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// :setup script transform
//
// setup scripts are written like Svelte components:
//
// let firstName = null
// $: fullName = `${firstName} ${lastName}`
// fetchUser().then(user => { firstName = user.firstName })
//
// and are executed inside `with ($scope)` against the component's reactive
// store, so plain assignments (even from async callbacks) go through the
// proxy's set trap and re-render whatever depends on them. To make that work
// the source is lightly rewritten - no full JS parser, just a scanner that is
// string/comment-aware and only touches code at brace/paren depth 0:
// - `let/var/const x = ...` at the top level loses its keyword, becoming a
// scope assignment (the name is pre-declared on the store so the `with`
// lookup resolves it)
// - `$: x = expr` becomes `$__effect(() => { x = expr })`, re-running when a
// dependency read inside expr changes ($__effect is deliberately NOT a
// property of the scope, so `with` falls through to the function parameter)
// ---------------------------------------------------------------------------
type SetupTransform = { vars: string[]; code: string }
// a declaration whose target is an identifier (`let x`), an object pattern
// (`let { a }`, space optional) or an array pattern (`let [x]`)
const DECLARATION_START_RE = /(?:let|var|const)(?:\s+(?=[A-Za-z_$])|\s*(?=[{[]))/y
const REACTIVE_LABEL_RE = /\$:\s*/y
const IMPORT_CALL_RE = /import(?=\s*\()/y
const REACTIVE_ASSIGN_RE = /\$:\s*([A-Za-z_$][\w$]*)\s*=(?!=)/y
const skipString = (src: string, start: number): number => {
const quote = src[start]
let i = start + 1
while (i < src.length) {
if (src[i] === "\\") { i += 2; continue }
if (src[i] === quote) return i + 1
i++
}
return src.length
}
const skipLineComment = (src: string, start: number): number => {
const end = src.indexOf("\n", start)
return end === -1 ? src.length : end
}
const skipBlockComment = (src: string, start: number): number => {
const end = src.indexOf("*/", start + 2)
return end === -1 ? src.length : end + 2
}
// index of the next thing that isn't whitespace or a comment
const skipToToken = (src: string, start: number): number => {
let i = start
while (i < src.length) {
if (/\s/.test(src[i])) { i++; continue }
if (src[i] === "/" && src[i + 1] === "/") { i = skipLineComment(src, i); continue }
if (src[i] === "/" && src[i + 1] === "*") { i = skipBlockComment(src, i); continue }
break
}
return i
}
// ---------------------------------------------------------------------------
// regex literals. The scanners walk the source counting bracket depth, and a
// regex walked as if it were code poisons that count: `split(/\//)` puts two
// slashes side by side (a line comment, as far as a scanner knows) and the
// `)` after them is skipped uncounted; `/[(]/` inflates the depth for good.
// So a `/` that opens a regex is consumed whole - and whether it opens one is
// the classic lexer call, made the way every tokenizer makes it: by what came
// before. Division needs a completed expression on its left; everywhere else
// a `/` can only be a regex.
// ---------------------------------------------------------------------------
// reserved words a regex can follow. Reserved only - `of` is not (`const of
// = 4; of / 2` is legal division), so `for (x of /re/)` stays unrescued
// rather than risking real code
const REGEX_AFTER_WORD = new Set([
"return", "typeof", "case", "in", "instanceof", "new", "delete", "void", "do", "else", "yield", "await",
])
// whether a `/` at `at` opens a regex literal rather than a division: looks
// backward past whitespace and block comments for the last meaningful thing.
