define "source" export condition

README.md

@@ -276,10 +276,12 @@ appropriate build target locations, like:
     "./foo": {
       "import": {
         "types": "./dist/esm/foo.d.ts",
+        "source": "./src/foo.ts",
         "default": "./dist/esm/foo.js"
       },
       "require": {
         "types": "./dist/commonjs/foo.d.ts",
+        "source": "./src/foo.ts",
         "default": "./dist/commonjs/foo.js"
       }
     }
@@ -345,20 +347,24 @@ be:
     ".": {
       "require": {
         "types": "./dist/commonjs/index.d.ts",
+        "source": "./src/index.ts",
         "default": "./dist/commonjs/index.js"
       },
       "import": {
         "types": "./dist/esm/index.d.ts",
+        "source": "./src/index.ts",
         "default": "./dist/esm/index.js"
       }
     },
     "./component/foo": {
       "require": {
         "types": "./dist/commonjs/component/foo.d.ts",
+        "source": "./src/component/foo.ts",
         "default": "./dist/commonjs/component/foo.js"
       },
       "import": {
         "types": "./dist/esm/component/foo.d.ts",
+        "source": "./src/component/foo.ts",
         "default": "./dist/esm/component/foo.js"
       }
     },
@@ -381,6 +387,31 @@ This would export a file at `./src/foo.ts` as `./foo`, and a file
 at `./src/utils/bar.ts` as `./utils/bar`, but would ignore a file
 at `./internal/private.ts`.
 
+### Live Dev
+
+Set `"liveDev": true` in the tshy config in `package.json` to
+build in link mode. In this mode, the files are hard-linked into
+place in the `dist` folder, so that edits are immediately visible.
+
+This is particularly beneficial in monorepo projects, where
+workspaces may be edited in parallel, and so it's handy to have
+changes reflected in real time without a rebuild.
+
+Of course, tools that can't handle TypeScript will have a problem
+with this, so any generic `node` program will not be able to run
+your code. For this reason:
+
+- `liveDev` is always disabled when the `npm_command` environment
+  variable is `'publish'` or `'pack'`. In these situations, your
+  code is being built for public consumption, and must be
+  compiled.
+- Code in dist will not be able to be loaded in the node repl
+  unless you run it with a loader, such as `node --import=tsx`.
+- Because it links files into place, a rebuild _is_ required when
+  a file is added or removed.
+
+See also: "Loading from Source", below.
+
 ### Package `#imports`
 
 You can use `"imports"` in your package.json, and it will be
@@ -574,10 +605,12 @@ will produce:
     ".": {
       "require": {
         "types": "./dist/commonjs/index.d.ts",
+        "source": "./src/index.js",
         "default": "./dist/commonjs/index.js"
       },
       "import": {
         "types": "./dist/esm/index.d.ts",
+        "source": "./src/index.ts",
         "default": "./dist/esm/index.js"
       }
     }
@@ -682,22 +715,27 @@ Will result in:
     ".": {
       "deno": {
         "types": "./dist/deno/index.d.ts",
+        "source": "./src/index.ts",
         "default": "./dist/deno/index.js"
       },
       "browser": {
         "types": "./dist/browser/index.d.ts",
+        "default": "./src/index.ts",
         "default": "./dist/browser/index.js"
       },
       "webpack": {
         "types": "./dist/webpack/index.d.ts",
+        "source": "./src/index.ts",
         "default": "./dist/webpack/index.js"
       },
