs);
}
string evalString(EvalState & state, Expr e, PathSet & context)
{
e = evalExpr(state, e);
string s;
if (!matchStr(e, s, context))
throwTypeError("value is %1% while a string was expected", showType(e));
return s;
}
string evalStringNoCtx(EvalState & state, Expr e)
{
PathSet context;
string s = evalString(state, e, context);
if (!context.empty())
throw EvalError(format("the string `%1%' is not allowed to refer to a store path (such as `%2%')")
% s % *(context.begin()));
return s;
}
int evalInt(EvalState & state, Expr e)
{
e = evalExpr(state, e);
int i;
if (!matchInt(e, i))
throwTypeError("value is %1% while an integer was expected", showType(e));
return i;
}
bool evalBool(EvalState & state, Expr e)
{
e = evalExpr(state, e);
if (e == eTrue) return true;
else if (e == eFalse) return false;
else throwTypeError("value is %1% while a boolean was expected", showType(e));
}
ATermList evalList(EvalState & state, Expr e)
{
e = evalExpr(state, e);
ATermList list;
if (!matchList(e, list))
throwTypeError("value is %1% while a list was expected", showType(e));
return list;
}
static void flattenList(EvalState & state, Expr e, ATermList & result)
{
ATermList es;
e = evalExpr(state, e);
if (matchList(e, es))
for (ATermIterator i(es); i; ++i)
flattenList(state, *i, result);
else
result = ATinsert(result, e);
}
ATermList flattenList(EvalState & state, Expr e)
{
ATermList result = ATempty;
flattenList(state, e, result);
return ATreverse(result);
}
string coerceToString(EvalState & state, Expr e, PathSet & context,
bool coerceMore, bool copyToStore)
{
e = evalExpr(state, e);
string s;
if (matchStr(e, s, context)) return s;
ATerm s2;
if (matchPath(e, s2)) {
Path path(canonPath(aterm2String(s2)));
if (!copyToStore) return path;
if (isDerivation(path))
throw EvalError(format("file names are not allowed to end in `%1%'")
% drvExtension);
Path dstPath;
if (state.srcToStore[path] != "")
dstPath = state.srcToStore[path];
else {
dstPath = readOnlyMode
? computeStorePathForPath(path).first
: store->addToStore(path);
state.srcToStore[path] = dstPath;
printMsg(lvlChatty, format("copied source `%1%' -> `%2%'")
% path % dstPath);
}
context.insert(dstPath);
return dstPath;
}
ATermList es;
if (matchAttrs(e, es)) {
Expr e2 = queryAttr(e, "outPath");
if (!e2) throwTypeError("cannot coerce an attribute set (except a derivation) to a string");
return coerceToString(state, e2, context, coerceMore, copyToStore);
}
if (coerceMore) {
/* Note that `false' is represented as an empty string for
shell scripting convenience, just like `null'. */
if (e == eTrue) return "1";
if (e == eFalse) return "";
int n;
if (matchInt(e, n)) return int2String(n);
if (matchNull(e)) return "";
if (matchList(e, es)) {
string result;
es = flattenList(state, e);
bool first = true;
for (ATermIterator i(es); i; ++i) {
if (!first) result += " "; else first = false;
result += coerceToString(state, *i,
context, coerceMore, copyToStore);
}
return result;
}
}
throwTypeError("cannot coerce %1% to a string", showType(e));
}
/* Common implementation of `+', ConcatStrings and `~'. */
static ATerm concatStrings(EvalState & state, ATermVector & args,
string separator = "")
{
if (args.empty()) return makeStr("", PathSet());
PathSet context;
std::ostringstream s;
/* If the first element is a path, then the result will also be a
path, we don't copy anything (yet - that's done later, since
paths are copied when they are used in a derivation), and none
of the strings are allowed to have contexts. */
ATerm dummy;
args.front() = evalExpr(state, args.front());
bool isPath = matchPath(args.front(), dummy);
for (ATermVector::const_iterator i = args.begin(); i != args.end(); ++i) {
if (i != args.begin()) s << separator;
s << coerceToString(state, *i, context, false, !isPath);
}
if (isPath && !context.empty())
throw EvalError(format("a string that refers to a store path cannot be appended to a path, in `%1%'")
% s.str());
return isPath
? makePath(toATerm(s.str()))
: makeStr(s.str(), context);
}
Path coerceToPath(EvalState & state, Expr e, PathSet & context)
{
string path = coerceToString(state, e, context, false, false);
if (path == "" || path[0] != '/')
throw EvalError(format("string `%1%' doesn't represent an absolute path") % path);
