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Add support for passing baseUrl when running
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Previously, `baseUrl` was supported at compile time.
That meant it wasn’t possible to use `compile` with `outputFormat:
'function-body'` on a server and `run` on a client, and choosing the
URL there, which is likely what you want in that setup, to pass
`import.meta.url`.

Additionally, `import()` expressions using an exression (e.g.,
`'@mdx-js/' + 'mdx'`) are now supported.

If you use `run` or `evaluate`, you *should* pass `baseUrl`, likely as
`import.meta.url`.

If you don’t, and it is needed (because `export … from`, `import`, or
`import.meta.url`), you will get a runtime error.
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@wooorm
wooorm committed Oct 23, 2023
1 parent c961af8 commit e12f307
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Showing 7 changed files with 429 additions and 67 deletions.
8 changes: 2 additions & 6 deletions packages/mdx/lib/core.js
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Original file line number Diff line number Diff line change
Expand Up @@ -16,12 +16,8 @@
* Add a source map (object form) as the `map` field on the resulting file
* (optional).
* @property {URL | string | null | undefined} [baseUrl]
* Resolve `import`s (and `export … from`, and `import.meta.url`) from this
* URL (optional, example: `import.meta.url`);
* this option is useful when code will run in a different place, such as
* when `.mdx` files are in path *a* but compiled to path *b* and imports
* should run relative the path *b*, or when evaluating code, whether in Node
* or a browser.
* Use this URL as `import.meta.url` and resolve `import` and `export … from`
* relative to it (optional, example: `import.meta.url`).
* @property {boolean | null | undefined} [development=false]
* Whether to add extra info to error messages in generated code and use the
* development automatic JSX runtime (`Fragment` and `jsxDEV` from
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294 changes: 263 additions & 31 deletions packages/mdx/lib/plugin/recma-document.js
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Original file line number Diff line number Diff line change
@@ -1,11 +1,13 @@
/**
* @typedef {import('estree-jsx').CallExpression} CallExpression
* @typedef {import('estree-jsx').Directive} Directive
* @typedef {import('estree-jsx').ExportAllDeclaration} ExportAllDeclaration
* @typedef {import('estree-jsx').ExportDefaultDeclaration} ExportDefaultDeclaration
* @typedef {import('estree-jsx').ExportNamedDeclaration} ExportNamedDeclaration
* @typedef {import('estree-jsx').ExportSpecifier} ExportSpecifier
* @typedef {import('estree-jsx').Expression} Expression
* @typedef {import('estree-jsx').FunctionDeclaration} FunctionDeclaration
* @typedef {import('estree-jsx').Identifier} Identifier
* @typedef {import('estree-jsx').ImportDeclaration} ImportDeclaration
* @typedef {import('estree-jsx').ImportDefaultSpecifier} ImportDefaultSpecifier
* @typedef {import('estree-jsx').ImportExpression} ImportExpression
Expand Down Expand Up @@ -36,6 +38,7 @@ import {create} from '../util/estree-util-create.js'
import {declarationToExpression} from '../util/estree-util-declaration-to-expression.js'
import {isDeclaration} from '../util/estree-util-is-declaration.js'
import {specifiersToDeclarations} from '../util/estree-util-specifiers-to-declarations.js'
import {toIdOrMemberExpression} from '../util/estree-util-to-id-or-member-expression.js'

/**
* Wrap the estree in `MDXContent`.
Expand All @@ -46,8 +49,8 @@ import {specifiersToDeclarations} from '../util/estree-util-specifiers-to-declar
* Transform.
*/
export function recmaDocument(options) {
const baseUrl_ = options.baseUrl || undefined
const baseUrl = typeof baseUrl_ === 'object' ? baseUrl_.href : baseUrl_
const baseUrl = options.baseUrl || undefined
const baseHref = typeof baseUrl === 'object' ? baseUrl.href : baseUrl
const outputFormat = options.outputFormat || 'program'
const pragma =
options.pragma === undefined ? 'React.createElement' : options.pragma
Expand Down Expand Up @@ -321,9 +324,68 @@ export function recmaDocument(options) {

tree.body = replacement

if (baseUrl) {
let usesImportMetaUrlVariable = false
let usesResolveDynamicHelper = false

if (baseHref || outputFormat === 'function-body') {
walk(tree, {
enter(node) {
if (
(node.type === 'ExportAllDeclaration' ||
node.type === 'ExportNamedDeclaration' ||
node.type === 'ImportDeclaration') &&
node.source
) {
// We never hit this branch when generating function bodies, as
// statements are already compiled away into import expressions.
assert(baseHref, 'unexpected missing `baseHref` in branch')

let value = node.source.value
// The literal source for statements can only be string.
assert(typeof value === 'string', 'expected string source')

