feat(overload): Use typescript-rtti to select implementations (#4)

Note that the changes to module resolution cause steps one and two no longer
  to run because node can't find the imports, although they still compile fine.

Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Reviewed-on: #4

README.md

@@ -7,7 +7,7 @@ Roadmap:
 1. Install over.ts and get an example of add with number and bigint implementations working with it. [DONE]
 2. Use the builder pattern to get add working with its implmentations defined incrementally before producing the final overload. [Didn't quite work the way we wnated, but maybe we can do an alternative later.]
 3. Make a version of over.ts, call it util/overload.ts, that takes an array of implementations without redundant type annotation. [DONE]
-4. Improve that version of overload with rtti to select the implementation without the implementations having to throw errors. [IN PROGRESS]
+4. Improve that version of overload with rtti to select the implementation without the implementations having to throw errors. [DONE]
 3. Use the builder pattern to get a single object with both an add and a negate method, with both defined incrementally, working.
 4. Incorporate a subtract method that works on numbers and bigint by separate definitions but with dependencies on add and negate.
 5. Incorporate a subtract method that works with one generic implementation that works for both number and bigint with dependencies on add and negate.

package.json5

@@ -5,6 +5,7 @@
   main: 'index.js',
   scripts: {
     test: 'echo "Error: no test specified" && exit 1',
+    build: 'ttsc -b',
   },
   keywords: [
     'math',
@@ -18,6 +19,13 @@
   license: 'Apache-2.0',
   dependencies: {
     'over.ts': 'github:m93a/over.ts',
+    'reflect-metadata': '^0.1.13',
     typescript: '^4.8.2',
+    'typescript-rtti': '^0.8.2',
+  },
+  devDependencies: {
+    '@types/node': '^18.7.21',
+    'ts-node': '^10.9.1',
+    ttypescript: '^1.5.13',
   },
 }

pnpm-lock.yaml

@@ -1,20 +1,204 @@
 lockfileVersion: 5.4
 
 specifiers:
+  '@types/node': ^18.7.21
   over.ts: github:m93a/over.ts
+  reflect-metadata: ^0.1.13
+  ts-node: ^10.9.1
+  ttypescript: ^1.5.13
   typescript: ^4.8.2
+  typescript-rtti: ^0.8.2
 
 dependencies:
   over.ts: github.com/m93a/over.ts/0fd6e18afd4ca5a23c9e09d1fcd6b7357b642247
+  reflect-metadata: 0.1.13
   typescript: 4.8.2
+  typescript-rtti: 0.8.2_jbmzfhhdwyaatac7voo5jihpea
+
+devDependencies:
+  '@types/node': 18.7.21
+  ts-node: 10.9.1_xxlomja3uhaizt5vuokco7nale
+  ttypescript: 1.5.13_s5ojjbx2isjkawqptqpitvy25q
 
 packages:
 
