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Merge pull request #78 from tc39/caridy/hooks-options
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fixes #77: importMetaHook and handler for options bag
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@caridy
caridy authored Sep 23, 2022
2 parents e3d74c8 + ba67fab commit a6e0bd6
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105 changes: 79 additions & 26 deletions 0-module-and-module-source.emu
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Expand Up @@ -83,6 +83,37 @@ location: https://tc39.es/proposal-compartments/
</emu-table>
</emu-clause>

<emu-clause id="sec-meta-properties">
<h1>Meta Properties</h1>

<emu-clause id="sec-meta-properties-runtime-semantics-evaluation" type="sdo">
<h1>Runtime Semantics: Evaluation</h1>

<emu-grammar>ImportMeta : `import` `.` `meta`</emu-grammar>
<emu-alg>
1. Let _module_ be GetActiveScriptOrModule().
1. Assert: _module_ is a Source Text Module Record.
1. Let _importMeta_ be _module_.[[ImportMeta]].
1. If _importMeta_ is ~empty~, then
1. Set _importMeta_ to OrdinaryObjectCreate(*null*).
1. <ins>If _module_.[[ModuleInstance]] is *undefined* or _module_.[[ModuleInstance]].[[ImportMetaHook]] is *undefined*, then</ins>
1. Let _importMetaValues_ be HostGetImportMetaProperties(_module_).
1. For each Record { [[Key]], [[Value]] } _p_ of _importMetaValues_, do
1. Perform ! CreateDataPropertyOrThrow(_importMeta_, _p_.[[Key]], _p_.[[Value]]).
1. Perform HostFinalizeImportMeta(_importMeta_, _module_).
1. <ins>Else,</ins>
1. <ins>Let _importMetaHook_ be _module_.[[ModuleInstance]].[[ImportMetaHook]].</ins>
1. <ins>Let _handler_ be _module_.[[ModuleInstance]].[[HandlerValue]].</ins>
1. <ins>Perform ? Call(_importMetaHook_, _handler_, &laquo; _importMeta_ &raquo;).</ins>
1. Set _module_.[[ImportMeta]] to _importMeta_.
1. Return _importMeta_.
1. Else,
1. Assert: Type(_importMeta_) is Object.
1. Return _importMeta_.
</emu-alg>
</emu-clause>
</emu-clause>

<emu-clause id="sec-modulesource-records">
<h1>Module Source Records</h1>

Expand Down Expand Up @@ -403,13 +434,23 @@ location: https://tc39.es/proposal-compartments/
</dl>
<emu-alg>
1. Assert: _moduleRecord_ is a Module Record.
1. Assert: Type(_specifier_) is String.
1. Assert: _moduleRecord_.[[ModuleInstance]] is an Object.
1. Assert: ResolveModuleRecordDependency has not been invoked with _moduleRecord_ and _specifier_ pair.
1. Let _moduleInstance_ be _moduleRecord_.[[ModuleInstance]].
1. Let _importHook_ be _moduleInstance_.[[ImportHook]].
1. Let _completion_ be Completion(Call(_importHook_, *undefined*, « _specifier_ »).
1. IfAbruptRejectPromise(_completion_, _promiseCapability_).
1. Let _importHookPromise_ be ? PromiseResolve(%Promise%, _completion_.[[Value]]).
1. If _importHook_ is *undefined*, then
1. NOTE: Default import hook.
1. Let _innerPromiseCapability_ be ! NewPromiseCapability(%Promise%).
1. TODO: This links/evaluates the imported module, but it should return it in it's initial status (if it was not already linked/evaluated for other reasons).
1. Perform HostImportModuleDynamically(_moduleRecord_, _specifier_, _innerPromiseCapability_).
1. Let _importHookPromise_ be _innerPromiseCapability_.[[Promise]].
1. Else,
1. Let _handler_ be _moduleInstance_.[[HandlerValue]].
1. Let _completion_ be Completion(Call(_importHook_, _handler_, « _specifier_ »).
1. IfAbruptRejectPromise(_completion_, _promiseCapability_).
1. Let _importHookPromise_ be Completion(PromiseResolve(%Promise%, _completion_.[[Value]])).
1. IfAbruptRejectPromise(_importHookPromise_, _promiseCapability_).
1. Let _fulfilledClosure_ be a new Abstract Closure with parameters (_result_) that captures _moduleRecord_ and _promiseCapability_ and performs the following steps when called
1. If _result_ is a Module Record, then
1. Perform ! Call(_promiseCapability_.[[Resolve]], *undefined*, &laquo; _result_ &raquo;).
Expand All @@ -432,7 +473,7 @@ location: https://tc39.es/proposal-compartments/
ResolveModuleRecordDependency Abstract Operation can not be called more than once for arguments _moduleRecord_ and _specifier_ pair.
</emu-note>
<emu-note type="editor">
Import Reflection Proposal can provide the expansion mechanism to delegate to the host the resolution of a particular dependency, allowing the [[ImportHook]] to return a Module Instance rather than having to open up the ImportHook to support module namespace exotic objects.
Import Reflection Proposal can provide the expansion mechanism to delegate to the host the resolution of a particular dependency, allowing the [[ImportHook]] to return a Module Instance rather than having to open up the ImportHook to support module namespace exotic objects.
</emu-note>
</emu-clause>