// A completed expression - identifier, number, closing quote or bracket,
// postfix ++/-- - takes division; a reserved word or any other punctuator
// admits a regex. Only consulted for the rare `/` that is neither `//` nor
// `/*`, so the scanners pay nothing on the common path
const regexAllowed = (src: string, at: number): boolean => {
let i = at - 1
while (i >= 0) {
const ch = src[i]
if (/\s/.test(ch)) { i--; continue }
if (ch === "/" && src[i - 1] === "*") {
const open = src.lastIndexOf("/*", i - 2)
Iif (open === -1) return true // an unopened comment tail: malformed input
i = open - 1
continue
}
break
}
if (i < 0) return true // the start of the source starts an expression
const ch = src[i]
if (/[\w$]/.test(ch)) {
let start = i
while (start > 0 && /[\w$]/.test(src[start - 1])) start--
return REGEX_AFTER_WORD.has(src.slice(start, i + 1))
}
if ((ch === "+" || ch === "-") && src[i - 1] === ch) return false // postfix ++/--
return !")]}\"'`.".includes(ch)
}
// consumes a regex literal (with its flags): backslash escapes, and character
// classes, where an unescaped `/` doesn't close the literal (`/[/]/` is one
// regex). A literal can't contain an unescaped newline, so hitting one means
// the classification was wrong or the input malformed - stop there, bounding
// any damage to a single line
const skipRegex = (src: string, start: number): number => {
let i = start + 1
let inClass = false
while (i < src.length) {
const ch = src[i]
if (ch === "\\") { i += 2; continue }
if (ch === "\n") return i
if (ch === "[") inClass = true
else if (ch === "]") inClass = false
else if (ch === "/" && !inClass) {
i++
while (i < src.length && /[a-z]/i.test(src[i])) i++ // flags
return i
}
i++
}
return src.length
}
// tokens that can't *start* a statement, so a line beginning with one is
// continuing the previous expression rather than opening a new statement -
// the same call JS's automatic semicolon insertion makes. Unary-only forms
// (!, ~, ++, --) are deliberately absent: those do start a statement, and JS
// inserts the semicolon before them
const CONTINUATION_RE = /^(\?\.|\?\?|&&|\|\||\*\*|[.,+\-*/%&|^<>=?:([])/
// the last meaningful character before `at`: walks back past whitespace and
// block comments, the way regexAllowed does. A line comment can't be skipped
// from behind (its start is only findable forwards), so a line ending in one
// reports the comment's text instead - callers treat that as "not the char I
// was looking for", which degrades to ending the statement, exactly as
// before this helper existed
const lastMeaningfulBefore = (src: string, at: number): string => {
let i = at - 1
while (i >= 0) {
const ch = src[i]
if (/\s/.test(ch)) { i--; continue }
Iif (ch === "/" && src[i - 1] === "*") {
const open = src.lastIndexOf("/*", i - 2)
if (open === -1) return ""
i = open - 1
continue
}
return ch
}
return ""
}
// end of a statement starting at `start`: the first `;` or line break that
// isn't inside a string/comment or unbalanced brackets. A line break only
// ends the statement if the next line can't continue it, so leading-dot
// method chains and multi-line operator chains stay in one piece:
//
// $: total = items
// .filter(item => item.active) <- still the same statement
// .length
//
// ...and only if the current line *can* end it: a line whose last meaningful
// character is `,` or `=` left its expression incomplete (a multi-line
// declarator list writes exactly this), so the statement continues - the
// same ASI call as the leading-token check, made from the other side
const findStatementEnd = (src: string, start: number): number => {
let depth = 0
let i = start
while (i < src.length) {
const ch = src[i]
if (ch === "'" || ch === '"' || ch === "`") { i = skipString(src, i); continue }
if (ch === "/" && src[i + 1] === "/") { i = skipLineComment(src, i); continue }
if (ch === "/" && src[i + 1] === "*") { i = skipBlockComment(src, i); continue }
if (ch === "/" && regexAllowed(src, i)) { i = skipRegex(src, i); continue }
if ("([{".includes(ch)) depth++
else if (")]}".includes(ch)) depth--
else if (depth <= 0 && ch === ";") return i
else if (depth <= 0 && ch === "\n") {
const next = skipToToken(src, i + 1)
const continues =
next < src.length &&
(CONTINUATION_RE.test(src.slice(next, next + 2)) || [",", "="].includes(lastMeaningfulBefore(src, i)))
if (!continues) return i
i = next
continue
}
i++
}
return src.length
}
// ---------------------------------------------------------------------------
// top-level declarations. `let x = 1` loses its keyword and becomes a scope
// assignment (x pre-declared on the store). A destructuring declarator
// becomes an *assignment pattern*: inside `with`, `({ a, b } = obj)` writes
// every binding through the reactive proxy - which is what makes it reactive.
// The parens keep the `{` from opening a block, and a leading `;` keeps the
// `(` from gluing onto the previous line as a call. Multi-declarator
// statements (`let a = 1, b = 2`) register every binding, not just the first.