       "require": {
         "types": "./dist/commonjs/index.d.ts",
+        "source": "./src/index.ts",
         "default": "./dist/commonjs/index.js"
       },
       "import": {
         "types": "./dist/esm/index.d.ts",
+        "source": "./src/index.ts",
         "default": "./dist/esm/index.js"
       }
     }
@@ -722,6 +760,44 @@ src/index-deno.mts     # esm variant for deno
 src/index-webpack.cts  # cjs variant for webpack
 ```
 
+If dialect overrides are used, then the `"source"` export
+condition will refer to the original source for the override. For
+example:
+
+```json
+{
+  "exports": {
+    ".": {
+      "deno": {
+        "types": "./dist/deno/index.d.ts",
+        "source": "./src/index-deno.mts",
+        "default": "./dist/deno/index.js"
+      },
+      "browser": {
+        "types": "./dist/browser/index.d.ts",
+        "default": "./src/index-browser.mts",
+        "default": "./dist/browser/index.js"
+      },
+      "webpack": {
+        "types": "./dist/webpack/index.d.ts",
+        "source": "./src/index-webpack.cts",
+        "default": "./dist/webpack/index.js"
+      },
+      "require": {
+        "types": "./dist/commonjs/index.d.ts",
+        "source": "./src/index-cjs.cts",
+        "default": "./dist/commonjs/index.js"
+      },
+      "import": {
+        "types": "./dist/esm/index.d.ts",
+        "source": "./src/index.ts",
+        "default": "./dist/esm/index.js"
+      }
+    }
+  }
+}
+```
+
 Note that the `commonjs` override uses the abbreviated `cjs`
 name (historical reasons, it was originally the only override
 supported), and that the file extension must be `cts` or `mts`
@@ -778,6 +854,39 @@ provided for you.
 Then the `tsconfig.json` file will be used as the default project
 for code hints in VSCode, neovim, tests, etc.
 
+### Loading from Source
+
+If you are using tshy in a monorepo environment, you can
+configure TypeScript (and other tools) to resolve to the _source_
+files rather than built artifacts by telling them to use the
+`"source"` export condition.
+
+For example, in editors such as VS Code and neovim/CoC that use
+the TypeScript language services, you can give them a `tsconfig`
+that contains this:
+
+```json
+{
+  "compilerOptions": {
+    "customConditions": ["source"]
+  }
+}
+```
+
+If you are loading your program with a custom Node.js importer
+like [`tsx`](https://npm.im/tsx) that can load TypeScript
+directly, you can specify it like this:
+
+```bash
+node --import=tsx --conditions=source ./script.ts
+```
+
+Other TypeScript-aware tools may have other mechanisms for
+specifying export conditions. Refer to their documentation for
+more information.
+
+See also: "Live Dev", above.
+
 ### Custom `project`
 
 Configure `tshy.project` if you want tshy to extend from a custom

src/build-live-commonjs.ts

@@ -0,0 +1,43 @@
+import chalk from 'chalk'
+import { linkSync, mkdirSync } from 'node:fs'
+import { dirname } from 'node:path'
+import { relative, resolve } from 'node:path/posix'
+import config from './config.js'
+import * as console from './console.js'
+import ifExist from './if-exist.js'
+import polyfills from './polyfills.js'
+import setFolderDialect from './set-folder-dialect.js'
+import sources from './sources.js'
+import './tsconfig.js'
+
+const { commonjsDialects = [] } = config
+
+// don't actually do a build, just link files into places.