// Resolve a specifier.
// This is the same as `_resolveDynamicMdxSpecifier`, which has to
// be injected to work with expressions at runtime, but as we have
// `baseHref` at compile time here and statements are static
// strings, we can do it now.
try {
// To do: use `URL.canParse` next major.
// eslint-disable-next-line no-new
new URL(value)
// Fine: a full URL.
} catch {
if (
value.startsWith('/') ||
value.startsWith('./') ||
value.startsWith('../')
) {
value = new URL(value, baseHref).href
} else {
// Fine: are bare specifier.
}
}

/** @type {SimpleLiteral} */
const replacement = {type: 'Literal', value}
create(node.source, replacement)
node.source = replacement
return
}

if (node.type === 'ImportExpression') {
usesResolveDynamicHelper = true
/** @type {CallExpression} */
const replacement = {
type: 'CallExpression',
callee: {type: 'Identifier', name: '_resolveDynamicMdxSpecifier'},
arguments: [node.source],
optional: false
}
node.source = replacement
return
}

if (
node.type === 'MemberExpression' &&
'object' in node &&
Expand All @@ -333,14 +395,38 @@ export function recmaDocument(options) {
node.object.property.name === 'meta' &&
node.property.name === 'url'
) {
/** @type {SimpleLiteral} */
const replacement = {type: 'Literal', value: baseUrl}
usesImportMetaUrlVariable = true
/** @type {Identifier} */
const replacement = {type: 'Identifier', name: '_importMetaUrl'}
create(node, replacement)
this.replace(replacement)
}
}
})
}

if (usesResolveDynamicHelper) {
if (!baseHref) {
usesImportMetaUrlVariable = true
}

tree.body.push(
resolveDynamicMdxSpecifier(
baseHref
? {type: 'Literal', value: baseHref}
: {type: 'Identifier', name: '_importMetaUrl'}
)
)
}

if (usesImportMetaUrlVariable) {
assert(
outputFormat === 'function-body',
'expected `function-body` when using dynamic url injection'
)
tree.body.unshift(...createImportMetaUrlVariable())
}

/**
* @param {ExportAllDeclaration | ExportNamedDeclaration} node
* Export node.
Expand Down Expand Up @@ -379,32 +465,6 @@ export function recmaDocument(options) {
* Nothing.
*/
function handleEsm(node) {
// Rewrite the source of the `import` / `export … from`.
// See: <https://html.spec.whatwg.org/multipage/webappapis.html#resolve-a-module-specifier>
if (baseUrl && node.source) {
let value = String(node.source.value)

try {
// A full valid URL.
value = String(new URL(value))
} catch {
// Relative: `/example.js`, `./example.js`, and `../example.js`.
if (/^\.{0,2}\//.test(value)) {
value = String(new URL(value, baseUrl))
}
// Otherwise, it’s a bare specifiers.
// For example `some-package`, `@some-package`, and
// `some-package/path`.
// These are supported in Node and browsers plan to support them
// with import maps (<https://github.com/WICG/import-maps>).
}

/** @type {Literal} */
const literal = {type: 'Literal', value}
create(node.source, literal)
node.source = literal
}

/** @type {ModuleDeclaration | Statement | undefined} */
let replace
/** @type {Expression} */
Expand Down Expand Up @@ -639,3 +699,175 @@ export function recmaDocument(options) {
]
}
}