// These lean on the pattern helpers defined with the props signature below
// (splitTopLevel, indexOfTopLevel, defaultAssignIndex); the scanner only
// runs long after the module evaluates, so the order is cosmetic
// ---------------------------------------------------------------------------
type Declarator = { raw: string; codeEnd: number }
// splits a declarator list at top-level commas, keeping each segment's raw
// text (layout and comments included) and where its last meaningful token
// ends - the spot a closing paren must go, so a trailing comment can't
// swallow it
const splitDeclarators = (src: string): Declarator[] => {
const parts: Declarator[] = []
let depth = 0
let start = 0
let lastEnd = 0
const flush = (end: number) => {
parts.push({ raw: src.slice(start, end), codeEnd: Math.max(0, lastEnd - start) })
start = end + 1
lastEnd = start
}
let i = 0
while (i < src.length) {
const ch = src[i]
if (ch === "'" || ch === '"' || ch === "`") { i = skipString(src, i); lastEnd = i; continue }
if (ch === "/" && src[i + 1] === "/") { i = skipLineComment(src, i); continue }
if (ch === "/" && src[i + 1] === "*") { i = skipBlockComment(src, i); continue }
if (ch === "/" && regexAllowed(src, i)) { i = skipRegex(src, i); lastEnd = i; continue }
if ("([{".includes(ch)) depth++
else if (")]}".includes(ch)) depth--
else if (ch === "," && depth <= 0) { flush(i); i++; continue }
if (!/\s/.test(ch)) lastEnd = i + 1
i++
}
flush(src.length)
return parts
}
// the *binding* names a destructuring pattern declares - unlike
// parsePropsPattern, which answers "which props" (the keys), this answers
// "which variables": `{ a: x }` binds x, `{ a: { b } }` binds b,
// `[x, ...rest]` binds x and rest. Defaults are stripped; what remains is a
// nested pattern (recurse) or the bound identifier
const patternBindings = (src: string): string[] => {
const pattern = src.trim()
if (!pattern.startsWith("{") && !pattern.startsWith("[")) {
return IDENTIFIER_RE.test(pattern) ? [pattern] : []
}
const names: string[] = []
for (let part of splitTopLevel(pattern.slice(1, patternCloseIndex(pattern)))) {
if (part.startsWith("...")) part = part.slice(3).trim()
const assign = defaultAssignIndex(part)
if (assign !== -1) part = part.slice(0, assign).trim()
if (pattern.startsWith("{")) {
const colon = indexOfTopLevel(part, ":")
if (colon !== -1) {
names.push(...patternBindings(part.slice(colon + 1)))
continue
}
}
names.push(...patternBindings(part))
}
return names
}
// one `let/var/const` declarator list, rewritten to scope assignments.
// Each segment's initializer is re-scanned so an `import()` inside it is
// rewritten like anywhere else - nothing else can match in there, since a
// nested top-level declaration inside a declarator is a SyntaxError in JS
const rewriteDeclarators = (src: string): SetupTransform => {
const vars: string[] = []
const rewritten = splitDeclarators(src).map(({ raw, codeEnd }) => {
const lead = raw.match(/^\s*/)![0]
Iif (codeEnd <= lead.length) return { text: raw, empty: true }
const body = raw.slice(lead.length, codeEnd)
const tail = raw.slice(codeEnd)
const assign = defaultAssignIndex(body)
const target = (assign === -1 ? body : body.slice(0, assign)).trim()
const isPattern = body[0] === "{" || body[0] === "["
if (isPattern) vars.push(...patternBindings(target))
else if (IDENTIFIER_RE.test(target)) vars.push(target)
const code = transformSetupScript(body).code
return { text: `${lead}${isPattern ? `(${code})` : code}${tail}`, empty: false }
})
// a trailing comment-only segment (`let a = 1, // note` cut at its line
// end) is re-attached without its comma, so the output stays a statement
const tail: string[] = []
while (rewritten.length && rewritten[rewritten.length - 1].empty) tail.unshift(rewritten.pop()!.text)
let code = rewritten.map(part => part.text).join(",") + tail.join("")
if (code.trimStart().startsWith("(")) code = `;${code}`
return { vars, code }
}
export const transformSetupScript = (src: string): SetupTransform => {
const vars: string[] = []
let out = ""
let i = 0
let depth = 0
let atStatementStart = true
while (i < src.length) {
const ch = src[i]
const next = src[i + 1]
if (ch === "'" || ch === '"' || ch === "`") {
const end = skipString(src, i)
out += src.slice(i, end)
i = end
atStatementStart = false
continue
}
if (ch === "/" && (next === "/" || next === "*")) {
const end = next === "/" ? skipLineComment(src, i) : skipBlockComment(src, i)
out += src.slice(i, end)
i = end
continue
}
if (ch === "/" && regexAllowed(src, i)) {
const end = skipRegex(src, i)
out += src.slice(i, end)
i = end
atStatementStart = false
continue
}
// `import(...)` is a keyword form, so it can't be intercepted through the
// scope - rewrite the identifier to the injected $__import (which loads