Expand All @@ -449,7 +490,7 @@ location: https://tc39.es/proposal-compartments/
<dd>It performs any necessary setup work in order to make available the module corresponding to module represented by _moduleRecord_. It then performs FinishModuleDynamicImport to finish the dynamic import process.</dd>
</dl>
<p>An implementation of HostImportModuleRecordDynamically must conform to the following requirements:</p>

<ul>
<li>
It must call ResolveModuleRecordDependency for every (_moduleRecord_, _specifierString_) pair, where _specifierString_ are the entries of _moduleRecord_.[[RequestedModules]] for each recursively resolved Cyclic Module Record _moduleRecord_. ResolveModuleRecordDependency must not be called twice with the same (_moduleRecord_, _specifierString_) pair: instead, the result of the first call should be cached and reused as the result of successive resolutions.
Expand All @@ -461,15 +502,15 @@ location: https://tc39.es/proposal-compartments/
The host environment must conform to one of the two following sets of requirements:
<dl>
<dt>Success path</dt>

<dd>
<ul>
<li>At some future time, the host environment must perform FinishModuleDynamicImport(_moduleRecord_, _promiseCapability_, _promise_), where _promise_ is a Promise resolved with *undefined*.</li>
</ul>
</dd>

<dt>Failure path</dt>

<dd>
<ul>
<li>At some future time, the host environment must perform FinishModuleDynamicImport(_moduleRecord_, _promiseCapability_, _promise_), where _promise_ is a Promise rejected with an error representing the cause of failure.</li>
Expand All @@ -488,7 +529,7 @@ location: https://tc39.es/proposal-compartments/
This host operation is hand-waving, similar to FinishDynamicImport. This will be addressed on a separate refactor that is orthogonal to this proposal.
</emu-note>
</emu-clause>

<emu-clause id="sec-finishmoduledynamicimport" type="abstract operation">
<h1>
FinishModuleDynamicImport (
Expand Down Expand Up @@ -537,27 +578,29 @@ location: https://tc39.es/proposal-compartments/
</ul>

