Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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+## jsparagus/js_parser: Generating a parser for JavaScript
+
+In this directory:
+
+*   **esgrammar.pgen** A grammar for the mini-language the ECMAScript
+    standard uses to describe ES grammar.
+
+*   **es.esgrammar** - The actual grammar for ECMAScript, in emu-grammar
+    format, extracted automatically from the spec.
+
+*   **extract_es_grammar.py** - The script that creates *es.esgrammar*.
+
+*   **es-simplified.esgrammar** - A hacked version of *es.esgrammar* that
+    jsparagus can actually handle.
+
+*   **generate_js_parser_tables.py** - A script to generate a JS parser
+    based on *es-simplified.esgrammar*.  Read on for instructions.
+
+
+## How to run it
+
+To generate a parser, follow these steps:
+
+```console
+$ cd ..
+$ make init
+$ make all
+```
+
+**Note:** The last step currently takes about 35 seconds to run on my
+laptop.  jsparagus is slow.
+
+Once you're done, to see your parser run, try this:
+
+```console
+$ cd crates/driver
+$ cargo run --release
+```
+
+The build also produces a copy of the JS parser in Python.
+After `make all`, you can use `make jsdemo` to run that.
+
+
+### How simplified is "es-simplified"?
+
+Here are the differences between *es.esgrammar*, the actual ES grammar,
+and *es-simplified.esgrammar*, the simplified version that jsparagus can
+actually handle:
+
+*   The four productions with [~Yield] and [~Await] conditions are dropped.
+    This means that `yield` and `await` do not match *IdentifierReference*
+    or *LabelIdentifier*. I think it's better to do that in the lexer.
+
+*   Truncated lookahead.
+
+    `ValueError: unsupported: lookahead > 1 token, [['{'], ['function'], ['async', ('no-LineTerminator-here',), 'function'], ['class'], ['let', '[']]`
+
+*   Delete a rule that uses `but not` since it's not implemented.
+
+        Identifier :
+          IdentifierName but not ReservedWord
+
+    Making sense of this rule in the context of an LR parser is an
+    interesting task; see issue #28.
+
+*   Ban loops of the form `for (async of EXPR) STMT` by adjusting a
+    lookahead assertion. The grammar is not LR(1).