#3: Very close to working, but not quite!

src/walkmap/edge.clj

@@ -11,7 +11,7 @@
   [v1 v2]
   (if
     (and (vertex? v1) (vertex? v2))
-    {:kind :edge :id (keyword (gensym "edge")) :start v1 :end v2}
+    {:kind :edge :walkmap.id/id (keyword (gensym "edge")) :start v1 :end v2}
     (throw (IllegalArgumentException. "Must be vertices."))))
 
 (defn edge?

src/walkmap/id.clj

@@ -0,0 +1,8 @@
+(ns walkmap.id
+  "The namespace within which the privileged keyword `:walkmap.id/id` is defined.")
+
+(def ^:const id
+  "The magic id key walkmap uses, to distinguish it from all other uses of
+  the unprotected keyword."
+  ::id)
+

src/walkmap/path.clj

@@ -19,7 +19,7 @@
       (seq? v)
       (> (count v) 2)
       (every? vertex? v)
-      (:id o)
+      (:walkmap.id/id o)
       (or (nil? (:kind o)) (= (:kind o) :path)))))
 
 (defn path
@@ -27,7 +27,7 @@
   [& vertices]
   (if
     (every? vertex? vertices)
-    {:vertices vertices :id (keyword (gensym "path")) :kind :path}
+    {:vertices vertices :walkmap.id/id (keyword (gensym "path")) :kind :path}
     (throw (IllegalArgumentException.
              (str
                "Each item on path must be a vertex: "

src/walkmap/polygon.clj

@@ -13,7 +13,7 @@
       (coll? v)
       (> (count v) 2)
       (every? vertex? v)
-      (:id o)
+      (:walkmap.id/id o)
       (or (nil? (:kind o)) (= (:kind o) :polygon)))))
 
 

src/walkmap/stl.clj

@@ -91,13 +91,13 @@
      ;; if it has :facets it's an STL structure, but it doesn't yet conform to `stl?`
      (:facets o) (assoc o
                    :kind :stl
-                   :id (or (:id o) (keyword (gensym "stl")))
+                   :walkmap.id/id (or (:walkmap.id/id o) (keyword (gensym "stl")))
                    :facets (canonicalise (:facets o) map-kind))
      ;; if it has :vertices it's a polygon, but it doesn't yet conform to `polygon?`
      (:vertices o) (centre
                      (tag
                        (assoc o
-                         :id (or (:id o) (keyword (gensym "poly")))
+                         :walkmap.id/id (or (:walkmap.id/id o) (keyword (gensym "poly")))
                          :kind :polygon
                          :vertices (canonicalise (:vertices o) map-kind))
                        :facet map-kind))

src/walkmap/superstructure.clj

@@ -1,6 +1,8 @@
 (ns walkmap.superstructure
   "single indexing structure for walkmap objects"
-  (:require [walkmap.path :as p]
+  (:require [clojure.walk :refer [postwalk]]
+            [taoensso.timbre :as l]
+            [walkmap.path :as p]
             [walkmap.polygon :as q]
             [walkmap.stl :as s]
             [walkmap.utils :as u]
@@ -22,25 +24,33 @@
 ;; superstructure - unless we replace the superstructure altogether with a
 ;; database, which may be the Right Thing To Do.
 
+(defn vertices
+  "If `o` is an object with vertices, return those vertices, else nil."
+  [o]
+  (cond
+    (v/vertex? o) (list o)
+    (q/polygon? o) (:vertices o)
+    (p/path? o) (:vertices o)))
+
 (defn index-vertex
   "Return a superstructure like `s` in which object `o` is indexed by vertex
   `v`. It is an error (and an exception may be thrown) if
 
