lix/src/libexpr/expr-to-xml.cc
Eelco Dolstra 9279174dde * Added an experimental feature suggested by Andres: ellipses ("...")
in attribute set pattern matches.  This allows defining a function
  that takes *at least* the listed attributes, while ignoring
  additional attributes.  For instance,

    {stdenv, fetchurl, fuse, ...}:
    
    stdenv.mkDerivation {
      ...
    };
    
  defines a function that requires an attribute set that contains the 
  specified attributes but ignores others.  The main advantage is that
  we can then write in all-packages.nix

    aefs = import ../bla/aefs pkgs;

  instead of

    aefs = import ../bla/aefs {
      inherit stdenv fetchurl fuse;
    };

  This saves a lot of typing (not to mention not having to update
  all-packages.nix with purely mechanical changes).  It saves as much
  typing as the "args: with args;" style, but has the advantage that
  the function arguments are properly declared (not implicit in what
  the body of the "with" uses).
2008-08-14 14:00:44 +00:00

157 lines
4.2 KiB
C++

#include "expr-to-xml.hh"
#include "xml-writer.hh"
#include "nixexpr-ast.hh"
#include "aterm.hh"
#include "util.hh"
#include <cstdlib>
namespace nix {
static XMLAttrs singletonAttrs(const string & name, const string & value)
{
XMLAttrs attrs;
attrs[name] = value;
return attrs;
}
/* set<Expr> is safe because all the expressions are also reachable
from the stack, therefore can't be garbage-collected. */
typedef set<Expr> ExprSet;
static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
ExprSet & drvsSeen);
static void showAttrs(const ATermMap & attrs, XMLWriter & doc,
PathSet & context, ExprSet & drvsSeen)
{
StringSet names;
for (ATermMap::const_iterator i = attrs.begin(); i != attrs.end(); ++i)
names.insert(aterm2String(i->key));
for (StringSet::iterator i = names.begin(); i != names.end(); ++i) {
XMLOpenElement _(doc, "attr", singletonAttrs("name", *i));
printTermAsXML(attrs.get(toATerm(*i)), doc, context, drvsSeen);
}
}
static void printPatternAsXML(Pattern pat, XMLWriter & doc)
{
ATerm name;
ATermList formals;
Pattern pat1, pat2;
ATermBool ellipsis;
if (matchVarPat(pat, name))
doc.writeEmptyElement("varpat", singletonAttrs("name", aterm2String(name)));
else if (matchAttrsPat(pat, formals, ellipsis)) {
XMLOpenElement _(doc, "attrspat");
for (ATermIterator i(formals); i; ++i) {
Expr name; ATerm dummy;
if (!matchFormal(*i, name, dummy)) abort();
doc.writeEmptyElement("attr", singletonAttrs("name", aterm2String(name)));
}
if (ellipsis == eTrue) doc.writeEmptyElement("ellipsis");
}
else if (matchAtPat(pat, pat1, pat2)) {
XMLOpenElement _(doc, "at");
printPatternAsXML(pat1, doc);
printPatternAsXML(pat2, doc);
}
}
static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
ExprSet & drvsSeen)
{
XMLAttrs attrs;
string s;
ATerm s2;
int i;
ATermList as, es;
ATerm pat, body, pos;
checkInterrupt();
if (matchStr(e, s, context)) /* !!! show the context? */
doc.writeEmptyElement("string", singletonAttrs("value", s));
else if (matchPath(e, s2))
doc.writeEmptyElement("path", singletonAttrs("value", aterm2String(s2)));
else if (matchNull(e))
doc.writeEmptyElement("null");
else if (matchInt(e, i))
doc.writeEmptyElement("int", singletonAttrs("value", (format("%1%") % i).str()));
else if (e == eTrue)
doc.writeEmptyElement("bool", singletonAttrs("value", "true"));
else if (e == eFalse)
doc.writeEmptyElement("bool", singletonAttrs("value", "false"));
else if (matchAttrs(e, as)) {
ATermMap attrs;
queryAllAttrs(e, attrs);
Expr a = attrs.get(toATerm("type"));
if (a && matchStr(a, s, context) && s == "derivation") {
XMLAttrs xmlAttrs;
Path outPath, drvPath;
a = attrs.get(toATerm("drvPath"));
if (matchStr(a, drvPath, context))
xmlAttrs["drvPath"] = drvPath;
a = attrs.get(toATerm("outPath"));
if (matchStr(a, outPath, context))
xmlAttrs["outPath"] = outPath;
XMLOpenElement _(doc, "derivation", xmlAttrs);
if (drvsSeen.find(e) == drvsSeen.end()) {
drvsSeen.insert(e);
showAttrs(attrs, doc, context, drvsSeen);
} else
doc.writeEmptyElement("repeated");
}
else {
XMLOpenElement _(doc, "attrs");
showAttrs(attrs, doc, context, drvsSeen);
}
}
else if (matchList(e, es)) {
XMLOpenElement _(doc, "list");
for (ATermIterator i(es); i; ++i)
printTermAsXML(*i, doc, context, drvsSeen);
}
else if (matchFunction(e, pat, body, pos)) {
XMLOpenElement _(doc, "function");
printPatternAsXML(pat, doc);
}
else
doc.writeEmptyElement("unevaluated");
}
void printTermAsXML(Expr e, std::ostream & out, PathSet & context)
{
XMLWriter doc(true, out);
XMLOpenElement root(doc, "expr");
ExprSet drvsSeen;
printTermAsXML(e, doc, context, drvsSeen);
}
}