// .html URLs as components via Component79.fetch and delegates the rest to
// native import). The `(` is left for the scanner so depth stays balanced
if (ch === "i" && (i === 0 || !/[\w$.]/.test(src[i - 1]))) {
IMPORT_CALL_RE.lastIndex = i
if (IMPORT_CALL_RE.test(src)) {
out += "$__import"
i += "import".length
atStatementStart = false
continue
}
}
if (depth === 0 && atStatementStart) {
DECLARATION_START_RE.lastIndex = i
const decl = DECLARATION_START_RE.exec(src)
if (decl) {
const start = i + decl[0].length
const end = findStatementEnd(src, start)
const { vars: names, code } = rewriteDeclarators(src.slice(start, end))
vars.push(...names)
out += code
i = end
atStatementStart = false
continue
}
REACTIVE_LABEL_RE.lastIndex = i
const label = REACTIVE_LABEL_RE.exec(src)
if (label) {
REACTIVE_ASSIGN_RE.lastIndex = i
const assign = REACTIVE_ASSIGN_RE.exec(src)
if (assign) vars.push(assign[1])
const start = i + label[0].length
const end = findStatementEnd(src, start)
// the body is re-scanned rather than sliced raw, so an `import()`
// inside it gets the $__import rewrite like anywhere else. Safe to
// recurse: strings/comments/regexes copy through unchanged, and a
// depth-0 declaration inside a labeled statement is a SyntaxError
// in JS anyway, so nothing else can rewrite
out += `$__effect(() => { ${transformSetupScript(src.slice(start, end)).code} });`
i = end
continue
}
}
if ("([{".includes(ch)) depth++
else if (")]}".includes(ch)) depth = Math.max(0, depth - 1)
if (ch === "\n" || ch === ";" || ch === "}") atStatementStart = true
else if (!/\s/.test(ch)) atStatementStart = false
out += ch
i++
}
return { vars, code: out }
}
// ---------------------------------------------------------------------------
// factory scripts - a <script> whose top level has `export default` runs as a
// plain lexical module instead of a `with`-scoped setup script: no implicit
// reactivity, no `$:` labels - standard JS that editors and type-checkers
// understand. The default export is called with the instance context
// ({ $data, $effect, $emit, $mounted, $destroyed, $attached, $detached, $computed, $self, $$self }) and a returned object
// is merged into the reactive store for the template to use.
// Detection is backwards-safe: `export default` is a SyntaxError inside a
// setup script, so no previously-working component can change behavior.
// The same scanner rewrites the module-only syntax into a Function body:
// - `export default X` -> `$__exports.default = X`
// - `import d from "m"` -> `const d = $__default(await $__import("m"))`
// (and the other static clause forms), so imports resolve through the same
// $__import as setup scripts: bundler map first, then fetch/native import
// ---------------------------------------------------------------------------
const EXPORT_DEFAULT_RE = /export\s+default(?![\w$])/y
// clause (default/namespace/named, no quotes or parens) + specifier; the
// no-clause alternative requires the specifier right away, so dynamic
// `import(...)` and `import.meta` never match
const STATIC_IMPORT_RE = /import\s*(?:([\w$\s,{}*]+?)\s*from\s*)?(["'])([^"'\n]+)\2/y
// splits an import clause on top-level commas: `d, { a, b as c }` keeps the
// braced group together
const splitImportClause = (clause: string): string[] => {
const parts: string[] = []
let depth = 0
let start = 0
for (let i = 0; i <= clause.length; i++) {
const ch = clause[i]
if (ch === "{") depth++
else if (ch === "}") depth--
else if (i === clause.length || (ch === "," && depth === 0)) {
const part = clause.slice(start, i).trim()
Eif (part) parts.push(part)
start = i + 1
}
}
return parts
}
// one static import statement -> const bindings from the awaited module
const staticImportToAwait = (clause: string | undefined, spec: string, n: number): string => {
const source = `await $__import(${JSON.stringify(spec)})`
if (clause === undefined) return source // side-effect import
const parts = splitImportClause(clause)
const bindings: string[] = []
let ref = source
if (parts.length > 1) {
const tmp = `$__mod${n}`
bindings.push(`${tmp} = ${source}`)
ref = tmp
}
for (const part of parts) {
if (part.startsWith("{")) bindings.push(`${part.replace(/\s+as\s+/g, ": ")} = ${ref}`)
else if (part.startsWith("*")) bindings.push(`${part.replace(/^\*\s*as\s+/, "")} = ${ref}`)
else bindings.push(`${part} = $__default(${ref})`)
}
return `const ${bindings.join(", ")}`
}
// ---------------------------------------------------------------------------
// the component's prop signature
//
// A component declares the props it takes as a destructuring pattern, in the
// place each script mode already puts its inputs: the `:setup` attribute's
// value, or the factory's *first* parameter (the ctx moved to the second).