   1. `s` is not a map;
   2. `o` is not a map;
-  3. `o` does not have a value for the key `:id`;
+  3. `o` does not have a value for the key `:walkmap.id/id`;
   4. `v` is not a vertex."
   [s o v]
   (if-not (v/vertex? o)
-    (if (:id o)
+    (if (:walkmap.id/id o)
       (if (v/vertex? v)
         (let [vi (or (:vertex-index s) {})
-              current (or (vi (:id v)) {})]
+              current (or (vi (:walkmap.id/id v)) {})]
           ;; deep-merge doesn't merge sets, only maps; so at this
           ;; stage we need to build a map.
-          (assoc vi (:id v) (assoc current (:id o) (:id v))))
+          (assoc vi (:walkmap.id/id v) (assoc current (:walkmap.id/id o) (:walkmap.id/id v))))
         (throw (IllegalArgumentException. "Not a vertex: " v)))
-      (throw (IllegalArgumentException. (u/truncate (str "No `:id` value: " o) 80))))
+      (throw (IllegalArgumentException. (u/truncate (str "No `:walkmap.id/id` value: " o) 80))))
     ;; it shouldn't actually be an error to try to index a vertex, but it
     ;; also isn't useful to do so, so I'd be inclined to ignore it.
     (:vertex-index s)))
@@ -51,7 +61,7 @@
 
   1. `s` is not a map;
   2. `o` is not a map;
-  3. `o` does not have a value for the key `:id`."
+  3. `o` does not have a value for the key `:walkmap.id/id`."
   [s o]
   (assoc
     s
@@ -60,26 +70,88 @@
       u/deep-merge
       (map
         #(index-vertex s o %)
-        (u/vertices o)))))
+        (vertices o)))))
 
-(defn add-to-superstructure
-  "Return a superstructure like `s` with object `o` added. If `o` is a collection,
-  return a superstructure like `s` with each element of `o` added. If only one
+(defn in-retrieve
+  "Internal guts of `retrieve`, q.v. `x` can be anything; `s` must be a
+  walkmap superstructure. TODO: recursive, quite likely to blow the fragile
+  Clojure stack. Probably better to do this with `walk`, but I don't yet
+  understand that."
+  [x s]
+  (cond
+    ;; if it's a keyword identifying something in s, retrieve that something.
+    (keyword? x) (if (s x)
+                   (in-retrieve (s x) s)
+                   x)
+    ;; if it's a map, for every key which is not `:walkmap.id/id`, recurse.
+    (map? x) (reduce
+               (fn [m k]
+                 (if (= k :walkmap.id/id)
+                   k
+                   (assoc m k (in-retrieve (x k) s))))
+               {}
+               (keys x))
+    (coll? x) (map #(in-retrieve % s) x)
+    :else x))
+
+(defn retrieve
+  "Retrieve the canonical representation of the object with this `id` from the
+  superstructure `s`."
+  [id s]
+  (in-retrieve (id s) s))
+
+(defn in-store-find-objects
+  "Return an id -> object map of every object within `o`. Internal to
+  `in-store`, q.v. Use at your own peril."
+  ([o]
+   (in-store-find-objects o {}))
+  ([o s]
+   (l/debug "Finding objects in:" o)
+   (cond
+     (map? o) (if (:walkmap.id/id o)
+                (assoc
+                  (in-store-find-objects (vals o) s)
+                  (:walkmap.id/id o)
+                  o)
+                (in-store-find-objects (vals o) s))
+     (coll? o) (reduce merge s (map #(in-store-find-objects % s) o))
+     :else s)))
+
+(defn in-store-replace-with-keys
+  "Return a copy of `o` in which each reified walkmap object within `o` has
+  been replaced with the `:walkmap.id/id` of that object. Internal to
+  `in-store`, q.v. Use at your own peril."
+  [o]
+  (assoc
+    (postwalk #(or (:walkmap.id/id %) %) (dissoc o :walkmap.id/id))
+    :walkmap.id/id
+    (:walkmap.id/id o)))
+
+;; (in-store-replace-with-keys (p/path (v/vertex 0 0 0) (v/vertex 0 1 2) (v/vertex 3 3 3)))
+;; (in-store-find-objects (p/path (v/vertex 0 0 0) (v/vertex 0 1 2) (v/vertex 3 3 3)))
+
+(defn store
+  "Return a superstructure like `s` with object `o` added. If only one
   argument is supplied it will be assumed to represent `o` and a new
   superstructure will be returned.
 