+  /@cspotcode/source-map-support/0.8.1:
+    resolution: {integrity: sha512-IchNf6dN4tHoMFIn/7OE8LWZ19Y6q/67Bmf6vnGREv8RSbBVb9LPJxEcnwrcwX6ixSvaiGoomAUvu4YSxXrVgw==}
+    engines: {node: '>=12'}
+    dependencies:
+      '@jridgewell/trace-mapping': 0.3.9
+    dev: true
+
+  /@jridgewell/resolve-uri/3.1.0:
+    resolution: {integrity: sha512-F2msla3tad+Mfht5cJq7LSXcdudKTWCVYUgw6pLFOOHSTtZlj6SWNYAp+AhuqLmWdBO2X5hPrLcu8cVP8fy28w==}
+    engines: {node: '>=6.0.0'}
+    dev: true
+
+  /@jridgewell/sourcemap-codec/1.4.14:
+    resolution: {integrity: sha512-XPSJHWmi394fuUuzDnGz1wiKqWfo1yXecHQMRf2l6hztTO+nPru658AyDngaBe7isIxEkRsPR3FZh+s7iVa4Uw==}
+    dev: true
+
+  /@jridgewell/trace-mapping/0.3.9:
+    resolution: {integrity: sha512-3Belt6tdc8bPgAtbcmdtNJlirVoTmEb5e2gC94PnkwEW9jI6CAHUeoG85tjWP5WquqfavoMtMwiG4P926ZKKuQ==}
+    dependencies:
+      '@jridgewell/resolve-uri': 3.1.0
+      '@jridgewell/sourcemap-codec': 1.4.14
+    dev: true
+
+  /@tsconfig/node10/1.0.9:
+    resolution: {integrity: sha512-jNsYVVxU8v5g43Erja32laIDHXeoNvFEpX33OK4d6hljo3jDhCBDhx5dhCCTMWUojscpAagGiRkBKxpdl9fxqA==}
+    dev: true
+
+  /@tsconfig/node12/1.0.11:
+    resolution: {integrity: sha512-cqefuRsh12pWyGsIoBKJA9luFu3mRxCA+ORZvA4ktLSzIuCUtWVxGIuXigEwO5/ywWFMZ2QEGKWvkZG1zDMTag==}
+    dev: true
+
+  /@tsconfig/node14/1.0.3:
+    resolution: {integrity: sha512-ysT8mhdixWK6Hw3i1V2AeRqZ5WfXg1G43mqoYlM2nc6388Fq5jcXyr5mRsqViLx/GJYdoL0bfXD8nmF+Zn/Iow==}
+    dev: true
+
+  /@tsconfig/node16/1.0.3:
+    resolution: {integrity: sha512-yOlFc+7UtL/89t2ZhjPvvB/DeAr3r+Dq58IgzsFkOAvVC6NMJXmCGjbptdXdR9qsX7pKcTL+s87FtYREi2dEEQ==}
+    dev: true
+
+  /@types/node/18.7.21:
+    resolution: {integrity: sha512-rLFzK5bhM0YPyCoTC8bolBjMk7bwnZ8qeZUBslBfjZQou2ssJdWslx9CZ8DGM+Dx7QXQiiTVZ/6QO6kwtHkZCA==}
+    dev: true
+
+  /acorn-walk/8.2.0:
+    resolution: {integrity: sha512-k+iyHEuPgSw6SbuDpGQM+06HQUa04DZ3o+F6CSzXMvvI5KMvnaEqXe+YVe555R9nn6GPt404fos4wcgpw12SDA==}
+    engines: {node: '>=0.4.0'}
+    dev: true
+
+  /acorn/8.8.0:
+    resolution: {integrity: sha512-QOxyigPVrpZ2GXT+PFyZTl6TtOFc5egxHIP9IlQ+RbupQuX4RkT/Bee4/kQuC02Xkzg84JcT7oLYtDIQxp+v7w==}
+    engines: {node: '>=0.4.0'}
+    hasBin: true
+    dev: true
+
