[PATCH 4/4] Fix some reserved word usages in ecmascript implementation

[Sean Lynch <sean@seanplynch.com>]

Reserved words are valid ecmascript in certain contexts, referred to
by the IdentifierName syntax rule. For example, while throw is a
keyword, using throw as a property accessor such as foo.throw is valid.
While this implementation isn't quite correct, it is an improvement. For
an example of how this might be incorrect, it will reject the expression
super.foo uncoditionally, however, that expression is valid inside a
member function of a class.

Further, the *keywords* alist is now updated to the that specified by
ECMAScript 2020, and *future-reserved-words* is merged into *keywords*
because in the end the only item that wouldn't be a keyword seems to be
enum.

* module/language/ecmascript/parse.scm: Add IdentifierName production
  that includes reserved word list.
* module/language/ecmascript/tokenize.scm: Update reserved word list and
  do not error upon encountering one. The parser will be responsible for
  rejecting an illegal usage of a reserved word.
---
 module/language/ecmascript/parse.scm    | 51 +++++++++++++--
 module/language/ecmascript/tokenize.scm | 84 +++++++++----------------
 2 files changed, 73 insertions(+), 62 deletions(-)

diff --git a/module/language/ecmascript/parse.scm b/module/language/ecmascript/parse.scm
index be41e4b9c..8fff96f54 100644
--- a/module/language/ecmascript/parse.scm
+++ b/module/language/ecmascript/parse.scm
@@ -55,9 +55,9 @@
     > <= >= == != === !== + - * % ++ -- << >> >>> & bor ^ ! ~ && or ? 
     colon = += -= *= %= <<= >>= >>>= &= bor= ^= / /=
 
-    break else new var case finally return void catch for switch while
-    continue function this with default if throw delete in try do
-    instanceof typeof null true false
+    await break case catch class const continue debugger default delete do else
+    enum export extends false finally for function if import in instanceof new
+    null return super switch this throw true try typeof var void while with yield
 
     Identifier StringLiteral NumericLiteral RegexpLiteral)
 
@@ -65,6 +65,45 @@
    (Program (SourceElements) : $1
             (*eoi*) : *eof-object*)
 
+   (IdentifierName (Identifier) : $1
+                   (await) : $1 
+                   (break) : $1
+                   (case) : $1
+                   (catch) : $1
+                   (class) : $1
+                   (const) : $1
+                   (continue) : $1
+                   (debugger) : $1
+                   (default) : $1
+                   (delete) : $1
+                   (do) : $1
+                   (else) : $1
+                   (enum) : $1
+                   (export) : $1
+                   (extends) : $1
+                   (false) : $1
+                   (finally) : $1
+                   (for) : $1
+                   (function) : $1
+                   (if) : $1
+                   (import) : $1
+                   (in) : $1
+                   (instanceof) : $1
+                   (new) : $1
+                   (null) : $1
+                   (return) : $1
+                   (super) : $1
+                   (switch) : $1
+                   (this) : $1
+                   (throw) : $1
+                   (true) : $1
+                   (try) : $1
+                   (typeof) : $1
+                   (var) : $1
+                   (void) : $1
+                   (while) : $1
+                   (with) : $1
+                   (yield) : $1)
    ;;
    ;; Verily, here we define statements. Expressions are defined
    ;; afterwards.
@@ -218,14 +257,14 @@
                   (lbrace PropertyNameAndValueList rbrace) : `(object ,@$2))
    (PropertyNameAndValueList (PropertyName colon AssignmentExpression) : `((,$1 ,$3))
                              (PropertyNameAndValueList comma PropertyName colon AssignmentExpression) : `(,@$1 (,$3 ,$5)))
-   (PropertyName (Identifier) : $1
+   (PropertyName (IdentifierName) : $1
                  (StringLiteral) : (string->symbol $1)
                  (NumericLiteral) : $1)
 
    (MemberExpression (PrimaryExpression) : $1
                      (FunctionExpression) : $1
                      (MemberExpression lbracket Expression rbracket) : `(aref ,$1 ,$3)
-                     (MemberExpression dot Identifier) : `(pref ,$1 ,$3)
+                     (MemberExpression dot IdentifierName) : `(pref ,$1 ,$3)
                      (new MemberExpression Arguments) : `(new ,$2 ,$3))
 