return path;
}
Expr autoCallFunction(Expr e, const ATermMap & args)
{
ATermList formals;
ATerm body, pos;
if (matchFunction(e, formals, body, pos)) {
ATermMap actualArgs(ATgetLength(formals));
for (ATermIterator i(formals); i; ++i) {
Expr name, def, value; ATerm def2;
if (!matchFormal(*i, name, def2)) abort();
if ((value = args.get(name)))
actualArgs.set(name, makeAttrRHS(value, makeNoPos()));
else if (!matchDefaultValue(def2, def))
throw TypeError(format("cannot auto-call a function that has an argument without a default value (`%1%')")
% aterm2String(name));
}
e = makeCall(e, makeAttrs(actualArgs));
}
return e;
}
/* Evaluation of various language constructs. These have been taken
out of evalExpr2 to reduce stack space usage. (GCC is really dumb
about stack space: it just adds up all the local variables and
temporaries of every scope into one huge stack frame. This is
really bad for deeply recursive functions.) */
LocalNoInline(Expr evalVar(EvalState & state, ATerm name))
{
ATerm primOp = state.primOps.get(name);
if (!primOp)
throw EvalError(format("impossible: undefined variable `%1%'") % aterm2String(name));
int arity;
ATermBlob fun;
if (!matchPrimOpDef(primOp, arity, fun)) abort();
if (arity == 0)
/* !!! backtrace for primop call */
return ((PrimOp) ATgetBlobData(fun)) (state, ATermVector());
else
return makePrimOp(arity, fun, ATempty);
}
LocalNoInline(Expr evalCall(EvalState & state, Expr fun, Expr arg))
{
ATermList formals;
ATerm pos, name;
Expr body;
/* Evaluate the left-hand side. */
fun = evalExpr(state, fun);
/* Is it a primop or a function? */
int arity;
ATermBlob funBlob;
ATermList args;
if (matchPrimOp(fun, arity, funBlob, args)) {
args = ATinsert(args, arg);
if (ATgetLength(args) == arity) {
/* Put the arguments in a vector in reverse (i.e.,
actual) order. */
ATermVector args2(arity);
for (ATermIterator i(args); i; ++i)
args2[--arity] = *i;
/* !!! backtrace for primop call */
return ((PrimOp) ATgetBlobData(funBlob))
(state, args2);
} else
/* Need more arguments, so propagate the primop. */
return makePrimOp(arity, funBlob, args);
}
else if (matchFunction(fun, formals, body, pos)) {
arg = evalExpr(state, arg);
try {
return evalExpr(state, substArgs(state, body, formals, arg));
} catch (Error & e) {
addErrorPrefix(e, "while evaluating the function at %1%:\n",
showPos(pos));
throw;
}
}
else if (matchFunction1(fun, name, body, pos)) {
try {
ATermMap subs(1);
subs.set(name, arg);
return evalExpr(state, substitute(Substitution(0, &subs), body));
} catch (Error & e) {
addErrorPrefix(e, "while evaluating the function at %1%:\n",
showPos(pos));
throw;
}
}
else throwTypeError(
"attempt to call something which is neither a function nor a primop (built-in operation) but %1%",
showType(fun));
}
LocalNoInline(Expr evalSelect(EvalState & state, Expr e, ATerm name))
{
ATerm pos;
string s = aterm2String(name);
Expr a = queryAttr(evalExpr(state, e), s, pos);
if (!a) throwEvalError("attribute `%1%' missing", s);
try {
return evalExpr(state, a);
} catch (Error & e) {
addErrorPrefix(e, "while evaluating the attribute `%1%' at %2%:\n",
s, showPos(pos));
throw;
}
}
LocalNoInline(Expr evalAssert(EvalState & state, Expr cond, Expr body, ATerm pos))
{
if (!evalBool(state, cond))
throw AssertionError(format("assertion failed at %1%") % showPos(pos));
return evalExpr(state, body);
}
LocalNoInline(Expr evalWith(EvalState & state, Expr defs, Expr body, ATerm pos))
{
ATermMap attrs;
try {
defs = evalExpr(state, defs);
queryAllAttrs(defs, attrs);
} catch (Error & e) {
addErrorPrefix(e, "while evaluating the `with' definitions at %1%:\n",
showPos(pos));
throw;
}
try {
body = substitute(Substitution(0, &attrs), body);
checkVarDefs(state.primOps, body);
return evalExpr(state, body);
} catch (Error & e) {
addErrorPrefix(e, "while evaluating the `with' body at %1%:\n",
showPos(pos));
throw;
}
}
LocalNoInline(Expr evalHasAttr(EvalState & state, Expr e, ATerm name))
{
ATermMap attrs;
queryAllAttrs(evalExpr(state, e), attrs);
return makeBool(attrs.get(name) != 0);
}
LocalNoInline(Expr evalPlusConcat(EvalState & state, Expr e))
{
Expr e1, e2;
ATermList es;
ATermVector args;
if (matchOpPlus(e, e1, e2)) {
/* !!! Awful compatibility hack for `drv + /path'.