+  /arg/4.1.3:
+    resolution: {integrity: sha512-58S9QDqG0Xx27YwPSt9fJxivjYl432YCwfDMfZ+71RAqUrZef7LrKQZ3LHLOwCS4FLNBplP533Zx895SeOCHvA==}
+    dev: true
+
+  /create-require/1.1.1:
+    resolution: {integrity: sha512-dcKFX3jn0MpIaXjisoRvexIJVEKzaq7z2rZKxf+MSr9TkdmHmsU4m2lcLojrj/FHl8mk5VxMmYA+ftRkP/3oKQ==}
+    dev: true
+
+  /diff/4.0.2:
+    resolution: {integrity: sha512-58lmxKSA4BNyLz+HHMUzlOEpg09FV+ev6ZMe3vJihgdxzgcwZ8VoEEPmALCZG9LmqfVoNMMKpttIYTVG6uDY7A==}
+    engines: {node: '>=0.3.1'}
+    dev: true
+
+  /function-bind/1.1.1:
+    resolution: {integrity: sha512-yIovAzMX49sF8Yl58fSCWJ5svSLuaibPxXQJFLmBObTuCr0Mf1KiPopGM9NiFjiYBCbfaa2Fh6breQ6ANVTI0A==}
+    dev: true
+
+  /has/1.0.3:
+    resolution: {integrity: sha512-f2dvO0VU6Oej7RkWJGrehjbzMAjFp5/VKPp5tTpWIV4JHHZK1/BxbFRtf/siA2SWTe09caDmVtYYzWEIbBS4zw==}
+    engines: {node: '>= 0.4.0'}
+    dependencies:
+      function-bind: 1.1.1
+    dev: true
+
+  /is-core-module/2.10.0:
+    resolution: {integrity: sha512-Erxj2n/LDAZ7H8WNJXd9tw38GYM3dv8rk8Zcs+jJuxYTW7sozH+SS8NtrSjVL1/vpLvWi1hxy96IzjJ3EHTJJg==}
+    dependencies:
+      has: 1.0.3
+    dev: true
+
+  /make-error/1.3.6:
+    resolution: {integrity: sha512-s8UhlNe7vPKomQhC1qFelMokr/Sc3AgNbso3n74mVPA5LTZwkB9NlXf4XPamLxJE8h0gh73rM94xvwRT2CVInw==}
+    dev: true
+
+  /path-parse/1.0.7:
+    resolution: {integrity: sha512-LDJzPVEEEPR+y48z93A0Ed0yXb8pAByGWo/k5YYdYgpY2/2EsOsksJrq7lOHxryrVOn1ejG6oAp8ahvOIQD8sw==}
+    dev: true
+
+  /reflect-metadata/0.1.13:
+    resolution: {integrity: sha512-Ts1Y/anZELhSsjMcU605fU9RE4Oi3p5ORujwbIKXfWa+0Zxs510Qrmrce5/Jowq3cHSZSJqBjypxmHarc+vEWg==}
+    dev: false
+
+  /resolve/1.22.1:
+    resolution: {integrity: sha512-nBpuuYuY5jFsli/JIs1oldw6fOQCBioohqWZg/2hiaOybXOft4lonv85uDOKXdf8rhyK159cxU5cDcK/NKk8zw==}
+    hasBin: true
+    dependencies:
+      is-core-module: 2.10.0
+      path-parse: 1.0.7
+      supports-preserve-symlinks-flag: 1.0.0
+    dev: true
+
+  /supports-preserve-symlinks-flag/1.0.0:
+    resolution: {integrity: sha512-ot0WnXS9fgdkgIcePe6RHNk1WA8+muPa6cSjeR3V8K27q9BB1rTE3R1p7Hv0z1ZyAc8s6Vvv8DIyWf681MAt0w==}
+    engines: {node: '>= 0.4'}
+    dev: true
+
+  /ts-node/10.9.1_xxlomja3uhaizt5vuokco7nale:
