diff options
Diffstat (limited to 'src/libexpr/eval.cc')
| -rw-r--r-- | src/libexpr/eval.cc | 500 |
1 files changed, 8 insertions, 492 deletions
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index e72538e60874..2d22a4fdc5c4 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -27,7 +27,14 @@ std::ostream & operator << (std::ostream & str, Value & v) str << (v.boolean ? "true" : "false"); break; case tString: - str << "\"" << v.string.s << "\""; // !!! escaping + str << "\""; + for (const char * i = v.string.s; *i; 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 str << *i; + str << "\""; break; case tPath: str << v.path; // !!! escaping? @@ -930,497 +937,6 @@ bool EvalState::eqValues(Value & v1, Value & v2) } -#if 0 -/* Pattern-match `pat' against `arg'. The result is a set of - substitutions (`subs') and a set of recursive substitutions - (`subsRecursive'). The latter can refer to the variables bound by - both `subs' and `subsRecursive'. */ -static void patternMatch(EvalState & state, - Pattern pat, Expr arg, ATermMap & subs, ATermMap & subsRecursive) -{ - ATerm name; - ATermList formals; - ATermBool ellipsis; - - if (matchVarPat(pat, name)) - subs.set(name, arg); - - else if (matchAttrsPat(pat, formals, ellipsis, name)) { - - arg = evalExpr(state, arg); - - if (name != sNoAlias) subs.set(name, arg); - - /* Get the actual arguments. */ - ATermMap attrs; - queryAllAttrs(arg, attrs); - unsigned int nrAttrs = attrs.size(); - - /* For each formal argument, get the actual argument. If - there is no matching actual argument but the formal - argument has a default, use the default. */ - unsigned int attrsUsed = 0; - for (ATermIterator i(formals); i; ++i) { - Expr name, def; - DefaultValue def2; - if (!matchFormal(*i, name, def2)) abort(); /* can't happen */ - - Expr value = attrs[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)); - subsRecursive.set(name, def); - } else { - attrsUsed++; - attrs.remove(name); - subs.set(name, value); - } - - } - - /* Check that each actual argument is listed as a formal - argument (unless the attribute match specifies a `...'). */ - if (ellipsis == eFalse && attrsUsed != nrAttrs) - throw TypeError(format("the function does not expect an argument named `%1%'") - % aterm2String(attrs.begin()->key)); - } - - else abort(); -} - - -/* Substitute an argument set into the body of a function. */ -static Expr substArgs(EvalState & state, - Expr body, Pattern pat, Expr arg) -{ - ATermMap subs(16), subsRecursive(16); - - patternMatch(state, pat, arg, subs, subsRecursive); - - /* If we used any default values, make a recursive attribute set - out of the (argument-name, value) tuples. This is so that we - can support default values that refer to each other, e.g. ({x, - y ? x + x}: y) {x = "foo";} evaluates to "foofoo". */ - if (subsRecursive.size() != 0) { - ATermList recAttrs = ATempty; - foreach (ATermMap::const_iterator, i, subs) - recAttrs = ATinsert(recAttrs, makeBind(i->key, i->value, makeNoPos())); - foreach (ATermMap::const_iterator, i, subsRecursive) - recAttrs = ATinsert(recAttrs, makeBind(i->key, i->value, makeNoPos())); - Expr rec = makeRec(recAttrs, ATempty); - foreach (ATermMap::const_iterator, i, subsRecursive) - subs.set(i->key, makeSelect(rec, i->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(EvalState & state, ATerm e, ATermList rbnds, ATermList nrbnds)) -{ - ATerm name; - Expr e2; - Pos pos; - Expr eOverrides = 0; - - /* 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 */ - if (name == sOverrides) eOverrides = e2; - subs.set(name, e2); - } - - /* If the rec contains an attribute called `__overrides', then - evaluate it, and add the attributes in that set to the rec. - This allows overriding of recursive attributes, which is - otherwise not possible. (You can use the // operator to - replace an attribute, but other attributes in the rec will - still reference the original value, because that value has been - substituted into the bodies of the other attributes. Hence we - need __overrides.) */ - ATermMap overrides; - if (eOverrides) { - eOverrides = evalExpr(state, eOverrides); - queryAllAttrs(eOverrides, overrides, false); - foreach (ATermMap::const_iterator, i, overrides) - subs.set(i->key, i->value); - } - - 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)); - } - - if (eOverrides) - foreach (ATermMap::const_iterator, i, overrides) - as.set(i->key, makeAttrRHS(i->value, makeNoPos())); - - /* 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); -} - - -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); -} - - -/* 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)) -{ - Pattern pat; - ATerm pos; - 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, pat, body, pos)) { - try { - return evalExpr(state, substArgs(state, body, pat, arg)); - } 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 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; - } -} - - -/* Implementation of the `==' and `!=' operators. */ -LocalNoInline(bool areEqual(EvalState & state, Expr e1, Expr e2)) -{ - e1 = evalExpr(state, e1); - e2 = evalExpr(state, e2); - - /* We cannot test functions/primops for equality, and we currently - don't support testing equality between attribute sets or lists - - that would have to be a deep equality test to be sound. */ - AFun sym1 = ATgetAFun(e1); - AFun sym2 = ATgetAFun(e2); - - if (sym1 != sym2) return false; - - /* Functions are incomparable. */ - if (sym1 == symFunction || sym1 == symPrimOp) return false; - - if (!state.allowUnsafeEquality && sym1 == symAttrs) - throw EvalError("comparison of attribute sets is not implemented"); - - /* !!! This allows comparisons of infinite data structures to - succeed, such as `let x = [x]; in x == x'. This is - undesirable, since equivalent (?) terms such as `let x = [x]; y - = [y]; in x == y' don't terminate. */ - if (e1 == e2) return true; - - if (sym1 == symList) { - ATermList es1; matchList(e1, es1); - ATermList es2; matchList(e2, es2); - if (ATgetLength(es1) != ATgetLength(es2)) return false; - ATermIterator i(es1), j(es2); - while (*i) { - if (!areEqual(state, *i, *j)) return false; - ++i; ++j; - } - return true; - } - - return false; -} - - -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 == 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(state, 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(areEqual(state, e1, e2)); - - if (matchOpNEq(e, e1, e2)) return makeBool(!areEqual(state, e1, 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; -} - - -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); -} -#endif - - void EvalState::printStats() { char x; |