factor out SegmentsFromFile

Signed-off-by: Jeff Epler <jepler@unpythonic.net>

Makefile

@@ -5,9 +5,9 @@ default: dashing
 bench: dashing
 	perf stat --log-fd=2 ./dashing -b -s .1 data/HWOOD6E1.pat data/sf.seg
 
-dashing: main.cc dashing.cc dashing.hh parse_numbers.hh
+dashing: main.cc dashing.cc dashing.hh parse_numbers.hh contours_and_segments.hh
 	g++ -W -Wall -O2 -g -std=c++11 $(filter %.cc, $^) -o $@ -lboost_random
-dashing-noopt: main.cc dashing.cc dashing.hh parse_numbers.hh
+dashing-noopt: main.cc dashing.cc dashing.hh parse_numbers.hh contours_and_segments.hh
 	g++ -W -Wall -O0 -g -std=c++11 $(filter %.cc, $^) -o $@ -lboost_random
 dashing-clang: main.cc dashing.cc dashing.hh parse_numbers.hh
 	clang++ -W -Wall -O2 -g -std=c++11 $(filter %.cc, $^) -o $@ -lboost_random

contours_and_segments.hh

@@ -0,0 +1,77 @@
+#include "dashing.hh"
+#include "parse_numbers.hh"
+#include <random>
+#include <iostream>
+
+namespace dashing
+{
+
+typedef std::vector<Segment> Segments;
+typedef std::vector<Point> Contour;
+typedef std::vector<Contour> Contours;
+
+void ContourToSegments(Segments &dest,
+        /* EXPLICIT COPY */ Contour src,
+        double jitter = 0)
+{
+    if(jitter)
+    {
+        static auto && gen = std::minstd_rand(std::random_device{}());
+        std::uniform_real_distribution<> dist(-jitter/2, jitter/2);
+        for(auto &p : src)
+        {
+            p.x += dist(gen);
+            p.y += dist(gen);
+        }
+    }
+
+    for(size_t i=0; i<src.size()-1; i++)
+        dest.emplace_back(Segment{src[i], src[i+1], false});
+
+    int i = src.size();
+    dest.emplace_back(Segment{src[i-1], src[0], false});
+}
+
+void ContoursToSegments(Segments &dest, Contours const &src, double jitter=0)
+{
+    dest.clear();
+
+    for(auto &contour : src)
+    {
+        ContourToSegments( dest, contour, jitter);
+    }
+}
+
+Contours ContoursFromFile(std::istream &fi)
+{
+    auto result = Contours{};
+    auto line = std::string{};
+
+    while(getline(fi, line)) {
+        auto && coordinates = parse_numbers(line);
+        if(coordinates.size() % 2 != 0)
+            throw std::invalid_argument("odd number of values in segment line");
+        if(coordinates.size() < 6)
+            throw std::invalid_argument("too few values in segment line");
+
+        auto contour = Contour{};
+        for(size_t i=0; i<coordinates.size(); i += 2)
+            contour.emplace_back(Point{coordinates[i], coordinates[i+1]});
+        result.emplace_back(std::move(contour));
+    }
+    return result;
+}
+
+Segments SegmentsFromFile(std::istream &fi, double jitter) {
+    auto && contours = ContoursFromFile(fi);
+    auto result = Segments{};
+    ContoursToSegments(result, contours, jitter);
+    return result;
+}
+
+std::vector<Segment> SegmentsFromFile(const char *filename, double jitter) {
+    std::fstream fi(filename);
+    return SegmentsFromFile(fi, jitter);
+}
+
+}

main.cc

@@ -21,45 +21,10 @@ freely, subject to the following restrictions:
 // demo and benchmark program for dashing
 
 #include "dashing.hh"
-#include "parse_numbers.hh"
-#include <iostream>
-#include <boost/random.hpp>
-#include <boost/random/random_device.hpp>
+#include "contours_and_segments.hh"
 
 using namespace dashing;
 
-std::vector<Segment> SegmentsFromFile(std::istream &fi, double jitter) {
-    static boost::random_device urandom;
-    static boost::taus88 gen(urandom);
-    boost::uniform_real<> dist(-jitter/2, jitter/2);
-    boost::variate_generator<boost::taus88&, boost::uniform_real<> >
-            random(gen, dist); 
-    std::vector<Segment> result;
-    std::string line;
-    while(getline(fi, line)) {
-        auto numbers = parse_numbers(line);
-        if(jitter)
-            for(auto & n : numbers) n += random();
-        if(numbers.size() % 2 != 0)
-            throw std::invalid_argument("odd number of values in segment line");
-        if(numbers.size() < 6)
-            throw std::invalid_argument("too few values in segment line");
-        for(size_t i=0; i<numbers.size() - 3 ; i += 2) {
-            Segment s{{numbers[i], numbers[i+1]}, {numbers[i+2], numbers[i+3]}, false};
-            result.push_back(s);
-        }
-        int i = numbers.size();
-        Segment s{{numbers[i-2], numbers[i-1]}, {numbers[0], numbers[1]}, false};
-        result.push_back(s);
-    }
-    return result;
-}
-
-std::vector<Segment> SegmentsFromFile(const char *filename, double jitter) {
-    std::fstream fi(filename);
-    return SegmentsFromFile(fi, jitter);
-}
-
 const char *argv0 = "dashing";
 
 #ifdef __GNUC__