// Position is fixed, so the signature is read straight from the source string -
// no parser, no execution - and the runtime can seed the defaults on the store
// before the first render, which is what makes them reach the template even in
// factory mode (where JS would only apply them inside the function body).
//
// <script :setup="{ label = 'Total', step = 1 }">
// export default ({ label = "Total" }, { $data }) => {}
//
// An object pattern *is* the declaration; anything else (`_`, a plain
// identifier, no attribute at all) declares nothing and stays permissive.
// ---------------------------------------------------------------------------
// `as` is the local name the pattern binds the key to, when it isn't the key
// itself (`{ item: row }`). A prop signature has no use for it - what the
// store holds is the key - but the slot binder (`:slot="{ item: row }"`) is
// the same pattern read for the other half: which names the content uses
export type PropDecl = { name: string; default?: string; as?: string }
const IDENTIFIER_RE = /^[A-Za-z_$][\w$]*$/
// index of the bracket that closes the one opening at src[0], skipping
// strings, comments and regex literals; src.length when unbalanced
const patternCloseIndex = (src: string): number => {
let depth = 0
let i = 0
while (i < src.length) {
const ch = src[i]
if (ch === "'" || ch === '"' || ch === "`") { i = skipString(src, i); continue }
Iif (ch === "/" && src[i + 1] === "/") { i = skipLineComment(src, i); continue }
if (ch === "/" && src[i + 1] === "*") { i = skipBlockComment(src, i); continue }
if (ch === "/" && regexAllowed(src, i)) { i = skipRegex(src, i); continue }
if ("([{".includes(ch)) depth++
else if (")]}".includes(ch) && --depth === 0) return i
i++
}
return src.length
}
// index of the first `ch` at bracket depth 0, skipping strings and comments
const indexOfTopLevel = (src: string, ch: string): number => {
let depth = 0
let i = 0
while (i < src.length) {
const c = src[i]
Iif (c === "'" || c === '"' || c === "`") { i = skipString(src, i); continue }
Iif (c === "/" && src[i + 1] === "/") { i = skipLineComment(src, i); continue }
Iif (c === "/" && src[i + 1] === "*") { i = skipBlockComment(src, i); continue }
Iif (c === "/" && c !== ch && regexAllowed(src, i)) { i = skipRegex(src, i); continue }
if ("([{".includes(c)) depth++
else if (")]}".includes(c)) depth--
else if (depth === 0 && c === ch) return i
i++
}
return -1
}
const splitTopLevel = (src: string): string[] => {
const parts: string[] = []
let depth = 0
let start = 0
let i = 0
while (i <= src.length) {
const ch = src[i]
if (ch === "'" || ch === '"' || ch === "`") { i = skipString(src, i); continue }
Iif (ch === "/" && src[i + 1] === "/") { i = skipLineComment(src, i); continue }
if (ch === "/" && src[i + 1] === "*") { i = skipBlockComment(src, i); continue }
if (ch === "/" && regexAllowed(src, i)) { i = skipRegex(src, i); continue }
if (ch !== undefined && "([{".includes(ch)) depth++
else if (ch !== undefined && ")]}".includes(ch)) depth--
else if (i === src.length || (ch === "," && depth === 0)) {
const part = src.slice(start, i).trim()
if (part) parts.push(part)
start = i + 1
}
i++
}
return parts
}
// the `=` that opens a default value: the first one at depth 0 that isn't part
// of `==`/`===` or an arrow's `=>` (so `{ format = a => a }` keeps its default)
const defaultAssignIndex = (src: string): number => {
let from = 0
while (from < src.length) {
const at = indexOfTopLevel(src.slice(from), "=")
if (at === -1) return -1
const i = from + at
Eif (src[i + 1] !== "=" && src[i + 1] !== ">" && src[i - 1] !== "=" && src[i - 1] !== "!") return i
from = i + 1
}
return -1
}
// a destructuring pattern -> the props it declares. null means "no signature":
// the pattern isn't an object one (`_`, `props`, nothing at all), so the
// component declares nothing and keeps the permissive, undeclared behavior.
