From 4fdafc751eeee6ecd9872b90ee333ea720b5d91a Mon Sep 17 00:00:00 2001
From: Glen Whitney <glen@nobody@nowhere.net>
Date: Sat, 23 Jul 2022 02:41:59 +0000
Subject: [PATCH] feat: Add a couple of ways to install generics safely. (#18)

Resolves #10.

Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Reviewed-on: https://code.studioinfinity.org/glen/pocomath/pulls/18
---
 src/core/PocomathInstance.mjs     | 39 ++++++++++++++++++++++++++++++-
 src/generic/subtract.concrete.mjs |  3 +++
 test/custom.mjs                   | 23 ++++++++++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 src/generic/subtract.concrete.mjs

diff --git a/src/core/PocomathInstance.mjs b/src/core/PocomathInstance.mjs
index dd4a6cc..4d32896 100644
--- a/src/core/PocomathInstance.mjs
+++ b/src/core/PocomathInstance.mjs
@@ -6,7 +6,7 @@ export default class PocomathInstance {
     * in that if a new top-level PocomathInstance method is added, its name
     * must be added to this list.
     */
-   static reserved = new Set(['install'])
+   static reserved = new Set(['install', 'importDependencies'])
 
    constructor(name) {
       this.name = name
@@ -52,6 +52,43 @@ export default class PocomathInstance {
       for (const key in ops) this._installOp(key, ops[key])
    }
 
+   /**
+    * Import (and install) all dependencies of previously installed functions,
+    * for the specified types.
+    *
+    * @param {string[]} types  A list of type names
+    */
+   async importDependencies(types) {
+      const doneSet = new Set(['self']) // nothing to do for self dependencies
+      while (true) {
+         const requiredSet = new Set()
+         /* Grab all of the known deps */
+         for (const func in this._imps) {
+            if (func === 'Types') continue
+            for (const definition of Object.values(this._imps[func])) {
+               for (const dependency of definition[0]) {
+                  const depName = dependency.split('(',1)[0]
+                  if (doneSet.has(depName)) continue
+                  requiredSet.add(depName)
+               }
+            }
+         }
+         if (requiredSet.size === 0) break
+         for (const name of requiredSet) {
+            for (const type of types) {
+               try {
+                  const modName = `../${type}/${name}.mjs`
+                  const mod = await import(modName)
+                  this.install(mod)
+               } catch (err) {
+                  // No such module, but that's OK
+               }
+            }
+            doneSet.add(name)
+         }
+      }
+   }
+         
    /* Used internally by install, see the documentation there */
    _installOp(name, implementations) {
       if (name.charAt(0) === '_') {
diff --git a/src/generic/subtract.concrete.mjs b/src/generic/subtract.concrete.mjs
new file mode 100644
index 0000000..39638aa
--- /dev/null
+++ b/src/generic/subtract.concrete.mjs
@@ -0,0 +1,3 @@
+export {subtract} from './subtract.mjs'
+export * from '../number/add.mjs'
+export * from '../number/negate.mjs'
diff --git a/test/custom.mjs b/test/custom.mjs
index aabbb8c..008218e 100644
--- a/test/custom.mjs
+++ b/test/custom.mjs
@@ -6,6 +6,9 @@ import * as numberAdd from '../src/number/add.mjs'
 import * as complex from '../src/complex/all.mjs'
 import * as complexAdd from '../src/complex/add.mjs'
 import * as complexNegate from '../src/complex/negate.mjs'
+import * as complexComplex from '../src/complex/complex.mjs'
+import * as concreteSubtract from '../src/generic/subtract.concrete.mjs'
+import * as genericSubtract from '../src/generic/subtract.mjs'
 import extendToComplex from '../src/complex/extendToComplex.mjs'
 
 const bw = new PocomathInstance('backwards')
@@ -55,4 +58,24 @@ describe('A custom instance', () => {
       assert.strictEqual('subtract' in cherry, false)
       assert.strictEqual('negate' in cherry, false)
    })
+
+   it("can use bundles that are closed under dependency", () => {
+      const ok = new PocomathInstance('concrete')
+      ok.install(concreteSubtract)
+      assert.strictEqual(ok.subtract(7, 5), 2)
+   })
+
+   it("can load generics and then import their dependences", async function () {
+      const chase = new PocomathInstance('Chase Dependencies')
+      chase.install(genericSubtract)
+      chase.install(complexComplex) // for convenience to build complex numbers
+      await chase.importDependencies(['bigint', 'complex'])
+      /* Now we have an instance that supports subtraction for Gaussian
+         integers.
+      */
+      assert.deepStrictEqual(
+         chase.subtract(chase.complex(3n, 2n), chase.complex(2n, 5n)),
+         math.complex(1n, -3n))
+   })
+
 })