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* Big cleanup of the semantics of paths, strings, contexts, string

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concatenation and string coercion.  This was a big mess (see
  e.g. NIX-67).  Contexts are now folded into strings, so that they
  don't cause evaluation errors when they're not expected.  The
  semantics of paths has been clarified (see nixexpr-ast.def).
  toString() and coerceToString() have been merged.

  Semantic change: paths are now copied to the store when they're in a
  concatenation (and in most other situations - that's the
  formalisation of the meaning of a path).  So

    "foo " + ./bla

  evaluates to "foo /nix/store/hash...-bla", not "foo
  /path/to/current-dir/bla".  This prevents accidental impurities, and
  is more consistent with the treatment of derivation outputs, e.g.,
  `"foo " + bla' where `bla' is a derivation.  (Here `bla' would be
  replaced by the output path of `bla'.)
This commit is contained in:
Eelco Dolstra 2006-10-16 15:55:34 +00:00
parent 4c9aa821b9
commit d7efd76394
17 changed files with 331 additions and 396 deletions
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37
src/libexpr/nixexpr.cc
View file

@ -293,13 +293,35 @@ Expr makeBool(bool b)
}
bool matchStr(Expr e, string & s, PathSet & context)
{
ATermList l;
ATerm s_;
if (!matchStr(e, s_, l)) return false;
s = aterm2String(s_);
for (ATermIterator i(l); i; ++i)
context.insert(aterm2String(*i));
return true;
}
Expr makeStr(const string & s, const PathSet & context)
{
return makeStr(toATerm(s), toATermList(context));
}
string showType(Expr e)
{
ATerm t1, t2, t3;
ATermList l1;
ATermBlob b1;
int i1;
if (matchStr(e, t1)) return "a string";
if (matchStr(e, t1, l1)) return "a string";
if (matchPath(e, t1)) return "a path";
if (matchNull(e)) return "null";
if (matchInt(e, i1)) return "an integer";
@ -309,18 +331,19 @@ string showType(Expr e)
if (matchAttrs(e, l1)) return "an attribute set";
if (matchList(e, l1)) return "a list";
if (matchPrimOp(e, i1, b1, l1)) return "a partially applied built-in function";
if (matchContext(e, l1, t1)) return "a context containing " + showType(t1);
return "an unknown type";
}
string showValue(Expr e)
{
ATerm s;
PathSet context;
string s;
ATerm s2;
int i;
if (matchStr(e, s)) {
string t = aterm2String(s), u;
for (string::iterator i = t.begin(); i != t.end(); ++i)
if (matchStr(e, s, context)) {
string u;
for (string::iterator i = s.begin(); i != s.end(); ++i)
if (*i == '\"' || *i == '\\') u += "\\" + *i;
else if (*i == '\n') u += "\\n";
else if (*i == '\r') u += "\\r";
@ -328,7 +351,7 @@ string showValue(Expr e)
else u += *i;
return "\"" + u + "\"";
}
if (matchPath(e, s)) return aterm2String(s);
if (matchPath(e, s2)) return aterm2String(s2);
if (matchNull(e)) return "null";
if (matchInt(e, i)) return (format("%1%") % i).str();
if (e == eTrue) return "true";