// `{}` parses to [] - a closed signature that declares zero props
export const parsePropsPattern = (pattern: string | undefined): PropDecl[] | null => {
const src = (pattern ?? "").trim()
if (!src.startsWith("{")) return null
// to the `}` that closes the pattern, so a parameter's own default value
// (`({ label } = {})`) is left out of it
const close = patternCloseIndex(src)
if (close >= src.length) return null // unbalanced: not a pattern we can read
const props: PropDecl[] = []
for (const part of splitTopLevel(src.slice(1, close))) {
if (part.startsWith("...")) continue // a rest element names no prop
const assign = defaultAssignIndex(part)
const named = assign === -1 ? part : part.slice(0, assign)
const fallback = assign === -1 ? undefined : part.slice(assign + 1).trim()
// `{ user: { id } }` and `{ user: renamed }` both declare `user`: what the
// store holds is the key, whatever the pattern binds it to
const colon = indexOfTopLevel(named, ":")
const name = (colon === -1 ? named : named.slice(0, colon)).trim()
Iif (!IDENTIFIER_RE.test(name)) continue
const decl: PropDecl = { name }
if (fallback !== undefined) decl.default = fallback
// only a plain rename is kept: `{ user: { id } }` binds no single name, so
// there is nothing to record - the prop is still declared under its key
const local = colon === -1 ? "" : named.slice(colon + 1).trim()
if (IDENTIFIER_RE.test(local)) decl.as = local
props.push(decl)
}
return props
}
// index just past a top-level `export default`, or -1
const findExportDefault = (src: string): number => {
let i = 0
let depth = 0
let atStatementStart = true
while (i < src.length) {
const ch = src[i]
if (ch === "'" || ch === '"' || ch === "`") { i = skipString(src, i); atStatementStart = false; continue }
if (ch === "/" && src[i + 1] === "/") { i = skipLineComment(src, i); continue }
Iif (ch === "/" && src[i + 1] === "*") { i = skipBlockComment(src, i); continue }
if (ch === "/" && regexAllowed(src, i)) { i = skipRegex(src, i); atStatementStart = false; continue }
if (ch === "e" && depth === 0 && atStatementStart && (i === 0 || !/[\w$.]/.test(src[i - 1]))) {
EXPORT_DEFAULT_RE.lastIndex = i
const found = EXPORT_DEFAULT_RE.exec(src)
Eif (found) return i + found[0].length
}
if ("([{".includes(ch)) depth++
else if (")]}".includes(ch)) depth = Math.max(0, depth - 1)
if (ch === "\n" || ch === ";" || ch === "}") atStatementStart = true
else if (!/\s/.test(ch)) atStatementStart = false
i++
}
return -1
}
const ASYNC_RE = /^async(?![\w$])/
const FUNCTION_RE = /^function(?![\w$])\s*\*?\s*[A-Za-z_$][\w$]*|^function(?![\w$])\s*\*?/
// source text of the exported function's first parameter, or null when there
// is no parameter list to read (`export default Factory`, `export default
// props => ...`, an exported object) - all of which declare nothing
const firstParameterSource = (src: string): string | null => {
const start = findExportDefault(src)
if (start === -1) return null
let i = skipToToken(src, start)
const rest = src.slice(i)
if (ASYNC_RE.test(rest)) i = skipToToken(src, i + "async".length)
const fn = FUNCTION_RE.exec(src.slice(i))
if (fn) i = skipToToken(src, i + fn[0].length)
if (src[i] !== "(") return null
// the parameter list runs to the `)` that closes this `(`
let depth = 0
let end = i
while (end < src.length) {
const ch = src[end]
if (ch === "'" || ch === '"' || ch === "`") { end = skipString(src, end); continue }
Iif (ch === "/" && src[end + 1] === "/") { end = skipLineComment(src, end); continue }
if (ch === "/" && src[end + 1] === "*") { end = skipBlockComment(src, end); continue }
if (ch === "/" && regexAllowed(src, end)) { end = skipRegex(src, end); continue }
if ("([{".includes(ch)) depth++
else if (")]}".includes(ch) && --depth === 0) break
end++
}
return splitTopLevel(src.slice(i + 1, end))[0] ?? ""
}
// the props declared by a factory script's first parameter. Throws the
// migration error when it finds the pre-0.4 signature there - the ctx used to