According to regular concatenation, /path should be
copied to the store and its store path should be
appended to the string. However, in Nix <= 0.10, /path
was concatenated. So handle that case separately, but
do print out a warning. This code can go in Nix 0.12,
maybe. */
e1 = evalExpr(state, e1);
e2 = evalExpr(state, e2);
ATermList as;
ATerm p;
if (matchAttrs(e1, as) && matchPath(e2, p)) {
static bool haveWarned = false;
warnOnce(haveWarned, format(
"concatenation of a derivation and a path is deprecated; "
"you should write `drv + \"%1%\"' instead of `drv + %1%'")
% aterm2String(p));
PathSet context;
return makeStr(
coerceToString(state, makeSelect(e1, toATerm("outPath")), context)
+ aterm2String(p), context);
}
args.push_back(e1);
args.push_back(e2);
}
else if (matchConcatStrings(e, es))
for (ATermIterator i(es); i; ++i) args.push_back(*i);
try {
return concatStrings(state, args);
} catch (Error & e) {
addErrorPrefix(e, "in a string concatenation:\n");
throw;
}
}
LocalNoInline(Expr evalSubPath(EvalState & state, Expr e1, Expr e2))
{
static bool haveWarned = false;
warnOnce(haveWarned, "the subpath operator (~) is deprecated, use string concatenation (+) instead");
ATermVector args;
args.push_back(e1);
args.push_back(e2);
return concatStrings(state, args, "/");
}
LocalNoInline(Expr evalOpConcat(EvalState & state, Expr e1, Expr e2))
{
try {
ATermList l1 = evalList(state, e1);
ATermList l2 = evalList(state, e2);
return makeList(ATconcat(l1, l2));
} catch (Error & e) {
addErrorPrefix(e, "in a list concatenation:\n");
throw;
}
}
static char * deepestStack = (char *) -1; /* for measuring stack usage */
Expr evalExpr2(EvalState & state, Expr e)
{
/* When changing this function, make sure that you don't cause a
(large) increase in stack consumption! */
char x;
if (&x < deepestStack) deepestStack = &x;
Expr e1, e2, e3;
ATerm name, pos;
AFun sym = ATgetAFun(e);
/* Normal forms. */
if (sym == symStr ||
sym == symPath ||
sym == symNull ||
sym == symInt ||
sym == symBool ||
sym == symFunction ||
sym == symFunction1 ||
sym == symAttrs ||
sym == symList ||
sym == symPrimOp)
return e;
/* The `Closed' constructor is just a way to prevent substitutions
into expressions not containing free variables. */
if (matchClosed(e, e1))
return evalExpr(state, e1);
/* Any encountered variables must be primops (since undefined
variables are detected after parsing). */
if (matchVar(e, name)) return evalVar(state, name);
/* Function application. */
if (matchCall(e, e1, e2)) return evalCall(state, e1, e2);
/* Attribute selection. */
if (matchSelect(e, e1, name)) return evalSelect(state, e1, name);
/* Mutually recursive sets. */
ATermList rbnds, nrbnds;
if (matchRec(e, rbnds, nrbnds))
return expandRec(e, rbnds, nrbnds);
/* Conditionals. */
if (matchIf(e, e1, e2, e3))
return evalExpr(state, evalBool(state, e1) ? e2 : e3);
/* Assertions. */
if (matchAssert(e, e1, e2, pos)) return evalAssert(state, e1, e2, pos);
/* Withs. */
if (matchWith(e, e1, e2, pos)) return evalWith(state, e1, e2, pos);
/* Generic equality/inequality. Note that the behaviour on
composite data (lists, attribute sets) and functions is
undefined, since the subterms of those terms are not evaluated.
