From 2c10bb68eff377ee3335ceb586476aaf4f71004f Mon Sep 17 00:00:00 2001
From: Hermann Kraus <herm@scribus.info>
Date: Sun, 18 Jul 2010 23:49:11 +0000
Subject: [PATCH] Enable metawriter_json to operate on any stream object.

---
 include/mapnik/metawriter_json.hpp |  5 +++--
 src/metawriter.cpp                 | 33 ++++++++++++++++++------------
 2 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/include/mapnik/metawriter_json.hpp b/include/mapnik/metawriter_json.hpp
index 4d29cc552..a8cb87e16 100644
--- a/include/mapnik/metawriter_json.hpp
+++ b/include/mapnik/metawriter_json.hpp
@@ -28,7 +28,7 @@
 #include <mapnik/metawriter.hpp>
 
 // STL
-#include <fstream>
+#include <ostream>
 
 namespace mapnik {
 /** JSON writer. */
@@ -36,6 +36,7 @@ class metawriter_json : public metawriter, private boost::noncopyable
 {
     public:
         metawriter_json(metawriter_properties dflt_properties, std::string fn);
+        metawriter_json(metawriter_properties dflt_properties, std::ostream);
         ~metawriter_json();
         virtual void add_box(box2d<double> box, Feature const &feature,
                              proj_transform const& prj_trans,
@@ -44,7 +45,7 @@ class metawriter_json : public metawriter, private boost::noncopyable
         virtual void start();
         virtual void stop();
     private:
-        std::fstream f;
+        std::ostream *f;
         std::string fn_;
         int count;
 };
diff --git a/src/metawriter.cpp b/src/metawriter.cpp
index 2ee9b1048..562489886 100644
--- a/src/metawriter.cpp
+++ b/src/metawriter.cpp
@@ -32,6 +32,7 @@
 // STL
 #include <iomanip>
 #include <cstdio>
+#include <fstream>
 
 namespace mapnik {
 
@@ -48,21 +49,27 @@ metawriter_json::~metawriter_json()
 
 void metawriter_json::start()
 {
-    if (f.is_open())
+    if (!fn_.empty())
     {
-        std::cerr << "ERROR: GeoJSON metawriter is already active!\n";
+        if (f)
+        {
+            std::cerr << "ERROR: GeoJSON metawriter is already active!\n";
+            return;
+        }
+        f = new std::fstream(fn_.c_str(), std::fstream::out | std::fstream::trunc);
+        if (f->fail()) perror((std::string("Failed to open file ") + fn_).c_str());
     }
-    f.open(fn_.c_str(), std::fstream::out | std::fstream::trunc);
-    if (f.fail()) perror((std::string("Failed to open file ") + fn_).c_str());
-    f << "{ \"type\": \"FeatureCollection\", \"features\": [\n";
+    assert(f);
+    *f << "{ \"type\": \"FeatureCollection\", \"features\": [\n";
 }
 
 void metawriter_json::stop()
 {
-    if (f.is_open())
+    if (f) *f << " ] }\n";
+    if (f && !fn_.empty())
     {
-        f << " ] }\n";
-        f.close();
+        dynamic_cast<std::fstream *>(f)->close();
+        f = 0;
     }
 }
 
@@ -105,8 +112,8 @@ void metawriter_json::add_box(box2d<double> box, Feature const &feature,
     double maxx = box.maxx();
     double maxy = box.maxy();
 
-    if (count++) f << ",\n";
-    f << std::fixed << std::setprecision(8) << "{ \"type\": \"Feature\",\n  \"geometry\": { \"type\": \"Polygon\",\n    \"coordinates\": [ [ [" <<
+    if (count++) *f << ",\n";
+    *f << std::fixed << std::setprecision(8) << "{ \"type\": \"Feature\",\n  \"geometry\": { \"type\": \"Polygon\",\n    \"coordinates\": [ [ [" <<
             minx << ", " << miny << "], [" <<
             maxx << ", " << miny << "], [" <<
             maxx << ", " << maxy << "], [" <<
@@ -123,11 +130,11 @@ void metawriter_json::add_box(box2d<double> box, Feature const &feature,
             //Property found
             text = boost::replace_all_copy(boost::replace_all_copy(itr->second.to_string(), "\\", "\\\\"), "\"", "\\\"");
         }
-        if (i++) f << ",";
-        f << "\n    \"" << p << "\":\"" << text << "\"";
+        if (i++) *f << ",";
+        *f << "\n    \"" << p << "\":\"" << text << "\"";
     }
 
-    f << "\n} }";
+    *f << "\n} }";
 }
 
 metawriter_properties::metawriter_properties(boost::optional<std::string> str)