The approach taken in this CL is to incrementally move toward the
currently-specced version of modules in ES6. The biggest change in this
patch is separating the parsing of modules from the parsing of scripts,
getting rid of the 'module' keyword and thus disallowing modules-in-scripts
as well as modules-in-modules.
The syntax supported by import/export declarations has not yet been significantly
changed, with the major exception being that import declarations require a string
as the 'from' part.
Most of the existing tests have been disabled, with a first new test added
in cctest/test-parsing.
BUG=v8:1569
LOG=n
Review URL: https://codereview.chromium.org/881623002
Cr-Commit-Position: refs/heads/master@{#26299}
This implements correct semantics for "extensible" top level lexical scope.
The entire lexical scope is represented at runtime by GlobalContextTable, reachable from native context and accumulating global contexts from every script loaded into the context.
When the new script starts executing, it does the following validation:
- checks the GlobalContextTable and global object (non-configurable own) properties against the set of declarations it introduces and reports potential conflicts.
- invalidates the conflicting PropertyCells on global object, so that any code depending on them will miss/deopt causing any contextual lookups to be reexecuted under the new bindings
- adds the lexical bindings it introduces to the GlobalContextTable
Loads and stores for contextual lookups are modified so that they check the GlobalContextTable before looking up properties on global object, thus implementing the shadowing of global object properties by lexical declarations.
R=adamk@chromium.org, rossberg@chromium.org
Review URL: https://codereview.chromium.org/705663004
Cr-Commit-Position: refs/heads/master@{#25220}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25220 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Legacy const is changed so that a declaration declares a configurable, but non-writable, slot, and the initializer reconfigures it (when possible) to non-configurable non-writable. This avoids the need for "the hole" as marker value in JSContextExtensionObjects and GlobalObjects. Undefined is used instead.
BUG=
R=rossberg@chromium.org
Review URL: https://codereview.chromium.org/379893002
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22379 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
I tried to limit the use of v8::Isolate::GetCurrent() and v8::internal::Isolate::Current() as much as possible, but sometimes this would have involved restructuring tests quite a bit, which is better left for a separate CL.
BUG=v8:2487
Review URL: https://codereview.chromium.org/12716010
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13953 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Modules now have their own local scope, represented by their own context.
Module instance objects have an accessor for every export that forwards
access to the respective slot from the module's context. (Exports that are
modules themselves, however, are simple data properties.)
All modules have a _hosting_ scope/context, which (currently) is the
(innermost) enclosing global scope. To deal with recursion, nested modules
are hosted by the same scope as global ones.
For every (global or nested) module literal, the hosting context has an
internal slot that points directly to the respective module context. This
enables quick access to (statically resolved) module members by 2-dimensional
access through the hosting context. For example,
module A {
let x;
module B { let y; }
}
module C { let z; }
allocates contexts as follows:
[header| .A | .B | .C | A | C ] (global)
| | |
| | +-- [header| z ] (module)
| |
| +------- [header| y ] (module)
|
+------------ [header| x | B ] (module)
Here, .A, .B, .C are the internal slots pointing to the hosted module
contexts, whereas A, B, C hold the actual instance objects (note that every
module context also points to the respective instance object through its
extension slot in the header).
To deal with arbitrary recursion and aliases between modules,
they are created and initialized in several stages. Each stage applies to
all modules in the hosting global scope, including nested ones.
1. Allocate: for each module _literal_, allocate the module contexts and
respective instance object and wire them up. This happens in the
PushModuleContext runtime function, as generated by AllocateModules
(invoked by VisitDeclarations in the hosting scope).
2. Bind: for each module _declaration_ (i.e. literals as well as aliases),
assign the respective instance object to respective local variables. This
happens in VisitModuleDeclaration, and uses the instance objects created
in the previous stage.
For each module _literal_, this phase also constructs a module descriptor
for the next stage. This happens in VisitModuleLiteral.
3. Populate: invoke the DeclareModules runtime function to populate each
_instance_ object with accessors for it exports. This is generated by
DeclareModules (invoked by VisitDeclarations in the hosting scope again),
and uses the descriptors generated in the previous stage.
4. Initialize: execute the module bodies (and other code) in sequence. This
happens by the separate statements generated for module bodies. To reenter
the module scopes properly, the parser inserted ModuleStatements.
R=mstarzinger@chromium.org,svenpanne@chromium.org
BUG=
Review URL: https://codereview.chromium.org/11093074
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13033 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