However, we don't want to make (==) strict, because that would
make operations like `big_derivation == null' very slow (unless
we were to evaluate them side-by-side). */
if (matchOpEq(e, e1, e2))
return makeBool(evalExpr(state, e1) == evalExpr(state, e2));
if (matchOpNEq(e, e1, e2))
return makeBool(evalExpr(state, e1) != evalExpr(state, e2));
/* Negation. */
if (matchOpNot(e, e1))
return makeBool(!evalBool(state, e1));
/* Implication. */
if (matchOpImpl(e, e1, e2))
return makeBool(!evalBool(state, e1) || evalBool(state, e2));
/* Conjunction (logical AND). */
if (matchOpAnd(e, e1, e2))
return makeBool(evalBool(state, e1) && evalBool(state, e2));
/* Disjunction (logical OR). */
if (matchOpOr(e, e1, e2))
return makeBool(evalBool(state, e1) || evalBool(state, e2));
/* Attribute set update (//). */
if (matchOpUpdate(e, e1, e2))
return updateAttrs(evalExpr(state, e1), evalExpr(state, e2));
/* Attribute existence test (?). */
if (matchOpHasAttr(e, e1, name)) return evalHasAttr(state, e1, name);
/* String or path concatenation. */
if (sym == symOpPlus || sym == symConcatStrings)
return evalPlusConcat(state, e);
/* Backwards compatability: subpath operator (~). */
if (matchSubPath(e, e1, e2)) return evalSubPath(state, e1, e2);
/* List concatenation. */
if (matchOpConcat(e, e1, e2)) return evalOpConcat(state, e1, e2);
/* Barf. */
abort();
}
Expr evalExpr(EvalState & state, Expr e)
{
checkInterrupt();
#if 0
startNest(nest, lvlVomit,
format("evaluating expression: %1%") % e);
#endif
state.nrEvaluated++;
/* Consult the memo table to quickly get the normal form of
previously evaluated expressions. */
Expr nf = state.normalForms.get(e);
if (nf) {
if (nf == makeBlackHole())
throwEvalError("infinite recursion encountered");
state.nrCached++;
return nf;
}
/* Otherwise, evaluate and memoize. */
state.normalForms.set(e, makeBlackHole());
try {
nf = evalExpr2(state, e);
} catch (Error & err) {
state.normalForms.remove(e);
throw;
}
state.normalForms.set(e, nf);
return nf;
}
Expr evalFile(EvalState & state, const Path & path)
{
startNest(nest, lvlTalkative, format("evaluating file `%1%'") % path);
Expr e = parseExprFromFile(state, path);
try {
return evalExpr(state, e);
} catch (Error & e) {
e.addPrefix(format("while evaluating the file `%1%':\n")
% path);
throw;
}
}
static Expr strictEvalExpr(EvalState & state, Expr e, ATermMap & nfs);
static Expr strictEvalExpr_(EvalState & state, Expr e, ATermMap & nfs)
{
e = evalExpr(state, e);
ATermList as;
if (matchAttrs(e, as)) {
ATermList as2 = ATempty;
for (ATermIterator i(as); i; ++i) {
ATerm name; Expr e; ATerm pos;
if (!matchBind(*i, name, e, pos)) abort(); /* can't happen */
as2 = ATinsert(as2, makeBind(name, strictEvalExpr(state, e, nfs), pos));
}
return makeAttrs(ATreverse(as2));
}
ATermList es;
if (matchList(e, es)) {
ATermList es2 = ATempty;
for (ATermIterator i(es); i; ++i)
es2 = ATinsert(es2, strictEvalExpr(state, *i, nfs));
return makeList(ATreverse(es2));
}
return e;
}
static Expr strictEvalExpr(EvalState & state, Expr e, ATermMap & nfs)
{
Expr nf = nfs.get(e);
if (nf) return nf;
nf = strictEvalExpr_(state, e, nfs);
nfs.set(e, nf);
return nf;
}
Expr strictEvalExpr(EvalState & state, Expr e)
{
ATermMap strictNormalForms;
return strictEvalExpr(state, e, strictNormalForms);
}
/* Yes, this is a really bad idea... */
extern "C" {
unsigned long AT_calcAllocatedSize();
}
void printEvalStats(EvalState & state)
{
char x;
bool showStats = getEnv("NIX_SHOW_STATS", "0") != "0";
printMsg(showStats ? lvlInfo : lvlDebug,
format("evaluated %1% expressions, %2% cache hits, %3%%% efficiency, used %4% ATerm bytes, used %5% bytes of stack space")
% state.nrEvaluated % state.nrCached
% ((float) state.nrCached / (float) state.nrEvaluated * 100)
% AT_calcAllocatedSize()
% (&x - deepestStack));
if (showStats)
printATermMapStats();
}
}