Fix errors a bit

Author: dy

README.md

@@ -138,10 +138,18 @@ codegen(['+', ['*', 'min', [,60]], [,'sec']])
 Bundle imports into a single file:
 
 ```js
-import { bundle } from 'subscript/util/bundle.js'
-
-const code = await bundle('subscript/jessie.js')
-// → self-contained ES module
+// Node.js
+import { bundleFile } from 'subscript/util/bundle.js'
+console.log(await bundleFile('jessie.js'))
+
+// Browser / custom sources
+import { bundle, fromSources } from 'subscript/util/bundle.js'
+const read = fromSources({
+  'main.js': `import { x } from './lib.js'; export default x * 2`,
+  'lib.js': `export const x = 21`
+})
+console.log(await bundle('main.js', read))
+// → "const x = 21;\nexport { x as default }"
 ```
 
 

package.json

@@ -76,7 +76,6 @@
   "devDependencies": {
     "@playwright/test": "^1.57.0",
     "esbuild": "^0.27.2",
-    "jsep": "^1.4.0",
     "terser": "^5.44.1",
     "tst": "^9.2.0"
   }

parse.js

@@ -14,10 +14,10 @@ export let idx, cur,
     last = lines.pop(),
     before = cur.slice(Math.max(0, at - 40), at),
     ptr = '\u032D',
-    chr = (cur[at] || '∅') + ptr,
+    chr = (cur[at] || ' ') + ptr,
     after = cur.slice(at + 1, at + 20)
   ) => {
-    throw SyntaxError(`${msg} at ${lines.length + 1}:${last.length + 1}\n${(cur[at-41]!=='\n' ? '...' : '') +before}${chr}${after}`)
+    throw SyntaxError(`${msg} at ${lines.length + 1}:${last.length + 1}\n${(cur[at-41]!=='\n' ? '' : '') +before}${chr}${after}`)
   },
 
   // attach location to node (returns node for chaining)

test/errors-demo.js

@@ -0,0 +1,48 @@
+// Demo: various parse error formats
+import t from 'tst'
+import { parse } from '../jessie.js'
+
+t.demo('error formats', {only:true, bail:true}, () => {
+  const cases = [
+    // Unexpected token
+    ['1 * * 2', 'double multiply (no unary *)'],
+    ['a..b', 'double dot'],
+    ['(a +)', 'trailing operator in group'],
+
+    // Unclosed groups
+    ['(a + b', 'unclosed paren'],
+    ['[1, 2, 3', 'unclosed bracket'],
+    ['{a: 1', 'unclosed brace'],
+    ['`hello ${x', 'unclosed template'],
+
+    // Unexpected end
+    ['a +', 'trailing operator'],
+    ['let x =', 'incomplete assignment'],
+
+    // Invalid syntax
+    ['function ()', 'anonymous function without arrow'],
+    ['class { constructor }', 'incomplete class'],
+
+    // Mismatched
+    ['(a + b]', 'mismatched brackets'],
+    ['[1, 2)', 'mismatched parens'],
+
+    // Deep nesting error
+    ['((((a + b)))', 'unclosed deep nesting'],
+
+    // Long line error position
+    ['let veryLongVariableName = anotherLongName + yetAnotherOne * andOneMore / plusThis - ', 'long line trailing op'],
+  ]
+
+  for (const [code, desc] of cases) {
+    console.log(`--- ${desc} ---`)
+    console.log(`Input: ${JSON.stringify(code)}`)
+    try {
+      const ast = parse(code)
+      console.error('Parsed:', JSON.stringify(ast))
+    } catch (e) {
+      console.log(e)
+    }
+    console.log()
+  }
+})

test/index.html

@@ -2,6 +2,7 @@
 <script type="importmap">{
     "imports": {
         "tst": "../node_modules/tst/tst.js",
+        "jsep": "../node_modules/jsep/dist/jsep.min.js",
         "es-module-lexer": "../node_modules/es-module-lexer/dist/lexer.js",
         "es-module-lexer": "https://unpkg.com/es-module-lexer?module"
     }

test/perf.js

@@ -4,8 +4,10 @@ const RUNS = 3e4
 const src = c => `1 + (a * b / c % d) - 2.0 + -3e-3 * +4.4e4 / f.g[0] - i.j(+k == 1)(${c})`
 const subscriptUrl = new URL('../subscript.js', import.meta.url).href
 const justinUrl = new URL('../justin.js', import.meta.url).href
+// Browser uses CDN, Node uses npm package
+const jsepUrl = typeof process !== 'undefined' ? 'jsep' : 'https://esm.sh/jsep'
 
-test.fork('perf: expr < jsep', {data: {RUNS, src, subscriptUrl}}, async ({ ok }, {RUNS, src, subscriptUrl}) => {
+test.fork('perf: expr < jsep', {data: {RUNS, src, subscriptUrl, jsepUrl}}, async ({ ok }, {RUNS, src, subscriptUrl, jsepUrl}) => {
   const bench = (fn) => {
     let best = Infinity
     for (let r = 0; r < 3; r++) {
@@ -17,7 +19,7 @@ test.fork('perf: expr < jsep', {data: {RUNS, src, subscriptUrl}}, async ({ ok },
   }
 
   const { parse } = await import(subscriptUrl)
-  const jsep = (await import('jsep')).default
+  const jsep = (await import(jsepUrl)).default
 
   for (let w = 0; w < RUNS; w++) { parse(src(w)); jsep(src(w)) }
 
@@ -27,7 +29,7 @@ test.fork('perf: expr < jsep', {data: {RUNS, src, subscriptUrl}}, async ({ ok },
   ok(time < baseline, `expr (${time.toFixed(0)}ms) should be < jsep (${baseline.toFixed(0)}ms)`)
 })
 
-test.fork('perf: justin <= jsep', {data: {RUNS, src, justinUrl}}, async ({ ok }, {RUNS, src, justinUrl}) => {
+test.fork('perf: justin <= jsep', {data: {RUNS, src, justinUrl, jsepUrl}}, async ({ ok }, {RUNS, src, justinUrl, jsepUrl}) => {
   const bench = (fn) => {
     let best = Infinity
     for (let r = 0; r < 3; r++) {
@@ -39,7 +41,7 @@ test.fork('perf: justin <= jsep', {data: {RUNS, src, justinUrl}}, async ({ ok },
   }
 
   const { parse } = await import(justinUrl)
-  const jsep = (await import('jsep')).default
+  const jsep = (await import(jsepUrl)).default
 
   for (let w = 0; w < RUNS; w++) { parse(src(w)); jsep(src(w)) }
 

test/test.js

@@ -19,11 +19,16 @@ import './feature/unit.js'
 import './feature/jessie.js'
 import './feature/async-class.js'
 
-import './meta.js'
 
 // Integration tests
 import './subscript.js'
 
-// Bundler tests (dogfooding)
-import './bundle.js'
-import './perf.js'
+// Node.js only tests (bundler uses fs, perf needs stable timing)
+if (typeof process !== 'undefined') {
+  await import('./meta.js')
+  await import('./bundle.js')
+  await import('./perf.js')
+}
+
+// Error formatting demo
+// import './errors-demo.js'