Allow row conversion function for d3.dsv.parse.

d3.js

@@ -5235,18 +5235,32 @@ d3 = function() {
   function d3_dsv(delimiter, mimeType) {
     var reFormat = new RegExp('["' + delimiter + "\n]"), delimiterCode = delimiter.charCodeAt(0);
     function dsv(url, callback) {
-      return d3.xhr(url, mimeType, callback).response(response);
+      var xhr = d3.xhr(url, mimeType, callback), row;
+      xhr.row = function(_) {
+        if (!arguments.length) return row;
+        xhr.response((row = _) == null ? response : typedResponse(_));
+        return xhr;
+      };
+      return xhr.row(null);
     }
     function response(request) {
       return dsv.parse(request.responseText);
     }
-    dsv.parse = function(text) {
+    function typedResponse(f) {
+      return function(request) {
+        return dsv.parse(request.responseText, f);
+      };
+    }
+    dsv.parse = function(text, f) {
       var o;
-      return dsv.parseRows(text, function(row) {
-        if (o) return o(row);
-        o = new Function("d", "return {" + row.map(function(name, i) {
+      return dsv.parseRows(text, function(row, i) {
+        if (o) return o(row, i - 1);
+        var a = new Function("d", "return {" + row.map(function(name, i) {
           return JSON.stringify(name) + ": d[" + i + "]";
         }).join(",") + "}");
+        o = f ? function(row, i) {
+          return f(a(row), i);
+        } : a;
       });
     };
     dsv.parseRows = function(text, f) {

src/dsv/dsv.js

@@ -3,20 +3,36 @@ function d3_dsv(delimiter, mimeType) {
       delimiterCode = delimiter.charCodeAt(0);
 
   function dsv(url, callback) {
-    return d3.xhr(url, mimeType, callback).response(response);
+    var xhr = d3.xhr(url, mimeType, callback),
+        row;
+
+    xhr.row = function(_) {
+      if (!arguments.length) return row;
+      xhr.response((row = _) == null ? response : typedResponse(_));
+      return xhr;
+    };
+
+    return xhr.row(null);
   }
 
   function response(request) {
     return dsv.parse(request.responseText);
   }
 
-  dsv.parse = function(text) {
+  function typedResponse(f) {
+    return function(request) {
+      return dsv.parse(request.responseText, f);
+    };
+  }
+
+  dsv.parse = function(text, f) {
     var o;
-    return dsv.parseRows(text, function(row) {
-      if (o) return o(row);
-      o = new Function("d", "return {" + row.map(function(name, i) {
+    return dsv.parseRows(text, function(row, i) {
+      if (o) return o(row, i - 1);
+      var a = new Function("d", "return {" + row.map(function(name, i) {
         return JSON.stringify(name) + ": d[" + i + "]";
       }).join(",") + "}");
+      o = f ? function(row, i) { return f(a(row), i); } : a;
     });
   };
 

test/dsv/csv-test.js

@@ -76,6 +76,27 @@ suite.addBatch({
       ]);
     }
   },
+
+  "parse with row function": {
+    "invokes the row function for every row in order": function() {
+      var rows = [];
+      d3.csv.parse("a\n1\n2\n3\n4", function(d, i) { rows.push({d: d, i: i}); });
+      assert.deepEqual(rows, [
+        {d: {a: "1"}, i: 0},
+        {d: {a: "2"}, i: 1},
+        {d: {a: "3"}, i: 2},
+        {d: {a: "4"}, i: 3}
+      ]);
+    },
+    "returns an array of the row function return values": function() {
+      assert.deepEqual(d3.csv.parse("a,b,c\n1,2,3\n", function(row) { return row; }), [{a: "1", b: "2", c: "3"}]);
+    },
+    "skips rows if the row function returns null or undefined": function() {
+      assert.deepEqual(d3.csv.parse("a,b,c\n1,2,3\n2,3,4", function(row) { return row.a & 1 ? null : row; }), [{a: "2", b: "3", c: "4"}]);
+      assert.deepEqual(d3.csv.parse("a,b,c\n1,2,3\n2,3,4", function(row) { return row.a & 1 ? undefined : row; }), [{a: "2", b: "3", c: "4"}]);
+    }
+  },
+
   "parseRows": {
     topic: function() {
       return d3.csv.parseRows;