Make source location info in the XML output optional.

* src/libexpr/expr-to-xml.cc (nix::showAttrs): Add `location'
  parameter.  Provide location XML attributes when it's true.  Update
  callers.
  (nix::printTermAsXML): Likewise.

* src/libexpr/expr-to-xml.hh (nix::printTermAsXML): Update prototype;
  have `location' default to `false'.

* src/nix-instantiate/nix-instantiate.cc (printResult, processExpr): Add
  `location' parameter; update callers.
  (run): Add support for `--no-location'.

* src/nix-instantiate/help.txt: Update accordingly.

* tests/lang.sh: Invoke `nix-instantiate' with `--no-location' for the
  XML tests.

* tests/lang/eval-okay-toxml.exp, tests/lang/eval-okay-to-xml.nix: New
  files.

7 files changed, 29 insertions, 19 deletions

diff --git a/src/libexpr/expr-to-xml.cc b/src/libexpr/expr-to-xml.cc
index 4ca71c88909b..5857537d7501 100644
--- a/src/libexpr/expr-to-xml.cc
+++ b/src/libexpr/expr-to-xml.cc
@@ -24,11 +24,11 @@ typedef set<Expr> ExprSet;
 
 
 static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
-    ExprSet & drvsSeen);
+    ExprSet & drvsSeen, bool location);
 
 
 static void showAttrs(const ATermMap & attrs, XMLWriter & doc,
-    PathSet & context, ExprSet & drvsSeen)
+    PathSet & context, ExprSet & drvsSeen, bool location)
 {
     StringSet names;
     for (ATermMap::const_iterator i = attrs.begin(); i != attrs.end(); ++i)
@@ -43,7 +43,7 @@ static void showAttrs(const ATermMap & attrs, XMLWriter & doc,
 	if(matchAttrRHS(attrRHS, attr, pos)) {
 	    ATerm path;
 	    int line, column;
-	    if (matchPos(pos, path, line, column)) {
+            if (location && matchPos(pos, path, line, column)) {
 		xmlAttrs["path"] = aterm2String(path);
 		xmlAttrs["line"] = (format("%1%") % line).str();
 		xmlAttrs["column"] = (format("%1%") % column).str();
@@ -52,7 +52,7 @@ static void showAttrs(const ATermMap & attrs, XMLWriter & doc,
 	    abort(); // Should not happen.
 
         XMLOpenElement _(doc, "attr", xmlAttrs);
-        printTermAsXML(attr, doc, context, drvsSeen);
+        printTermAsXML(attr, doc, context, drvsSeen, location);
     }
 }
 
@@ -83,7 +83,7 @@ static void printPatternAsXML(Pattern pat, XMLWriter & doc)
 
 
 static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
-    ExprSet & drvsSeen)
+    ExprSet & drvsSeen, bool location)
 {
     XMLAttrs attrs;
     string s;
@@ -137,28 +137,28 @@ static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
 
             if (drvsSeen.find(e) == drvsSeen.end()) {
                 drvsSeen.insert(e);
-                showAttrs(attrs, doc, context, drvsSeen);
+                showAttrs(attrs, doc, context, drvsSeen, location);
             } else
                 doc.writeEmptyElement("repeated");
         }
 
         else {
             XMLOpenElement _(doc, "attrs");
-            showAttrs(attrs, doc, context, drvsSeen);
+            showAttrs(attrs, doc, context, drvsSeen, location);
         }
     }
 
     else if (matchList(e, es)) {
         XMLOpenElement _(doc, "list");
         for (ATermIterator i(es); i; ++i)
-            printTermAsXML(*i, doc, context, drvsSeen);
+            printTermAsXML(*i, doc, context, drvsSeen, location);
     }
 
     else if (matchFunction(e, pat, body, pos)) {
         ATerm path;
 	int line, column;
 	XMLAttrs xmlAttrs;
-	if (matchPos(pos, path, line, column)) {
+	if (location && matchPos(pos, path, line, column)) {
 	    xmlAttrs["path"] = aterm2String(path);
 	    xmlAttrs["line"] = (format("%1%") % line).str();
 	    xmlAttrs["column"] = (format("%1%") % column).str();
@@ -172,12 +172,12 @@ static void printTermAsXML(Expr e, XMLWriter & doc, PathSet & context,
 }
 
 
-void printTermAsXML(Expr e, std::ostream & out, PathSet & context)
+void printTermAsXML(Expr e, std::ostream & out, PathSet & context, bool location)
 {
     XMLWriter doc(true, out);
     XMLOpenElement root(doc, "expr");
     ExprSet drvsSeen;    
-    printTermAsXML(e, doc, context, drvsSeen);
+    printTermAsXML(e, doc, context, drvsSeen, location);
 }
 
  
diff --git a/src/libexpr/expr-to-xml.hh b/src/libexpr/expr-to-xml.hh
index 36b8e40424d8..de9d55f320ac 100644
--- a/src/libexpr/expr-to-xml.hh
+++ b/src/libexpr/expr-to-xml.hh
@@ -9,7 +9,7 @@
 
 namespace nix {
 
-void printTermAsXML(Expr e, std::ostream & out, PathSet & context);
+void printTermAsXML(Expr e, std::ostream & out, PathSet & context, bool location = false);
     
