From 4a5d11548c3145c47c54aa09e5390e886405a7a1 Mon Sep 17 00:00:00 2001
From: Tom Hulton-Harrop <tom.hultonharrop@gmail.com>
Date: Sat, 22 Apr 2023 22:04:47 +0100
Subject: [PATCH] add gsl span support

---
 CMakeLists.txt                  |  8 ++++++++
 poly2tri/sweep/cdt.cc           |  4 ++--
 poly2tri/sweep/cdt.h            |  6 ++++--
 poly2tri/sweep/sweep_context.cc | 17 ++++++++++-------
 poly2tri/sweep/sweep_context.h  |  8 +++++---
 5 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1a237b9..b4dd47f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,13 @@ cmake_minimum_required(VERSION 3.12)
 project(poly2tri LANGUAGES CXX)
 set(CMAKE_CXX_STANDARD 14)
 
+include(FetchContent)
+FetchContent_Declare(
+  gsl
+  GIT_REPOSITORY https://github.com/microsoft/GSL.git
+  GIT_TAG 1d036585ccea8a57dc5fdc84406181db3d1f3205)
+FetchContent_MakeAvailable(gsl)
+
 option(P2T_BUILD_TESTS "Build tests" OFF)
 option(P2T_BUILD_TESTBED "Build the testbed application" OFF)
 
@@ -10,6 +17,7 @@ file(GLOB SOURCES poly2tri/common/*.cc poly2tri/sweep/*.cc)
 file(GLOB HEADERS poly2tri/*.h poly2tri/common/*.h poly2tri/sweep/*.h)
 add_library(poly2tri ${SOURCES} ${HEADERS})
 target_include_directories(poly2tri INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
+target_link_libraries(poly2tri PUBLIC GSL)
 
 get_target_property(poly2tri_target_type poly2tri TYPE)
 if(poly2tri_target_type STREQUAL SHARED_LIBRARY)
diff --git a/poly2tri/sweep/cdt.cc b/poly2tri/sweep/cdt.cc
index 4dfe6a6..6b72cb0 100644
--- a/poly2tri/sweep/cdt.cc
+++ b/poly2tri/sweep/cdt.cc
@@ -32,13 +32,13 @@
 
 namespace p2t {
 
-CDT::CDT(const std::vector<Point*>& polyline)
+CDT::CDT(gsl::span<Point> polyline)
 {
   sweep_context_ = new SweepContext(polyline);
   sweep_ = new Sweep;
 }
 
-void CDT::AddHole(const std::vector<Point*>& polyline)
+void CDT::AddHole(gsl::span<Point> polyline)
 {
   sweep_context_->AddHole(polyline);
 }
diff --git a/poly2tri/sweep/cdt.h b/poly2tri/sweep/cdt.h
index 7c54ea9..2d181da 100644
--- a/poly2tri/sweep/cdt.h
+++ b/poly2tri/sweep/cdt.h
@@ -35,6 +35,8 @@
 #include "sweep_context.h"
 #include "sweep.h"
 
+#include <gsl/span>
+
 #include "../common/dll_symbol.h"
 
 /**
@@ -54,7 +56,7 @@ public:
    *
    * @param polyline
    */
-  CDT(const std::vector<Point*>& polyline);
+  explicit CDT(gsl::span<Point> polyline);
 
    /**
    * Destructor - clean up memory
@@ -66,7 +68,7 @@ public:
    *
    * @param polyline
    */
-  void AddHole(const std::vector<Point*>& polyline);
+  void AddHole(gsl::span<Point> polyline);
 
   /**
    * Add a steiner point
diff --git a/poly2tri/sweep/sweep_context.cc b/poly2tri/sweep/sweep_context.cc
index 7b9432f..593acc5 100644
--- a/poly2tri/sweep/sweep_context.cc
+++ b/poly2tri/sweep/sweep_context.cc
@@ -34,7 +34,7 @@
 
 namespace p2t {
 
-SweepContext::SweepContext(std::vector<Point*> polyline) : points_(std::move(polyline)),
+SweepContext::SweepContext(gsl::span<Point> polyline) :
   front_(nullptr),
   head_(nullptr),
   tail_(nullptr),
@@ -42,14 +42,17 @@ SweepContext::SweepContext(std::vector<Point*> polyline) : points_(std::move(pol
   af_middle_(nullptr),
   af_tail_(nullptr)
 {
-  InitEdges(points_);
+  for (auto& point : polyline) {
+    points_.push_back(&point);
+  }
+  InitEdges(polyline);
 }
 
-void SweepContext::AddHole(const std::vector<Point*>& polyline)
+void SweepContext::AddHole(gsl::span<Point> polyline)
 {
   InitEdges(polyline);
-  for (auto i : polyline) {
-    points_.push_back(i);
+  for (auto& point : polyline) {
+    points_.push_back(&point);
   }
 }
 
@@ -95,12 +98,12 @@ void SweepContext::InitTriangulation()
 
 }
 
-void SweepContext::InitEdges(const std::vector<Point*>& polyline)
+void SweepContext::InitEdges(gsl::span<Point> polyline)
 {
   size_t num_points = polyline.size();
   for (size_t i = 0; i < num_points; i++) {
     size_t j = i < num_points - 1 ? i + 1 : 0;
-    edge_list.push_back(new Edge(*polyline[i], *polyline[j]));
+    edge_list.push_back(new Edge(polyline[i], polyline[j]));
   }
 }
 
diff --git a/poly2tri/sweep/sweep_context.h b/poly2tri/sweep/sweep_context.h
index 11d5739..cac153b 100644
--- a/poly2tri/sweep/sweep_context.h
+++ b/poly2tri/sweep/sweep_context.h
@@ -31,6 +31,8 @@
 
 #pragma once
 
+#include <gsl/span>
+
 #include <list>
 #include <vector>
 #include <cstddef>
@@ -51,7 +53,7 @@ class SweepContext {
 public:
 
 /// Constructor
-explicit SweepContext(std::vector<Point*> polyline);
+explicit SweepContext(gsl::span<Point> polyline);
 /// Destructor
 ~SweepContext();
 
@@ -82,7 +84,7 @@ Point* GetPoints();
 
 void RemoveFromMap(Triangle* triangle);
 
-void AddHole(const std::vector<Point*>& polyline);
+void AddHole(gsl::span<Point> polyline);
 
 void AddPoint(Point* point);
 
@@ -147,7 +149,7 @@ Point* tail_;
 Node *af_head_, *af_middle_, *af_tail_;
 
 void InitTriangulation();
-void InitEdges(const std::vector<Point*>& polyline);
+void InitEdges(gsl::span<Point> polyline);
 
 };