    (NewExpression (MemberExpression) : $1
@@ -234,7 +273,7 @@
    (CallExpression (MemberExpression Arguments) : `(call ,$1 ,$2)
                    (CallExpression Arguments) : `(call ,$1 ,$2)
                    (CallExpression lbracket Expression rbracket) : `(aref ,$1 ,$3)
-                   (CallExpression dot Identifier) : `(pref ,$1 ,$3))
+                   (CallExpression dot IdentifierName) : `(pref ,$1 ,$3))
    (Arguments (lparen rparen) : '()
               (lparen ArgumentList rparen) : $2)
    (ArgumentList (AssignmentExpression) : `(,$1)
diff --git a/module/language/ecmascript/tokenize.scm b/module/language/ecmascript/tokenize.scm
index 8289b950c..cbae3bbe4 100644
--- a/module/language/ecmascript/tokenize.scm
+++ b/module/language/ecmascript/tokenize.scm
@@ -173,69 +173,44 @@
                           loc str))))))))
 
 (define *keywords*
-  '(("break" . break)
-    ("else" . else)
-    ("new" . new)
-    ("var" . var)
+  '(("await" . await) 
+    ("break" . break)
     ("case" . case)
-    ("finally" . finally)
-    ("return" . return)
-    ("void" . void)
     ("catch" . catch)
-    ("for" . for)
-    ("switch" . switch)
-    ("while" . while)
+    ("class" . class)
+    ("const" . const)
     ("continue" . continue)
-    ("function" . function)
-    ("this" . this)
-    ("with" . with)
+    ("debugger" . debugger)
     ("default" . default)
-    ("if" . if)
-    ("throw" . throw)
     ("delete" . delete)
-    ("in" . in)
-    ("try" . try)
     ("do" . do)
-    ("instanceof" . instanceof)
-    ("typeof" . typeof)
-
-    ;; these aren't exactly keywords, but hey
-    ("null" . null)
-    ("true" . true)
-    ("false" . false)))
-
-(define *future-reserved-words*
-  '(("abstract" . abstract)
+    ("else" . else)
     ("enum" . enum)
-    ("int" . int)
-    ("short" . short)
-    ("boolean" . boolean)
     ("export" . export)
-    ("interface" . interface)
-    ("static" . static)
-    ("byte" . byte)
     ("extends" . extends)
-    ("long" . long)
-    ("super" . super)
-    ("char" . char)
-    ("final" . final)
-    ("native" . native)
-    ("synchronized" . synchronized)
-    ("class" . class)
-    ("float" . float)
-    ("package" . package)
-    ("throws" . throws)
-    ("const" . const)
-    ("goto" . goto)
-    ("private" . private)
-    ("transient" . transient)
-    ("debugger" . debugger)
-    ("implements" . implements)
-    ("protected" . protected)
-    ("volatile" . volatile)
-    ("double" . double)
+    ("false" . false)
+    ("finally" . finally)
+    ("for" . for)
+    ("function" . function)
+    ("if" . if)
     ("import" . import)
-    ("public" . public)))
+    ("in" . in)
+    ("instanceof" . instanceof)
+    ("new" . new)
+    ("null" . null)
+    ("return" . return)
+    ("super" . super)
+    ("switch" . switch)
+    ("this" . this)
+    ("throw" . throw)
+    ("true" . true)
+    ("try" . try)
+    ("typeof" . typeof)
+    ("var" . var)
+    ("void" . void)
+    ("while" . while)
+    ("with" . with)
+    ("yield" . yield)))
 
 (define (read-identifier port loc)
   (let lp ((c (peek-char port)) (chars '()))
@@ -247,9 +222,6 @@
         (let ((word (list->string (reverse chars))))
           (cond ((assoc-ref *keywords* word)
                  => (lambda (x) (make-lexical-token x loc #f)))
-                ((assoc-ref *future-reserved-words* word)
-                 (syntax-error "word is reserved for the future, dude."
-                               loc word))
                 (else (make-lexical-token 'Identifier loc
                                           (string->symbol word)))))
         (begin (read-char port)
-- 
2.29.1