/**
* @param {Expression} importMetaUrl
* @returns {FunctionDeclaration}
*/
function resolveDynamicMdxSpecifier(importMetaUrl) {
return {
type: 'FunctionDeclaration',
id: {type: 'Identifier', name: '_resolveDynamicMdxSpecifier'},
generator: false,
async: false,
params: [{type: 'Identifier', name: 'd'}],
body: {
type: 'BlockStatement',
body: [
{
type: 'IfStatement',
test: {
type: 'BinaryExpression',
left: {
type: 'UnaryExpression',
operator: 'typeof',
prefix: true,
argument: {type: 'Identifier', name: 'd'}
},
operator: '!==',
right: {type: 'Literal', value: 'string'}
},
consequent: {
type: 'ReturnStatement',
argument: {type: 'Identifier', name: 'd'}
},
alternate: null
},
// To do: use `URL.canParse` when widely supported (see commented
// out code below).
{
type: 'TryStatement',
block: {
type: 'BlockStatement',
body: [
{
type: 'ExpressionStatement',
expression: {
type: 'NewExpression',
callee: {type: 'Identifier', name: 'URL'},
arguments: [{type: 'Identifier', name: 'd'}]
}
},
{
type: 'ReturnStatement',
argument: {type: 'Identifier', name: 'd'}
}
]
},
handler: {
type: 'CatchClause',
param: null,
body: {type: 'BlockStatement', body: []}
},
finalizer: null
},
// To do: use `URL.canParse` when widely supported.
// {
// type: 'IfStatement',
// test: {
// type: 'CallExpression',
// callee: toIdOrMemberExpression(['URL', 'canParse']),
// arguments: [{type: 'Identifier', name: 'd'}],
// optional: false
// },
// consequent: {
// type: 'ReturnStatement',
// argument: {type: 'Identifier', name: 'd'}
// },
// alternate: null
// },
{
type: 'IfStatement',
test: {
type: 'LogicalExpression',
left: {
type: 'LogicalExpression',
left: {
type: 'CallExpression',
callee: toIdOrMemberExpression(['d', 'startsWith']),
arguments: [{type: 'Literal', value: '/'}],
optional: false
},
operator: '||',
right: {
type: 'CallExpression',
callee: toIdOrMemberExpression(['d', 'startsWith']),
arguments: [{type: 'Literal', value: './'}],
optional: false
}
},
operator: '||',
right: {
type: 'CallExpression',
callee: toIdOrMemberExpression(['d', 'startsWith']),
arguments: [{type: 'Literal', value: '../'}],
optional: false
}
},
consequent: {
type: 'ReturnStatement',
argument: {
type: 'MemberExpression',
object: {
type: 'NewExpression',
callee: {type: 'Identifier', name: 'URL'},
arguments: [{type: 'Identifier', name: 'd'}, importMetaUrl]
},
property: {type: 'Identifier', name: 'href'},
computed: false,
optional: false
}
},
alternate: null
},
{
type: 'ReturnStatement',
argument: {type: 'Identifier', name: 'd'}
}
]
}
}
}

/**
* @returns {Array<Statement>}
*/
function createImportMetaUrlVariable() {
return [
{
type: 'VariableDeclaration',
declarations: [
{
type: 'VariableDeclarator',
id: {type: 'Identifier', name: '_importMetaUrl'},
init: toIdOrMemberExpression(['arguments', 0, 'baseUrl'])
}
],
kind: 'const'
},
{
type: 'IfStatement',
test: {
type: 'UnaryExpression',
operator: '!',
prefix: true,
argument: {type: 'Identifier', name: '_importMetaUrl'}
},
consequent: {
type: 'ThrowStatement',
argument: {
type: 'NewExpression',
callee: {type: 'Identifier', name: 'Error'},
arguments: [
{
type: 'Literal',
value:
'Unexpected missing `options.baseUrl` needed to support `export … from`, `import`, or `import.meta.url` when generating `function-body`'
}
]
}
},
alternate: null
}
]
}
2 changes: 1 addition & 1 deletion packages/mdx/lib/plugin/recma-jsx-rewrite.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -446,7 +446,7 @@ export function recmaJsxRewrite(options) {

createErrorHelper = true

if (development && place !== '1:1-1:1') {
if (development && place) {
parameters.push({type: 'Literal', value: place})
}

Expand Down
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