+    resolution: {integrity: sha512-NtVysVPkxxrwFGUUxGYhfux8k78pQB3JqYBXlLRZgdGUqTO5wU/UyHop5p70iEbGhB7q5KmiZiU0Y3KlJrScEw==}
+    hasBin: true
+    peerDependencies:
+      '@swc/core': '>=1.2.50'
+      '@swc/wasm': '>=1.2.50'
+      '@types/node': '*'
+      typescript: '>=2.7'
+    peerDependenciesMeta:
+      '@swc/core':
+        optional: true
+      '@swc/wasm':
+        optional: true
+    dependencies:
+      '@cspotcode/source-map-support': 0.8.1
+      '@tsconfig/node10': 1.0.9
+      '@tsconfig/node12': 1.0.11
+      '@tsconfig/node14': 1.0.3
+      '@tsconfig/node16': 1.0.3
+      '@types/node': 18.7.21
+      acorn: 8.8.0
+      acorn-walk: 8.2.0
+      arg: 4.1.3
+      create-require: 1.1.1
+      diff: 4.0.2
+      make-error: 1.3.6
+      typescript: 4.8.2
+      v8-compile-cache-lib: 3.0.1
+      yn: 3.1.1
+    dev: true
+
+  /ttypescript/1.5.13_s5ojjbx2isjkawqptqpitvy25q:
+    resolution: {integrity: sha512-KT/RBfGGlVJFqEI8cVvI3nMsmYcFvPSZh8bU0qX+pAwbi7/ABmYkzn7l/K8skw0xmYjVCoyaV6WLsBQxdadybQ==}
+    hasBin: true
+    peerDependencies:
+      ts-node: '>=8.0.2'
+      typescript: '>=3.2.2'
+    dependencies:
+      resolve: 1.22.1
+      ts-node: 10.9.1_xxlomja3uhaizt5vuokco7nale
+      typescript: 4.8.2
+    dev: true
+
+  /typescript-rtti/0.8.2_jbmzfhhdwyaatac7voo5jihpea:
+    resolution: {integrity: sha512-MZUHMX+Up1+7dYaAcOYSTxKc4PNLNXhuXYBkIzEKvQvxJ6xp7wcjTtiIYmB9+RJxRH5/9phZLqKTMpy20aQ4Aw==}
+    engines: {node: '>=10'}
+    peerDependencies:
+      reflect-metadata: ^0.1.13
+      typescript: '4.6'
+    dependencies:
+      reflect-metadata: 0.1.13
+      typescript: 4.8.2
+    dev: false
+
   /typescript/4.8.2:
     resolution: {integrity: sha512-C0I1UsrrDHo2fYI5oaCGbSejwX4ch+9Y5jTQELvovfmFkK3HHSZJB8MSJcWLmCUBzQBchCrZ9rMRV6GuNrvGtw==}
     engines: {node: '>=4.2.0'}
     hasBin: true
-    dev: false
+
+  /v8-compile-cache-lib/3.0.1:
+    resolution: {integrity: sha512-wa7YjyUGfNZngI/vtK0UHAN+lgDCxBPCylVXGp0zu59Fz5aiGtNXaq3DhIov063MorB+VfufLh3JlF2KdTK3xg==}
+    dev: true
+
+  /yn/3.1.1:
+    resolution: {integrity: sha512-Ux4ygGWsu2c7isFWe8Yu1YluJmqVhxqK2cLXNQA5AcC3QfbGNpM7fu0Y8b/z16pXLnFxZYvWhd3fhBY9DLmC6Q==}
+    engines: {node: '>=6'}
+    dev: true
 