// be the first parameter, and the change is silent otherwise ($data would just
// come back undefined). `$` is what tells them apart: what carries one comes
// from the library, what doesn't comes from the parent, everywhere in jq79
export const parseFactoryProps = (src: string): PropDecl[] | null => {
const first = firstParameterSource(src)
if (first === null) return null
const props = parsePropsPattern(first)
const ctxName = props?.find(prop => prop.name.startsWith("$"))?.name
if (ctxName) {
throw new Error(
`jq79: the factory signature is (props, ctx), so \`${ctxName}\` can't be destructured from the first parameter. ` +
`Write \`export default (props, { ${ctxName} }) => …\`, or \`_\` in place of props if the component takes none.`
)
}
return props
}
// rewrites a factory script into a Function body, or returns null when the
// script has no top-level `export default` (i.e. it's a regular setup script)
export const transformFactoryScript = (src: string): string | null => {
let out = ""
let i = 0
let depth = 0
let atStatementStart = true
let isFactory = false
let modCount = 0
while (i < src.length) {
const ch = src[i]
const next = src[i + 1]
const atWordBoundary = i === 0 || !/[\w$.]/.test(src[i - 1])
if (ch === "'" || ch === '"' || ch === "`") {
const end = skipString(src, i)
out += src.slice(i, end)
i = end
atStatementStart = false
continue
}
if (ch === "/" && (next === "/" || next === "*")) {
const end = next === "/" ? skipLineComment(src, i) : skipBlockComment(src, i)
out += src.slice(i, end)
i = end
continue
}
if (ch === "/" && regexAllowed(src, i)) {
const end = skipRegex(src, i)
out += src.slice(i, end)
i = end
atStatementStart = false
continue
}
if (ch === "i" && atWordBoundary) {
// dynamic import() -> $__import, same rewrite as setup scripts
IMPORT_CALL_RE.lastIndex = i
if (IMPORT_CALL_RE.test(src)) {
out += "$__import"
i += "import".length
atStatementStart = false
continue
}
if (depth === 0 && atStatementStart) {
STATIC_IMPORT_RE.lastIndex = i
const staticImport = STATIC_IMPORT_RE.exec(src)
if (staticImport) {
out += staticImportToAwait(staticImport[1], staticImport[3], modCount++)
i += staticImport[0].length
atStatementStart = false
continue
}
}
}
if (ch === "e" && atWordBoundary && depth === 0 && atStatementStart) {
EXPORT_DEFAULT_RE.lastIndex = i
const exportDefault = EXPORT_DEFAULT_RE.exec(src)
Eif (exportDefault) {
isFactory = true
out += "$__exports.default ="
i += exportDefault[0].length
atStatementStart = false
continue
}
}
if ("([{".includes(ch)) depth++
else if (")]}".includes(ch)) depth = Math.max(0, depth - 1)
if (ch === "\n" || ch === ";" || ch === "}") atStatementStart = true
else if (!/\s/.test(ch)) atStatementStart = false
out += ch
i++
}
return isFactory ? out : null
}
// ---------------------------------------------------------------------------
// free identifiers in a template expression
//
// What a compiled expression reads from the scope, so it can be resolved by
// name instead of by `with ($scope)` - which is 60% of an evaluation over a
// store proxy, because it resolves every mention through [[HasProperty]] (the
// proxy's `has` trap as well as its `get`) and consults Symbol.unscopables
// besides. See RECORD/2026-08-27.name-resolution-without-with.md
//
// This is a scanner, not a parser, and it is deliberately conservative: `null`
// means "keep `with`", and every shape that binds a name, assigns to one or
// resolves one dynamically returns it. The caller falls back rather than
// guesses, so a name this misses costs a slower evaluation, never a wrong one.
// ---------------------------------------------------------------------------
// words that scan as an identifier and are never a free variable read
const NOT_A_FREE_NAME = new Set([
"true", "false", "null", "undefined", "this", "typeof", "instanceof", "in", "new", "void",
"delete", "of", "await", "yield", "NaN", "Infinity", "arguments", "case", "do", "else", "return",
])
// anything that introduces a binding or reaches the scope by another route.
