commit cb0f6111cea8c67b21e0afd48dddc8ff86e5dd3c
Author: Trevor Slocum <trevor@rocketnine.space>
Date:   Mon May 24 02:51:12 2021 -0700

    Initial commit

diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.idea/
+vendor/
+*.sh
+
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2021 Trevor Slocum <trevor@rocketnine.space>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
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+++ b/README.md
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+# world
+[![GoDoc](https://code.rocketnine.space/tslocum/godoc-static/raw/branch/master/badge.svg)](https://docs.rocketnine.space/code.rocketnine.space/tslocum/world)
+[![Donate](https://img.shields.io/liberapay/receives/rocketnine.space.svg?logo=liberapay)](https://liberapay.com/rocketnine.space)
+
+Tile-based worldbuilding library
+
+## Install
+
+```go get code.rocketnine.space/tslocum/world```
+
+## Documentation
+
+All documentation is available via [godoc](https://docs.rocketnine.space/code.rocketnine.space/tslocum/world).
+
+## Support
+
+Please share issues and suggestions [here](https://code.rocketnine.space/tslocum/world/issues).
diff --git a/entity.go b/entity.go
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--- /dev/null
+++ b/entity.go
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+package world
+
+import "sync"
+
+// Entity represents an entity within the world.
+type Entity struct {
+	t       int // Type
+	x, y, z int
+
+	sync.RWMutex
+}
+
+// NewEntity returns a new Entity.
+func NewEntity(t int) *Entity {
+	return &Entity{t: t}
+}
+
+// Is returns whether the Entity matches the specified type.
+func (e *Entity) Is(t int) bool {
+	e.RLock()
+	defer e.RUnlock()
+
+	return e.t == t
+}
+
+// Coordinates returns the position of the entity.
+func (e *Entity) Coordinates() (x, y, z int) {
+	e.RLock()
+	defer e.RUnlock()
+
+	return e.x, e.y, e.z
+}
diff --git a/go.mod b/go.mod
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--- /dev/null
+++ b/go.mod
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+module code.rocketnine.space/tslocum/world
+
+go 1.16
diff --git a/map.go b/map.go
new file mode 100644
index 0000000..93c3173
--- /dev/null
+++ b/map.go
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+package world
+
+import (
+	"strconv"
+	"sync"
+)
+
+// Coordinates returns the provided coordinates as a comma-delimited string.
+func Coordinates(x, y, z int) string {
+	return strconv.Itoa(x) + "," + strconv.Itoa(y) + "," + strconv.Itoa(z)
+}
+
+// Map represents a collection of entities in a 3D space.
+type Map struct {
+	contents map[string]*Entity
+
+	sync.RWMutex
+}
+
+// NewMap returns a new Map.
+func NewMap() *Map {
+	return &Map{}
+}
+
+// Contents returns the entities contained in the Map.
+func (m *Map) Contents() map[string]*Entity {
+	m.RLock()
+	defer m.RUnlock()
+
+	c := make(map[string]*Entity)
+	for key, value := range m.contents {
+		c[key] = value
+	}
+	return c
+}
+
+// Add adds an entity to the Map.
+func (m *Map) Add(e *Entity, x, y, z int) {
+	m.Lock()
+	defer m.Unlock()
+
+	if m.contents == nil {
+		m.contents = make(map[string]*Entity)
+	}
+
+	e.x, e.y, e.z = x, y, z
+	m.contents[Coordinates(x, y, z)] = e
+}
diff --git a/map_test.go b/map_test.go
new file mode 100644
index 0000000..eb06f0f
--- /dev/null
+++ b/map_test.go
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+package world
+
+import "testing"
+
+const (
+	EntityNone = iota
+	EntityFloor
+	EntityWall
+	EntityCeiling
+	EntityActor
+)
+
+func TestMap(t *testing.T) {
+	m := NewMap()
+
+	e := NewEntity(EntityFloor)
+	m.Add(e, 0, 0, 0)
+
+	c := m.Contents()
+	found := 0
+	for position, entity := range c {
+		if entity.Is(EntityFloor) {
+			if position != "0,0,0" {
+				t.Errorf("unexpected position: wanted %s, got %s", "0,0,0", position)
+			}
+			found++
+		}
+	}
+	if found != 1 {
+		t.Errorf("unexpected number of floor tiles: wanted %d, got %d", 1, found)
+	}
+}