+export const buildLiveCommonJS = () => {
+  for (const d of ['commonjs', ...commonjsDialects]) {
+    const pf = polyfills.get(d === 'commonjs' ? 'cjs' : d)
+    console.debug(chalk.cyan.dim('linking ' + d))
+    for (const s of sources) {
+      const source = s.substring('./src/'.length)
+      const target = resolve(`.tshy-build/${d}/${source}`)
+      mkdirSync(dirname(target), { recursive: true })
+      linkSync(s, target)
+    }
+    setFolderDialect('.tshy-build/' + d, 'commonjs')
+    for (const [override, orig] of pf?.map.entries() ?? []) {
+      const stemFrom = resolve(
+        `.tshy-build/${d}`,
+        relative(resolve('src'), resolve(override))
+      ).replace(/\.cts$/, '')
+      const stemTo = resolve(
+        `.tshy-build/${d}`,
+        relative(resolve('src'), resolve(orig))
+      ).replace(/\.tsx?$/, '')
+      ifExist.unlink(`${stemTo}.js.map`)
+      ifExist.unlink(`${stemTo}.d.ts.map`)
+      ifExist.rename(`${stemFrom}.cjs`, `${stemTo}.js`)
+      ifExist.rename(`${stemFrom}.d.cts`, `${stemTo}.d.ts`)
+    }
+    console.error(chalk.cyan.bold('linked commonjs'))
+  }
+}

src/build-live-esm.ts

@@ -0,0 +1,41 @@
+import chalk from 'chalk'
+import { linkSync, mkdirSync } from 'node:fs'
+import { dirname, relative, resolve } from 'node:path'
+import config from './config.js'
+import * as console from './console.js'
+import ifExist from './if-exist.js'
+import polyfills from './polyfills.js'
+import setFolderDialect from './set-folder-dialect.js'
+import sources from './sources.js'
+import './tsconfig.js'
+
+const { esmDialects = [] } = config
+
+export const buildLiveESM = () => {
+  for (const d of ['esm', ...esmDialects]) {
+    const pf = polyfills.get(d)
+    console.debug(chalk.cyan.dim('linking ' + d))
+    for (const s of sources) {
+      const source = s.substring('./src/'.length)
+      const target = resolve(`.tshy-build/${d}/${source}`)
+      mkdirSync(dirname(target), { recursive: true })
+      linkSync(s, target)
+    }
+    setFolderDialect('.tshy-build/' + d, 'esm')
+    for (const [override, orig] of pf?.map.entries() ?? []) {
+      const stemFrom = resolve(
+        `.tshy-build/${d}`,
+        relative(resolve('src'), resolve(override))
+      ).replace(/\.mts$/, '')
+      const stemTo = resolve(
+        `.tshy-build/${d}`,
+        relative(resolve('src'), resolve(orig))
+      ).replace(/\.tsx?$/, '')
+      ifExist.unlink(`${stemTo}.js.map`)
+      ifExist.unlink(`${stemTo}.d.ts.map`)
+      ifExist.rename(`${stemFrom}.mjs`, `${stemTo}.js`)
+      ifExist.rename(`${stemFrom}.d.mts`, `${stemTo}.d.ts`)
+    }
+    console.error(chalk.cyan.bold('linked ' + d))
+  }
+}

src/build.ts

@@ -1,4 +1,5 @@
 import chalk from 'chalk'
+import config from './config.js'
 import { syncContentSync } from 'sync-content'
 import bins from './bins.js'
 import { buildCommonJS } from './build-commonjs.js'
@@ -18,14 +19,22 @@ import {
   unlink as unlinkImports,
 } from './unbuilt-imports.js'
 import writePackage from './write-package.js'
+import { buildLiveESM } from './build-live-esm.js'
+import { buildLiveCommonJS } from './build-live-commonjs.js'
 
 export default async () => {
   cleanBuildTmp()
 
   linkSelfDep(pkg, 'src')
   await linkImports(pkg, 'src')
-  if (dialects.includes('esm')) buildESM()
-  if (dialects.includes('commonjs')) buildCommonJS()
+  const liveDev =
+    config.liveDev &&
+    process.env.npm_command !== 'publish' &&
+    process.env.npm_command !== 'pack'
+  const esm = liveDev ? buildLiveESM : buildESM
+  const commonjs = liveDev ? buildLiveCommonJS : buildCommonJS
+  if (dialects.includes('esm')) esm()
+  if (dialects.includes('commonjs')) commonjs()
   await unlinkImports(pkg, 'src')
   unlinkSelfDep(pkg, 'src')
 

src/config.ts

@@ -40,7 +40,8 @@ const validConfig = (e: any): e is TshyConfigMaybeGlobExports =>
   (e.exclude === undefined || validExclude(e.exclude)) &&
   validExtraDialects(e) &&
   validBoolean(e, 'selfLink') &&
-  validBoolean(e, 'main')
+  validBoolean(e, 'main') &&
+  validBoolean(e, 'liveDev')
 
 const match = (e: string, pattern: Minimatch[]): boolean =>
   pattern.some(m => m.match(e))