1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
#ifndef __NIXEXPR_H
#define __NIXEXPR_H
#include <map>
#include "aterm-map.hh"
#include "types.hh"
namespace nix {
MakeError(EvalError, Error)
MakeError(AssertionError, EvalError)
MakeError(Abort, EvalError)
MakeError(TypeError, EvalError)
/* 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;
typedef ATerm DefaultValue;
typedef ATerm ValidValues;
typedef ATerm Pos;
/* A STL vector of ATerms. Should be used with great care since it's
stored on the heap, and the elements are therefore not roots to the
ATerm garbage collector. */
typedef vector<ATerm> ATermVector;
/* A substitution is a linked list of ATermMaps that map names to
identifiers. We use a list of ATermMaps rather than a single to
make it easy to grow or shrink a substitution when entering a
scope. */
struct Substitution
{
ATermMap * map;
const Substitution * prev;
Substitution(const Substitution * prev, ATermMap * map)
{
this->prev = prev;
this->map = map;
}
Expr lookup(Expr name) const
{
Expr x;
for (const Substitution * s(this); s; s = s->prev)
if ((x = s->map->get(name))) return x;
return 0;
}
};
/* Show a position. */
string showPos(ATerm pos);
/* 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 ~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, bool withPos = false);
/* Query a specific attribute from an attribute set expression. The
expression must be in normal form. */
Expr queryAttr(Expr e, const string & name);
Expr queryAttr(Expr e, const string & name, ATerm & pos);
/* 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 Substitution & subs, Expr e);
/* Check whether all variables are defined in the given expression.
Throw an exception if this isn't the case. */
void checkVarDefs(const ATermMap & def, Expr e);
/* Canonicalise a Nix expression by sorting attributes and removing
location information. */
Expr canonicaliseExpr(Expr e);
/* Create an expression representing a boolean. */
Expr makeBool(bool b);
/* Manipulation of Str() nodes. Note: matchStr() does not clear
context! */
bool matchStr(Expr e, string & s, PathSet & context);
Expr makeStr(const string & s, const PathSet & context = PathSet());
/* Showing types, values. */
string showType(Expr e);
string showValue(Expr e);
}
#endif /* !__NIXEXPR_H */
|