 }
 
diff --git a/src/nix-instantiate/help.txt b/src/nix-instantiate/help.txt
index fa0a4590ee92..21822132aece 100644
--- a/src/nix-instantiate/help.txt
+++ b/src/nix-instantiate/help.txt
@@ -22,6 +22,8 @@ Options:
 For --eval-only / --parse-only:
 
   --xml: print an XML representation of the abstract syntax tree
+  --no-location: don't provide source location information in the
+    output XML tree
 
 For --eval-only:
 
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 3822de5c6289..21f352f2580d 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -38,13 +38,13 @@ static bool indirectRoot = false;
 
 
 static void printResult(EvalState & state, Expr e,
-    bool evalOnly, bool xmlOutput, const ATermMap & autoArgs)
+    bool evalOnly, bool xmlOutput, bool location, const ATermMap & autoArgs)
 {
     PathSet context;
     
     if (evalOnly)
         if (xmlOutput)
-            printTermAsXML(e, std::cout, context);
+            printTermAsXML(e, std::cout, context, location);
         else
             std::cout << format("%1%\n") % canonicaliseExpr(e);
     
@@ -67,7 +67,7 @@ static void printResult(EvalState & state, Expr e,
 
 void processExpr(EvalState & state, const Strings & attrPaths,
     bool parseOnly, bool strict, const ATermMap & autoArgs,
-    bool evalOnly, bool xmlOutput, Expr e)
+    bool evalOnly, bool xmlOutput, bool location, Expr e)
 {
     for (Strings::const_iterator i = attrPaths.begin(); i != attrPaths.end(); ++i) {
         Expr e2 = findAlongAttrPath(state, *i, autoArgs, e);
@@ -76,7 +76,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
                 e2 = strictEvalExpr(state, e2);
             else
                 e2 = evalExpr(state, e2);
-        printResult(state, e2, evalOnly, xmlOutput, autoArgs);
+        printResult(state, e2, evalOnly, xmlOutput, location, autoArgs);
     }
 }
 
@@ -89,6 +89,7 @@ void run(Strings args)
     bool evalOnly = false;
     bool parseOnly = false;
     bool xmlOutput = false;
+    bool xmlOutputSourceLocation = true;
     bool strict = false;
     Strings attrPaths;
     ATermMap autoArgs(128);
@@ -124,6 +125,8 @@ void run(Strings args)
             indirectRoot = true;
         else if (arg == "--xml")
             xmlOutput = true;
+        else if (arg == "--no-location")
+            xmlOutputSourceLocation = false;
         else if (arg == "--strict")
             strict = true;
         else if (arg[0] == '-')
@@ -139,7 +142,7 @@ void run(Strings args)
     if (readStdin) {
         Expr e = parseStdin(state);
         processExpr(state, attrPaths, parseOnly, strict, autoArgs,
-            evalOnly, xmlOutput, e);
+            evalOnly, xmlOutput, xmlOutputSourceLocation, e);
     }
 
     for (Strings::iterator i = files.begin();
@@ -148,7 +151,7 @@ void run(Strings args)
         Path path = absPath(*i);
         Expr e = parseExprFromFile(state, path);
         processExpr(state, attrPaths, parseOnly, strict, autoArgs,
-            evalOnly, xmlOutput, e);
+            evalOnly, xmlOutput, xmlOutputSourceLocation, e);
     }
 
     printEvalStats(state);
diff --git a/tests/lang.sh b/tests/lang.sh
index 18eb0278cfcc..54f01076371e 100644
--- a/tests/lang.sh
+++ b/tests/lang.sh
@@ -54,7 +54,8 @@ for i in lang/eval-okay-*.nix; do
     fi
     
     if test -e lang/$i.exp.xml; then
-        if ! $nixinstantiate --eval-only --xml --strict lang/$i.nix > lang/$i.out.xml; then
+        if ! $nixinstantiate --eval-only --xml --no-location --strict \
+                lang/$i.nix > lang/$i.out.xml; then
             echo "FAIL: $i should evaluate"
             fail=1
         elif ! cmp -s lang/$i.out.xml lang/$i.exp.xml; then
diff --git a/tests/lang/eval-okay-toxml.exp b/tests/lang/eval-okay-toxml.exp
new file mode 100644
index 000000000000..379f3c07617e
--- /dev/null
+++ b/tests/lang/eval-okay-toxml.exp
@@ -0,0 +1 @@
+Str("<?xml version='1.0' encoding='utf-8'?>\n<expr>\n  <attrs>\n    <attr name=\"a\">\n      <string value=\"s\" />\n    </attr>\n  </attrs>\n</expr>\n",[])
diff --git a/tests/lang/eval-okay-toxml.nix b/tests/lang/eval-okay-toxml.nix
new file mode 100644
index 000000000000..068c97a6c1b3
--- /dev/null
+++ b/tests/lang/eval-okay-toxml.nix
@@ -0,0 +1,3 @@
+# Make sure the expected XML output is produced; in particular, make sure it
+# doesn't contain source location information.
+builtins.toXML { a = "s"; }