fbcc2e874d
Design doc: bit.ly/v8-repl-mode
This CL adds a new REPL mode that can be used via
DebugEvaluate::GlobalREPL. REPL mode only implements re-declaration
of 'let' bindings at the moment. Example:
REPL Input 1: let x = 21;
REPL Input 2: let x = 42;
This would normally throw a SyntaxError, but works in REPL mode.
The implementation is done by:
- Setting a 'repl mode' bit on {Script}, {ScopeInfo}, {ParseInfo}
and script {Scope}.
- Each global let declaration still gets a slot reserved in the
respective {ScriptContext}.
- When a new REPL mode {ScriptContext} is created, name clashes
for let bindings are not reported as errors.
- Declarations, loads and stores for global let in REPL mode are
now "load/store global" instead of accessing their respective
context slot directly. This causes a lookup in the ScriptContextTable
where the found slot for each name is guaranteed to be the same
(the first one).
Bug: chromium:1004193, chromium:1018158
Change-Id: Ia6ab526b9f696400dbb8bfb611a4d43606119a47
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1876061
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64793}
38 lines
937 B
JavaScript
38 lines
937 B
JavaScript
// Copyright 2019 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Test that *local* debug-evaluate properly works for REPL 'let'
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// re-declarations.
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Debug = debug.Debug
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let exception = null;
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function listener(event, exec_state, event_data, data) {
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if (event != Debug.DebugEvent.Break) return;
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try {
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assertEquals(42, exec_state.frame(0).evaluate("x").value());
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} catch (e) {
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exception = e;
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print(e + e.stack);
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}
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}
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Debug.setListener(listener);
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// First script introduces a let-binding 'x'. The value of
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// 'x' lives in the ScriptContext of this REPL script.
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Debug.evaluateGlobalREPL('let x = 21;');
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// The second script re-declares 'x', but then breaks and
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// evaluates x.
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Debug.evaluateGlobalREPL(`
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let x = 42;
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(function foo() {
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debugger;
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})();
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`);
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Debug.setListener(null);
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assertNull(exception);
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