   It is an error (and an exception may be thrown) if
 
   1. `s` is not a map;
-  2. `o` is not a map, or a sequence of maps."
+  2. `o` is not a recognisable walkmap object"
   ([o]
-   (add-to-superstructure {} o))
-  ([s o]
-  (cond
-    (map? o) (let [o' (if (:id o) o (assoc o :id (keyword (gensym "obj"))))]
-               (index-vertices (assoc s (:id o') o') o'))
-    (coll? o) (reduce u/deep-merge (map #(add-to-superstructure s %) o))
-    (nil? o) o
-    :else
-    (throw (IllegalArgumentException. (str "Don't know how to index " (or (type o) "nil")))))))
-
+   (store {} o))
+  ([o s]
+;;    (when-not (:walkmap.id/id o)
+;;      (throw
+;;        (IllegalArgumentException.
+;;          (str "Not a walkmap object: no value for `:walkmap.id/id`: "
+;;               (u/kind-type o)))))
+;;    (when-not (map? s)
+;;      (throw
+;;        (IllegalArgumentException.
+;;          (str "Superstructure must be a map: " (u/kind-type s)))))
+   (assoc
+     (u/deep-merge s (in-store-find-objects o))
+     (:walkmap.id/id o)
+     (in-store-replace-with-keys o))))

src/walkmap/tag.clj

@@ -37,7 +37,7 @@
   It's legal to include sequences of keywords in `tags`, so that users can do
   useful things like `(tag obj (map keyword some-strings))`."
   [object & tags]
-  (l/debug "Tagging" (or (:kind object) (type object) nil) "with" tags)
+  (l/debug "Tagging" (kind-type object) "with" tags)
   (let [tags' (flatten tags)]
     (if
       (map? object)

src/walkmap/utils.clj

@@ -10,14 +10,6 @@
     (apply merge-with deep-merge vals)
     (last vals)))
 
-;; (defn vertices
-;;   "If `o` is an object with vertices, return those vertices, else nil."
-;;   [o]
-;;   (cond
-;;     (v/vertex? o) (list o)
-;;     (q/polygon? o) (:vertices o)
-;;     (p/path? o) (:vertices o)))
-
 (defn truncate
   "If string `s` is more than `n` characters long, return the first `n`
   characters; otherwise, return `s`."

src/walkmap/vertex.clj

@@ -42,7 +42,7 @@
   [o]
   (and
     (map? o)
-    (:id o)
+    (:walkmap.id/id o)
     (number? (:x o))
     (number? (:y o))
     (or (nil? (:z o)) (number? (:z o)))
@@ -57,15 +57,15 @@
 
 (defn vertex
   "Make a vertex with this `x`, `y` and (if provided) `z` values. Returns a map
-  with those values, plus a unique `:id` value, and `:kind` set to `:vertex`.
-  It's not necessary to use this function to create a vertex, but the `:id`
+  with those values, plus a unique `:walkmap.id/id` value, and `:kind` set to `:vertex`.
+  It's not necessary to use this function to create a vertex, but the `:walkmap.id/id`
   must be present and must be unique."
   ([x y]
    (let [v {:x x :y y :kind :vertex}]
-     (assoc v :id (vertex-key v))))
+     (assoc v :walkmap.id/id (vertex-key v))))
   ([x y z]
    (let [v (assoc (vertex x y) :z z)]
-     (assoc v :id (vertex-key v)))))
+     (assoc v :walkmap.id/id (vertex-key v)))))
 
 (defn canonicalise
   "If `o` is a map with numeric values for `:x`, `:y` and optionally `:z`,
@@ -77,7 +77,7 @@
       (number? (:x o))
       (number? (:y o))
       (or (nil? (:z o)) (number? (:z o))))
-    (assoc o :kind :vertex :id (vertex-key o))
+    (assoc o :kind :vertex :walkmap.id/id (vertex-key o))
     (throw
       (IllegalArgumentException.
         (truncate