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#ifndef __NIXEXPR_H
#define __NIXEXPR_H
#include <map>
#include <aterm2.h>
#include "util.hh"
/* Nix expressions are represented as ATerms. The maximal sharing
property of the ATerm library allows us to implement caching of
normals forms efficiently. */
typedef ATerm Expr;
/* Mappings from ATerms to ATerms. This is just a wrapper around
ATerm tables. */
class ATermMap
{
private:
unsigned int maxLoadPct;
ATermTable table;
public:
ATermMap(unsigned int initialSize = 16, unsigned int maxLoadPct = 75);
ATermMap(const ATermMap & map);
~ATermMap();
void set(ATerm key, ATerm value);
void set(const string & key, ATerm value);
ATerm get(ATerm key) const;
ATerm get(const string & key) const;
void remove(ATerm key);
void remove(const string & key);
ATermList keys() const;
};
/* Convert a string to an ATerm (i.e., a quoted nullary function
applicaton). */
ATerm string2ATerm(const string & s);
string aterm2String(ATerm t);
/* Generic bottomup traversal over ATerms. The traversal first
recursively descends into subterms, and then applies the given term
function to the resulting term. */
struct TermFun
{
virtual ATerm operator () (ATerm e) = 0;
};
ATerm bottomupRewrite(TermFun & f, ATerm e);
/* Query all attributes in an attribute set expression. The
expression must be in normal form. */
void queryAllAttrs(Expr e, ATermMap & attrs);
/* Query a specific attribute from an attribute set expression. The
expression must be in normal form. */
Expr queryAttr(Expr e, const string & name);
/* Create an attribute set expression from an Attrs value. */
Expr makeAttrs(const ATermMap & attrs);
/* Perform a set of substitutions on an expression. */
Expr substitute(const ATermMap & subs, Expr e);
/* Create an expression representing a boolean. */
Expr makeBool(bool b);
#endif /* !__NIXEXPR_H */
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