   github.com/m93a/over.ts/0fd6e18afd4ca5a23c9e09d1fcd6b7357b642247:
     resolution: {tarball: https://codeload.github.com/m93a/over.ts/tar.gz/0fd6e18afd4ca5a23c9e09d1fcd6b7357b642247}

src/steps/four.ts

@@ -0,0 +1,26 @@
+import 'reflect-metadata'
+import overload from '../util/overload.js'
+
+const addImps = [
+    (x: number, y: number) => {
+        if (typeof x === 'number' && typeof y === 'number') return x + y
+        throw new TypeError('Can only add numbers')
+    },
+    (x: string, y: string) => {
+        if (typeof x === 'string' && typeof y === 'string') {
+            return 'Yay' + x + y
+        }
+        throw new TypeError('or strings')
+    },
+    (x: bigint, final?: string) => x.toString() + final
+] as const
+
+const adder = overload(addImps)
+
+console.log(adder(1, 2))
+console.log(adder('a', 'b'))
+console.log(adder(2n))
+
+// And make sure typescript complains on signatures not covered by an imp:
+//@ts-expect-error
+console.log(adder(2n, 4n))

src/steps/one.ts

@@ -1,4 +1,4 @@
-import { useTypes } from 'over.ts/src/index.js';
+import { useTypes } from '../../node_modules/over.ts/src/index.js';
 
 const types = {
    number: (x: unknown): x is number => typeof x === 'number',

src/steps/three.ts

@@ -6,7 +6,10 @@ const adder = overload([
         throw new TypeError('Can only add numbers')
     },
     (x: string, y: string) => 'Yay' + x + y
-])
+] as const)
 
 console.log(adder(1, 2))
 console.log(adder('a', 'b'))
+//@ts-expect-error
+console.log(adder(3n, 4n))
+

src/steps/two.ts

@@ -1,4 +1,4 @@
-import { useTypes } from 'over.ts/src/index.js';
+import { useTypes } from 'over.ts';
 
 const types = {
    number: (x: unknown): x is number => typeof x === 'number',
@@ -69,6 +69,8 @@ addImps.addImp('number, number -> number', (a: number, b: number) => a+b) // ima
 const addAll = addImps.addImp('bigint, bigint -> bigint', (a: bigint, b: bigint) => a+b) // and this is in the `bigint` file
 const add = overload(addAll.finalize() as Omit<typeof addAll, 'finalize'|'addImp'>) // We wrap everything up elsewhere
 
+// This should **NOT** be an error but sadly it is:
+//@ts-expect-error
 console.log('Sum of 5 and 7 is', add(5,7))
 console.log('Sum of 5n and 7n is', add(5n, 7n))
 

src/util/overload.ts

@@ -1,17 +1,42 @@
+import {reflect, CallSite} from 'typescript-rtti'
+
 type UnionToIntersection<U> =
     (U extends any ? (k: U) => void : never) extends ((k: infer I) => void)
     ? I
     : never;
 
 export default function overload<T extends readonly [...any[]]>(
-    imps: T): UnionToIntersection<T[number]> {
+    imps: T, callSite?: CallSite): UnionToIntersection<T[number]> {
+    const impTypes = reflect(callSite).parameters[0].elements
     return <any>((...a: any[]) => {
         for (let i = 0; i < imps.length; ++i) {
-            try {
+            const paramTypes = impTypes[i].type.parameters
-                const val = imps[i](...a)
+            let match = true
-                return val
+            const haveArgs = a.length
-            } catch {
+            let onArg = 0
+            for (const param of paramTypes) {
+                if (param.isRest) {
+                    // All the rest of the arguments must be of param's type
+                    match = a.slice(onArg).every(
+                        arg => param.type.matchesValue(arg))
+                    break
                 }
+                if (onArg === haveArgs) {
+                    // We've used all of the arguments, so better be optional
+                    match = param.isOptional
+                    break
                 }
+                // This argument must match this param's type and both are used
+                match = param.type.matchesValue(a[onArg])
+                onArg += 1
+                if (!match) break
+            }
+            // Make sure we used all the arguments
+            match &&= (onArg == haveArgs)
+            if (match) return imps[i](...a)
+        }
+        throw new TypeError(
+            `Actual arguments ${a} of type ${a.map(arg => typeof arg)} `
+            + 'did not match any implementation')
     })
 }

tsconfig.json

@@ -1,12 +1,18 @@
 {
     "compilerOptions": {
         "target": "ES2022",
-        "moduleResolution": "node",
+        "baseUrl": ".",
-        "rootDir": "src",
+        "paths": {
+            "over.ts": ["node_modules/over.ts/src/index.js"],
+            "typescript-rtti": ["node_modules/typescript-rtti/dist/index.js"]
+        },
+        "plugins": [{ "transform": "typescript-rtti/dist/transformer" }],
+        "rootDir": ".",
         "outDir": "obj"
     },
     "include": [
-        "src/steps/three.ts",
+        "node_modules/over.ts/src/index.ts",
+        "src/steps/*.ts",
         "src/util/*.ts"
     ]
 }