mirror of
https://github.com/privatevoid-net/nix-super.git
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59b94ee18a
print a nice backtrace of the stack, rather than vomiting a gigantic
(and useless) aterm on the screen. Example:
error: while evaluating file `.../pkgs/system/test.nix':
while evaluating attribute `subversion' at `.../pkgs/system/all-packages-generic.nix', line 533:
while evaluating function at `.../pkgs/applications/version-management/subversion/default.nix', line 1:
assertion failed at `.../pkgs/applications/version-management/subversion/default.nix', line 13
Since the Nix expression language is lazy, the trace may be
misleading. The purpose is to provide a hint as to the location of
the problem.
90 lines
2.3 KiB
C++
90 lines
2.3 KiB
C++
#ifndef __NIXEXPR_H
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#define __NIXEXPR_H
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#include <map>
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#include <aterm2.h>
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#include "util.hh"
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/* Nix expressions are represented as ATerms. The maximal sharing
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property of the ATerm library allows us to implement caching of
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normals forms efficiently. */
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typedef ATerm Expr;
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/* Mappings from ATerms to ATerms. This is just a wrapper around
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ATerm tables. */
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class ATermMap
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{
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private:
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unsigned int maxLoadPct;
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ATermTable table;
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public:
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ATermMap(unsigned int initialSize = 64, unsigned int maxLoadPct = 75);
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ATermMap(const ATermMap & map);
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~ATermMap();
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void set(ATerm key, ATerm value);
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void set(const string & key, ATerm value);
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ATerm get(ATerm key) const;
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ATerm get(const string & key) const;
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void remove(ATerm key);
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void remove(const string & key);
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ATermList keys() const;
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void add(const ATermMap & map);
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void reset();
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private:
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void add(const ATermMap & map, ATermList & keys);
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};
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/* Convert a string to an ATerm (i.e., a quoted nullary function
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applicaton). */
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ATerm string2ATerm(const string & s);
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string aterm2String(ATerm t);
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/* Show a position. */
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string showPos(ATerm pos);
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/* Generic bottomup traversal over ATerms. The traversal first
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recursively descends into subterms, and then applies the given term
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function to the resulting term. */
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struct TermFun
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{
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virtual ATerm operator () (ATerm e) = 0;
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};
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ATerm bottomupRewrite(TermFun & f, ATerm e);
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/* Query all attributes in an attribute set expression. The
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expression must be in normal form. */
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void queryAllAttrs(Expr e, ATermMap & attrs, bool withPos = false);
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/* Query a specific attribute from an attribute set expression. The
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expression must be in normal form. */
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Expr queryAttr(Expr e, const string & name);
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Expr queryAttr(Expr e, const string & name, ATerm & pos);
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/* Create an attribute set expression from an Attrs value. */
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Expr makeAttrs(const ATermMap & attrs);
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/* Perform a set of substitutions on an expression. */
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Expr substitute(const ATermMap & subs, Expr e);
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/* Check whether all variables are defined in the given expression.
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Throw an exception if this isn't the case. */
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void checkVarDefs(const ATermMap & def, Expr e);
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/* Create an expression representing a boolean. */
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Expr makeBool(bool b);
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#endif /* !__NIXEXPR_H */
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