<emu-clause id="sec-module">
<h1>Module ( _moduleSource_, _referral_, _importHook_ [, _importMeta_ ] )</h1>
<p>When the `Module` function is called with the arguments _moduleSource_, _referral_, _importHook_ and _importMeta_, the following steps are taken:</p>
<h1>Module ( _moduleSource_, _handler_ )</h1>
<p>When the `Module` function is called with the arguments _moduleSource_ and _handler_, the following steps are taken:</p>
<emu-alg>
1. If NewTarget is *undefined*, throw a *TypeError* exception.
1. If Type(_moduleSource_) is not Object, throw a *TypeError* exception.
1. If IsCallable(_importHook_) is *false*, throw a *TypeError* exception.
1. If _importMeta_ is *undefined*, then
1. Set _importMeta_ to *null*.
1. Else, if Type(_importMeta_) is not Object, then
1. Throw a *TypeError* exception.
1. Perform ? RequireInternalSlot(_moduleSource_, [[ModuleSource]]).
1. Let _O_ be ? OrdinaryCreateFromConstructor(NewTarget, *"%Module.prototype%"*, « [[Module]], [[ModuleSourceInstance]], [[ImportHook]] »).
1. Let _moduleRecord_ to ! CreateModuleRecord(_moduleSource_.[[ModuleSource]]).
1. If Type(_handler_) is Object, then
1. Let _importHook_ be ? GetMethod(_handler_, *"importHook"*).
1. If _importHook_ is not *undefined* and IsCallable(_importHook_) is *false*, throw a *TypeError* exception.
1. Let _importMetaHook_ be ? GetMethod(_handler_, *"importMetaHook"*).
1. If _importMetaHook_ is not *undefined* and IsCallable(_importMetaHook_) is *false*, throw a *TypeError* exception.
1. Else if _handler_ is *undefined*, then
1. Let _importHook_ be *undefined*.
1. Let _importMetaHook_ be *undefined*.
1. Else,
1. Throw a *TypeError* exception.
1. Let _O_ be ? OrdinaryCreateFromConstructor(NewTarget, *"%Module.prototype%"*, « [[Module]], [[ModuleSourceInstance]], [[HandlerValue]], [[ImportHook]], [[ImportMetaHook]] »).
1. Set _O_.[[ModuleSourceInstance]] to _moduleSource_.
1. Set _O_.[[HandlerValue]] be _handler_.
1. Set _O_.[[ImportHook]] be _importHook_.
1. Set _O_.[[ImportMetaHook]] be _importMetaHook_.
1. Set _moduleRecord_.[[ModuleInstance]] to _O_.
1. Set _moduleRecord_.[[ImportMeta]] to _importMeta_.
1. Let _importHookClosure_ be a new Abstract Closure with parameters (_specifier_) that captures _importHook_ and _referral_ and performs the following steps when called
1. Assert: Type(_specifier_) is String.
1. return ? Call(_importHook_, *undefined*, « _specifier_, _referral_ »).
1. Set _O_.[[Module]] to _moduleRecord_.
1. Set _O_.[[ModuleSourceInstance]] to _moduleSource_.
1. Set _O_.[[ImportHook]] be CreateBuiltinFunction(_importHookClosure_, 1, *""*, &laquo; &raquo;).
1. Return _O_.
</emu-alg>
</emu-clause>
Expand Down Expand Up @@ -632,10 +675,20 @@ location: https://tc39.es/proposal-compartments/
<td>ModuleSource Instance or *null*</td>
<td>The ModuleSource Instance associated to Module Instance. *null* if this Module Instance has not a source associated to it.</td>
</tr>
<tr>
<td>[[HandlerValue]]</td>
<td>an ECMAScript language value</td>
<td>This is the *this* value used for invocation of the hook functions.</td>
</tr>
<tr>
<td>[[ImportHook]]</td>
<td>a callable Object</td>
<td>The callable Object associated to the [[Module]] record to resolve module dependencies.</td>
<td>a function object or *undefined*</td>
<td>Defaults to *undefined*. The function can return a module instance to resolve module dependencies.</td>
</tr>
<tr>
<td>[[ImportMetaHook]]</td>
<td>a function object or *undefined*</td>
<td>Defaults to *undefined*. The function can augment the `import.meta` object provided as the first argument.</td>
</tr>
</tbody>
</table>
Expand Down
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