// A dynamic `import(...)` is absent deliberately: naming it here would put the
// word next to a quote in the bundle, which is what tests/no-bundle.test.ts
// greps for. It needs no entry - `import` is collected as a free name, the
// prologue's `const import = …` will not compile, and compileScoped falls back
const BINDS_A_NAME = new Set(["function", "class", "let", "const", "var", "eval", "with"])
// the compiled function's own parameters and temporary: an expression that
// mentions one would be reading the codegen's variable, not the author's
const CODEGEN_NAMES = new Set(["$scope", "$r", "$t"])
// operators that write, or bind - any of them and the expression keeps `with`
const WRITES_RE = /^(?:\+\+|--|=>|\*\*=|<<=|>>>=|>>=|&&=|\|\|=|\?\?=|[+\-*/%&|^]=(?!=))/
// operators that merely read, longest first so `===` is never read as `==` + `=`
const READS_RE = /^(?:>>>|===|!==|\*\*|<<|>>|==|!=|<=|>=|&&|\|\||\?\?|\?\.)/
const isIdentifierStart = (ch: string): boolean => /[A-Za-z_$]/.test(ch)
// a numeric literal, consumed whole so `1e5` does not scan as the name `e5`
const NUMBER_RE = /^(?:0[xXbBoO][\da-fA-F_]+|\d[\d_]*(?:\.[\d_]*)?(?:[eE][+-]?\d+)?)n?/
export const freeIdentifiers = (expr: string): string[] | null => {
const names = new Set<string>()
// one entry per open bracket, counting the `?`s waiting for their `:` at that
// depth - which is what tells `{ danger: x }`'s key from `a ? b : c`'s colon
const ternaries: number[] = [0]
const brackets: string[] = []
let shortCircuits = false
let prev = "" // the last meaningful token: "name", "value", "." or "?." or a punctuator
let i = 0
while (i < expr.length) {
const ch = expr[i]
if (/\s/.test(ch)) { i++; continue }
if (ch === "/" && expr[i + 1] === "/") { i = skipLineComment(expr, i); continue }
Iif (ch === "/" && expr[i + 1] === "*") { i = skipBlockComment(expr, i); continue }
if (ch === "/" && regexAllowed(expr, i)) { i = skipRegex(expr, i); prev = "value"; continue }
if (ch === '"' || ch === "'") { i = skipString(expr, i); prev = "value"; continue }
if (ch === "`") {
// a template literal reads names inside every ${...}, and nothing else
let j = i + 1
while (j < expr.length) {
Iif (expr[j] === "\\") { j += 2; continue }
if (expr[j] === "`") { j++; break }
if (expr[j] === "$" && expr[j + 1] === "{") {
let depth = 1
const start = (j += 2)
while (j < expr.length && depth > 0) {
Iif (expr[j] === "{") depth++
else if (expr[j] === "}") depth--
j++
}
const inner = freeIdentifiers(expr.slice(start, j - 1))
Iif (inner === null) return null
inner.forEach(name => names.add(name))
continue
}
j++
}
i = j
prev = "value"
continue
}
if (/\d/.test(ch) && prev !== "." && prev !== "?.") {
const match = NUMBER_RE.exec(expr.slice(i))
i += match ? match[0].length : 1
prev = "value"
continue
}
if (isIdentifierStart(ch)) {
let end = i
while (end < expr.length && /[\w$]/.test(expr[end])) end++
const word = expr.slice(i, end)
i = end
if (BINDS_A_NAME.has(word)) return null
if (prev === "." || prev === "?.") { prev = "value"; continue } // a property, not a name
if (NOT_A_FREE_NAME.has(word)) { prev = word === "this" ? "value" : "op"; continue }
if (CODEGEN_NAMES.has(word)) return null
let after = i
while (after < expr.length && /\s/.test(expr[after])) after++
// A free name that is CALLED is called with the with-object as its
// receiver: `add()` inside `with ($scope)` runs with `this === $scope`,
// and a factory component's `{ items: [], add() { this.items… } }`
// depends on it. A `const` cannot reproduce that - the call would get
// `undefined` - so a called name keeps `with`. Measured at 11 of this
// repository's 239 resolvable expressions, and 8 of those are handlers
if (expr[after] === "(") return null
// `{ danger: … }` names a key; `a ? b : c` names a value
const isKey = expr[after] === ":" && expr[after + 1] !== ":" &&
brackets[brackets.length - 1] === "{" && ternaries[ternaries.length - 1] === 0
if (!isKey) names.add(word)
prev = "value"
continue
}
const rest = expr.slice(i)
if (WRITES_RE.test(rest)) return null
const reads = READS_RE.exec(rest)
if (reads) {
if (reads[0] === "&&" || reads[0] === "||" || reads[0] === "??") shortCircuits = true
prev = reads[0] === "?." ? "?." : "op"
i += reads[0].length
continue
}
if (ch === "=") return null // a bare `=` left after READS_RE is an assignment
if (ch === "(" || ch === "[" || ch === "{") { brackets.push(ch); ternaries.push(0) }
else if (ch === ")" || ch === "]" || ch === "}") { brackets.pop(); if (ternaries.length > 1) ternaries.pop() }
else if (ch === "?") { ternaries[ternaries.length - 1]++; shortCircuits = true }
else if (ch === ":" && ternaries[ternaries.length - 1] > 0) ternaries[ternaries.length - 1]--
prev = ch
i++
}
// every name is resolved before the expression runs, so a branch that would
// not have been taken is read anyway: one more dep than `with` would track,
// and a ReferenceError for a name only the dead branch mentions. With one
// name there is no branch to be wrong about
if (shortCircuits && names.size > 1) return null
return [...names]
}
|