add support for scoped tags

- tags have new scope field, giving the source span
  in which they are in scope
- new option "--locals" adds tags for local declarations and parameters;
  scope format is startline:startcolumn-endline:endcolumn
- export object properties have "global" scope

This depends on narcissus patch for column tracking and source spans.
Patch preview:

add column tracking/line:column srcspans
clausreinke/narcissus@6d1ae3f

First client implementation, scoped tags navigation for Vim:
  https://github.com/clausreinke/scoped_tags

bin/jsctags.js

@@ -56,6 +56,7 @@ function usage() {
     sys.puts("    -j, --jsonp function  use JSONP with a function name");
     sys.puts("    -o, --output file     synonym for -f");
     sys.puts("        --oneprog         combine all inputs into one program");
+    sys.puts("        --locals          add scoped tags for local variables");
     sys.puts("    -L, --libroot dir     add a CommonJS module root (like " +
              "require.paths)")
     sys.puts("    -W, --warning level   set log level (debug/info/warn/" +
@@ -65,8 +66,8 @@ function usage() {
 
 var opts;
 try {
-    opts = getopt("help|h", "jsonp|j=s", "libroot|L=s@", "oneprog", "output|o|f=s",
-                  "sort|=s", "warning|W=s");
+    opts = getopt("help|h", "jsonp|j=s", "libroot|L=s@", "oneprog", "locals",
+                  "output|o|f=s", "sort|=s", "warning|W=s");
 } catch (e) {
     sys.puts(e);
     usage();
@@ -101,6 +102,8 @@ if ('libroot' in opts) {
     });
 }
 
+var options = opts.locals ? {params: true, localVars: true} : {};
+
 var tags = new Tags();
 
 // Ascend the directory hierarchy to find the CommonJS package this module is
@@ -172,6 +175,11 @@ function getModuleInfo(fullPath) {
     return { commonJS: false };
 }
 
+function addOptions(options,addIns) {
+  for (var a in addIns) options[a] = addIns[a];
+  return options;
+}
+
 var idsSeen = {};
 function processPath(p,named) {
     var st = fs.statSync(p);
@@ -189,7 +197,7 @@ function processPath(p,named) {
     } else if (ext === ".js" || ext === ".jsm" || named) {
         try {
             var data = fs.readFileSync(p, "utf8");
-            tags.scan(data, p, getModuleInfo(p));
+            tags.scan(data, p, addOptions(getModuleInfo(p),options));
         } catch (e) {
             if ('lineNumber' in e) {
                 sys.puts("error:" + p + ":" + e.lineNumber + ": " + e);
@@ -230,7 +238,7 @@ function processMany() {
 
   for (data = "", i = pcm1; i >= 0; --i) data = fileinfo[i].data + data;
   // the decision to pass argv[2] here is arbitrary
-  tags.scan(data, argv[2], getModuleInfo(argv[2]));
+  tags.scan(data, argv[2], addOptions(getModuleInfo(argv[2]),options));
 
   function getFileInfo(ln) {
     var i = 0, f, s = 0, e = pcm1, floor = Math.floor;

lib/cfa2/jscfa.js

@@ -3675,6 +3675,7 @@ function getTags(ast, pathtofile, lines, options) {
       tag.type = type;
       tag.module = options.module;
       tag.lineno = exports_object.lines[tag.name].toString();
+      tag.scope  = "global"; // global modulo tag.module-import
       tags.push(tag);
     });
   }
@@ -3687,8 +3688,31 @@ function getTags(ast, pathtofile, lines, options) {
                 kind : "f",
                 type : funToType(f),
                 lineno : f.lineno.toString(),
-                sortno : f.lineno.toString()
+                sortno : f.lineno.toString(),
+                scope  : f.context.startPos+'-'+f.context.endPos
               });
+    options.params && f.params.forEach(function(param,i){
+      tags.push({ name : param.name,
+                  tagfile : pathtofile,
+                  addr : regexify(lines[f.lineno - 1]),
+                  kind : "vp", // distinguish params from other vars?
+                  type : summaries[addr].type[0][i+1].toType(),
+                  lineno : f.lineno.toString(),
+                  sortno : f.lineno.toString(),
+                  scope  : f.startPos+'-'+f.endPos
+                });
+    });
+    options.localVars && f.body.varDecls.forEach(function(vd){
+      tags.push({ name : vd.name,
+                  tagfile : pathtofile,
+                  addr : regexify(lines[vd.lineno - 1]),
+                  kind : "v",
+                  type : flags[vd.addr] ? heap[vd.addr].toType() : "(local)", // local types?
+                  lineno : vd.lineno.toString(),
+                  sortno : vd.lineno.toString(),
+                  scope  : f.body.startPos+'-'+f.body.endPos
+                });
+    });
   }
   ast.varDecls.forEach(function(vd) {
     tags.push({ name : vd.name,
@@ -3697,7 +3721,8 @@ function getTags(ast, pathtofile, lines, options) {
                 kind : "v",
                 type : heap[vd.addr].toType(),
                 lineno : vd.lineno.toString(),
-                sortno : vd.lineno.toString()
+                sortno : vd.lineno.toString(),
+                scope  : ast.startPos+'-'+ast.endPos // TODO: non-module scripts?
               });
   });
   return tags;